Difficult Lathe Fixture Problem

[seco]

I was wondering if anyone can give me some advice on a difficult fixturing problem I have run into.

We are turning a casting that is generally football shaped on the OD. The current solution is to chuck an adapter of sorts with a pocket milled out of the face. We are manually bolting each part to this adapter which is VERY time consuming. The pocket takes care of the rotational forces and the bolts hold the piece flat against the chuck.

The job probably will not support replacing the three jaw chuck with anything more elaborate, a 4 jaw or magnetic, although I think either of these may offer some interesting possibilities.

We really need to increase production, and any ideas would be greatly appreciated.

[Geof]

Post a picture of the part.

[little bubba]

You can mill the profile directly into a set of soft jaws, or pie jaws depending on the part. If its a manual chuck, you can just pull the chuck and slap it down on the mill. If its hydraulic, you are going to have to draw it up and figure out what to mill where on each jaw individually, not that big of a deal. Depending on the shape of the part, you may have to design in some relief for the jaw to open and close.

Another option, make up two of the fixtures that you are using now, then pull the whole fixture with the part, chuck up the second fixture and go. While your changing parts, the machine is making chips, this assumes a CNC and a fixture/part combo that can be easily lifted and chucked.

[CNCRim]

Post picture will help.

[seco]

Thank you for the quick responses, I will try and get a picture this afternoon.

Thanks Bubba for the excellent suggestions. We tried pie jaws originally, but couldn't get a very good hold because of the way the casting is drafted (and the variations in the sand casting itself). Nice idea about swapping fixtures, but it would be a back breaker. The part is already 12 lbs and the steel fixture the way it is designed is another 10. We could lighten the fixture up though, and as a last resort we may try something like that out.

Thanks again everyone for the feedback. I did some searching today looking a some sort of quick clamp system that may hold together in a turning application, but I pretty much struck out on that front too.