Modeling tolerance question for inserts, hardware, hinges, etc.?

[KaisoBuild]

I just received my Creality CR-10. I’ll be using it to makesitems like the picture. (approx. 2.5”-1.5”) My questions regards tolerancesfor modeling. e.g. The nut for the clamp fits into the recess. The screw goesthrough the hole. Any suggestions on a tolerance for easy insertion that’s notto slack? Would tolerances be different for different materials, PLA, ABS,Nylon, etc.? I realize each material may have different requirements, I’m justlooking for a place to start.

Also, how precise is a printer like the CR-10? My clamp doesnot currently have the edges filleted. However, I do not want them to be sharp. Should Ifilet the edges in the model, or it the print resolution such that the edgeswould not be sharp?


clamp.jpg

[curious aardvark]

edges shouldn't be sharp. A set of small files and sanding blocks also comes in handy.
You should find that if you print stuff at 0.2mm layer height, tolearances are pretty good.

First time I made a threaded part I was surprised at just how much difference there was in the bolt thread and hole. It does depend on the size of the thread - but I think I was making the bolts around 30% smaller than the threaded hole for a smallish clamp.

Every machine and filament combination is different.
So you'll just have to print some stuff and then work out if you need to adjust anything.
3d printing is currently as much an art as a science and every 'machine-operator-workshop-filament-print surface' combination is unique.
What works for me may not work for you and vice versa.

[KaisoBuild]

Thanks for the reply. Did you really mean 30% or 3%? Or am I misunderstanding something? I've finished the model and exported the .stl. All check show watertight and no errors.

[curious aardvark]

I know right - I meant 30%
That was for a fairly large thread that was fairly loose but still could be tightened without a problem.

Presumably the smaller the thread the lower the size difference needs to be.

It might depend on what cad software you use and how you generate threads. I use openscad and used a thread module someone wlse wrote.
But I was surprised at just how much smaller I had to make the bolt.
(checks openscad script
)
Oops tell a lie - it was actually 16.5 %
Still a fair bit of difference, but a but more realistic than 30 %
Sorry :-)