[Lionclaw]

My father recently purchased a 3 jaw chuck and adpter from littlemachineshop.com. He apparently selected the wrong thread for our lathe.

Could anyone help identify the thread, and which adapter plate should match it?

Here's some pictures of the dimensions.

On the lathe the thread pitch is approximately .12 and the diameter is 2.15.

[widgitmaster]

Are you sure it's not a metric thread?
Are any other threads or hex nplts metric?

It looks like a 2.15 x 11 TPI, but that is not a standard!
So it could be around 55mm x 3 pitch !

Good luck wiith it!
Eric

[Lionclaw]

I'm really not sure. I suppose it could be a 3mm pitch? I'm really a total noob when it comes to threads and machining metals.

I can't find a lot of info on this lathe. It's a model 1910 A.V. Caroll. The lathe is massive. I might just have to model up the adapter and post it in the RFQ section.

Edit: All the nuts and bolts on the lathe are standard english measurements.

[little bubba]

The only spindle sizes I know of in that range are a 2.25-8 and a 2 3/16-10.

I would say it is definitely 8tpi, but the 2.15 is confusing. Being from a 1910 I highly doubt it is metric. I would suggest you check out Practicalmachinist.com or homeshopmachinist.net. There is probably more traffic over there that has knowledge of the old time machines than here. One of them even has a forum for antique machines.

If you do need a backing plate made, I would suggest calling a tooling supplier, and they can get you a quote from the people that actually make backing plates , and they may even be able to find one on the shelf for you.

Good luck.

[widgitmaster]

Actually it is an error to measure a thread from the points, you would be better to measure the thread using the three wire method!
The pitch diameter is the true dimension of the thread, and the points could have been worn or polished down over the years!

Getting a couple sets of screw pitch gages to see exactly what pitch it is would also be more accurate!

A 6"x1" thick cast iron disk is only about $11 at Enco, and making a lathe's back plate is mearly basic lathe work!

Eric

[Lionclaw]

Thanks for the info guys. I checked up on the adapter that we got from little machine shop. It's 2.25-8. It screws on right, so I'm pretty sure the 8 tpi is correct, it's just a bit sloppy. I'll poke around on those websites and see what I can find.