Making threads

I have been reading all the problems with making threads. But the real problem has been the creation of the nut afterwards. So see if this would be a little easier, I have downloaded a cupping nut from McMaster Carr then put a rod slightly larger than the threads and did a subtract. This gives me the master die to do the threads for the screws

But I have a problem once I make the master I have noticed the inside of the threads are hollow, what is causing this to happen. I can do a subtract on a solid and it works fine, it leaves a hole right where I want it. Since it works fine this is just out of curiosity as to why this is happening

Some of the thread models on McMaster do this, I’ve experienced as well.
I think I remember selecting an edge on one the the threads and pulling it out slightly, and it made it a solid body without changing the thread profile.
I can’t remember exactly what edge does it, so just play with it.
Maybe it was even the minor diameter?

So does this method solve the problem of threads for the screws, the reason I asked is I would like to add the threads to my project and not have to use a tap and die afterward.

Are you chasing threads after 3D printing? As far as that goes I have no experience with that.

But as far as correcting the model, I vaguely remember what I said above working.

Have you tried to download another fastener with the same thread profile, or download the Solidworks model vs STEP? Are you only using the downloaded fasteners for subracting from the body to make a threaded hole?

Your explanation for how to correct the problem is fine, also trying a different type of file is a good way to check to see what will happen. I got a head of myself. I am trying to keep from going back and chasing the threads afterwards. I didn’t make it very clear sorry I was referring to using the master I created to subtract the threads for the screws.

@Past1320 no sweat. Although I have no experience with printing threads, I can imagine, depending on the print method used, and the size of the thread geometry, that you may have to chase the threaded holes, or even tap them altogether.

Its high time that thread creation is an in-built feature like other legacy softwares like Solid Edge/Works etc instead of the user keying in the parameters and doing boolean operations.