MT3 Emergency or Soft Collet?

[Robo_Pi]

Here's a better picture of my lathe spindle:



It's just basically a disk with three clearance bolt holes. The ridge in the middle is the register lip. And the center is an MT3 taper. It's a real simple lathe.

The only problem is that the threads are in the chuck so the bolts that hold the chuck on have to be screwed in from the back. And there's hardly any room to get at them between this spindle plate and the headstock.

So I'm going to try to drill and tap three holes in this spindle plate and drill through holes in my chuck so I can bolt the chuck on from the front. I hope I can drill through the chuck too. It might be hardened too. Darn it!

I might have to live with this stupid arrangement forever. I have no good words for the person who designed this lathe.

 

[Robo_Pi]

Wow ! Gotta make a quick trip , but I'll get back with you . Your objective is to have quick change tooling correct ?

Yes, but only at reasonable cost.

If I had big bucks to spend I'd just buy a better lathe altogether.

If I can drill these parts out like I'm hoping to do I can live with the bolts on the front of the chuck. I don't mind bolting and unbolting as long as they are easy to get at,

 

[rgray]

The only problem is that the threads are in the chuck so the bolts that hold the chuck on have to be screwed in from the back. And there's hardly any room to get at them between this spindle plate and the headstock.

Should have studs in the chuck probably. Then nuts in the tight area.

 

[Robo_Pi]

Should have studs in the chuck probably. Then nuts in the tight area.

I'm kind of doing that already in a way.

I use a very small piece of a hex allen key that I cut. I stick that into the screw head and then use a 6 mm open end wrench to take the screw out. This works way better than trying to the Allen key which is really hard to keep reinserting into the cap screw.



Below is a shot of the screw just about all the way out. You can just barely get your fingers in there to turn it. I would just rather do away with having to get behind this plate at all if possible. If everything was done from the front it would be a piece of cake.
In this photo I'm actually attaching the new backing plate for the 6" 4-jaw chuck.



The 3-jaw chuck isn't so bad because it's only 4" in diameter which is the same as the lathe spindle plate. But with the 6" chuck you have another inch of chuck sticking out beyond the spindle plate, that's much further to reach back in there.

The 4-jaw chuck I bought actually has mounting screws on the front of it. But they will screw into the backing plate I'm making. The backing plate then needs to be attached to the spindle. I could try using studs on the backing plate with nuts like you say. But I'd rather have it just screw onto the spindle plate directly from the front.

I'll see whether I can drill and tap that spindle plate. That will determine what I can or cannot do. If I can't drill and tap it, then I'll go with the studs and nuts. I could go with studs and nuts on the 3-jaw too. That'd be better than the way it is now.

 

[magicniner]

Is there such a thing as an ER series emergency or soft collet that can be modified like in the above video?

I think it's a pretty cool idea and would be far faster for a small production run of parts than having to set up each part in a 4-jaw independently.

Get an ER collet chuck on a straight shank and offset that in a 4 jaw chuck - one set up and a repeatable offset.

 

[Robo_Pi]

Get an ER collet chuck on a straight shank and offset that in a 4 jaw chuck - one set up and a repeatable offset.

You're too clever. I'm embarrassed that I didn't think of that myself. That's a super solution. Definitely the way to go. I'm surprised Joe Pie didn't think of that. Although I suppose with his 5C collets he has the added advantage of having a quick collet release handle.

But yeah if you'd need to unscrew an ER collet chuck every time you may as well just do it as you describe. No special collets required.