Buttress Threads

[Matthew]

Anyone ever turn Buttress threads? I've had a request for a bushing for a plastic 45 gallon drum which appears to have a buttress thread, approx 2", 5 TPI (.200 pitch). Just curious, for the one thread I've been asked to make (2 pcs), would I be best to grind up a HSS tool (will be turning delrin for the bushings)? Is there a form gage used to grind the tool to the proper size? I think I used one for ACME threads in trade school a while ago.

 

Any information is appreciated.

 

Thanks.

[Matthew Hajicek - Singularity]

We've done some buttress threads here. You'll have to use a custom tool, and gaging is going to be hard to come by. We had to have a custom go-nogo gage made, but you sure don't want to do that for two parts. Be very certain which buttress thread standard the customer wants, there are a few different ones with different angles. Then you'll either have to get friendly with your optical comparator or job it out to a cutter grinder like we do.

[crazy^millman]

Yes very different angles. Standard is 7 deg but I have cut 0 deg and that just sucks. It was on 18" long 3/4 dia A2 toolsteel once I got the owner to switch to D2 it as better but still sucked. I would order the tool I think Micro-100 makes a swiss tool for a lathe. I would ask the customer for a mating part and go from there. The idea of the thread is one of strength. We were using them in a pipe bending application and they were about 75% stronger than the standard acme against shearing off.

 

HTH

 

[ 04-02-2007, 05:46 PM: Message edited by: Crazy^Millman ]

[robk]

One of the parts that I'm working on @ this moment has 12.225-10 BUTT-3B threads in it... We are getting them ground. Crazy is correct saying they are @ 7.0°... We are having a custom gage made for these threads.

[Matthew]

All this guy wants is a bushing to go into a plastic 45 gallon drum with a 1 3/4" straight thread in the center (the 45 gallon drum has the buttress thread on it). I have a male and female of the thread so maybe I can duplicate it to a piece of HSS and cut the thread. He wants it turned out of Delrin so I don't really need to worry about it lasting too long.

 

Thanks for the info everyone!