Calibration problems

#1

So I’ve been calibrating my moai and got all the corner columns in spec. A- 10.74, B-10.69, C-10.70, D-10.71. I followed by printing the moai heads which came out flawless. I then printed the ring which was slightly skewed. I tried adjusting the x and y and it got worse and worse. I then reset the values and printed out a calibration cube and again looked flawless. But the ring was even worse. Tried loading a few of my own models and they were terrible! So I redid my calibrations again only this time spending most of the day tweaking hair by hair the galvo and potentiometers via advanced calibration. I’ve gotten it perfect on all but the left side (facing the machine) and just cant get a perfect circle, only an egg shape. Plz help! Also I can only put one photo at a time. Guess cause I’m new?

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#2

i suggest you to go through the Moai checkup guide: http://wiki.peopoly.net/doku.php?id=moai-checkup
the issue is most likely caused by the galvos

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#3

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#4

I’ve literally spent the entire weekend doing a similar thing. I actually found it a lot easier to use the yuan gcode instead, the really fast circle one instead of this as you can instantly tell how far out it is instead of having to wait for it to move around so much.

I used the yuan gcode and then slightly loosened the galvo screws until I could move the motors as per the advanced calibration and tweaked them until they were in the correct spot giving perfect circles, tweaking the potentiometers a little bit to adjust for the squished sides.

Hope that helps

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#5

Are the Galvos pressed all the way in their sockets?

When you say you adjusted X and Y, did you follow this guide? https://docs.google.com/document/d/17EYM9WTy9HMLh6x3lLFIOnQ_dxqDnTRWgukOVBkIxvg/edit

By adjusting the potentiometer you should be able to get the laser to scan the outer circle easily

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#6

Calibration of the galvo is 3 steps:

  1. the inital circle scanning to check, as long as it is close enough, you can skip to step 3

  2. if you find your circle is off center, or significantly bigger or smaller or mishaped, use advanced calibration to fix
    Advance Moai calibration guide:
    https://drive.google.com/open?id=17EYM9WTy9HMLh6x3lLFIOnQ_dxqDnTRWgukOVBkIxvg

  3. once you got it scanning close enough to circle, the remain difference would be taken care in Asura.
    http://wiki.peopoly.net/doku.php?id=moai:asura

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#7

“3. once you got it scanning close enough to circle,…”

What is close enough? We need a measurement or marks on the circle guide to indicate some sort of tolerance. I have no idea how to measure “close enough” without a visual to compare to, or a measurement, or more descriptive text.

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#8

“Close Enough” really means just that. This is a rough calibration and operational verification, not a fine tuning.

If the laser describes a circle that matches the printed pattern without serious deviation, then that is close enough. If the laser is uniformly 1mm off the printed circle then that is a fine start. However, if the laser is describing 1 mm off the circle at 3 o’clock and 3mm inside the circle at 12 o’clock, then you have some work to do.

Your laser printer is probably not accurate enough to make this into a precision calibration. However, as long as the galvos are able to reliably produce a circle then you should be able to do the rest of the Moai’s calibration using the advanced techniques and/or calibration prints.

Welcome to the world of SLA.

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#9

Hi Jevs,

The Moai has a basic inaccuracy in the corner areas. This can not be eliminated by the extended calibration and the subsequent correction in Asura (up to 2.2.2).

Here is a picture of Moai 200 from my post Moai 200 - Measurement and correction of accuracy:

Since the exposure principle is the same for both Moai, the deviations in the corners should also look similar for the Moai 130. This condition is currently “normal”. If you want to print true to size, avoid the corners:

moai200__2019-02-22_critical%20areas

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