CoMeDoONE for Ultimaker2

[Cohen 4]

By the way I will continue testing to rule it out, but I don't think the resistors are the problem. Even with a big fan blowing air over the board Illuminartis test starts visually failing at 5mm^3/s

 

[aaronalai 2]

Thanks for the update Cohen, I understand you are pretty busy over there at Ultimaker and need to prioritize your time. When I get my printer (should be within about a week, give or take several days) I plan on using a hall-effect current sensor to measure the current over time of the two motor coils. I'll post a link to the results here for easy reference. Perhaps the data will help you, perhaps not; but it's an independent test that may help yield conclusions with respect to your own data.

Thanks again .

 

[Cohen 4]

Very nice Aaron! Looking forward to that data!

 

[mnis 11]

It could also quite simply be a another problem for some users.

A friend told me the following:

Step motors can, on reaching their performance limit, suddenly running back. Maybe the engines are not all the same powerful?

So when the holding and feeding force is insufficient, then it may go backwards.

I would need for further testing an original spare motor ...

But Aaron, you're very interested in electromagnetics, right? What are you saying to this theory?

Markus

[illuminarti 18]

It could also quite simply be a another problem for some users.A friend told me the following:Step motors can, on reaching their performance limit, suddenly running back.So when the holding and feeding force is insufficient, then it may go backwards.I would need for further testing an original spare motor ...But Aaron, you're very interested in electromagnetics, right? What are you saying to this theory?Markus

 

Well, yes, that's exactly what happens when the extruder skips steps. It can't move the filament forwards with it's available current, and it can't crush the filament out of the way, so it runs backwards to a stable position.

[mnis 11]

@ illuminarti

Can you or anyone else for me once do the following:

Directly on the knurled wheel, measure the temperature during a Long printing period?

Maybe someone has already made the original UM2 measurements, also I would like to know more, please. :smile:

[Cohen 4]

Here is a screenshot taken with the thermal camera with the board under extreme heat stress. The board is taped to a heated bed which is at 100C, with all motors connected and powered, and the XYZ stepper current set to 2000mA (E to the standard 1250), to get them as hot as possible. Cold start current is 1,03A, again measured with a multimeter through one coil, with the motor powered and set to full-step. At the highest temperature the sense resistors themselves got to 116 C, with the current dropping to 0,936A. And while it's not nothing, I think the resistors hold up well at such high temperatures.

 

[aaronalai 2]

Woah Cohen! You really went above and beyond in your analysis; I'm totally jealous with the thermal cam you got to play with :mrgreen:. I'm really excited to try and measure the current now. I'm really curious to see if I can see the current profile over time given the speed of the microstepping, the little devices I have yield a 5us response time. I, and I'm sure many other Ultimakers, appreciate all the time you spent testing the device so thoroughly. Looking forward to comparing notes in the future.

Thanks again :-P.

 

[gadgetfreak 7]

Measuring temperature can be difficult.

The thermal camera is a great tool but best to use to compare relative differences.

The picture looks a bit out of focus, for a correct temperature reading it's important to have correct focus (use the focus ring ) as well as having correct emissivity setting for the material setting. I suggest calibrating at room temperature (adjust emissivity to report room temperature before turning on printer when it has cooled off) as well as using a thermocouple or other contact thermometer attached to a measuring point as a secondary reference. Beware though that the secondary sensor might act as a heat sink.

For best results the components should be somehow blackened/sootened to emulate a blackbody.

I think other memebers like Bertho or Joergen might have useful input on this

Regardless, good work!

[Dim3nsioneer 557]

Very nice summary about thermal imaging, gadgetfreak! :smile:

You may add another point to be taken care of: the background. It is reflected on the part you are observing (although you don't see any reflection in visible light at all) and should therefore have a reasonable temperature (room temperature). An open sky as background is e.g. very bad (-80°C). :wacko: