Horizontal axis inaccurate - M3 SE

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polygonprint
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Horizontal axis inaccurate - M3 SE

Post by polygonprint » Thu Oct 04, 2018 1:06 am

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

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ednisley
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Re: Horizontal axis inaccurate - M3 SE

Post by ednisley » Thu Oct 04, 2018 1:00 pm

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.
Last edited by ednisley on Fri Oct 05, 2018 1:20 pm, edited 1 time in total.

airscapes
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Re: Horizontal axis inaccurate - M3 SE

Post by airscapes » Thu Oct 04, 2018 5:46 pm

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.

polygonprint
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Re: Horizontal axis inaccurate - M3 SE

Post by polygonprint » Fri Oct 05, 2018 4:44 am

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

polygonprint
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Re: Horizontal axis inaccurate - M3 SE

Post by polygonprint » Thu Oct 25, 2018 8:38 pm

I'm hoping I havn't out worn my welcome here :) I need to ask a few more questions about calibration. I realise there are many forum topics on the subject but some seem quite old and most are on the M2. None seem to be helping really so I wanted to ask in brief if I am calibrating my machine correctly for ABS. Here is my process;

note - bed is level and z height set with blue feeler gauge according to Makergear instructions in Octoprint

1. Set tension on filament drive correctly (15-25% bite mark depth of filament)
2. Extrusion multiplier set to 1. Extrusion width set to 0.4mm manual. (default for latest Makergear ABS profile). First layer height 100%
3. Set z height by printing 25x25x8mm (x, y, z) box. Adjust z height in Simplify3D under global gcode offsets until height is exactly 8mm high. In my case I had to add 0.06mm
4. Print single walled box of same object, same extrusion multiplier and width. Calculate new extrusion multiplier and set. Reprint and adjust if need be until correct width is measured. My extrusion multiplier came to 0.95

Do I then leave the extrusion width in S3D at manual 0.4mm or switch it over to automatic and let S3D calculate that as it needs too. Also, I am assuming I switch my first layer height setting in S3D back to 70% (default MG profile for ABS)?

I'd appreciate anyone looking over the above. Am I missing anything or doing anything incorrectly?

Cheers
Evan

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ednisley
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Re: Horizontal axis inaccurate - M3 SE

Post by ednisley » Thu Oct 25, 2018 10:54 pm

polygonprint wrote:
Thu Oct 25, 2018 8:38 pm
switch it over to automatic and let S3D calculate that as it needs
Yup, the whole point of the Extrusion Multiplier dance is to match the actual amount of extruded plastic to the expected amount. With that set up, when the slicer calls for 1 mm³ of plastic, the extruder delivers exactly 1 mm³.

The EM won't be valid after large changes (like new temperatures or, heck, different plastics), but you can let the slicer optimize the thread widths / thicknesses / suchlike, with reasonable confidence the right thing will happen, under the conditions you did the calibration.

airscapes
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Re: Horizontal axis inaccurate - M3 SE

Post by airscapes » Thu Oct 25, 2018 11:07 pm

ednisley wrote:
Thu Oct 25, 2018 10:54 pm
polygonprint wrote:
Thu Oct 25, 2018 8:38 pm
switch it over to automatic and let S3D calculate that as it needs

The EM won't be valid after large changes (like new temperatures or, heck, different plastics), but you can let the slicer optimize the thread widths / thicknesses / suchlike, with reasonable confidence the right thing will happen, under the conditions you did the calibration.
In other words, you will re calibrate it often :D .. I put tape on the spools of plastic and mark nozzle size (I have 3 different sizes) EM, Filament thinkness, sometimes the average is 1.73 so I enter that into the other tab.. and the E width.. Next time I need to use that particular roll I can enter those values, print my square and hopefully be good to go..

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ednisley
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Re: Horizontal axis inaccurate - M3 SE

Post by ednisley » Fri Oct 26, 2018 2:26 pm

airscapes wrote:
Thu Oct 25, 2018 11:07 pm
In other words, you will re calibrate it often
You have become one with the spirit of the thing … [grin]

polygonprint
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Re: Horizontal axis inaccurate - M3 SE

Post by polygonprint » Sat Oct 27, 2018 2:18 am

Appreciate it ed and airscapes! I think I'm finally getting somewhere with my settings and prints. At least now my height is close to perfect, with enough bed adhesion to keep the part on the platform (or not warp). Now to sort out the x and y . Thanks again!

polygonprint
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Joined: Thu Jul 26, 2018 2:38 am

Re: Horizontal axis inaccurate - M3 SE

Post by polygonprint » Sat Oct 27, 2018 12:41 pm

Came across another odd thing today while printing. See attached. Not having much luck with S3D at the moment. The fine ribs on the S3D print are warped. Feed up with results using S3D I jumped across too Cura and quickly setup a profile at 0.2 layer height trying to match setting as best I could. I printed a small portion of the part and the ribs look straight. The S3D print is at 0.1mm layer height however.

Would anyone have an idea why this is occurring?
Attachments
IMG20181027221847b.jpg

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