Too much or too little tension in filament feeder?

[stephenbrooks 1]

Hi,

My Ultimaker 2 (original) at home has started making a clicking sound from the filament feeder motor quite a lot.

Recently I found that I was getting severe underextrusion, even though if I push the PLA manually into the nozzle (at the default print temperature of 210C), it goes through fine with a bit of pressure.  When the printer tries to do the same using its motor e.g. at the beginning of a print, it is unable to push any through now. (NB: I've done the atomic method through about 5 cycles to clean the nozzle).

I've not changed the feeder motor tensioner at all since I bought this, but which way should I change it?  Less or more tension?

Currently the filament that's been through the motor has a regular pattern of tiny holes down one side, but otherwise is not distorted or ground up.

Edited May 20, 2016 by Guest

[fbrc8-erin 272]

Hi, Stephen,

You could be seeing too much resistance from your bowden tube or PTFE coupler. Both parts are soft and can experience wear and tear, that will cause resistance in the filament's feed path if they're worn out. How much print time is on your machine? You can check this in Maintenance --> Advanced --> Print Time.

You can check bowden tube for damage by sliding the blue clip out sideways, and pushing down on the white collet while pulling up on the tube, at both ends of the machine. If you push a fresh piece of filament through by hand and find a particular point that's resisting you, there could be damage inside the tube. You can also check the feeder end for damage. You can see feeding problems if starts to look too chewed up. I have a photo here showing a good bowden tube and one in need of replacing.

If the coupler is bad, there isn't any way to see that short of taking your printhead apart, but a good rule of thumb on the coupler's lifespan is about 500 print hours with PLA. Over time, due to wear and tear, and heat, the end of the coupler closest to the nozzle widens out and forms a lip, which can create feeding issues.

The other thing that may have changed over the course of your printing, is how tightly wound your filament is on the spool. The closer you get to the end of a spool of filament the tighter the curvature is, making the printer have to work that much harder to fight against it and extrude the same amount of plastic. Are you very near the end of a spool?

[stephenbrooks 1]

How much print time is on your machine? You can check this in Maintenance --> Advanced --> Print Time.

My total printing time is 161h57m.  Although some of that was when I experimented with ABS (didn't print much with it though as ultimately fairly unsuccessful), it was mostly PLA.

 

You can check bowden tube for damage by sliding the blue clip out sideways, and pushing down on the white collet while pulling up on the tube, at both ends of the machine. If you push a fresh piece of filament through by hand and find a particular point that's resisting you, there could be damage inside the tube.

The end on the nozzle is perfect.  The one in the extruder is less perfect but I checked pushing a filament through and there is no excessive resistance from the tube.

 

Are you very near the end of a spool?

No this is a new spool!  It actually got a bit worse when I changed to white PLA from grey PLA (although it was also under-extruding with the grey).  I tried upping the temperature but that didn't help the extrusion at all and it extruded fine manually.

Somehow the feeder motor is not pushing enough?  Should I change the tension setting on the motor?  If so, in what direction?

When I re-loaded the material just now, as soon as the filament started to extrude from the nozzle, the feeder motor kept skipping back (about once per second making a "tock" noise).

I just tried a print and although the initial extrusion looked hopeful, it under-extruded during printing (with the same settings that have been fine before), with the internal structure grid not forming solidly.

Edited May 21, 2016 by Guest

[stephenbrooks 1]

For educational purposes, I took the nozzle apart. Doesn't appear to be anything wrong with the PTFE coupler - a bit blackened but the shape is fine. With the coupler out I poured some acetone through the nozzle in case there was residual plastic there.

Put it all back together... exactly the same! Under-extrusion particularly on high speed moves like making the internal grid in prints.

I noticed there is a tuning setting for print speed. I thought printing slower might help, but it seems too little material comes out even when it's going slower.

If it's not the nozzle I figure it must be the feeder motor, unless my filament is bad for some reason.

[stephenbrooks 1]

Well, setting the extrusion flow factor to 125% made the print look "healthier" with less gap behind the wall layers. I'm now wondering if my filament (White PLA from 3D universe shop) is a smaller diameter than stated but I don't have a micrometer/caliper to check.

The "tocking" from the motor has now stopped after my various cleaning operations and the filament comes out of the nozzle a bit more at the start of the print (still not as easily as other materials though).

I tried changing the print settings from 10% fill (a rather large internal grid) and 50mm/s maximum speed to 18% fill (the Ultimaker 2+ setting) and 25mm/s maximum speed since my print is small anyway. This made *almost* solid internal grid walls, albeit a bit thin looking.

I saw on the web once a table of ideal print settings for different filament colours and suppliers but can't seem to find it. At the moment hoping a combination of further reduced max print speed and increased flow (or correcting the filament diameter) will get a passable print.

[fbrc8-erin 272]

Hey, Stephen,

I'm sorry, I've been away from the forums for a few days. It's very rare that I've seen a feeder motor be the issue. Is your knurled sleeve still tightly in position? What size nozzle setting and layer height are you using when you slice?

You mentioned correcting the diameter--is the diameter of your filament not 2.85? What diameter is it?

Acetone will flush out any ABS in the nozzle, but won't do anything for PLA. You can also try loosening the 4 screws holding the feeder housing on by a quarter turn each. If they're too tight, you can get under extrusion.

[stephenbrooks 1]

Thanks for your reply.  I've taken a break from it but will continue to fiddle around later and will post here when I do.

The feeder motor stopped clicking so much after I cleaned the nozzle, so perhaps I made some progress there.

 

Is your knurled sleeve still tightly in position?

I had to look up what a "knurled sleeve" is It's the thing rotates, grips and pushes the filament right? I'll look when I go home. How would I know if it was loose?

 

What size nozzle setting and layer height are you using when you slice?

Layer height of 0.15mm and nozzle 0.4mm I seem to remember (the default for "Fast" in Cura for Ultimaker 2).

I wonder if this a material-specific problem: basically it doesn't print at the fast speeds (100mm/s for infill on "Fast" on Ultimaker 2).  I should try changing back to my silver PLA and see if that works.  

 

You mentioned correcting the diameter--is the diameter of your filament not 2.85? What diameter is it?

It's supposed to be 2.85mm, but this was "cheap" PLA filament from 3D universe and not the Ultimaker's own brand, so maybe I don't trust it.   I've ordered a micrometer to accurately measure the diameter (didn't have one but I wanted one anyway).

The other thing I notice is that "Fast" in Cura on the Ultimaker 2+ is not as fast (60mm/s for fill) as on the Ultimaker 2, plus they increased the fill factor from 10% to 18%.  Not sure if using the 2+ settings on the 2 would improve matters, I did something similar already and it did improve the quality.

Finally I've been getting some "melting" on fine details with this white filament.  I'd guess that means I'm printing too *hot* (currently at the default 210C) although this was on very small layers so perhaps I should increase the layer cooldown time.

Edited May 25, 2016 by Guest

[fbrc8-erin 272]

That sounds like progress.

Sorry about that. :-) The knurled sleeve is the sleeve around the motor shaft. Early on the knurled sleeve was 12mm long and seated at the edge of the shaft. Later, a 15mm sleeve was used instead so filament didn't slip behind the edge of the sleeve. There was an intermediate period where the 12mm sleeve was recessed 3mm from the end of the shaft. Your sleeve should be secure on the shaft (we use Loctite to hold in in place), and the set screw should be tightened down to the flat side of the motor shaft for added stability.

100mm/s is definitely a lot faster than I usually print at. I generally print at 50mm/s. The faster you print, the more likely you will be to get shaking and lose quality.

 

Thanks for your reply.  I've taken a break from it but will continue to fiddle around later and will post here when I do.

The feeder motor stopped clicking so much after I cleaned the nozzle, so perhaps I made some progress there.

It's a good idea to check the diameter if you're not sure; I haven't used that particular filament, so I can't really say anything about it one way or another. If you're checking the diameter the best way to check it is to pick a point, check it, rotate it 90 degrees, and check again, then repeat this at several spots along the filament. You want it to not only be 2.85, but also around...if you're getting readings that look oval, it's not going to feed well.

The fill factor increase I don't think should affect your print quality, but I'd be more inclined to print at 60mm/s than 100mm/s myself. With your UM2 feeder, if the printer can't keep up it will skip back rather than grinding the filament. With the UM2+ feeder, since it's geared, if the printer can't push out enough plastic, it would have no choice but to grind away, which may be why the settings changed to a more cautious setting, but that is only a guess. If you're printing at 100mm/s I'd increase the temperature to compensate for the speed.

With small layers, are you talking about objects like this?

Something small (that's a bit of an extreme example) definitely doesn't quite have enough cooling time generally with PLA. You could either slow it down when it gets to that point if you're near the printer, or you could print 2 at once, or, add a second item (a thin post for example) at the other side of the printer. It will have to go and work on that and then come back, which should give it ample time to cool.

With something like this dragon (it's one of my favorite models), the printer had a little more time to cool going between the 2 wing tips, which helped it turn out well.

Still, with the white and with the change in filament brand, you may want to try turning down the temperature to 200 or 205. I think the prettiest Ultimaker robot I ever printed was a 204. The overhangs were beautiful.

[stephenbrooks 1]

Brief question about print speed: the Cura software has two tabs of print speed settings on "full settings" mode: [u2E+ settings shown here]

...but changing the overall print speed in the "Basic" tab does not seem to do anything.  I only got changes by changing the individual numbers in the "Advanced" tab, which are different, such as reducing the infill speed.

Edited May 26, 2016 by Guest

[stephenbrooks 1]

Since I've got a U2E+ at work as well as the U2 original at home, I can now eliminate a few possibilities:

The white PLA printed just fine on the U2E+, on the same model, temperature and even the same speed settings, since I copied those more conservative settings (in the post above) to the U2 at home.

My caliper arrived and the "2.85mm" filament measured as something like 2.85x2.86mm, or ridiculously close to what it should be.

...so I don't think it's the material.  I might also try the original grey PLA at home to confirm.  That means there's something wrong with my home (U2) printer.

I'm interested by your comment that acetone will only remove ABS and not PLA from the nozzle.  Certainly, my brief attempt at ABS gave me a lot of grief with burnt particles of that clogging up the nozzle.  So perhaps I'll try disassembling the print head again and following the (slightly scary) instructions that say to reheat the head, while keeping it from burning adjacent wires, and then clean out with a Q-tip or similar.

My home printer is showing a bunch of symptoms right now that might all boil down to an underextrusion problem: incomplete infill, too "melty" appearance at the standard 210C temperature.  If I reduce to 200C, the detail improves but the feeder motor "tocking" comes back and the first layer no longer sticks to the build plate reliably any more, despite it being level and clean (maybe not enough material to stick).

Edited May 27, 2016 by Guest

[gr5 2,167]

q-tip might leave a string in there. I dont' recommend it. Do you have the Olsson block? I recommend that as then you can just unscrew the nozzle and clean it or replace ti for a quick test.

The "tock" or "nock" or whaver sound from the feeder has nothing to do with tension. It is a skip back on the stepper motor because it can only push so hard - about 10 pounds pressure which is a ton - more than I can push manually without breaking the filament. Enough to pick the printer right up off the table.

I suspect you need to change your white teflon part. Even though you said it looks fine I'm pretty sure it's been softened after those 100 hours of printing. The new teflon parts aren't white -they are white but transluscent. You can kind of see through them. The new ones can handle much higher temperatures so you probably won't have to change the new one. I recommend you get the Olsson block and the teflon piece and a .6mm or .8mm nozzle all at the same time. You can get all that at Erin's store (fbrc8) or you can get it from me (gr5.org/store/).

Indeed the overall speed is ignored if you set all those other speeds - I have all but the travel speed blank so that it defaults to the primary speed. Or you can set them to zero which defaults to the speed on the basic tab.

100mm/sec with .15 layers and .4 nozzle multiplies out to 6mm^3/sec. The UM2 printers are usually tested at 8mm^3/sec at 230C. At 210C it shouldn't be able to do that fast - you are above the nominal capabilities of your printer (but some printers can do it) so either slow ti down (my recommendation) or make the layer's thinner or go up to 230C (240C is great for fast - low quality - printing but don't go above that). In cura if you hover over the speed or layer height it tells you the cubic volume per second so you can keep it under 4 (I recommend under 4mm^3/sec). If you are in a rush get a .8mm nozzle - that can go 4x fast (16mm^3/sec) no problem - even faster if you want low quality.

[stephenbrooks 1]

Do you have the Olsson block?

Yes, it came bundled with my UM2.  Haven't installed it yet, though.  But since I've disassembled the head once already I might as well try it next time...

 

The "tock" or "nock" or whaver sound from the feeder has nothing to do with tension. It is a skip back on the stepper motor because it can only push so hard - about 10 pounds pressure which is a ton

Right, but hearing that tocking noise is bad, right?  It's a symptom of under-extrusion, insufficient temperature or a blocked nozzle?  (At least that's what I guessed).

 

I suspect you need to change your white teflon part.

I'll upload a photo of it if I take the head apart again.

 

The new teflon parts aren't white -they are white but transluscent. You can kind of see through them. The new ones can handle much higher temperatures so you probably won't have to change the new one.

I think mine is solid white, I'll have to check.  So there's an improved version?  Good to know, I might buy one.

 

Indeed the overall speed is ignored if you set all those other speeds

Ah!  OK, I didn't know you could set all those others to blank or zero.

 

100mm/sec with .15 layers and .4 nozzle multiplies out to 6mm^3/sec. The UM2 printers are usually tested at 8mm^3/sec at 230C. At 210C it shouldn't be able to do that fast - you are above the nominal capabilities of your printer

Kind of weird that this is the default "Fast" setting in quickprint in Cura for the UM2, then! :( Unless they expect people to also raise the temperature when they print on "Fast".

Like I said, the UM2E+ "Fast" default is more conservative and uses no more than 60mm/s (3.6mm^3/s).

Edited May 27, 2016 by Guest

[gr5 2,167]

>I'll upload a photo of it if I take the head apart again.

That won't help. You have to squeeze it while passing filament through it to see if it grips the filament. It's subtle unless you've played with many of these teflon parts.

Since you don't have the olsson block installed I'm going to raise the probability that your nozzle just has gunk in it (but extremely thin layer) and putting in a new nozzle will bring you back to "good as new". Or if you order anything from my store I send out a free nozzle cleaner that I find does wonders if you rub it around in the tip of a working nozzle for 10 seconds. You may also already have a spare teflon part. If so - don't buy anything - just put in the block and the new teflon part.

> Kind of weird that this is the default "Fast" setting in quickprint

I agree. I've never used any of those. I think the people who created those didn't do thorough research on them but who knows. Remember this is cura 15.04.X which is over a year old now - well there have been some bug fixes but basically it's a year old (april 2015 = 15.04). Check out the "quick print" settings in the latest cura from this month - the beta one - I don't even know if it has quickprint.

[stephenbrooks 1]

Well, the good news is that my UM2 printer came with not only an Olsson block but four different-sized nozzles too (it was from fbrc8).

The bad news is that at the step where I'm supposed to take the temperature sensor and heater out of the brass nozzle block, the temperature sensor came out fine but my heater is completely stuck (see photo below).

It looks a bit burnt around the edges.  I tried quite a bit of pull force and wiggling it around but only succeeded in pulling the insulation up the cable and fraying the metal weave a bit.

The only thing I can try is switching the heater itself on, although I can't see that helping much since the heater would presumably expand...

Can I buy a replacement heater and cable? Not sure where the other end of the cable is connected so might be difficult to replace.

Edited May 30, 2016 by Guest

[fbrc8-erin 272]

Hi, Stephen,

That's your temperature sensor, not your heater. I do not recommend heating your printer while the temp sensor and heater are not both in the brass block. If the heater and temp sensor aren't seeing one another, your heater will heat indefinitely and that would end very, very badly.

Since you have an Ultimaker 2 Extended, your printer did come with a hot end pack, which has a spare temp sensor, for exactly this reason--it's very difficult to remove the temp sensor intact from the nozzle, due to a tight fit. Your heater and temp sensor wires both run from the printhead to the electronics board underneath your printer (left hand side). Unplugging the temp sensor and replacing it isn't too difficult. I have instructions here: https://fbrc8.zendesk.com/hc/en-us/articles/206151456-Changing-Parts-in-the-Print-Head

Since the temp sensor cable is pretty slick, if you open up the electronics cover and pull out the existing cable from the TEMP 1 slot, you should be able to feed the wire up pretty easily through the black mesh.

[neotko 1,417]

If everything fails you could drill a hole from the other side of the pt100. Carefully (but since you might lose it anyway isn't biggie). Then when you reach the pt100 you can hammer from one side to push it out.

[stephenbrooks 1]

That's your temperature sensor, not your heater.

Oops! I wondered if that might be the case. Was following this video https://ultimaker.com/en/resources/18016-disassembling-the-hot-end and realised it didn't actually specify which was which. I'd been assuming the order mentioned in the text was the same as the video...

 

Since you have an Ultimaker 2 Extended, your printer did come with a hot end pack, which has a spare temp sensor

My home one was only a plain UM2, but looking at the materials again, yes it does (and I guess this means my work one also came with a spare). Good, this might be simpler than I thought. I'll try the suggestion in the guide of "applying WD40" to get it out, and if that doesn't work I'll try to follow the instructions you linked to for replacing the sensor.

 

If everything fails you could drill a hole from the other side of the pt100. Carefully (but since you might lose it anyway isn't biggie). Then when you reach the pt100 you can hammer from one side to push it out.

I've got some titanium drill bits that go through metal and was wondering the same thing, but I'll try non-destructive methods first. Also if I take the sensor out with the block stuck on it anyway during replacement, it'll be easier to drill out and maybe I could recover a working temperature sensor from it.

[neotko 1,417]

Just in case you end up drilling it. Brass it's quite easy to drill, just needs a firm grip. It isn't as soft as aluminium but not hard at all.

Edited May 31, 2016 by Guest

[stephenbrooks 1]

Well, tried WD-40 on the stuck temperature sensor, pulled on it some more and the wires ripped out but the outer shell stuck in the brass block.  So replacing the temperature sensor it is.

I've installed the spare temperature sensor.  This went quite well, although re-threading it through the black cable sleeve was kind of painful.

Then I continued to install the Olsson block (as my old head had the remains of the old temperature sensor stuck in it).  This also went fine until I failed at the last hurdle: the fan shroud wouldn't go back on easily.

That picture (NB: in a mirror) shows the temperature sensor and heater cable going into the new Olsson block.  The heater cable is turning a horribly tight 90 degree bend and is fraying.  This is because it conflicts with the back of the metal fan shroud when I put it back on.

I've checked I can't push the heater in any further (when the block is unscrewed) and getting the Olsson block nozzle centered in the shroud hole requires this conflict.  Do I just take pliers to the back of the fan shroud metal and bend it out a bit?  It doesn't seem to be that important.

Edited May 31, 2016 by Guest

[gr5 2,167]

It's too bad you didn't try heat in addition to WD40. That combination works great for me. I've changed about 5 temp sensors on old printers this way. It can be scary and feel like you'll never get it out but I usually do (have also destroyed 2 temp sensors). I don't know why heat works but it does. Also I use a sewing needle to pry the temp sensor a little bit around the edges.

[fbrc8-erin 272]

If your machine at work is an Ultimaker 2+, then it won't have a spare temp sensor. Since the 2+ comes with the Olsson block installed, you're unlikely to need to remove the temp sensor (unless it fails), so a spare is not included, just the extra nozzle tips. If your machine at work is an Ultimaker 2, whether or not it came with a spare hot end pack will depend on the serial number/when it shipped out.

You can bend the back flap on your fan shroud out a little, or break it off altogether. The Ultimaker 2+ fan shroud does away with the back flap on the shroud.

Edited May 31, 2016 by Guest

[stephenbrooks 1]

OK, I put it back together and it's printing again now. Infill looks good. Top of the print is still a bit "melty".

The nozzle of the Olsson block sticks out weirdly but looking at pictures on the web it's supposed to be like that. I also noticed the entrance to my PTFE coupler is slightly lopsided. The filament goes through OK, I think, but on one occasion where I was feeding in filament with a squared-off end, it caught on the side.

[stephenbrooks 1]

Meltiness seems to be material-dependent: 3D universe grey PLA gave better detailing on the top layers. My blue PLA from the same company seems oddly "gummy", I don't know if it's low melting point or some other aspect of the consistency.

[ultibrain 5]

There are a lot of filaments around. A lot of them are REALLY bad. I only use premium brands these days.

[stephenbrooks 1]

There are a lot of filaments around. A lot of them are REALLY bad. I only use premium brands these days.

 

Do you have a preferred brand of PLA?

So far Ultimaker's $70 filament works fine. Most of 3D universe's $38 filament is good (in my work UM2E+ printer at least). A colleague bought some $20 filament from who-knows-where and it prints but it's brittle as anything.