X/Y steps per mm adjustment? parts coming out slightly smaller  

Please clarify:  Is PrusaSlicer reporting and slicing smaller than your design software specified.

Or is the printer producing objects smaller than PrusaSlicer reports.

It has some small 3mm holes for bolts, But when I use X/Y compensation enough to correct the outer dimensions my holes are almost completely closed.

Almost all design software undersizes holes, extruding into a concave curve is tricky, calibration, as you are doing, is generally suggested but apply the calibration in the source file.

Cheerio,

RE: X/Y steps per mm adjustment? parts coming out slightly smaller

Prusa slicer is reporting same size as design software but when printing x/y dimension is 5% smaller. (always 5% no matter how big or small so its isnt belt slop)

Holes being undersized isn't an issue.  The problem really arises when 3mm holes spaced 100mm apart are now off by 2.5mm each side

On an older printer I was able to modify the steps per mm to dial this in.

I prototype on my i3 then send off to shapeways to have done in MJF which is very accurate. So using the wrong dimensions or scaling on my designs to end up with the correct sizing when printed on the i3 isn't really an option

I happen to have printed a graticule last week for a bridging gauge, at 22cm it is accurate to within an extrusion width, say better than 0.4mm or around 0.01% without calibration.  This is linear, not circular.  If you have not wrongly set the scale value this is what you should expect.

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Cheerio,