topic Re: Threaded contersunk hole mismodelled? in Fusion Design, Validate & Document Forum

Threaded contersunk hole mismodelled?

lukas.kochRS23P — Wed, 21 Apr 2021 20:22:00 GMT

Hello,

I would like to actually model a countersunk threaded hole, so I can 3D print it. Unfortunately, it seems to me like the combination of "threaded", "countersunk", and "modelled" does not work correctly. It looks like the thread is only added to the straight part of the hole and does not extend into the countersunk part (see attached screenshot).

Am I missing something here, or is this "wrong" behaviour? Is there a quick way around this?

Re: Threaded contersunk hole mismodelled?

jhackney1972 — Wed, 21 Apr 2021 21:05:22 GMT

Yes, you are missing something, material. The thread ends as it enters the countersink since there is no more material there to cut. You are showing a partial thread and it is sharp due to the angle of the countersink.

Re: Threaded contersunk hole mismodelled?

lukas.kochRS23P — Thu, 22 Apr 2021 08:31:34 GMT

Hello jhackney,

Thanks for the answer, but I don't think I quite follow. If I imagine a screw inside the thread, wouldn't that sharp edge interfere with it? I have managed to create a thread as I think it should look like by splitting the operation in two:

First I add a threaded hole without a countersink, then I add another hole at the same position which only adds the countersink (see screenshot). There you can see that the imaginary screw in blue does not interfere with the material. The drew in the sharp edge I see in the single-operation threaded-and-countersunk hole in red.

Re: Threaded contersunk hole mismodelled?

HughesTooling — Thu, 22 Apr 2021 09:26:57 GMT

Yes this is a bug and id you print will not work. @jeff_strater is anything going to be done about this, I brought this up a long time ago when the new hole dialog was implemented.

The workaround is to create a hole, add the thread as another feature then a chamfer. After adding the chamfer drag it back between the hole and thread feature.

Mark

Re: Threaded contersunk hole mismodelled?

HughesTooling — Thu, 22 Apr 2021 09:37:23 GMT

Here's another way, adding a chamfer to an already threaded hole. The key is you need to pick the edge where the core hole intersects the face.

Here's I've selected the core cylinder and the edge is highlighted. What has to be done is the thread has to be created first then the chamfer added. The hole tool is creating a chamfered hole then adding the thread and you end up with an undercut.

Screencast shows adding the chamfer to the threaded hole.

Mark