When is it OK to give up on calibration and use Maslow_Scale_X and Maslow_Scale_Y to "fix" scale errors

Troubleshooting
,
1

I’ve been struggling to get my maslow to draw squares - it is giving me rectangles

Rather than burn through wood I have a pen holder fitted and am drawing on cardboard with it

I have tried the automatic calibration, and a manual measurement calibration and I get the same result.

Drawing a 500x500mm square results in a 502x489mm drawing
Nice right angles, but short on the Y axis by 2.25%

This is fairly consistent between the auto and manual calibration

I have a horizontal setup approx 3700x2700mm between anchors
This is the results from @dlang’s fantastic calulator showing the dimensions and a 1mm measurement error in the manual diaganol measurements

image
image502×779 26.4 KB

For the automatic calibration I get numbers that look something like this

Flex measurement: TLBR: 2.514 TRBL: 2.848
...
Calibration values:
Fitness: 0.8983546724010442
Maslow_tlX: 2.8
Maslow_tlY: 2640.5
Maslow_trX: 3720.0
Maslow_trY: 2648.4
Maslow_blX: 0.0
Maslow_blY: 0.0
Maslow_brX: 3756.8
Maslow_brY: 0.0

So, not good, in that they don’t match the measured values at all well but they do give me the same X and Y scale errors when I plot my test squares.

So is it time for me to give up on getting the perfect calibration and just set Maslow_Scale_Y = 1.0225?

It feels like cheating to fix the issue this way without understanding the cause

Any advice is welcome

-Andrew

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2

if it works for you it works for you, period.

keep an eye on it, the error may not be linear, so the scaling may need to
change (either due to position, say near the edge, or due to improvements in
future firmware upgrades)

the x/y scaling is a hack, but that just means it works for at least some
people, even if not the theoretical ‘right’ answer.

David Lang

4 Likes