Torgeir
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Posts posted by Torgeir
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Hi Shiren1981,
Thanks for the reply.
Yes, the SLA prints is some under extruded and it is done by purpose.
They are made with same standard settings for 0.4 and 0.25 in order to compare, not to dress them as good as I could..
This objects is very small and they are printed with as lo temperature as advised, however, it is possible to go further down - with some more stringing..
I did this to see more of the details, tend to happen when printing "dry".. (lo temp).
Thanks.
Regards.
Torgeir.
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Hi Folks,
As I’ve been testing the hubbed MK8 feeder wheel for some time as it was assumed to be better than the knurled feeder wheel that’s used on the Ultimaker 3D family, I’d simply had to try this type of feeder wheel and here is my findings.
It is important to note this test is done with a MK8 feeder wheel only, having an effective diameter of approx. 7 mm.
This test is done with the feeder wheel driving on the inside of the filaments “memorized curve” when rolled out from the filament roll. Using the inside of this curve drastically reduce the friction between the filament and the bowden tube when printing using high pressure.
The first thing I observed is that the hubbed feeder wheel needed much more torque than the knurled feeder wheel to feed the filament. This is caused by the fact that the small radial “knifes” have to cut across the filament and leave a track line that is notable wider than the track line from the knurled feeder wheel.
What is also counting here is that the distance between the “hubbing” (the radial knifes) that is only 0.6 mm apart, versus the distance between each small squared “pyramid” on the knurled wheel that is approx. 1 mm apart each other. So the knurled wheel make a punched track that is smaller and has a wider grip to the filament.
This explain why hubbed feeder wheel needs more torque than knurled feeder wheel!
I’ve made a picture of the hubbed wheel track here:
Between the every lines the distance is 0.5 mm. (Taken with an USB microscope.)
The above picture is the track line from the MK8 during high load printing first layer. Here you see that the compression and stepper slip can lead to a double track, kind of slicing, but no separation. This slicing reduce the grab on the feeder and lead to grinding..
Here’s a pictures of a grind part of a filament when using hubbed wheel:
As in the previous picture; 0.5 mm between the lines.
I’ll have to mention that the print finished without any issue..
I also made same print with a knurled feeder wheel and made a picture with the two feeders at same place during a printing of exactly the same print object.
OK., I’m using a stepper that’s geared 1:2 for both test.
The truth is, the knurled wheel could extrude without any slippage, but the hubbed wheel could not.
But mind you, this hubbed wheel type also grind during “lots” of retraction under high load!
As you see, the knurled wheel also makes a little more rough looking track during load, but do not slip the filament or grind it. I did this three times with same result, not very scientific but have some indication of a practical result.
This show clearly to me why Ultimaker still go for this type of feeder wheel!
Here is another interesting thing to see, this is that you can adjust the position of the knurled wheel and the pressure on it in order to have a better grip!
And finally, the knurled wheel is sure better for the softer type of filament..
Here’s a macro picture of the two feeder wheels.
This picture is taken after I removed the hubbed feeder and put back the knurled feeder wheel type to the printer.
You’d see the remains of some PLA in between the “knifes” on the hubbed wheel.
It is important to note that this subjective test only made on the MK8 feeder wheel with 7 mm effective diameter. This makes the radius for this wheel only to be 3.5 mm and with this small radius the knifes dig “kind of” hard into the filament!
Other types of hubbed feeder wheel with larger diameter do not dig this much into filament, but need more torque during feed as more knife’s is to be forced into the filament when rotating.
But for this particular comparison, the knurled feeder wheel is a winner in this case!
.. - ..
So, a little breath from my side, I’d see lots of you folks still using the “old” feeder with feeding the filament on the outside of the “normal” filament curve (Ultimaker standard). As the filament is rolled off and cut to proper length in order to have as lo friction as possible, or to put the roll on the side on a chair to obtain the same..
A loose few turns of the rolls make less friction for sure and a roll lying on the side create less friction as the filament rotate during feeding. But with a feeder unit mounted so the that the feeder wheel is driving the filament on the inside of the loop is so much better that you NEVER again have to do this anymore.
This procedure is as follows;
1) Turn your feeder unit around, so that the reverse side become the front, the pressure adjustment will on the inner side of the printer. Oh yes, -hold the feeder stepper motor when loosening the last screw or it will drop down inside.. :( There is a good description of how to do this in the manual.
2) Use the firmware for the Ultimaker 2+, this will change the rotation of the stepper for the feeder.
3) Adjust the E-step pr/mm to same value as before, or requested.
4) Any correction that’s needed due to different heath block, standard Olsson or anything else.
There might be something else, but I’ll assume someone may chime in for correction here.
Sorry folks, but I had to mention this.
Wish you all a happy 3D printing.
Thanks.
Torgeir.
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Hi Folks,
As I've finally made all thing to work in the “Chinese extruder head” with an Olsson heath block and Laberns heath duct, thanks Labern, I'd like to shear some of the final result.
Since I've modified my printer sometime ago, I've never seen any sign of the zebra stripes anymore.
This first picture is a few prints of the “Calibration Block for SLA printers” with some notes. For the note in this picture, correction; it is possible to see through 3 holes...
The second one is a picture of the “MakeRook prints”, yes the print that won the 3Dexpo price made by GuyS in the Team Ultimaker.
In this picture there is three "Make:Rook" prints.
The one in the middle is the first I printed and I thought, wow, how small this thing is.. Until I realized this was the version made for the SLA, well its a charming little thing that’s missing the on top text.
The little one is only 26 mm and the normal one for PLA is 50 mm.
The left print is made at center of the bed, while the right is made at the very far down right corner that’s have less vibration due to “in fill” hit on retraction.
Sure all this rocks.
Good Luck.
Thanks.
Torgeir.
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Just come to thing about something else, since you mentioned an intermittent connection when you applied a little force to the contact. This contact do not have any connection between the upper part (where the tightening screw is) and the lo part. So make sure that the thermistor wires is completely cleaned for insulation material and clamped well to the lo part of the block. If the wires is of the tiny ones, fold it back so you have double size here.
What you see here also confirm that there is a kind of rupture when bended (expansion) or heated. So I'll think your problem is close to this finding.
Thanks
Torgeir.
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Hi photoresistor,
When you said you swapped the bed temp sensor with the nozzle temp sensor, do you mean that you swapped the connectors on the main board?
I'll assume the latter.. Such failure is one of the most problematic to solve in the electronics circuits, this due to expansion/retraction on the PCB (printed circuit board), however, in this case it should be easy..
Most “probably” it is just the soldering at the surface mounted PT100 thermistor, but can also be the thermistor itself or the PCB track involved here.
You need to remove the heat bed and try resoldering the thermistor.
Another method is to use a heath gun, heating the aluminium side of the heat bed and measure the resistanse during heat in order to observe the failure, then resolder the thermistor and do another test.
Heres a picture of the connection at the heat bed and the PT100 termistor.
Good luck.
Thanks.
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Hi Sander,
Thanks.
When I saw this post I installed the extra feeder unit I've into my printer installed two rolls of filament and shot another picture and here it is.
I'll hope this better describe my point in this topics.
Edit: One small note here: This have been my setup from day one and I never had any issue with the feeder, none! Also, the filament stay where it should be.
Any question, just fire off..
Regards.
Torgeir.
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Hi LePaul,
I'm very sorry to see this, however, you will be one of those printing perfect print every time I'm sure!
So what happened here? As the filament is “grabbed” on the “outside of the loop” and forced to bend against its memorized (born) position, it will always try to go back to the memorized position. If there is a slightly mating offset, the filament will easily go the way it is guided and stay at this side. The result is a filament that is twisted all the time when it is feeding toward one side or the other, and then ending up as your picture shows.
The other more “normal” effect of using the outside curve of the filament for feeder wheel, is the additional friction that’s created in the top of the bowden tube under load, the higher the load the more friction (as the rough track from the feeder wheel grab into top of the Teflon house(the bowden tube)! So, at high load, the filament will be forced toward the top of the bowden tube and acting as some sort of a brake.
So what is the solution for you?
Since you've already upgraded to a 2+ version, the feeder should be repositioned to the right side of the back (looking from the front side), the side where the number two feeder was planed to go.
If the feeder is installed there, the feeder track line will be on the inside of the natural loop of the feeder. This is the place where there is less friction when feed through the bowden tube. Do this and I'm sure you'll be as happy as those always print nice..
Sure, there is another one as well; put back the old feeder.. :( -Or roll off the filament from the spool and put it on a chair, like here.
Here is some pictures about the issues:
Edit: I marked the filament with a black line, to make the track visible through the bowden tube. First outer path, then the inner path (inside and outside the loop).
This first one is when the track line is on the outside loop.
As you see, the track line is going all the way at the top if you're using outside feeder wheel route.
Edit:
So where did it go when using the inside part of the filament loop for the feeder wheel to drive the filament?
Starting at the feeder, track is inside the loop.
And at the extruder, inside the loop.
Well, this is all and I'll hope that things sink in now...
If you like to dig into the post, there is several engineers pointing this out.
For those with the old black feeding unit (Ultimaker 2 version), just turn it around so the back become the front, and you'll become a happy 3D printing member as well.
Here is a little more:
I'll think that the design engineer NEVER wanted the feeder to go this way. (?)
So how can I assume this? Well, have a closer look at the old stock (black) feeder unit and you will find that on one side there is one hole larger than the others. Actually, this is the front side as the engineer/designer made it. This extra wide hole is to allow you to remove the front side of the extrude hose in order to clean out dust/particles without loosening the fourth screw holding the other part of the feeder half and the feeder stepper motor.
Here's a picture of the one half of the old feeder with no 4 scew:
Here's a picture of the old feeder with no 4 scew and top cover half loosely installed:
Here's what I've want to show you, and I'm really hope this attempt start some forward moving. If not all three printers (UM2, 2+ and 3 (left extruder when looking from front) will suffer due to this problem.
When writing this, I do hope I did not offend anyone as this never was my intention.
Thanks
Torgeir.
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Hi LePaul,
I'll think this is the nozzle hitting the infill when retracting over here. (Yes I have same things happen on some prints).
There is a setting in Cura, see the "Preferences" and go to settings, find "Travel" and cross out "Avoid printed parts".
I have not tried out this in Cura, but it does work in S3D.
OK.
Good luck.
Torgeir.
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Hi Johan,
Almost overlooked this one..
Sorry about that, however, you're very close to a success I'll think..
By using a twisted shielded wire, this should work unless your fan radiate very high energy. If so, you might be forced to use both methods, screening your input signal (the very lo dc voltage from the cold junction amplifier located inside the extruder) and try to kill most of the radiation from your fan by decouple (lo pass filter) using an electrolyte capacitor (100 micro Farad 25VDC) as close as possible to the cooling fan.
It may also be possible to screen this amplifier using some special foil, that is only grounded to the upper end of the shielded wire routed from the main board.
The above capacitor is only 0.7 gram and measure (10X6) mm.
Good Luck.
Torgeir.
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Hi flowalistik,
Sure I'll do, but first the two remaining mods to mention.
3) Is the MK8 feeder wheel from RepRap, you'll see it on one of the pictures below.
5) This is a 1.5 mm carbon fiber rod that running along with the wiring in order to assure that the movement of the wires is made evenly over the whole radius.
This is important in order to avoid wiring breakage and make it last as long as possible!
This first picture is of the feeder unit with both half split, where you can see what's done inside.
Second picture is of the feeder and a stepper motor with my release handle installed in extreme open position (all the way to the stop).
The third picture show the above unit with filament installed and in normal closed position (the normal printing position).
The fourth picture is from the unit installed to the printer where the handle is in normal open position and filament ready to be installed.
Number five, same as above, but from another angle.
Picture number six is just with the filament pushed in, but still with the handle in open position.
OK., this is as my feeder is setup today and save me the fiddling on the back when feeding new filament. I've found that it's best to just feed it through and then leave the rest to the standard "filament feed" in the advanced setup menu.
Thanks.
Torgeir.
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Hi Onkelgeorg,
1) Metal bowden coupling yes, right.
The benefit of this is that the coupling turn with the bowden tube, so there is no shafting to the tube by "small knifes". Inside the feeder unit there is a nut plate made in PLA with tread type BSP pipe type and G 1/8-28.
2) Yes it is a belt driven feeder geared 1:2 into a plastic housing.
This was made as I only had a 200 step/rev stepper available. Reading this forum I found some issues/concern about a very hot shaft on the stepper making grip to filament less effective and step back (more torque needed hence the 1:2 gearing).(Yes I built my printer). By using this setup I got 400 step/rev on the knurled wheel, same as the UM2 -so no firmware change.
3) Still open, -and hard to see..
4) Lever on the feeder, yes you're right.
I never talked about this one, but this is one thing that needed a few rounds before I could put it into test. There is a lock as well on this one..
Number five, you was “close”.. But no cigar.. eh..
Regards.
Torgeir.
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Hi Folks,
This is my first post with some modification ideas that's all present in one picture.
Can you find all four modification at the feeder, how about the modification number 5 (not on the feeder)?
This might be a “quiz” before the big news arrive.
Thanks.
Torgeir.
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Hi Paul,
Try printing without using the heat bed, use only glue.
I've had som issues like this when printing small object at lo height and using heat bed.
Use extruder temp 192 -195 deg. C.
Thanks.
Torgeir.
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Hi Folks,
As a follow up, I'll like to post some of the remaining issues that James Strawson pointed out in his post found here:
As they figured out that the track line made by the feeder wheel on the filament was running on the outside of the bowden tube, they turned around the feeder unit to make the track line move the lower side track along the bowden tube. This little detail improved the printers failure rate drastically, since the less friction in the bowden tube improved very much.
(This was a kind of surprise for me, cause I never had any problem with my feeder and never noticed that the UM2 had the feeder turned the other way.)
James also suggested installing another feeder wheel, a new hobbed wheel, this one:
https://www.amazon.com/gp/product/B00XP3NJSE?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s01
This is a wheel with a diameter of 6.7mm across the bottom of the hobbed part, improving the grip as well giving a little more torque.
I found this very interesting, as I've been experimenting with a double wheel feeder that's using MK 8 feeder wheel from RepRap.
You'll find all those feeder wheel here:
http://reprap.org/wiki/Drive-gear
The interesting thing is this MK 8 feeder wheel can be used on both, (3 and 1.75 (edited)) mm filament.
The MK 8 feeder wheel measure 7.5 mm across grove section (where the filament go), however, they use to say that the efficient diameter is 7 mm.!
I did some reverse engineering, calculating from the ideal step setting (UM2) 282 step/mm in order to find this (calculated) diameter of the original feeder wheel and got the number of 7.2 mm. So our knurled feeder wheel that's measures just close to 8 mm is «reduced» to 7.2 mm, -interesting!
Well long story short, I just installed the MK 8 into the stock feeder and did not perform any adjustment of the E-step. It perform as before, full flow test with absolutely no problem.
I'll think that, since I'm using quite a hard PLA filament that's prevent the hubbed part to go that deep into the feeder, so all in all the diameter is more or less the same for both feeder wheels when it come to practical use. But ofc., it will all come to the properties of the type (hardness of) filament we are using at any time.
Here is a picture of my setup using MK 8.
Thanks
Torgeir.
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Hi Brent,
Just a little additional stuff.
It's easy to remember, -PT100 is reading 100 Ohm at zero deg. Celsius.
Here's a table for "all" other values;
http://www.micropik.com/PDF/pt100.pdf
(Also interesting to know about the original thermocouple in UMO;
Chromel-Alumel thermocouple is reading zero Volt DC when the temperature is zero deg. Celsius. (a mixture of ice cubes and water).)
(The other known referance point is; "clean boiling water" is 100 deg. Celsius at sea level.)
This is just some part of the metric system..
In order to check that if your boards is reading the correct temperature, use resistors to simulate the temperature you want, normally two point, zero deg. Celsius and the high point (say) 260 deg. Celsius.
Remember that normal resistors have tolerances (good ones +/- 2%), so use a good multimeter and the multimeter value for your "calibration"/check.
Thanks.
Torgeir.
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Aha, sorry I missed that..
I like gray, -but is it that much better...
36 hours, Oh me..
Then this is even more strange.
Anyway, good luck -maybe remove the cover over the X stepper..
Thanks.
Torgeir.
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Hi Bray,
This is one of a special thing..
The last print looks very nice, question is; is this objects height less that the height were the "error" occurred on you full scale model?
Cause the only common thing here is the Z-axes, so this is just a theory;. Suppose that the bed does miss two step -or more (hanging somehow), then assume a little lo torque on the X-stepper or high friction when hot(?). When the extruder then hit the print object, the X-stepper miss some step due to this collision (and now has got an offset), the heat bed move a little down and the printing process continue printing with this X-offset.
A monitoring of this problem would be interesting to observe.
Well, this is just a little theory, but.. Who knows.
Thanks.
Torgeir.
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Great job Johan.
Thanks.
Torgeir.
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Forgot one thing.
There will only be smoke until it dry some up, then it will be fine, just went a little.
Torgeir.
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Hi Johan,
OK., you should use shielded for the signal wire between those board.
BTW., I've just checked the EMI from the two fans on the UM2, here there is two fan in series (12 VDC each. And 24 VDC feeding both). There was a lot of spurious (Lots of HF spikes) in the middle of the two fans.
I've also tested with a 100 micro Farad capacitor, this capacitor removed all the spikes..
If you have an oscilloscope, you'll see it all.
On an UM2, those spikes do not create a problem since the level of the signal from here is much stronger and do not need to be amplified that much.
Good luck.
Torgeir.
(Edit: Sorry for the misspelling of your name.)
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Hi Bray,
This is kind or rare, -sure the slicer program can do strange thing, but so can the hardware..
A few missing "full step" on the x-axis at a certain spot will do the same thing!
This is very true as the firmware only can synchronize at the X/Y and Z end switches, from there on it is only the number of steps that's the true reference.
Also, is your R/H stepper (the X-axis) very hot, or just hand warm? Compare with the Y-axis stepper.
Did you try to print this object (edit:) "sliced" in Cura without this issue?
Just a thought.
Thanks.
Torgeir.
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Hi Johanes,
Come to think about those fans as they do radiate lots of pulses when we adjust the pulse width and some of them also radiate when at full speed (the max voltage).
Sometimes we'll use ferrite bed, but this is mostly for high frequencies, so at lo frequencies we simply put an electrolyte capacitor as close as possible to the fan. For those fan we're using a 100 micro Farad / 25 VDC will do the trick. (PS. remember the polarity.)
(This volatge advice is for UMO, for UM2 and like select at least 40 VDC.)
This kind of "EMI" noise from the fan use the feeder wires to the fan as an antenna!
Just my 10 cent..
Thanks.
Torgeir.
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Hi Folks,
A last report about the testing after this modification.
When I loaded a roll of black PLA (Verbatim), the usual thing happen and it started to extrude filament out of the nozzle, then I heard the feeder stepper started to skip. As I watch this, it seemed to have a little less flow than before and the feeder act as it was compressing a "strong spring"! Every time it skipped it moved about 90 deg. back, then started to compress again. I was wondering if there was any remains/gums etc. inside the nozzle, so I did a few "atomic Bob". To my surprise the filament broke of right at the top of the Teflon coupler, I've had to reload manually and squeeze out a little PLA. After this, let the temp go down to 60 deg. Celsius, then set it to 90 deg. C and when at 90 deg. pull..
Then it come out "almost as" normal, but -just about where the Teflon coupler is insulating the heat block from the upper "cold part" of the extruder there was a circle/section of the filament with less diameter than the filament diameter(2.95 mm).
This set me somehow out.. After some thickening, I realized that I've lifted the heat block a little up. Aha., so I reduced the gap back to about 0.8 mm and made another test, bingo...
The little fan improved the cooling so much that is also cooled more of the upper part of the heat block. So, the faster the filament was tried to be feeded through that passage the more energy was needed to melt the filament.
So now I'll know how important the adjustment of the height of the Teflon coupler is.
You're actually adjusting the width/sharpness of the hot/cold zone for the hot end.
As a final test I printed the "extruder feed test", started with the temperature of 205 deg. Celsius and monitored the temperature until finish. When the temp descended one deg. I rolled it up one deg. more and so on. It finished at 207 deg, Celsius with no issue..
All in all, I'm very pleased with this result.
Thanks.
Torgeir.
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Hi Tom,
Thanks.
Grate job in finding your problem.
Torgeir.
4 Modifications, plus one more..
in Third party products & modifications
Posted
Hi Folks,
As I recently removed the MK8 feeder wheel from my printer, cause it did not improve at all over the knurled wheel.
I'd just want to inform anyone interested in this modification about this matter.
For more info about this, see this tread:
https://ultimaker.com/en/community/33367-knurled-feeder-wheel-versus-hubbed-mk8-feeder-wheel-for-filament-drive
Thanks.
Torgeir.