Threading alternate Ivory?

[Hendu3270]

Is it just me, or is alternate Ivory not a good candidate for threading? Was trying to make a section last night and the tenon would chip very badly while trying to cut. Tenon correct size, well lubed with cooking spray, die in a holder, going extremely slow. Haven't had this issue with anything else I've threaded. I could get it threaded, and good enough to actually hold in the body, but it wasn't pretty. Just wondering if this is a "me" issue, or if it's a known material that is difficult.

 

[Brooks803]

that stuff is very difficult to thread. It's a poly resin so it's on the more brittle side of things. Some have had success threading PR's. I don't recommend it just bc with it being so brittle the threads are most likely going to fail one day and snap off.

 

[BRobbins629]

Materials like alternate ivory do much better when threads are cut with a single point tool on a metal lathe or CNC. An easier but more expensive choice is celluloid ivory which threads very easily with tap and die.

you can find some here:
American Art Plastics: Celluloid Pricing and Availability

 

[Hendu3270]

Thanks guys. That's the confirmation I was hoping for. I've only threaded a few of the PR blanks I've poured but they have all threaded easily and smoothly. That's for the body and cap only though. PR just doesn't seem to have the strength for the section (threaded in and out) since it's so thin. Thanks again.

 

[Hendu3270]

Well, I got one of the alternate ivory blanks from Exotics to thread pretty good. One little chip, but really small and near the edge of the threads so I pressed on. Got all the various holes drilled to the appropriate depths to allow the feed housing to insert and screw in snugly, then during shaping, this bubble showed up that was almost all the way to the internal chamber. Ugh! Have another one on the lathe now back at the shaping stage. Fingers crossed there are no internal voids in this one. Talk about taking the wind out of your sails. It's all part of it though. Learn from mistakes, right?