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Prints are oversized compare to drawing

I got Form 3 at the end 2019. Still printing on the basic black resin on the highest quality. But all parts I print are little bit oversized. I see all dimensions are around 0,1 - 0,2mm larger. It means holes with the expected inner diameter 3mm are actually only around 2,9mm, parts length are around +0,1mm longer., wider…etc. I still need to do a lot of sanding with the sand paper.

I work with the endineering prototypes. Smaller mechanical parts with the tolerance around 0,1mm. So when I print components, I canot assembly unless I sand all dimension. Which is sometimes crazy :-(.

This “oversize” is directly after printing and washing in alcohol. After curing still same.

Is it normal? Just printer limits? Or any more expensive resin could have better results? My firmware is rc-1.4.4-468

Thank you for your advice. I could not find similar topic on this forum.

Jan (Czech Republic)

General tolerance for most additive manufacturing processes are +/- 0.2 mm. you can verify this with any service bureau,(materialise, shapeways, xometry) it’s still difficult to offer tighter tolerances for general purpouses. You can do two things, design to compensate the machine error or get a form 2 to tune X/Y dimensions.

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Any holes you make in a print are going to end up slightly smaller than designed

@airsoftpro did this ever get resolved? I bought a Form 3 a couple months ago and though the parts look good, the sizes are off such that mating parts don’t fit properly. I’m not new to 3D printing, just new to Formlabs and am surprised to hear there’s no way to calibrate the dimensions. Sure I could go manually compensate my models but that’s something I’d expect using an entry-level printer. Has Formlabs added a calibration function for the Form 3 that you know of?


I see now after searching for “accuracy” that there’s a “Fit Tuning” function on the Form 3 that looks pretty cool. Using the fit between two printed samples (peg and hole if you will) rather than relying on an individual’s ability to measure parts is a clever idea.