Radius undersized  

Re: Radius undersized

I printed this check fixture and all of the dimensions are coming out good except the circular dimension. It is way undersized. It is supposed to be 31.73mm and it is measuring 31.2 in the X direction and 30.5 in the Y. Any suggestions?

Ummm, 31.73 and 30.5 is a HUUUGE discrepancy.

I mean, If you said you were off by 0.2mm I would say "uhhh there's something HUGE wrong."

I'm honestly sitting here grinding my mind. A picture of the printed part would help.

I seriously don't have any idea, a picture might tell a story though?

EDIT:
What filament are you printing with?
Is it ABS? I bet it's ABS... ASA?

Re: Radius undersized

I have measured this part several times with different calipers and still have the same results. All other dimensions are within .2mm.
Hatchbox PLA / Prusa control using standard PLA settings / 15% infill.
Attached is a picture of the part.
I am going to print several circles at different sizes 20mm high and see where it goes.

Re: Radius undersized

Interested to hear how this went. I printed a rather large fitting for a dust collector, and the dimensions on one of the holes was way off, as you have described. I shrugged it off as being due to needing support.. and will try again soon. Instead, maybe I should print a few simple circles, in multiple orientations, and measure them first

Re: Radius undersized

Brian, you may also want to change the axis 90 degrees and see if that affects the print. I would also try taking the cad drawing and import it to a different slicer. Test your variables with different combinations.

Re: Radius undersized

I was thinking that I may not have turned my tolerances up when I exported it but if that was the case but directions should be out the same in both directions. Solidworks will not measure a STL file. I am printing several rings tonight. 1", 3" and 6" diameters. Maybe 1/2" on each width. Will post results tomorrow.

Re: Radius undersized

I printed some test calibration cubes and they are not coming out square. A 20mm cube is coming out 20.08 x 20.28. I don't know where the additional 0.2mm is coming from.

Re: Radius undersized

I can handle .2mm. (2 sheets of notebook paper). Can't handle more than .5mm. I have tried to see if Prusa posted repeatability and accuracy but didn't see it.

Re: Radius undersized

If everything is equal size why are these cubes filling in differently? I started with one cube in Slic3r, made copies and rotated each cube to a different direction.
The cubes on the right of the bed seem to be even, but on the right the top one is behind all of the rest and the bottom one is ahead of them all.

What causes this? If it's bed leveling how do I check it? All of the calibration checks I've done have been good.

The reason I'm posting is I'm wondering if the same issue that's causing the odd sizes you are experiencing is causing my differences?