Prints not keeping tolerance

These are models i made with the hopes of dialing in the fit of these nesting parts. I used fusion360.

The parts in question are a male part with 8mm diameter cross section at it’s widest point with a 6deg taper and 10mm length. They need to nest with a tight fit into a female negative. I added 10mm additional length for a little handle.
The female parts I made with a 10mm length and a similar 6deg taper; I made several iterations of the female with the 8mm diameter but offset these in 0.05mm increments +/-.

I printed the males with supports and some without supports right on the build plate.

My calipers read the females to be within 0.01mm. of the critical dimensions.
The males printed on platform and supports are way off in length due platform layer compression and due to support distortion. The prints using supports have their bases rounded instead of perfectly flat as van be seen in the pictures.

How can I get these to print with proper fit so that it maintains the tolerances?






The Form printers suck in maintaining proper Z dimension. You can’t win on the build plate and you can’t win with supports. I have better dimensional accuracy printing on my $200 elegoo mars. That said, the Form printers are pretty repeatable, so it may take a few tries, but compensate for the inaccuracy in CAD. If it’s printing 0.6mm too tall, knock back the height - reprint - measure. It usually takes me 5 trials to dial it in. Also, if you’re printing on the build platform, repeatability is going to be hit or miss. Forms’ QC has gone out the window and their build platforms are not flat, I can measure a 0.005" variance in depth across the build plate so a part printed in the middle will be a different height than one on the edge. Do you have a way to measure the accuracy of the angle in your print? If there is Z compression, I bet that angle is going to off too.

Good luck.

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