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The slicer does maintain hole diameters, but just like CNC milling HDPE, you should expect dimensions to change a little after printing. If you need to have a t
by LeifCarrotson 5y ago
The slicer does maintain hole diameters, but just like CNC milling HDPE, you should expect dimensions to change a little after printing. If you need to have a tight tolerance fit on something, expect to run a drill or chucking reamer through it after printing. If it's really tight tolerances, it's easy enough to melt or press a drill bushing or threaded insert into an oversized hole to get fits tighter than you're likely able to hit with a mill.
Your expensive parts likely go through many steps before and after manufacturing already that involve things like fixturing the material in place, rotating it and reacquiring datums, running taps through by hand, deburring sharp edges, etc; you should not expect 3D printing to be as easy as sending the STEP file to the machine and getting a complete part out. Sanding, acetone vapor polish, drilling, reaming, tapping, etc. are normal parts of the manufacturing and prototyping process.
- andi999 5y agoWhich slicer do you use? It seems to be a known problem of cura.
- sokoloff 5y agoI use Cura. It’s across FDM printing techniques and is (somewhat) akin to the errors in subtractive manufacturing. Subtractive errors/inaccuracies tend to be of the type that remove too much material. Additive errors/inaccuracies tend to add material. My models for FDM often include a “hole size compensation” user parameter and I tweak it to introduce an offsetting bias in through-holes. (Non through holes tend to get heat-set brass inserts, which are more forgiving of the 0.1mm or less radial errors.)
- 2muchcoffeeman 5y agoYou can print a clearance tolerance test to see how accurate your printer is. I use a Prusa mk3s and as accurate as it is, at best my tolerance is 0.1mm. Enough to stop your parts fitting together. I normally build in a 0.2mm tolerance for close fitting parts.
- _carbyau_ 5y agoI have had the issue with both Cura and Simplify3D. For a circular hole, as far as I can tell the slicer commands the hotend path to trace the circle exactly, rather than tracing a slightly bigger circle to account for output thickness. I imagine if you were to use smaller nozzles the issue would be lesser, but not gone.
- theelous3 5y agoJust an fyi drills are not good for tight tolerances. They cut trilobular holes, not circles. Reaming or boring are the route to tight tolerances.
- elil17 5y agoIt is much tighter than 3D printing, though - good enough for most cases if you’re using a drill press