Difficult Machine Bolts On Lathe Chuck

[Martin Angus]

Ok, looks like they were just filling the hole. They were cylindrical nuts with a slot. They didn't shoulder onto anything so I assume they were just pressed in place. Too much rust to even see if they had a knurl on them...very strange. I drilled from the nut side and then the impact did its job and 5 of the 6 came free. Of course there is one in every crowd which just wanted to spin the nut. I made a driver out of an old socket which failed instantly...so I sacrificed a cold chisel and gripped it with vice grips...and 2 hours (and a lot of cursing) later it came apart. Now I need to devise some type of puller to split the chuck open.

Anyway, thanks very much for the suggestions and sympathies. I came to the right place. I do appreciate it.

 

[Wreck™Wreck]

Looks like solid threaded inserts, the slots are for the installation tool. As mentioned it appears to be an American taper spindle mount wherein the SHCS holes affix the chuck to the taper.

It is unlikely yet not impossible that the threads are left handed.
As seen here http://www.ezlok.com/inserts-for-metal/solid-threaded-inserts

 

[TOOLMASTER]

soak it in a bucket of oil for a day

 

[Johnwright]

I think Big Bore Builder is correct. Make some type of spanner type socket to loosen the nuts on the back, possibly using some heat!

 

[Silverbullet]

You will find they are nuts.A special spanner is made to fit them. You should be able to make one to work .