BUG thread changes the hole diameter :(

[johnptc314159]

if i have a 1 inch diameter hole 3 inches deep and created 1 inch of 1x8 thread at the top of the hole, the diameter of the bottom of the hole changes to 0.872 (which might be the minor diameter of a 1x8)

[ryan.bales]

This is normal. The thread tool will automatically adjust the size of a hole to adhere to the the standard of that type. If you enable modeled threads you can see that the major diameter is 1". Simple threads only show the minor diameter.

[johnptc314159]

BUT it should not change the diameter of the hole below the threads.  Yes the diameter should be to size where the threads are but not where there are no threads 😞

[HughesTooling]

Yes this is a long time bug. Same problem with shafts, here I start with a 30mm diameter shaft and want a M20 thread 20mm long but the whole shaft is changed to 20! I know I can get what I want if I model the shaft with 20mm ends but it adds more steps than's really needed.

Mark

[ryan.bales]

I disagree on it being a bug for holes. You would not drill a 1" diameter hole to put a 1"-8 thread on it. So the bottom hole diameter will be the diameter of the #'d bit used to drill the hole. 

In this case for internal threads - a bit for threading a 1"-8 hole will NOT be 1" in diameter. Its a 7/8" hole.

So you can't have a bottom of hole thats 1" in diameter AND then cut 1"-8 threads on it. The bottom of an untapped hole will be the minimum diameter. Even with a partially threaded hole you still will drill out the diameter for the desired % of threads. 

Shafts is likely because its one body and i agree that is super annoying.

[johnptc314159]

put a one inch hole thru a 2 inch diameter by 3 inch long bar.

thread one end for one inch.

the other end of the hole is changed 😞

[ryan.bales]

Are both threads the same diameter? If not you do need to make TWO holes. If so this does not make sense, i was able to place a through hole and add two threads to it - you can't edit the diameter of one and not effect the other however. Because its two thread features on ONE hole.

As you can see from my timeline - one hole and two threads on either end. Same diameter:

[johnptc314159]

only thread ONE end.  the bore or hole size at the other end ( the end with no thread)  is changed 😞

[johnptc314159]

see attached

[ryan.bales · Accepted solution]

Yes it would be. If you drill for a 1-8 thread, your hole will be the minor diameter to allow for thread cutting in the major diameter of 1". Fusion is exact in that it is based off the minor diameter of what will be drilled rather than the major diameter for adding threads. 

What you are showing is the need for two holes or a counter bore like so:

[johnptc314159]

thanks......  understand your reasoning, took a while 🙂

[ryan.bales · Accepted solution]

Perfect! its honestly easier to see when the threads are modeled too: