Extruder Drive Cannot Push Filament Through Hot End

[calinb 11]

Despite investing around 60 to 70 hours in this project (and about half of a spool of PLA!) I have yet to even get close to successfully printing anything with my new Ultimaker. I have the V2 hot end and the pre-Bertho feeder mechanism and I am trying to simply extrude the white PLA provided with the kit. Any attempts to print with Cura result in a jam of the filament very quickly. I am using the RepG 026 Console to debug the problem. I have tried temperatures from 185 C to 250 C. I can push the filament though the head by hand (requiring about 30 N to 40 N of finger-applied force on the filament (about 7 to 10 lbs), or maybe a little more, depending on temperature, but the extruder drive cannot manage to do it. The extruder drive mechanism can very smoothly push plastic right up to the head, however. It can also continue to push it though a cold head, if I remove the nozzle. If the Delrin pressure "foot" in the clamp is adjusted to provide enough pressure against the filament to drive it through the head, the filament is distorted severely by the pressure needed to generate the filament drive. This results in a jam as soon as the distorted section reaches the hot end.

Is 30 N to 40 N of force normal to manually feed the filament? The biggest problem I have with my debug effort is I have no other machine to inspect and compare to my machine.

I have positioned my hobbed drive bolt such that the knurling exposed to the filament is 100% "good part" knurling. (The knurling nearest the clip groove is best, because it is cut more deeply and aggressively into the bolt than the knurling nearest the big gear end.)

I could print parts if were to manually assist the extruder with my fingers, but that's not going to be much fun for a 6 or 24 hour print! I have disassembled and reassembled the hot end and cannot identify any problems or any means to reduce the amount of force required to push filament though it.

Thanks for any help. Joergen has provided many excellent suggestions to me offline and been very generous with his time, but I have yet to discover a solution. If I didn't live on the other side of the continent from him, I'd offer to meet him at a local pub with Ultimaker under arm!

Thanks for any help you might lend,

-Cal

[fuchs 0]

Mhh, maybe your filament is just a bit too large? Can you measure it, preferably micrometer-wise?

[calinb 11]

Mhh, maybe your filament is just a bit too large? Can you measure it, preferably micrometer-wise?

I measured straightened virgin filament (not yet distorted by my drive mechanism) in orthogonal directions in a few places with a micrometer:

2.8448 mm minimum

2.8956 mm maximum

I'm thinking about removing the Teflon tube and V2 nozzle and installing the V1 nozzle, brass pipe, and Teflon tape. It probably won't make any difference but it appears that it would be compatible with the other V2 components, most of which are identical to V1 (PEEK insulator, aluminum heater block, etc.).

The V1 might provide a longer heated section, given the long brass pipe will replace the Teflon pipe.

My gut mechanical feeling is the amount of force required to push filament though the hot section on my printer is unreasonable for the drive mechanism design. I don't know why so much force is required.

Oh--and thanks! I'm quite desperate to get this thing working for my startup business.

[joergen 2]

Is 30 N to 40 N of force normal to manually feed the filament? The biggest problem I have with my debug effort is I have no other machine to inspect and compare to my machine.

we had spoken about this on Skype, 20-30N filament holding force in the feeding mechanism is enough clamping force for the delrin (which btw works good and adequate, the bertho upgrade is nice, but not mission critical).

 

I have positioned my hobbed drive bolt such that the knurling exposed to the filament is 100% "good part" knurling. (The knurling nearest the clip groove is best, because it is cut more deeply and aggressively into the bolt than the knurling nearest the big gear end.)

great that that part worked out. as said before, you need to dial back the pressure of the thumb screw to almost no deformation (certainly not past 3.15mm), and just some gentle tooth marks.

 

I could print parts if were to manually assist the extruder with my fingers, but that's not going to be much fun for a 6 or 24 hour print! I have disassembled and reassembled the hot end and cannot identify any problems or any means to reduce the amount of force required to push filament though it.

Thanks for any help. Joergen has provided many excellent suggestions to me offline and been very generous with his time, but I have yet to discover a solution. If I didn't live on the other side of the continent from him, I'd offer to meet him at a local pub with Ultimaker under arm!

I believe all UM can print, yours as well, it might have had been some info of the avalanche of info I unleashed on you, have been lost.

[calinb 11]

>we had spoken about this on Skype, 20-30N filament holding force in the feeding mechanism is enough clamping force >for the delrin (which btw works good and adequate, the bertho upgrade is nice, but not mission critical).

That sounds good, but 20-30N holding force is not sufficient to be consistent with the application of a filament feeding force in the range of 30-40N, which is what I've estimated to be necessary to force filament through my extruder head. Thanks for the information. It supports my hypothesis--my Ultimaker requires too much feeding force, for some reason yet unknown.

I've now snapped my nozzle, in trying to install it for the third time after tear-down and inspection, but I will try to heat it up, clean it out, and determine that the orifice is 0.40 mm instead of something smaller. I don't know what my next move will be. Catch up on my sleep for a few days?

[calinb 11]

During our approximately 1-1/2 hour Skype video call, Joergen and I took many caliper measurements and compared our machines. We identified two differences between our machines that may be contributing my my printer's inability to feed filament and extrude plastic.

1. Joergen's older revision of the hobbed drive bolt has far more aggressive knurling than my latest version of the bolt.

I may fabricate my own bolt.

2. Joergen's older white Delrin filament drive rubbing block (I think it's a one-piece) is considerably narrower (front to back) than my two-piece black Delrin rubbing block. When my adjuster screw is backed all the way out (and doing nothing) AND my clamp latch is only latched to the 90 degree position (not fully latched "over-center") my rubbing block still provides about 0.5 mm "worth" more pressure than Joergen's typical setting while printing. In other words, Joergen's printer does about 0.5 mm less filament squeezing than my printer. Furthermore, I have no adjustment range available to reduce pressure, because my adjusting screw is already backed all the way out.

I may put the rubbing block in my lathe and mill a curved slot centered into its rubbing surface using a small ball nose end mill. This will render my adjuster screw functional and also keep the filament centered in the groove and slot.

Since breaking my nozzle, I've made many measurements of both my V1 and V2 hot end parts. I verified that the V2 Teflon tube's flange makes hard contact with the recess in the PEEK (next to the knurling) but the tube portion does NOT make hard contact with the V2 brass pipe, because the flange bottoms first in the sandwich stackup between the aluminum and wooden plates. The tube to tube junction is a point of leakage into the internal threads of the PEEK, even if the molten plastic never makes it past the Teflon pipe's flange. I did find some signs of plastic leakage on the PEEK threads from that junction in my PEEK after looking closely. I wonder if I'm getting the dreaded PEEK leak, or whatever it is called, that can cause jams.

Given that I broke my V2 nozzle, but all the V1 parts were also shipped in my kit, I may assemble a hybrid V1/V2 configuration that could prove to be superior to either of the former hot end configurations. I will use the V1 nozzle, brass tube with the Teflon tube. No Teflon tape should be necessary. As in the V1 configuration, my peek will be hard up against the aluminum block. Micrometer measurements indicate that this still results in about a 0.125mm gap between the end of the Teflon tube and the brass tube so I will mill 0.250mm from the top face of the V1 nozzle where the nozzle contacts the aluminum block. This will permit the placement of the brass tube through the aluminum block to be higher, while still bottoming into the nozzle and permit the brass tube to make hard contact with the Teflon tube. Due to the compression of the Teflon tube after tightening the assembly between the aluminum and wooden plates, I predict that the Teflon tube flange will still be hard up against the recess in the PEEK and provide a backup to external leakage, but only a trial run will determine whether it leaks or retains the molten plastic. My goal is to eliminate all leakage into the internal PEEK threads. It would be nice if it didn't spring unsightly and mess external leaks too!

The advantages of the hybrid configuration are (hopefully):

a. No plastic within the aluminum block, because a single brass tube passes entirely though it.

b. One less potential leakage area where leakage is very bad (at the Teflon/PEEK junction). The V2 can leak there but will also leak into the internal threads of the aluminum block (semi-bad, because it makes cold disassembly and assembly difficult, resulting in broken nozzles! :( If the hybrid configuration leaks between the nozzle and the brass pipe, it will merely glue the nozzle to the brass pipe, which can be removed as a unit from the nice and clean internal threads of the aluminum block.

My main problem is I don't have time for all this debug and the machining of new parts or modifications of the old parts contained in my ($1900 US) 3D printer kit! I'm at the 70 hours invested point now and still far from successfully printing parts!

Again, thanks to Joergen for his most generous contribution of help on Skype and to others here in the forum posts too.

-Cal

[Daid 306]

Care to share a photo of your hotend?

It should NOT look like this:

https://ultimaker.googlegroups.com/atta ... w=1&part=3

I've seen 2 cases of the hotend being assembled like this, and both times it causes 80% blockage in the hotend.

It should look like this:

http://www.flickr.com/photos/ultimaker/ ... /lightbox/

With no threads showing.

[hcpl 0]

Do you have a recent kit? I received mine about 2 weeks ago and received V2 hot end only but both V1 and V2 extruder clamp mechanism.

I have no tools to measure the required force to put filament through nozzle at this time. I'll try to get that done. I have a caliper so I can measure the filament diameter. I'll do that this evening and complete this post.

The symptoms on mine are very similar. If I let the extruder drive filament through an open hot end it goes fine up to 2000 rpm, 3000 rpm got the motor screaming but that's not abnormal I understand. When I try to let it run through a heated hot end with nozzle it only goes well for a few seconds. Soon the extruder will begin slipping and grinding into to the filament making the problem even worse since these spots make it harder for the filament to get through the tube.

This is what I've tried so far (spread over 3 evenings/nights):

I cleaned and remounted the complete hot end. At first it was leaking a lot on top of the alu block where the brass part comes in. Turned out I had the nozzle bolted against the alu block instead of against the top brass part. That and running some ABS through fixed the leaking issue. As long as the 2 brass tubes meet in the alu block there is no need for the nozzel to touch the alu block? Or is that truely a requirement? Since mine now has the nozzle about 1mm apart from the alu block. Maybe needed for heat spreading?

I also had filament getting up into the white plastic part between the PEEK and the bowden tube. That was caused because of a gap there between the bowden and that white plastic. Remounted that also and got that fixed. No more clogging there (I checked in between tests).

I tested with several temperatures from 195 to 240. No real difference. Except for the difference in the palstic coming out. But still blocking eventually.

At the extruder drive end I played with several tensions. From what I understand it should leave some toothmarks but not deform. I can get to that point so no issue there.

Every time the extruder slipped I took it apart to clean up the driving bolt so it would be perfectly clean and ready for the next test. The bolt is in the perfect spot, the best part of it like explained on the assembly instructions.

The big wheel can spin freely if the stepper motor is turned of. I can push filament up by turning the wheel by hand. As long as it doesn't get blocked once (starts grinding and deforming filament) I can push it through a heated nozzle this way. It's slow but it works. And from what I saw during the sparse printing time that is close to what it should keep doing during a print.

The motor does get quite hot, still touchable but hot. Because of that I'm not very keen on increasing the power to that motor using the pot. Should I try that? It's not that the motor can't turn any longer, it's more that the motor starts grinding into the plastic instead of pushing it up.

I did some tests with the control panel setting an rpm for the extruder motor. If I put it to something near 500 rpm (that is slow) it will keep going forever (or at least as long as I was willing to look at it wasting plastic). If I turn it up to 1000 rpm it will get blocked eventually. At 2000 rpm it gets blocked almost immediately after the first filament gets through the nozzle.

I did try to print some things. During the print it seems to function until it gets blocked again and the filament stops running out of the nozzle. If I prepare for a print I heat up the nozzle with the ulticontroller and let the filament get to the nozzle. Once I start the build on my macbook I have to confirm the build on the ulticontroller (not completely sure on that procedure).

First the build platform will go down (Z+) for about 5cm and the extruder start running fast (around 1000 rpm I guess). This is the part where the filament gets damaged. After that the build platform goes up again and the head starts print. At this point the extruder is much slower and it gets there for some time. But because of the damaged filament it gets into trouble quite fast. At first I can help it by hand (resulting in too much filament on the build) but eventually it will block up again.

I believe that if I can prevent the fast extrusion at the beginning of the print I would be able to print something completely (or at least a lot more) since then the filament wouldn't be damaged from the beginning and as long as it runs as slow as during the build I think it could work.

The documentation about first prints shows some intsructions on running filament through at 2000 rpm. So that should be possible without blocking?

[calinb 11]

Thanks for posting, Daid. Joergen mentioned that problem during our Skype lab session too, but my assembly is correct in this regard. It would be nice if the instructions included guidance besides the adage that the assembly is incorrect if threads are showing. The V2 brass tube does have a short end and long threaded end (on each side of the flange) and the orientation can be described using those features (short threaded end of the V2 brass tube goes into the aluminium block and the long threaded end goes into the PEEK.) It is also very important to screw and bottom the nozzle into the aluminum block before installing the brass pipe. Otherwise, there well be a gap between the other end of the brass pipe and the Teflon tube. (The brass pipe will sit lower in the PEEK threads.) Actually, my micrometers tell me there is a slight gap there regardless--about the same as it would be in my V1/V2 hybrid assembly (0.125mm-- see my above post) and it cannot be corrected without modifying parts. I'm concerned that this gap might be causing my jams, much like the PEEK leak in the old V1.

I know it's a detailed and lengthy post, but did you have a chance to review my proposed V1/V2 hybrid configuration? I"m planning to make the small change to the V1 nozzle and try it. I snapped my V2 nozzle off at the aluminum block anyway. I would appreciate you opinion.

Thanks,

-Cal

[hcpl 0]

This thread has info no the end about the long screws in the head that shouldn't be too tight. viewtopic.php?f=7&t=1450

[calinb 11]

Do you have a recent kit? I received mine about 2 weeks ago and received V2 hot end only but both V1 and V2 extruder clamp mechanism.

So you received the Bertho-style clamp in the drive mechanism? I did not receive that upgrade. Luckily, I received both a V1 and V2 hot end parts. Now I need the spares! :(

 

I have no tools to measure the required force to put filament through nozzle at this time. I'll try to get that done. I have a caliper so I can measure the filament diameter. I'll do that this evening and complete this post.

I need to dig out my fish spring scale and rig that up. I used a bathroom scale and just went back and forth applying my finger pressure between the scale and the filament. You can get pretty repeatable results by "touch" with a little practice indicating at least reasonable accuracy for this purpose.

The symptoms on mine are very similar. If I let the extruder drive filament through an open hot end it goes fine up to 2000 rpm, 3000 rpm got the motor screaming but that's not abnormal I understand. When I try to let it run through a heated hot end with nozzle it only goes well for a few seconds. Soon the extruder will begin slipping and grinding into to the filament making the problem even worse since these spots make it harder for the filament to get through the tube.

Yep--those are my symptoms too, but I can't even get it to work at 250 or 500 rpm. I just get to the fail point faster at 1000 and I've not attempted higher. My two attempts at printing were also a waste of time and the same for all the plastic in these trials, because about 2/3 meter is wasted each time the drive chews it up and rams it up to the head!

 

This is what I've tried so far (spread over 3 evenings/nights):

I cleaned and remounted the complete hot end. At first it was leaking a lot on top of the alu block where the brass part comes in. Turned out I had the nozzle bolted against the alu block instead of against the top brass part.

I believe that the V2 nozzle should be screwed into the aluminum block all the way before screwing the brass tube into the other side. See my post in response to Daid's post, above.

That and running some ABS through fixed the leaking issue. As long as the 2 brass tubes meet in the alu block there is no need for the nozzel to touch the alu block? Or is that truely a requirement? Since mine now has the nozzle about 1mm apart from the alu block. Maybe needed for heat spreading?

I believe the nozzle should touch the aluminum block because, in this position, the top of the brass tube that is inside the PEEK will just about make contact with the bottom of the Teflon tube. I think it SHOULD make contact with some pressure, to make sure molten plastic does not leak into the PEEK at this junction. As measured with my micrometers, I do not believe the dimension of the parts are correct to make this possible. There is about a 0.125mm gap between the bottom of the Teflon tube and the top of the brass tube. This junction is inside the PEEK, so it cannot be observed not measured directly. You can only measure the disassembled parts and deduce this gap.

 

I also had filament getting up into the white plastic part between the PEEK and the bowden tube. That was caused because of a gap there between the bowden and that white plastic. Remounted that also and got that fixed. No more clogging there (I checked in between tests).

By "white plastic part" I assume you mean the Teflon tube (new to the V2 design). The Bowden tube and the top of the Teflon tube should be too cool to melt plastic at this junction. If you were getting any molten plastic up there, it cam up from the Teflon tube / brass tube junction below. This is the junction that concerns me, as I said above.

 

I tested with several temperatures from 195 to 240. No real difference. Except for the difference in the palstic coming out. But still blocking eventually.

Ditto again here from 185 to 250. It just gets a little easier to push manually with finger approaching 250.

 

At the extruder drive end I played with several tensions. From what I understand it should leave some toothmarks but not deform. I can get to that point so no issue there.

Then you are one issue better-off than I am, but you have the Bertho-style adjuster. My Delrin adjuster is still too tight when backed all the way out. Hence another mod is necessary in my machine shop.

 

Every time the extruder slipped I took it apart to clean up the driving bolt so it would be perfectly clean and ready for the next test. The bolt is in the perfect spot, the best part of it like explained on the assembly instructions.

Same here, but I even turned the 2 mm slot in the drive bolt 2 mm wider, which completely filled the width of the filament channel with the "good part" of the knurling (by shifting the bolt to the left 2 mm). I don't think it helped, however.

 

The big wheel can spin freely if the stepper motor is turned of. I can push filament up by turning the wheel by hand. As long as it doesn't get blocked once (starts grinding and deforming filament) I can push it through a heated nozzle this way. It's slow but it works. And from what I saw during the sparse printing time that is close to what it should keep doing during a print.

Again--all too familiar to me!. I don't have the patience to do it but I suspect that I could print successfully if I don't completely close the latch on my drive mechanism (this compensates for my Delrin adjuster that's still too tight with the adjustment screw backed all the way out) AND I just sit there and "assist" the feed with my fingers. The motor will change speed, as programmed by gcode, and my extra 20 Newtons of force will keep it extruding. Of course if my worries about the Teflon tube / brass tube hot end gap are valid, it still might jam eventually.

 

The motor does get quite hot, still touchable but hot. Because of that I'm not very keen on increasing the power to that motor using the pot. Should I try that? It's not that the motor can't turn any longer, it's more that the motor starts grinding into the plastic instead of pushing it up.

I did some tests with the control panel setting an rpm for the extruder motor. If I put it to something near 500 rpm (that is slow) it will keep going forever (or at least as long as I was willing to look at it wasting plastic). If I turn it up to 1000 rpm it will get blocked eventually. At 2000 rpm it gets blocked almost immediately after the first filament gets through the nozzle.

Given the similarity of our printers' symptoms, I don't believe a solution lies in increasing the power (or speed) of the motor. There is plenty of power available to grid and distort plastic already!

 

I did try to print some things. During the print it seems to function until it gets blocked again and the filament stops running out of the nozzle. If I prepare for a print I heat up the nozzle with the ulticontroller and let the filament get to the nozzle. Once I start the build on my macbook I have to confirm the build on the ulticontroller (not completely sure on that procedure).

Same print result here too. I haven't even bothered to assembly my Ulticontroller yet. It has no value to me w/o a working printer!

First the build platform will go down (Z+) for about 5cm and the extruder start running fast (around 1000 rpm I guess). This is the part where the filament gets damaged. After that the build platform goes up again and the head starts print. At this point the extruder is much slower and it gets there for some time. But because of the damaged filament it gets into trouble quite fast. At first I can help it by hand (resulting in too much filament on the build) but eventually it will block up again.

I believe that if I can prevent the fast extrusion at the beginning of the print I would be able to print something completely (or at least a lot more) since then the filament wouldn't be damaged from the beginning and as long as it runs as slow as during the build I think it could work.

The documentation about first prints shows some intsructions on running filament through at 2000 rpm. So that should be possible without blocking?

I don't know what rpm is reasonable. I've focused down around 250 to 500 rpm and even that doesn't work.

I'll let you know how my V1/V2 hybrid configuration works out. Keep in touch. I think we have the same problem--at least the same major root cause (there could be other contributors.

[calinb 11]

This thread has info no the end about the long screws in the head that shouldn't be too tight. viewtopic.php?f=7&t=1450

Yes--I read that thread too. I think most of the concern would only apply to the V1 hot end.

 

the critical part the is the transition from bowden to brass tube, which needs to be tight, so no PLA can come in contact with the PEEK, which will be catastrophic. but if you make the transition too tight via the screws, the filament can't pass, and you still get a popping bowden. the filament really needs to get through the transition nice and easy.

I'm not sure why too tight would keep the filament from passing, except that the Bowden tube will get distorted at the end at some point with excessive pressure. Also, if it is cocked or the aluminum and wooden plates are far from parallel there could be problems.

The forces and pressure points (I'm too tired to think of the definitive technical word I'm trying to recall right now) are different in our V2 stackup of parts than the V1. One huge advantage to the V2 is the Teflon tube is trapped between the the wooden plate and the PEEK. It can handle a lot more pressure than the Bowden tube in the V1 and it's not necessary to have much force at all on the V2 Bowden tube because it's no longer at a junction that can leak (unless it leaks up the entire length of the Teflon tube from the Teflon tube / brass tube interface below)! The Bowden tube just needs to be touching the top of the Teflon tube--not jammed up hard against it such that it is under much stress and exhibiting strain. In the V2 stackup, we have the Teflon tube held fast against the PEEK (or even better, the brass tube inside the PEEK threads), because they are both squeezed between the wooden and aluminum brackets. I believe it's necessary to sandwich them tightly with the screws, because that is what keeps plastic from leaking into the PEEK! It also keeps the PEEK and everything below it from rotating in the aluminum plate.

Again, I think the force applied by the screws to the stackup should be significant, in order to preclude leaks. I also think that the Teflon pipe should, optimally, bottom tightly against the brass pipe, [bold]inside the PEEK[/bold] instead of bottoming against the PEEK with its flange in the recess area on the top of the PEEK. There should be a small gap between the aluminum and wooden plates in the corner with the PEEK assembly. This way you know the parts in the stackup have bottomed (although it doesn't guarantee where--the Telfon pipe may be bottoming against the PEEK at its flange and not at the brass pipe, where I think it should bottom tightly!)

I don't think we can expect a solution to come from Ultimaker tech support. They will probably never wade though all the information necessary to solve it! We must find a solution ourselves (or another brand of printer!).

-Cal

[hcpl 0]

So you received the Bertho-style clamp in the drive mechanism? I did not receive that upgrade. Luckily, I received both a V1 and V2 hot end parts. Now I need the spares! :(

Indeed got that bertho-style upgrade shipped. It provides better controller over pressure (I agree on that) and should compensate for differences in the filament (looks like it does to some level). Once printer works with the original clamp mechanism you can print one yourself. UM should work with original also. Or this completely new design:

http://www.thingiverse.com/thing:27626

... If only we could print

 

Yep--those are my symptoms too, but I can't even get it to work at 250 or 500 rpm. I just get to the fail point faster at 1000 and I've not attempted higher. My two attempts at printing were also a waste of time and the same for all the plastic in these trials, because about 2/3 meter is wasted each time the drive chews it up and rams it up to the head!

Yes cutting off another wasted length of filament is getting harder and harder to do.

 

I believe the nozzle should touch the aluminum block because, in this position, the top of the brass tube that is inside the PEEK will just about make contact with the bottom of the Teflon tube. I think it SHOULD make contact with some pressure, to make sure molten plastic does not leak into the PEEK at this junction. As measured with my micrometers, I do not believe the dimension of the parts are correct to make this possible. There is about a 0.125mm gap between the bottom of the Teflon tube and the top of the brass tube. This junction is inside the PEEK, so it cannot be observed not measured directly. You can only measure the disassembled parts and deduce this gap.

This link has good, and visual information on that plug issue:

http://daid.eu/blag/2012/08/31/ult ... v2-hotend/

I borrowed a picture from there and added some color codes to explain what I did (see attachment). The red line between the nozzle and the alu block is where I have a 1mm gap. This doesn't influence the gap between the top brass part and the PEEK though (green line). I have those 2 tight onto each other. Not overdone though. It's plastic so I didn't dare putting more tention on these 2.

The white part is on top of that PEEK and the bowden tube goes in the white part as far as possible. I posted a link in one of my previous posts here about the long fasteners of the head that shouldn't be fastened too much. I probably over did these (will test this evening). That is what closes the gap between the parts at the blue lines.

An important pat to prevent the leaking on the head for me was putting some ABS through (not included in my kit though) and fastening the 2 copper/brass parts against each other so they meet closely inside the alu block

 

Again--all too familiar to me!. I don't have the patience to do it but I suspect that I could print successfully if I don't completely close the latch on my drive mechanism (this compensates for my Delrin adjuster that's still too tight with the adjustment screw backed all the way out) AND I just sit there and "assist" the feed with my fingers. The motor will change speed, as programmed by gcode, and my extra 20 Newtons of force will keep it extruding. Of course if my worries about the Teflon tube / brass tube hot end gap are valid, it still might jam eventually.

Given the similarity of our printers' symptoms, I don't believe a solution lies in increasing the power (or speed) of the motor. There is plenty of power available to grid and distort plastic already!

I agree.

 

Same print result here too. I haven't even bothered to assembly my Ulticontroller yet. It has no value to me w/o a working printer!

I don't know what rpm is reasonable. I've focused down around 250 to 500 rpm and even that doesn't work.

I'll let you know how my V1/V2 hybrid configuration works out. Keep in touch. I think we have the same problem--at least the same major root cause (there could be other contributors.

I'll keep posting here if I find something interesting. I hope you'll find a solution to your problem soon (so you can post it and I can get mine solved also ).

[calinb 11]

Thanks for the share, hcpl! It sure sounds a lot like what I've experienced with V2! This part is interesting:

 

The brass tube has been replaced by a shorter one to compensate for the brass tube part on the nozzle. It also creates a void between the PEEK and the heater. Lowering the heated area and creating a better cooled top. Less heat in the higher areas means less chance for plugs. Which is good. However, with a lower point of heating the plastic will have less time to melt before it reaches the nozzle. Maybe this will impact the maximum extrusion speed

My V1/V2 hybrid will lack the void--same as a V1. I'm still going to assemble it, because I have the parts!

I've been wondering about the ~0.125 mm gap between the V2 Teflon pipe and the brass pipe within the PEEK. I was talking to fluxline and he doesn't think the gap is significant, but an extruder nozzle orifice is 0.400 so it seems like 0.125 mm could potentially cause a leak into the PEEK. Maybe it's too small of a leak to cause a plug and a jam.

[hcpl 0]

I'm going to abuse this thread to collect info for myself also. It might help you. I was talking earlier about the pressure on the long threads that keep the head together. I have that wrong in my setup for sure. The first answer in this thread viewtopic.php?f=7&t=1317 has great info on why that tention has to be exact.

The tube doesn't melt down but flexes when heated and then can deform making it harder for the PLA to come through. When I retract PLA I sometimes also have to use more force because the molted end is bigger and causes more friction against the tube.

=> edit: fixed this but didn't give any improvement.

Somehow I think my extrusion went better in the beginning. That is when I had it assembled and running for the first time. I then had issues with the nozzle leaking so I didn't pay much attention to anything else. I think I had it running on 1000 rpm then without issues.

While testing over the past days I also tried several heat settings and finally used some ABS on higher temp for sealing. I have to remount the nozzle closer to the alu block so I'll take it apart again for cleaning. And then tighten the top brass part with 2 bolts tightened against each other to drive it in completely against the nozzle for proper closure.

I've read about people heating up the head and putting pressure on the bowden tube with a bike pump. That might be a good way for cleaning without remounting.

My head sometimes kind of plops a bigger amount of PLA out at once like a plug was popped out. Not sure when exactly this happens but I'll pay attention to it from now on.

I see metal parts on the white retention clips. I didn't see these on mine.

=> edit: I've got that metal in the clips also.

Oh and might not be related at all but I had black tubes labeled as motor stands (or something like that) included in my kit. Comparable to the white parts used to mount the electronics board away from the bottom. Problem is that I never used them!? No idea what they are ment for.

This thread also looks similar: viewtopic.php?f=7&t=601

and info about an alternative head:

http://blog.arcol.hu/?p=1746

edit: you must read this one also! Info on the bowden tube and alternatives etc. : viewtopic.php?f=7&t=902

edit2: I was able to remove the first fast extrusions from my gcode so I couldn't print from the beginning without grinding. After 2 layers same problem again though. I checked the retention on the extruder and that is fine now, leaving only toothmarks. It's clear to me that there is too much pressure build up in the tube/head/nozzle causing the extruder to slip/grind after some time. Don't know why yet. Not sure if it's worth it to get an extra head. I check dimension of both filament and tube and that seems ok. Filament is around 2.9 while tube is just below 3.2.

[calinb 11]

I'm going to abuse this thread to collect info for myself also. It might help you. I was talking earlier about the pressure on the long threads that keep the head together. I have that wrong in my setup for sure. The first answer in this thread viewtopic.php?f=7&t=1317 has great info on why that tention has to be exact.

Haha--I started the thead and I say abuse away! The more information, the better. That's a good thread that I'd not yet read. I was talking to fluxline about the problem this morning via Skype and he clarified a step for me. The instructions say to displace the Teflon tube away from the wooden plate the width of the supplied allen wrench before tightening the screws. This ensures that the Teflon tube bottoms on the PEEK but fluxline pointed out that it also ensures that the Bowden tube is pressed into position. However, this only occurs if the Bowden tube is first pushed against the slightly displaced Teflon tube AND the Bowden tube clip is installed before tightening the hot end screws. The V2 instructions do not mention the clip and Bowden tube part of the process or provide reasons behind what the instructions are dictating. (The instructions rarely provide reasons for anything, severely limiting our education!) Tightening the hot end screws will sandwich the parts stack together with clamping force, seat the Bowden tube and compress it between the Teflon tube and the Bowden tube quick connector. It now occurs to me that these things are somewhat independently controllable, because it is possible to partially tighten the screws, and then install the Bowden tube clip before completely tightening the screws. Joergen and fluxline (the initial posters in the thread) are both experienced Ultimaker users and very sharp guys. I'm in touch with both of them via Skype and I will feed back the information our continuing conversation produces to you. Of course, we may need to buy them a "6-pack" of filament in gratitude when this is all over!

 

Oh and might not be related at all but I had black tubes labeled as motor stands (or something like that) included in my kit. Comparable to the white parts used to mount the electronics board away from the bottom. Problem is that I never used them!? No idea what they are ment for.

I didn't receive those parts, but I remember seeing a picture of black parts somewhere in the instructions--maybe it was just a black version of the white stand-offs used to support the cover over the electronics board. You do have a cover installed, right? The screws insert down through the bottom of the frame. Hollow white tube spacers or "stand-offs" (what we sometimes call them in the U.S.) are slipped over the 3 mm screws (we call small bolts "screws" in the U.S.) from the bottom before the board is installed. Then threaded hex standoffs are screwed onto the remaining threads on the screws to secure the electronics board. Finally, the cover is secured with short screws into the threaded hex standoffs. The cover I received is different than the cover in the instructions and maybe you missed it.

 

This thread also looks similar: viewtopic.php?f=7&t=601

Wow--from a guy with so much 3D printing experience too!

 

and info about an alternative head:

http://blog.arcol.hu/?p=1746

 

Thanks for that link. I'd not seen it, but I've already started shopping for a new extruder and hot end. I needed this printer for my new business two weeks ago! It may soon be a question of installing another extruder or placing an order for a Makerbot R2 for me. Either way, I just ordered $11,000 in urethane molds for my business because I can't get my Ulimaker to print! I have customers waiting to receive our first product shipped.

 

edit: you must read this one also! Info on the bowden tube and alternatives etc. : viewtopic.php?f=7&t=902

I saw that one. Friction is low for me. Unmelted plastic "extrudes" just great when the machine is run cold without a nozzle!

[joergen 2]

Just as a quick reply, since I hadn't read the complete thread, but just skimmed for keywords:

The firmware should limit the extruder speed to 40ish mm/sec. The standard e steps necessary to push 1mm filament is 865.888

If you happen to try to print gcode sliced with netfabb (which for unknown reasons decided to be stuck in the dark ages for a long time), your e motor will scream and run wild, since netfabb expects an e step value of 14 (or similar garbage), and hence your e motor will run about 60x faster than its supposed to.

Please stop using the outdated version of netfabb, if you are using it, and try slicing with cura, and printing with printrun

[hcpl 0]

Calinb: I feel your pain. Mine is a business investment also. Not return on investment yet though since it can only barely print 3 layers.

The black stand offs were in a separate bag labeled motor stand-offs. I received the white ones also and these were indeed mounted like you describe. I have noisy cooling.

Indeed since it works without head the tube ain't my issue either. Ebay has tubes listed in case yours gets bitemarks out of frustration.

I watched mine closely while printing those first and only layers. The white teflon part on top of the peek got pushed up at least 1mm when it went wrong. I'm going to mark the bowden also to check if that gets pushed out or not. Just to make sure I'll also print at 240C.

And I'm ordering a new head today. ultimaker is in business! If that one fails also I'm buying another hot end to mod on my UM.

Edit: Some picture of my setup in attachments.

Edit2: could less heat make an improvment? I'm testing at 210°C now. It looks like the tip just on top of the heated top brass part is swelling and causing a jam inside the white plastic (teflon?) part on top of the peek. Now if I would apply less heat it might be swelling less causing a better extrusion? Just a theory. Tests will be done this evening. I'll test again from 180 to 240 with manual pressure so I don't grind the filament down and don't need to clean up the mess in between all the time.

If the issue is filament blocking between the parts stacked on top of each other, then why are there so many parts in between? Why isn't the tube mounted on top of the top brass? Much like the jamming wiki explains as a mod =>

http://wiki.ultimaker.com/Jamming

. If done that way nothing can get in between, no?

[calinb 11]

Edit: Some picture of my setup in attachments.

Thanks! I am printing now and my filament barely has any drive marks in it. Your filament is obviously being deformed, ground, and chewed-up to force it though the hot end. I''ve made three changes to parts in my kit (one with my lathe and two with my mill). I'll describe more about them later, but you have the Bertho drive, so only one of my mods might apply to you.

 

Edit2: could less heat make an improvment?

I think it might. I think temperature can change how and where plastic jams in the hot end.

 

If the issue is filament blocking between the parts stacked on top of each other, then why are there so many parts in between? Why isn't the tube mounted on top of the top brass?

The link you provided explains the official reasons.

http://daid.eu/blag/2012/08/31/ult ... v2-hotend/

Some of them, I question. For example:

The new white connection part seems to be designed to stop plugs and making the bowden tube connection less prone to errors. As the bottom part has a slightly thinner diameter then the brass tube on which it rests. This means any plug that tries to form is of a diameter that will fit back into the brass tube.

I have made very careful measurements of the parts with micrometers and calipers and the Teflon tube discussed here has the same internal diameter and the brass tube on which it rests. The other beneficial claims for it are true, I believe.

I am running the V1 nozzle and brass pipe in the V2 hot end, because I broke my V2 in the repeated wrenching I've done to take things apart and put them back together many times for debug. I'll provide more details later, but I found that a gap exists internally between the Teflon tube and the brass tube (regardless of V1 or V2 parts used in a V2 hot end). So I closed the gap by milling 0.011" (280 microns) off of my V1 nozzle. You could achieve the same dimensional change by milling (or carefully filing) the same amount off the bottom face of the PEEK where the flange from your V2 brass pipe seats against the PEEK. This will move the other end of the brass tube into the Teflon pipe above. If your parts have the same dimension as my parts, this should seal the gap between the Teflon tube and the brass tube. I milled enough to create about a 150 micron (0.006") "crush zone" in the end of the Teflon tube to seal it well against the brass tube. Again, my parts vary a bit. For example, I have two PEEKS and the depth of the recesses in the top end of the PEEKS (that accomodates the flange of the Teflon) tube varies by 100 microns between the two PEEKS.

However, I think your problem is likely to be assembly (mine quite possibly as well!). I was very, very careful in the assembly of my modified V1/V2 hybrid hot end. fluxline helped me to realize the possible importance of a step left out of the V2 instructions: The Teflon tube must be displaced from the wooden plate by the width of the small allen wrench provided in the kit. This is covered in the instructions. What might be equally important (I"m not certain about this), but not covered in the instructions, is the clip in the Bowden tube quick connect must be inserted before tightening the assembly together with the screws. The Bowden tube must be fully inserted into the Teflon tube (the pen marks line up) at this point too. This was required in V1 because the Bowden tube had to seal or it would leak plastic. In the V2, the plastic should be solid at the end of the Bowden tube, but we still want it to be hard against the Teflon pipe.

In my case, I think the finger pressure required to feed filament manually has dropped from 30-40N to about 20N. However, I also think that (after my modifications to the drive hobbed bolt and Delrin rubbing block, my extruder drive mechanism could now drive the previous 30-40N if necessary!

If you feel the force required to push the filament though the hot extruder is excessive. I think you may need to reassemble the hot end very carefully with regard to above procedure.

Much like the jamming wiki explains as a mod =>

http://wiki.ultimaker.com/Jamming

. If done that way nothing can get in between, no?

In the V2, our Bowden tube terminates at the Teflon tube. This should not cause leakage problems because the plastic is solid there! However, my mod was directed at the equivalent junction in the V2--the interface between the Teflon tube and the brass tube. There IS a gap there in both my V1 parts and V2 parts (about 125 microns, but it varies between my sets of parts a bit). Is that significant enough to cause leakage and a jam inside the PEEK? I don't know. The nozzle orifice is 400 microns, in comparison. Some plastic was sticking to my internal PEEK threads so I know plastic was in the gap! My hot end requires less force to feed filament now, however. Is it because of something about my V1/V2 hybrid? Is it because I filled this gap? Is it because I was very careful and methodical about assembly. I don't know for sure. I'm pretty sure my printer would have function at least a little bit before (it would less fuctional than your printer), if my Delrin had valid dimensions!

[hcpl 0]

In the V2, our Bowden tube terminates at the Teflon tube. This should not cause leakage problems because the plastic is solid there! However, my mod was directed at the equivalent junction in the V2--the interface between the Teflon tube and the brass tube. There IS a gap there in both my V1 parts and V2 parts (about 125 microns, but it varies between my sets of parts a bit). Is that significant enough to cause leakage and a jam inside the PEEK? I don't know. The nozzle orifice is 400 microns, in comparison. Some plastic was sticking to my internal PEEK threads so I know plastic was in the gap! My hot end requires less force to feed filament now, however. Is it because of something about my V1/V2 hybrid? Is it because I filled this gap? Is it because I was very careful and methodical about assembly. I don't know for sure. I'm pretty sure my printer would have function at least a little bit before (it would less fuctional than your printer), if my Delrin had valid dimensions!

In mij 3rd picture you can see that the green filament also got around the brass part in the PEEK. You can see the green ring it formed. Also the blob of filament there is too big to fit in the teflon part I believe. It looks like a jam. That picture is taken after the jamp but already cooled down.

once I receive my second I can start modifying the head. For instance removing some material on the down side of the PEEK would allow the brass part to insert completely and touch the teflon white insert.

[calinb 11]

I don't think the small mod to seal the Teflon tube against the brass tube can hurt, but I suspect following the V2 hot end instructions precisely is more important. I was wrong and step 31 does say to insert the clip in at the appropriate time:

http://wiki.ultimaker.com/Hot_end_v2

Do you have access to a milling machine? It's often difficult to make accurate measurements where needed (make many and look for repeatability) but you could just take off 0.280 mm / 0.011" with a file. Lay the file on a flat surface (or your lap where it won't slide) and more the PEEK across it with your fingers, keeping pressure even and the PEEK square to the file. Measure your progress often and use the standard machinist's trick: try to remove no more than half of what remains to be removed after each measurement. Actually, lacking the benefits of graduated leadscews or digital readouts on a mill, you'd better go even slower than that at first! I could do it for you very precisely on my mill in about 3 minutes, including setup. I have an extra PEEK and we could swap after I send it to you modified, if you'd rather not modify your PEEK. I don't think this is super critical. You want a bit of force seal the junction but no so much that you significantly deform the Teflon tube end.

[hcpl 0]

I don't think the small mod to seal the Teflon tube against the brass tube can hurt, but I suspect following the V2 hot end instructions precisely is more important. I was wrong and step 31 does say to insert the clip in at the appropriate time:

http://wiki.ultimaker.com/Hot_end_v2

 

I followed these steps closely. From my understanding step 30 and 31 will compensate for each other. By creating a gap the size of the blue horseshoe clip at the bottom, then putting the clip in place you push the tube up, that will be compensated once you assembly the long screws so the white part in between on the bottom is pushed up again and the 2 parts meet.

 

Do you have access to a milling machine? It's often difficult to make accurate measurements where needed (make many and look for repeatability) but you could just take off 0.280 mm / 0.011" with a file. Lay the file on a flat surface (or your lap where it won't slide) and more the PEEK across it with your fingers, keeping pressure even and the PEEK square to the file. Measure your progress often and use the standard machinist's trick: try to remove no more than half of what remains to be removed after each measurement. Actually, lacking the benefits of graduated leadscews or digital readouts on a mill, you'd better go even slower than that at first! I could do it for you very precisely on my mill in about 3 minutes, including setup. I have an extra PEEK and we could swap after I send it to you modified, if you'd rather not modify your PEEK. I don't think this is super critical. You want a bit of force seal the junction but no so much that you significantly deform the Teflon tube end.

No no milling machine here. Thanks for the offer but I'm in Europe so it would take a lot of shipping time and money. I'll try it once I have the spare. With a file should be doable very careful like you mention. Thanks for the tips!

I was also looking at this thread:

https://groups.google.com/forum/#!topic ... EmVIgFKRzY

. Many familiar names by now. Looks like the same people are contributing a lot. The thread starts at a pre V2 hot end era so keep that in mind when reading about the tube thread tips etc. It's also talking about temperature measure variations up to 15-20°C and PLA bonding to PEEK very well.

[joergen 2]

Calin, I think you we're over thinking the precision a bit too much, especially considering that we are dealing with wood parts, and parts that get warm and expand, but I am happy to hear that you are printing now.

Hcpl, I hope you get your extrusion under control, as calin did. Just as a side note: if you are messing with the current going into the steppers, make sure you make any adjustment to the trim pots while the printer is completely unplugged from power and USB. The steppers don't need much current to workerfectly, and run barely over room temperature... They will continue to work at hot water temp (60C) and up (until they will simply stop and loose steps when too hot), but that is absolutely not necessary. If you adjust the trim pots, the 9-10 o'clock rule is a great starting point (see wiki, stepper motor tuning)

[hcpl 0]

Lol I missed this crucial post! Let me reply to that also.

 

Thanks! I am printing now and my filament barely has any drive marks in it. Your filament is obviously being deformed, ground, and chewed-up to force it though the hot end. I''ve made three changes to parts in my kit (one with my lathe and two with my mill). I'll describe more about them later, but you have the Bertho drive, so only one of my mods might apply to you.

Great to hear your set now! That picture of filament was before I understood that my extruder drive was indeed abusing the filament. Today it's much better on that side, leaving only small toothmarks. I'll make a picture of that improvement this evening.

 

Edit2: could less heat make an improvment?

I think it might. I think temperature can change how and where plastic jams in the hot end.

Also to report back this evening after some new heat tests now that I have the extruder drive fixed.

 

If the issue is filament blocking between the parts stacked on top of each other, then why are there so many parts in between? Why isn't the tube mounted on top of the top brass?

The link you provided explains the official reasons.

http://daid.eu/blag/2012/08/31/ult ... v2-hotend/

Some of them, I question. For example:

The new white connection part seems to be designed to stop plugs and making the bowden tube connection less prone to errors. As the bottom part has a slightly thinner diameter then the brass tube on which it rests. This means any plug that tries to form is of a diameter that will fit back into the brass tube.

I have made very careful measurements of the parts with micrometers and calipers and the Teflon tube discussed here has the same internal diameter and the brass tube on which it rests. The other beneficial claims for it are true, I believe.

 

Yes I've read that but thanks to my experience I don't agree with everything also. Maybe this v2 head assembly is less prone to the plugs found before but it sure has other problems then. Just need to find out what exactly. If just a slight over temperature (hypothese only for now) is causing these jams then that would be an important warning at the instructions. Not to mention the official wiki has several different temperatures listed to start with.

 

I am running the V1 nozzle and brass pipe in the V2 hot end, because I broke my V2 in the repeated wrenching I've done to take things apart and put them back together many times for debug. I'll provide more details later, but I found that a gap exists internally between the Teflon tube and the brass tube (regardless of V1 or V2 parts used in a V2 hot end).

Exactly what I found after many taking aparts and cleaning etc.

 

So I closed the gap by milling 0.011" (280 microns) off of my V1 nozzle. You could achieve the same dimensional change by milling (or carefully filing) the same amount off the bottom face of the PEEK where the flange from your V2 brass pipe seats against the PEEK. This will move the other end of the brass tube into the Teflon pipe above. If your parts have the same dimension as my parts, this should seal the gap between the Teflon tube and the brass tube. I milled enough to create about a 150 micron (0.006") "crush zone" in the end of the Teflon tube to seal it well against the brass tube. Again, my parts vary a bit. For example, I have two PEEKS and the depth of the recesses in the top end of the PEEKS (that accomodates the flange of the Teflon) tube varies by 100 microns between the two PEEKS.

I don't have the V1 nozzle so I don't really understand how removing material from that part helps but I understand the rest of the story regarding the V2 parts and I do agree on that idea. In fact I had the same conclusion so far. Great minds think alike, isn't it

You're really talking about microns here, probably not a good idea to do so by hand then. I'm at a fablab monday and tuesday next week with a real engineer (I'm only a software engineer, the soft kind that is). I'll check with him what's possible.

 

However, I think your problem is likely to be assembly (mine quite possibly as well!). I was very, very careful in the assembly of my modified V1/V2 hybrid hot end. fluxline helped me to realize the possible importance of a step left out of the V2 instructions: The Teflon tube must be displaced from the wooden plate by the width of the small allen wrench provided in the kit. This is covered in the instructions. What might be equally important (I"m not certain about this), but not covered in the instructions, is the clip in the Bowden tube quick connect must be inserted before tightening the assembly together with the screws. The Bowden tube must be fully inserted into the Teflon tube (the pen marks line up) at this point too. This was required in V1 because the Bowden tube had to seal or it would leak plastic. In the V2, the plastic should be solid at the end of the Bowden tube, but we still want it to be hard against the Teflon pipe.

At first assembly I followed these steps but I agree I might have been not precise enough at that point. Later on I redid the whole assembly with a better understanding of the need of all the steps so I did pay much more attention to details. I'm confident I did these steps correct that second time.

I'm not sure however if running the head the first time could have cause damage or blocking PLA in the PEEK part. There sure is PLA in the tube now and maybe that is just bonding with the passing filament when heated causing plugs anyway. That is how I got to the gap between brass and teflon inside PEEK theory. Not how to remove that. I saw the teflon popping up at a certain point while jamming so I'm pretty sure material was inside.

Let's say I get away too much of the PEEK material. Would it be a real issue if the plate on the brass screw, between the heated alu block and the PEEK, would be apart from the PEEK? As long as the brass and the teflon meet inside the PEEK I think it should work no?

I'll be able to compare the PEEK and brass parts measurements once I have my spare v2 hot end assembly. I'm curious if that would introduce a lot of room for error.

 

In my case, I think the finger pressure required to feed filament manually has dropped from 30-40N to about 20N. However, I also think that (after my modifications to the drive hobbed bolt and Delrin rubbing block, my extruder drive mechanism could now drive the previous 30-40N if necessary!

If you feel the force required to push the filament though the hot extruder is excessive. I think you may need to reassemble the hot end very carefully with regard to above procedure.

I definitely need too much force from the 3 layer on. So during the print.

 

Much like the jamming wiki explains as a mod =>

http://wiki.ultimaker.com/Jamming

. If done that way nothing can get in between, no?

In the V2, our Bowden tube terminates at the Teflon tube. This should not cause leakage problems because the plastic is solid there! However, my mod was directed at the equivalent junction in the V2--the interface between the Teflon tube and the brass tube. There IS a gap there in both my V1 parts and V2 parts (about 125 microns, but it varies between my sets of parts a bit). Is that significant enough to cause leakage and a jam inside the PEEK? I don't know. The nozzle orifice is 400 microns, in comparison. Some plastic was sticking to my internal PEEK threads so I know plastic was in the gap! My hot end requires less force to feed filament now, however. Is it because of something about my V1/V2 hybrid? Is it because I filled this gap? Is it because I was very careful and methodical about assembly. I don't know for sure. I'm pretty sure my printer would have function at least a little bit before (it would less fuctional than your printer), if my Delrin had valid dimensions!

I agree on your findings, they match mine. Really a good thing yours is working now and many thinkgs for reporting back. Really appreciated!

[joergen 2]

Just for reference, hot and soft PLA bonds extremely well to PEEK, and this is the main cause for all the dreaded plugs in the V1 hot end. Once it has bonded, new filament pushing by will bond to the plug, and then it's only manual cleaning out the PLA from the PEEK by heating it up and removing it carefully with tweezers. For all practical terms, consider the PLA "radioactive" and never let it touch the PEEK ever.

It is also impossible to push the plug through, since it will be either too tough, or some PLA will remain bonded to the PEEK, and cause trouble the next time. You need an absolute tight path from the Teflon to the brass