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adjusting for dimensional accuracy?

Posted: November 9th, 2017, 10:15 am
by syadnom
hictop i3 on 1.6.1

I'm losing about .7mm per 100mm on a print (both x and y), is the best method to resolve this to change the default axis steps per unit? currently set at x 80 and y 80. 80x1.007 is 80.56 so it looks like I can be ~.07 under, or ~.06 over.

...or is there another way?

Re: adjusting for dimensional accuracy?

Posted: November 9th, 2017, 12:25 pm
by LePaul
Esteps calculation is the best way. If your firmware allows edits to be saved, you can do it there. My CR-10 does not so I have to run a M92 line with the settings on my code start up

Re: adjusting for dimensional accuracy?

Posted: November 9th, 2017, 12:34 pm
by syadnom
M92 will just set the steps/unit though. Can I do partial steps? Also, what does the M92 line look like for X and Y?

Re: adjusting for dimensional accuracy?

Posted: November 9th, 2017, 2:57 pm
by LePaul
Well, for example, my first line of GCODE for my CR-10 looks like this...

Code: Select all

M92 x81.12 y81.08 E108.13 Z417.18
I did 20mm calibration blocks and used the calipers to find out how far off I was.

Now this video shows you how to calibrate the extruder, but you can carry on this lesson on the X, Y and Z axis too


Re: adjusting for dimensional accuracy?

Posted: November 9th, 2017, 3:00 pm
by syadnom
Thanks. I'll have to do some test'n'measures.

Re: adjusting for dimensional accuracy?

Posted: November 9th, 2017, 3:55 pm
by LePaul
Digital calipers are your best friend!

Re: adjusting for dimensional accuracy?

Posted: November 9th, 2017, 3:57 pm
by syadnom
That's how I found the .7mm discrepancy.

Printing calibration tests now.

Re: adjusting for dimensional accuracy?

Posted: November 10th, 2017, 6:07 pm
by MTVDNA
A discrepancy of .7 mm isn't a whole lot. Keep in mind that some plastics shrink as they cool down, and this may differ per filament, color, etc. If you really need accurate parts, you should probably print a new calibration cube every time you use a different spool.

Re: adjusting for dimensional accuracy?

Posted: November 11th, 2017, 4:48 pm
by LePaul
Good point. I seem to find some colors of the same brand print a bit differently....with white being the worst to dial in