I have been wanting to chase threads on my wood lathe for a long time now and just could not find the parts I needed to do it. I wish I could have made a video but I have watched this one many times and I’ll add it here:
He makes it look so easy and I found out that it is!!!!!!!!!!!
All the threading tools they sell are either 12 TPI or 16TPI and they cost about $75. I wanted tools at 11 1/2 TPI- pipe threads because that is what the threads are on all the standard PVC and you never know when you might join the two .
I started looking for an old 1 1/2” or 2” pipe threading die for a couple of years now and could not find one cheap enough to destroy it to get the threaded sections…..........until last Friday at a flea market. I found this 1 1/2” pipe dies from a threading machine and it had one chipped insert.
I used 2 of the inserts and welded them into some 1/4” bar stock to make an internal and external threading tools:
I learned a lot from that video and the first thing is that you need to thread at 100 to 300 rpm.
I checked my lathe and it ran a little over 300 for the slowest and not 200 like advertized for the fastest.
I tried out the tools first on some rounds I had turned and this one was in the sap wood and it worked but the threads were rough.
But it fit the PVC. I did one for the internal thread and had the other piece of PVC:
Any way what you need to do it it start with a chamfer on the outer end of the piece and cut a relief on the inside for a place to stop with the tool before hitting a shoulder.
start withe tool on an angle to cut at least one deep thread.
Then straighten out the tool and let the pitch of the thread pull the tool in . You make and oval pattern of in to the relief then back and in to the threads and round a round like that. Add a little pressure each time until you get to full thread depth. Adding wax on the wood helps and it is best to use a hard wood and turn the piece with the grain and not across end grain
I did some threads on more scrap pieces and they came out pretty clean.
this one is pistachio male and juniper female.
I made a little picture of how to select the diameter of the mating piece
This is the thought process to get to the double depth of threads which is .150” for 100% threads. I go for 66% so I make the hole .100” smaller than what the thread finished at.
I thought this was real hard to learn but it is real simple once you get the right tools. This will open up a whole new realm of wood working for me. In some pieces it will be necessary to make the insert in hardwood and them glue them into the piece so that you don’t have crumbly threads or ruin the piece entirely.
I also think this will be extremely useful on funeral urns.
-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!!