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Horizontal axis inaccurate - M3 SE

Posted: Thu Oct 04, 2018 1:06 am
by polygonprint
Is it possible to adjust horizontal movements / steps in firmware to achieve a more accurate print? I find X & Y differ. Not by a lot but enough to have customers come back to me and say a part is off. I am playing around with manually scaling the digital model, mentioned in another post here, which seems to be working so far, but it would be nice not to have to do that. Horizontal scaling in the process window of S3D is no good in this case.

This may all be common knowledge, my apologies if so. Coming from a Zortrax M200 workflow/environment which is pretty much plug and play and prints accurate each time I have never really had to deal with the above. The M3 has been a bit of a learning experience, which I am sure everyone here has been through, but can be frustrating and has me questioning at times if I made the right choice moving away from my previous machines.

Cheers

Re: Horizontal axis inaccurate - M3 SE

Posted: Thu Oct 04, 2018 1:00 pm
by ednisley
polygonprint wrote:
Thu Oct 04, 2018 1:06 am
Not by a lot but enough to have customers … say a part is off
What tolerances do they expect? It seems everybody wants micron tolerances, even for Stanford Bunnies. [sigh]

If ±0.1 mm will suffice, it's likely a mechanical problem. Check for:
  • A loose lock screw in a stepper drive pulley
  • A loose mounting screw in a belt idler pulley
  • Any play in the hot end mount
  • Loose platform hardware / clamps (*)
AFAICT, you can hold ±0.2 mm tolerances without too much effort and you can tune the model / slicing to hold ±0.1 mm on any given model. Under ±0.1 mm, you gotta remind people the parts come from molten goo squeezed onto a pile of plastic, not plastic from an injection mold.

And, as you've surely discovered, small holes require pre-compensation to get the right size, no matter how accurate the hardware may be; it's that molten goo thing again.

(*) Somebody went through a whole bunch of debugging aggravation before discovering he'd omitted the clamps on the glass plate, which moved slightly as the platform accelerated. He 'fessed up; definitely a courageous act under the circumstances.

Re: Horizontal axis inaccurate - M3 SE

Posted: Thu Oct 04, 2018 5:46 pm
by airscapes
I have seen the sliding glass post and seen it in action on my own M2. I made plastic (imagine that with a 3d printer :D ) shims to install between the glass and rubber corners to keep it from moving without cranking down on the plastic hold downs.

Re: Horizontal axis inaccurate - M3 SE

Posted: Fri Oct 05, 2018 4:44 am
by polygonprint
Thank you ednisley and airscapes, I appreciate the comments, suggestions, etc.

ednisey - the parts I was printing at the time were small 30 x 60 x 10 mm optic lighting enclosures in ABS, with a base and lid which snapped together. There had never been an issue before while I had my Zortrax's, so I hadn't really been measuring them too closely after running a few 100 through the MakerGear. My error I know, but it came as a surprise when the customer complained the lids were not to spec and way too tight on one axis. I don't recall the exact amount, but enough obviously. Thankfully I hadn't done a lot of the lids and I could adjust them inside my 3D modelling program. I had calibrated before the job with as close to perfect measurements as I could get. Not perfect but I thought close enough. I'm now a lot more careful which is why I am trying to work out a solution, or to at least learn what I need to know.

I have gone over everything you noted to check for. I have had issues with the glass bed moving before so I generally tighten the bed clips before each print, which generally do need tightening each time. Not a great design right there I think.

If the glass plate was/is the cause of my frustration I'd happily admit and accept responsibility. As airscapes has suggested, I've printed out some shims for the rather large gaps between the glass plate and rubber edging.

Thanks again