I have used my chuck for quite awhile but I was just wondering why there is a threaded hole in the back end of the adaptor (the side facing the headstock when mounted). The threads in the hole are quite fine but there is nothing in the hole. If I shine a flashlight into the hole I can see the threads from my headstock. Is this meant to use as and additional hold down? I would hesitate to do that as it would ruin the headstock threads. Any thoughts on this?
The treaded hole is for keeping the chuck spinning off of the headstock when you have a lathe that can turn reverse or one that can be stopped quickly. These lathes have a groove turned for the setscrew to tightened to, metal lathes all have those grooves. As your lathe does not have a flat groove, you probably don't need the setscrew, but if you want to use one than the easiest way would be to use a nylon/plastick setscrew, it will not damage the spindle thread, or you could use a plastic plug between the setscrew and the spindle.
I believe that hole is for putting a grub screw in to hold the chuck on when turning in reverse. I'm not sure, but I think some spindles have a flat at that spot. Mine doesn't, but I don't have a Oneway lathe...
Hi Bradford If you have an adapter to fit another lathe, it would not be in your chuck when on the first lathe, wouldn't fit right. You would keep the adapter on your other lathe so you can use the same chuck on both lathes even so one lathe has a different thread size from the other. There is a problem with the set screw, in that it was made to fit on the Oneway lathes, some of the other lathes also have the flat area machined into their spindle but not at exactly the same distance from the shoulder the chuck seats against, and some lathes just don't have the flat area. Most people do not need to have the chuck locked to the lathe, but for the very large lathes that have the breaking resistor to quickly slow down the lathe the large bowl blank could spin the chuck off the spindle, when the lathe is stopped, or if the lathe is reverse turned on. Have fun and take care Leo Van Der Loo
Bob, Are there perhaps two threaded holes like you describe instead of only one? If so, these are used when you're removing the threaded insert. You remove the screws (3) that are holding the insert in place, and thread them through the threaded holes. Then you tighten them sequentially to force the adapter to 'pop' out of the chuck body. Tom Weber
leo is right as to the purpose. But he is mistaken in that not all metal lathes have a groove for such a use - for example my metal lathe does not - it has 2 1/4X8 threads but no groove - and the chucks that go with it don't have the set screw either (and a little setscrew wouldn't do much against the forces a metal lathe sees anyway)
My wood lathe will turn in reverse, and I have not had any problem with the chuck unscrewing with a finished piece on it - so I'm not convinced the little screw is needed - I have had the chuck start to unscrew if I brake too fast with a heavy piece on the lathe (e.g. 50 pounds or 100 pounds), but that's a different matter, and it's why I keep the tailstock in place when roughing big pieces.
Hi William I assume there are always exceptions, however that has been my experience, (metal lathes having a groove for a setscrew, to keep the chuck from unwinding) Of course the machining is done in forward and no forces are applied to the setscrew, as for the chucks, when we would get a new chuck, they where just plain back chucks and the semi machined back plates, we'd have to machine those for the lathe and the chuck, and yes drill and tap for a setscrew, of course no camlock spindle noses. I use the large #5 MT on my chuck so there is no unscrewing with that, (I can flip it from outboard to inboard as I have only thread on the inboard side, but taper on both sides), however if I had a 100/150 pound piece of wood starting to unscrew the chuck because my lathe was stopping to fast, I would not expect the sliding resistance of a tailstock to keep it from doing so, and a good setscrew would be a more appropriate way of not having this happen IMO. It would be nice though if all the wood lathe manufacturers could come to a common position for a groove in their lathe spindles, but I guess I shouldn't hold my breath for that. Have fun and take care Leo Van Der Loo
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