Sliding parts - tolerances

I am making a 3 piece sculpture that will have pieces that slide together, sort of like a puzzle box. What kind of gap would I need to make it tight but not too tight? Let's use white plastic for an example. And one thing that is important would be, is the gap measurement on both sides combined or one side only? This makes a big difference! I hope the ascii diagram below shows my 2 parts in a simple form

┌──────┐
│ ╔══╗ │
│ ║ ╔╝ │
╞═╝ ╚══╡
│. . . │
└──────┘


Thanks much!
R.L. Hamm

Hi.

Take a look on material portfolio, click on the desired material and where is read "clearance" you can take this distance.

This is the minimum distance between the parts to be sure they don't melt between them. From A to B, not from A-middlepart plus middlepart-B.

I' ve been reducing this distance in some of my models and it works, but lately shapeways is checking this as rejections.

I hope this helps you. Regards

Luis

You will be able to make a much closer fit if you print them as separated parts, not "as assembled." I have successfully printed mating threads (substantially larger than your garden variety screw) that fit together with only a few thousandths of an inch clearance. You may need to do a few test items of a size similar to your end product to get the geometry just right, as the process varies in consistency as the parts become thicker, due to what might be called "secondary fusion," as the part cools in the powder bed. For a start, in WSF, allow 0.005 inch PER SIDE over and above the clearance you desire at assembly. Do NOT upload the modelled parts in an assembled state, for with only 0.010 inches of clearance they WILL fuse together.

Thanks for your reply, I guess I should have added that I plan to print them separately then fit them together. I guess I will do a test and if it's too tight, I will sand it or oil it
R.L. Hamm

I have used 0.3mm clearance to good effect. If both pieces are printed separately, then fit together afterward, this gives a nice firm snap fit.

I would recommend this number as a starting point for the plastic materials. Other materials will likely have a different clearance requirement.

Thank you!