stevo1
Cast Iron
- Joined
- May 27, 2008
- Location
- Great State Of Wisconsin
I have not been around in some time now. I hope everyone is doing well.
I have a controversial question for all regarding minor diameter on a thread call out. Let’s use a .625-18 UNF call out on the print. Our customer prints call out the drill size to use for the hole. So the call out looks like so on the print.
.5781 +.015/-.005 DRILL THRU
.625-18 UNF TAP THRU
Question I have gone a few rounds with some colleges on is that the minor diameter of the thread has to be within the .5781 +.015/-.005 call out once the hole has been tapped. The hole tightens up once the tap runs thru and sometimes the .5781 hole is undersized by a few thousands. I always check the hole size before I tap to make sure I am in spec. Once tapped I no longer check it as I would think that the minor should be developed if need be by the tap. Also the fact they call the drill size and do not say that the .5781 is the minor diameter.
The argument with others is they state that because it is called out on the print that you have to maintain the hole size even after it is tapped and the customer should be able to put a pin gage thru and still be in spec.
Anyone know some kind of official standard on this so I can close this discussion? I breezed thru the machinist book and didn’t find anything.
Thoughts??
Thanks,
Stevo
I have a controversial question for all regarding minor diameter on a thread call out. Let’s use a .625-18 UNF call out on the print. Our customer prints call out the drill size to use for the hole. So the call out looks like so on the print.
.5781 +.015/-.005 DRILL THRU
.625-18 UNF TAP THRU
Question I have gone a few rounds with some colleges on is that the minor diameter of the thread has to be within the .5781 +.015/-.005 call out once the hole has been tapped. The hole tightens up once the tap runs thru and sometimes the .5781 hole is undersized by a few thousands. I always check the hole size before I tap to make sure I am in spec. Once tapped I no longer check it as I would think that the minor should be developed if need be by the tap. Also the fact they call the drill size and do not say that the .5781 is the minor diameter.
The argument with others is they state that because it is called out on the print that you have to maintain the hole size even after it is tapped and the customer should be able to put a pin gage thru and still be in spec.
Anyone know some kind of official standard on this so I can close this discussion? I breezed thru the machinist book and didn’t find anything.
Thoughts??
Thanks,
Stevo