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CoMeDoONE for Ultimaker2

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Posted · CoMeDoONE for Ultimaker2

@Aaron. Thanks for doing the calculations. 55.4mA does not seem anywhere near enough to cause issues, and certainly not in my case.

There is another "feature" of the A4988 no-one has mentioned so far: Thermal Shutdown, which happens at a junction temperature of around 165C. I don't think its caused any issues so far as it would cause a total stop of the extruder motor.

 

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Posted · CoMeDoONE for Ultimaker2

Hey Markus,

I guess nobody tried your solution for these reasons:

1. The alterations to the machine are irreversible. If it turns out that it won't do any good, you don't have the choice to send it back to UM for replacement (that's my case - I sent my printer back - waiting for replacement now).

2. You'd need additional hardware. Again, if this turns out to be in vain, then the money is wasted.

We are still not sure where this issue originates from. Also it is not clear how many users are really affected. Maybe it is just me, Woofy and Mr. Waldorf...

You (successfully) treated the same symptomps but you may have had an entierly different problem. I've seen many posts with subpar extrusion tests. Some fail at 6mm^3/s, others later. This might simply be due to some factors playing together (badly coiled filament, high ambient temperature, bent electronics cover touching the board, and so on).

By the way. I don't know if this is a forum issue, but I am unable to view your videos. I am on a Mac using Chrome. When I load one, Quicktime appears inline, but the video won't start. I think the safest way to share videos would be Youtube or Vimeo (if you want to password protect them).

 

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Posted · CoMeDoONE for Ultimaker2

yep, same at me with the videos.

I solved it by downloading them from Markus' dropbox link at the beginning of the thread. Maybe this info helps.

Note: some files from the dropbox were unzippable on my computer cause of too long file names. But these can be renamed, then it worls.

 

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Posted · CoMeDoONE for Ultimaker2

Greetings Markus,

I fear that bringing up the resistor idea has derailed your thread, and people may not look at the other modifications you made.

This was not my intention, I think the modifications you made were useful and I was trying to help explain why they worked. You also put fans on the motors which is something the thread hasn't talked about much, and my be important. From my experience though, I think steppers are designed to run hot so the fans on the stepper motors were lower on my list of explanations. That being said, the fans may help in conjunction with your other modifications.

I wanted to address three points you brought up in your last post:

 

 

Policy discussions are very important , I am sure. But I miss the simplicity of curious experimentation with possible alternatives.

 

I agree with you, I would like to see some more active testing and probing of the machine to see if there are consistent results from members in the forum. I also agree with Nicolinux though, that many people may be satisfied with how their printer is operating. This may be a temporary satisfaction though, as some people may find their print results degrading over time; so perhaps curiosity will grow over time. I also believe some people may not be as daring as you and do not perceive their UM2 like they did the hackable UM1.

Rest assured though, that when I get my UM2 I will be measuring and adjusting everything I am capable of and will report my findings in as detailed a fashion as I can muster. Even at work when we purchase new transducers and equipment that we pay 100,000+ dollars for we still need to test them. The tools are so important that we need assurance that they are functioning correctly, and I view the UM2 with such importance.

Some people in the forum may scoff at the idea; 100K+ dollars for something, you would think it would work without fault. I can assure you this is definitely not the case. I have found numerous very very important errors in very expensive equipment we have purchased. Without testing these pieces of equipment before a big test we would have not collected any data and would have lost several hundred thousands in time and specimen costs. I have learned that blind faith in something working as the manufacture intended is not always the best idea, and that rigorously testing the product is very important.

 

- I need to learn how to make simple and almost correct tests, has anyone have suggestions? What should I start? I am looking for a brief explanation and a test file.

 

Here is my suggestion, I know I brought it up earlier with you but I think this may yield some interesting findings.

1. Print out illuminarti's test cylinder here all you have to do is put it on your SD card and print.

2. Print out the cylinder with and without your active fan cooling turned on. I would print it with your added fans on first, then turn your added fans off to print it a second time.

3. Make regular notes of the system temperature provided by your snazzy monitoring setup.

4. I would then replace your more efficient extrusion motor with the original one provided with the machine, and repeat steps 1,2, and 3 again; providing a total of 4 cylinder tests.

5. For future printing I would purchase one of these http://www.robotshop.com/en/pololu-5a-acs715-current-sensor.html to constantly monitor current during a print. I can't be positive these will work for this application, but I've used them in the past for other stuff with good success. If you need help figuring out a way to interface it with your machine and read the data coming out of the device, I would be more than happy to help.

6. Check out Mr. Waldorf's thread here it's pretty interesting to see how others are either successfully or not successfully printing out the test cylinder.

 

 

- I can not fast enough absorb and understand information because I am occupationally very busy.

 

 

We very much understand, there is no need to feel rushed to respond or post something. Look at Nicolinux's mega post about under-extrusion; that thing has been going on for almost two solid months with 28 pages of responses. Take your time, we appreciate the work you have taken thus far, and I believe forum members will contribute to the best of their abilities.

:-P

 

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Posted · CoMeDoONE for Ultimaker2

I seriously doubt this is a problem. For one thing, the other steppers all run at a higher current. The feeder is at the lowest setting. For another, resistors tend to be pretty tough. We are running them at .078 watts max typically but in reality if the feeder is moving then the current goes up and down depending on the current step and so on average should be at half that power. And it's rated to .125 watts.

It's possible but it just doesn't seem likely. Eventually I plan to spray cold spray and heat gun on those 2 resistors and repeat my "pull test".

 

I've been thinking about this as well. If this resistor phenomena is happening to the extruder, why isn't it happening to the other steppers with the exact same circuitry. I think that it could be happening to the other stepper motors it's just we can't see the results of the lower current flow as a function of how the steppers are setup inside the machine. Also, now that you are saying that these steppers use more current than the extruder motors, it may be even more difficult to perceive the problem.

The extruder stepper motor is constantly building up potential energy in the form of a flexing bowden tube and corresponding filament. This is why it has to retract so much, to dissipate the potential energy then the filament physically translates a bit. Throughout the entire print cycle the extruder stepper is the only motor with constant opposing force being applied to its axle. The other stepper motors are not burdened with this build up of potential energy/constant opposing force, although they are to some extent via the momentum of the print head, but this may be much lower and intermittent. So I don't know if a comparison between the two different operating procedures can be made.

I agree the average current going through the resistor would be less than 0.078 watts due to the nature of the stepping sequence and corresponding current application. But there must be 0.078 watts being facilitated by the resistor at discrete time intervals, and the Derating Curve may come into play at these specific instances in time, where the peak current is at its highest.

I appreciate your willingness to manipulate the temperature of the resistors, I think this will provide valuable insight as to how sensitive the resistors are to heat. Looking forward to your results, knowing full well you are committing your own free time.

Thank you

 

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Posted · CoMeDoONE for Ultimaker2

@Aaron. Thanks for doing the calculations. 55.4mA does not seem anywhere near enough to cause issues, and certainly not in my case.

There is another "feature" of the A4988 no-one has mentioned so far: Thermal Shutdown, which happens at a junction temperature of around 165C. I don't think its caused any issues so far as it would cause a total stop of the extruder motor.

 

I think I made an error in what to include in my calculations:

No problem, I was headed out the door for work and a thought just occurred to me so I rechecked my calculations. I forgot to include the trace resistance in my calculations and only included the % change in trace resistance. If I include the trace resistance then I get that the stepper motor is only receiveing 1.090 Amps of current or a reduction of 159 mA; this could be quite significant. I'll post all of my calculations later today for scrutiny, I could take a picture of my notebook if anyone wants to try and wade through my handwriting though :shock:.

 

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Posted · CoMeDoONE for Ultimaker2

Thank you for your clarifying words Nico and Aaron:

I should mention the following, and then be silent...perhaps silent forever (...regarding the profound for me Discussion):

In our home there is a good spell for the overall situation:

Who does not like to try, will never know what it tastes.

Not to be dismissed out of hand is still a fact:

I am compelled by the new engine to reduce the preset material-flow to 65 percent. So I now have a huge trouble with over-extrusion, which I can manage much more easily. :smile: :smile: :smile:

 

Also, I was smart enough to start my first tests with the most curved material. For this purpose I have wrapped the material of a new role to an empty shell. And finally, I have assembled a useful material guide.

 

The presented Trinamic motor cost almost three times more than the conventional engines. It basically goes around nearly 30 euros, and therefore to find a matching connector. Then you will also need a fan for almost 5 euros. A small external power supply for the single fan will cost probably not much more than 10 euros. Who then also prints a matching side panel itself, has everything he Needs for a new experience with the machine.

Less than 50 euros are required for the simpliest test environment. The total cost required would be disproportionate to the price of the UM2 machine. I can not believe that no one dares. Who it will implement skilled enough can do without almost any risk own tests, without leaving any traces on the machine.

Even all the components of comedo can be constructively implemented as the UM2 does not get a single scratch. The frame, all the sensors, the additional electronics, etc. can also be removed easily with thoughtful attachment.

But I understand that such a thing is not for the totally inexperienced persons, they should wait for a possible upgrade option that is abundant tested and well documented.

 

AND Who is ready with its own tests he can send me all purchased items, I can use this in any case and pay for it. I'm very curious who actually makes it. :mrgreen:

 

To me it looks more like this:

The material feed requires much more force than was originally calculated, so that everything harmonizes better. Time will bring it to daylight. And new UM2 owners must first learn under extrusion in all its facets correctly identified that requires a bit more routine and a watchful eye. Gradually may come more problem reports. But i wish for all, I am wrong with my assumptions.

I have also been detected for me, the colored PLA is easier to process than natural PLA. This also happens to be an additional interesting thing and what I want to learn more.

It is not excluded that my coming tests, show you and me, how wrong I am at the end with everything.

And a word about the mechanics of the material feeder:

I call the part now easy BlackBox.

I noticed that allow the four screw holes of the BlackBox offer some leeway. Just try to be mounted intentionally wrong this box. The lower region to go to the center of the rear wall and non-parallel to the side wall. Then take anything to make the filament thread running perpendicular and slightly toward the side wall. This small procedure could improve the reliability of the material feed. Please try it ...

I will:

- truncate the file names of the Videos for easier Access.

- try to complete my comedo instructions for interested people.

- try to make comprehensible tests for me and all.

- try to make comedo even prettier.

- try to integrate an small operating hours counter in comedo.

bye

Markus

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Posted · CoMeDoONE for Ultimaker2

Hi Markus,

 

I should mention the following, and then be silent...perhaps silent forever.:

 

 

Please don´t do that, I am very curious about your weekend/future tests.

I am so sorry if Aaron and I hijacked the thread jabbering about some theorys, it wasn't intentionally. You told us that you only will make more tests on the wekeend so I was just "jabbering" until receive more news about your testings.

So... please continue the awesome work and share with us, because no body will make fun of you even that in the near future you realize you were wrong. Most honestly, I do like your modifications and apreciate your commitment and sharing

Cheers

 

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Posted · CoMeDoONE for Ultimaker2

Markus, if I understand you correctly, you're seeing massive over-extrusion when using a different motor? I would presume that's because the new motor has fewer steps per rotation (probably half as many). The stepper motor used on the UM2 extruder is 400 steps per rotation, not the more normal 200 steps.

Maybe you can increase the microstepping to compensate (if not already maxed out), but I don't know how well that will work. With fewer available steps per mm of filament fed in, I think you could have extrusion accuracy issues; the UM2 already seems a bit short of resolution on the e-axis, given the tiny amounts of filament required for short print segments.

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Posted · CoMeDoONE for Ultimaker2

Hey illuminarti, you are correct. The stepper resolution of the motor Markus purchased is 1.8 deg/step or 200 steps/revolution.

The plot thickens...

 

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Posted · CoMeDoONE for Ultimaker2

@ Mr. Waldorf

I've corrected the second line in the post and added near the end something, sorry.

@ illuminarti and Aaron

All correct so far as.

But "Ready for microstepping"

Does it not possible 400 steps?

I got the information that up to 1/16 steps are not a problem, but now am unsure.

Printed objects look normal. Anyway, if I reduce the flow of material. And The Retract lenght I had to cut in half.

How can I detect what is now no longer possible?

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Posted · CoMeDoONE for Ultimaker2

Regarding the stepper accuracy; it's dictated by the stepper hardware itself. A 1.8 degree/step motor cannot get the same resolution as a 0.9 degree/step motor. The pole resolution is more coarse on the stator, this site has some pretty good pictures:

http://www.shinano.com/stepping-motor-operation-theory-pg2.php

The stepper controller chip will still do 1/2, 1/4, 1/8, or 1/16th a turn, but the turn is dictated by the hardware inside the motor.

It would be interesting to see how well you can print something with a lot of retractions; I'm not sure if reducing the retraction length in half and reducing the flow by about half can compensate for the courser stepper resolution. Not saying it's impossible, I really simply don't know. Perhaps you could try reprinting stuff you successfully printed with your old motor to detect a difference in the quality of your prints.

From your posted video the print seems to look okay, have you been able to control your over extrusion yet? or are you still trying to find a suitable setting?

Don't worry though, as all is not lost; if the more course motor does not serve the purposes you need it to, you can simply solder your old motor back to the motor lead wires. But you may end up in the same boat as everyone else who has under-extrusion issues, but there seem to be many solutions out there and one of them may remedy your problem; increased stepper current, different extruder design, smoother spool holder.

Please report your findings with your course motor though; I think since you already have it installed it wouldn't hurt to print out some of your previous prints to gauge the success of your new stepper motor.

Regarding this development about the stepper though, the circuitry overheating hypothesis may not pan out. This being said I'm still going to look more closely into the matter (I'm going to probe the hell out of my machine), and I hope gr5 still does his temperature manipulation of the resistor components with the mass pull test. I agree with him, and also believe it would yield valuable insight into the thermal sensitivity of the precision resistors.

It seems like increasing the current going to the extruder motor can help in some cases. If the current to the extruder motor needs to be increased, I would ask myself why this is the case. I still think the precision resistors drifting out of spec could explain the reason; but still nothing conclusive yet.

 

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Posted · CoMeDoONE for Ultimaker2

Please have some patience, the results will come soon. Currently I have finished the third cylinder, and there is at the label at the end of 10mm ³ / s two or three very small dropouts.

Basically, it looks good, but I'm still a few attempts.

Markus

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Posted · CoMeDoONE for Ultimaker2

Alright now for those calculations you have all be dying to see :mrgreen:

First some assumptions and some facts:

Assumptions:

A 25 to 100 degree change in temperature: delta T = 75C (delta means change in something and is often represented with a little triangle from the greek alphabet).

0.005 ohms of trace resistance (the resistance of the copper on the printed circuit board)

0.393%/C change in trace resistance (how much the resistance of the copper on the printed circuit board changes with each 1 degC increase in temperature)

The precision resistor is at it's full 1% error (more resistive by 1%)

The precision resistor is at it's full 200ppm/C thermal coefficient (this describes how much the resistor value changes as a function of a change in temperature; this says that the resistor will not change resistance by more than 0.0002 ohms per deg C if it is operating within its stated temperature range measured from room temp, which is understood to be 25 C)

Facts:

The precision resistor is 0.05 ohms

The function that describes how the stepper controller chip decides when there is enough current going to the motor is (Vref)/(8*precision resistor value)

Vref is the reference voltage facilitated by the microcontroller chip; this is how the current is changed in the firmware.

Alright, let's do some calculations:

delta T of 75 * 0.393%/C trace resistance change = 29.475% change in trace resistance

0.29475 * 0.005 ohms of trace resistance = 0.001474 ohms of increased trace resistance

0.05 ohm precision resistor * 0.01 (the percent error) = 0.0005 ohms of increased resistor resistance

0.05 ohms + 0.0005 ohms = 0.0505 ohms of resistor resistance

0.0505 ohms * 0.0002 (thermal coefficient) * delta T of 75 = 0.000758 ohms of increased resistor resistance

0.0505 ohms (a resistor that is 1% higher in resistance than its nominal value) + 0.001474 ohms (the increased trace resistance) + 0.000758 ohms (the increased resistance of the precision resistor as a function of its thermal coefficient and our temperature change) = 0.0527 ohms of resistance. (the astute reader will recognize I made a mistake in my last post, geez where is my head :shock:)

I don't know for sure what the Vref value should be, if Cohen did not include the trace resistance in his Vref calculation and only used the value of the precision resistor. Vref should be:

1.25 amps (max current) = Vref / (8*0.05)

Some algebra and we find Vref to be 0.5 volts

For now if we take Vref to be 0.5 volts and plug in our new resistor value of 0.0527 ohms we get a new max current of 1.185 amps

(0.5 volts) / (8*0.0527 ohms) = 1.185 amps

or 64.7 mA less than our target goal of 1.25 amps

This is where things get a little tricky and why I wish Cohen would come back to the thread. See if he did include the trace resistance in his calculations my Vref assumption would be off. But if he didn't include the trace resistance in his calculation for Vref no one would get 1.25 amps going to their stepper motor and everyone would be getting some small value less than 1.25 amps, which probably isn't a big deal until you include the compounding resistance increases calculated above.

Let's include the increase in trace resistance AND the trace resistance in our max current calculation.

(0.5 volts) / (8*(0.0527 ohms + 0.005 ohms)) = 1.082 amps

or a 167.4 mA reduction in the amount of current going to the stepper motor.

Take these values with a grain of salt. The trace resistance may be estimated too high, the Vref may be calculated with the trace resistance in mind meaning the overall change in current isn't as big as calculated; but inversely the resistor temp may be getting higher than 100 C and the trace resistance could be higher than estimated meaning the overall change in current is bigger than calculated. The take home message is that if there is a resistor soldered to a board that is within spec then there is a chance of having a roughly 13% drop in current going to the stepper motor under normal operating conditions from the expected 1.25 amps we all think is reaching the stepper motor.

Edited to make a clearer distinction of which resistances I am computing.

Edit for the more visually inclined:

SCtzAA4.png

 

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Posted · CoMeDoONE for Ultimaker2

Hey take your time Markus, most of us in the forums are adults with full time jobs, children, bills to pay ... and all those fun adult responsibilities; and probably see the forum as a luxury. We all understand :p.

The only reason I respond so quickly sometimes is because I don't have a girlfriend or children, and I have already done all of my chores for the day; I'm just a single dude with a cat and a deep fascination with 3D printers at the moment :mrgreen:.

 

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Posted · CoMeDoONE for Ultimaker2

Oh man... can I click two times on "Like This" ?

Hey Aaron, if you want to came to Portugal I will get you 2 girlfriends and four cats!!

 

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Posted · CoMeDoONE for Ultimaker2

Ahahah, lol; I'm in :mrgreen:. I love all the ladies, and snuggling with cats.

 

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Posted · CoMeDoONE for Ultimaker2

Guys, I think here comes the stuff to which we are all waiting.

I will give you a first impression at this point:

 

Further material relating to the tests you find in my DropBox.

For my night thoughts:

- What I can exactly with the new setup UM2 no longer do?

- I have already printed with the new engine things that apparently looked better than before.

- I can not currently back to the old stepper motor, which would have to wait a few days. So I make no comparison tests with the old setup.

- During all tests, there was no return jump of the filament in the Bowden.

- The engine had no dropouts during all tests.

- The engine has in fact a huge amount of power.

- I need a more powerful fan that can keep the material stepper at 45 degrees.

- I had to increase the back pressure on the knurled wheel.

- I had to increase the flow of materials for better testing-results, but not for normal printing.

- I need to improve my Filamentguide a little.

- I've had no nozzle-problems with the new setup.

I think sleep is currently impossible ... but I have to try it ...

Oh, I still have a few delicious mini-donuts, which should help me now.

Bye for now :smile:

Markus

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Posted · CoMeDoONE for Ultimaker2

A little more thinking about the recent experiments:

I had to reduce the retraction length. It may do with the fact that the movement of the material is now more accurate, and the material flow is more constant. 3mm seem to be enough to date, but also that I need to observed more.

Without cooling system, it was apparently not possible the cylinder to print successfully. I have the test between 5 and 6mm canceled, suddenly anxious, but I will try it again later.

But I had to find first useful settings for the material flow.

Only at the end of my tests I got the idea to increase the force against the knurled wheel. In the original UM2 is so not recommended because it scarcely brings an improvement.

In my case it was the right choice for more consistent material flow. So I would have the material flow, do not need to set so high, but that's fine-tuning for later.

Markus

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Posted · CoMeDoONE for Ultimaker2

Thanks for posting some progress, we understand with your busy schedule it's difficult to find time to report back. It's interesting that you are reporting you cannot finish the cylinder test without active cooling on the board. Hmm, I wish more people would try and put a fan on their board to see if it makes a difference. I know Mr. Waldorf tried and couldn't see much of a difference, I think he's going to try and cool the other side of the board when he gets a chance; to focus the cooling on the suspect components. Although from the thread he started about recording the success of printing the cylinder test, it looks like his problem was because of http://umforum.ultimaker.com/index.php?/topic/4586-can-your-um2-printer-achieve-10mm3s-test-it-here/?p=39708 that keep the printer assembly together.

Perhaps loosening the 4 long bolts should be next on your list of things to try out.

 

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Posted · CoMeDoONE for Ultimaker2

To follow up on my earlier mention of the steps per rotation for the extruder motor, as it affects extrusion resolution, it's not so much an issue of mechanical resolution of the motor, but simply the math as to the volume of plastic per step.

The default extruder steps-per-mm setting on the UM2 is 282; with a 400 step-per-revolution motor, and 16 times microstepping, a single step will drive 1/282mm of 3mm filament into the extrusion system. Compare this to the UM1, with it's geared drive bolt - there the steps-per-mm value for e is around 830 - much finer control.

What does that look like at the hot end? Well 1/282mm of input filament is 0.0226mm³ (assuming 2.85mm diameter filament: 2.85² x pi / 4 / 282). At the output end, if we assume a 0.4mm bead width and 0.1mm layer height, that corresponds to a line length of 0.57mm roughly. (and that ignores any issue of the positional accuracy of the motor, when microstepped).

So, at 0.1mm layer height, the minimum segment length for which the printer can even begin to control extrusion is just over half a mm. And even then, the control is going to be crude - a single all-or-nothing step that is going to dump all the plastic at a single point on that line (ignoring time delays, pent-up-pressure etc). Certainly there's no room for any subtlety in terms of accelerating and decelerating the extrusion amount since there's only a single stepper firing event to control. In contrast, in drawing the same line, the x and y steppers will have fired about 45 times (at 80 steps/mm).

To get any kind of effective acceleration-linked control, I'd imagine you need at least 3 or 4 step events, implying a line segment of 1.5 to 2mm long. If you reduce the layer height even further - say to 0.02mm, the finest I've seen claimed on the UM2 - then now you need lines 5 times as long as that before you have effective extruder control.

And this is why having a motor with half as many natural steps per revolution is a bad thing - the number of steps per mm then halves; doubling the minimum segment length that can be controlled to 1.13mm with 0.1mm layers.

 

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Posted · CoMeDoONE for Ultimaker2

I wish more people would try and put a fan on their board to see if it makes a difference. I know Mr. Waldorf tried and couldn't see much of a difference, I think he's going to try and cool the other side of the board when he gets a chance; to focus the cooling on the suspect components.

 

Humm... I can make a few more tests, since I still have the temp probe installed and the board is accessible. However I don´t know how to make the tests since the litle bastard is always geting the 12mm3/s sucessfull even with a half empty spool. So if I tighten again the 4 head screws to generate under extrusion I think that this test wouldn´t be accepted, at least for me...

Maybe MostlyAtomicBob or Woofys or other person with severe underextrusion problems?

Right now my printer fails at 13mm3/s but this is normal. any sugestions to the tests?

Additional note: I ordered a sensor current, so when he comes I can play a bit with that and maybe we can cross some data

 

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Posted · CoMeDoONE for Ultimaker2

Thanks for the report Mr. Waldorf :-P. Yeah, I'm starting to question the validity of the resistor/heat/current hypothesis; that's why it's a hypothesis though. Extraordinary claims require extraordinary evidence, and as of yet the extraordinary evidence seems to be lacking.

I don't know if you have stated it on another post, but just so everyone knows he was getting 87C on the board during 12mm3/s so it's unlikely that this is the issue. I'm going to interface the motors with the current sensing circuitry and heat up my board with a hot air reflow station in small increments to simulate a higher than average ambient temperature to see if it makes any difference without risking any damage to the board; I think a current vs temperature graph would really help put this idea to bed. But as it sits now, I'm less convinced that this is the problem; but still think it's worth testing out if for nothing else than to have some quantifiable documentation about the actual amount of current reaching the motors, which could provide useful in the future.

Nope, no suggestions from me about what to test, I think you nailed the reason for under extrusion on your unit :mrgreen:. I hope it helps others with similar issues, it's such an easy thing to test for, it would be the first thing I would test for if I were experiencing the under-extrusion issue.

Looking forward to comparing notes in the future though :grin:.

 

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Posted · CoMeDoONE for Ultimaker2

Thank you illuminarti

I need to see if I ever finer resolutions need <0.1mm for my purposes.

I miss definitely the experience to recognize practical disadvantages immediately. All objects in 0.1mm thickness are apparently good enough for my needs. Well, an engine is changed quickly when needed. :smile:

 

The you mentioned relationships are for anyone who is interested in an alternative engine very important. When I write something about the Trinamic motor, I will point definitely it.

Then get a different question more meaning:

Is there any step motors with real 400 steps and identical construction, requiring less energy and thereby also even more power than the original engine?

Markus

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Posted · CoMeDoONE for Ultimaker2

Hey Guys,

haven't forgotten about this post, took me a while to catch up reading though :-) A couple things: The current settings in Marlin doesnt match the actual current precisely. It was some time ago since I last measured motor power, so I set up an Ultimainboard, set the stepper to full stepping, powered the motor and meausured 1,03 amps through the coil. I attached the board to a heated bed with heat conducting tape and heated it up. I got the sense resistor up to about 73C (measured with the awesome thermal camera borrowed from our Swedish friends Daniel and Anders, thanks guys!), and the current dropped to 0,96A, so that's a drop of 70mA. That was just a first test, I want to stress the board some more, I agree these tests should be done at the highest temperatures the board could reach. I'll keep you posted.

Another test I want to do is run a few prints with and without cooling the board and then measuring the weight of the printed object to determine a change in extrusion, so also more on this later.

About damaging the resistors when subjected to heat (70-80C) for a long time, I dont think this would quickly cause problems if the datasheet advertises the maximum operating temperature is 125C.

If anyone has any suggestions for tests where an Ultimainboard might be damaged, and you dont want to risk your own, you can post it here. If I think it can be usefull to figure out the cause of the problem I can do it, we have spares here as you might imagine :-)

 

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