ID Workholding question

[rlivergood]

I have a part that needs to go into production to be machined and I have, to my thinking, a nightmare of a workholding situation. I attached a bit of a blueprint for reference, but I need to use a 0.310 diameter hole with flats that are only open to 0.205 to hold my parts. I tried using a 1/2" head diameter 5c collet turned and machined to size, but the head sides end up so thin that they just twist and break. Just to get the sample out, I made a mandrel to size and drilled and tapped the end so that the parts could be machine that way, but that isn't going to cut it when it comes time for production. Also, of the 7 turning centers that I have, only 2 of them have a tailstock, so I can't rely on that for workholding. My idea was that we shouldn't be doing these parts, but that fell on deaf ears. So, any thoughts on how to possibly hold this would be appreciated.

 

[mhajicek]

Are you remachining a cast or printed part? This is often more work than just machining the whole part from scratch.

 

[Zeuserdoo]

Have a look at this. 5C Mini Collets (For Bore Diameters from .065″ '-' .250″) >> Rovi Products, Inc. I think these could work and they can be used in a standard 5C collet chuck.

 

[dandrummerman21]

Can you make a big countersunk hole with a tapped hole in the middle?

Put the bevel gear end into the countersink, and clamp it with the biggest screw that fits in the hole.

Bonus points if you can instead push a custom machined live center in the end. Basically turn it "between centers"

 

[SeymourDumore]

Hard to believe that a website dedicated to purchasing items can be made worse and worse with each "upgrade", and yet it appears Hardinge has managed to perfect that impossible feat!

Anyhow.
The best ID workholding system I have ever seen is the Hardinge expanding collet:
5EC-70 Master Expanding Collet Assembly | 5EC-70 Master Expanding (hardinge.com)

 

[MwTech Inc]

I thought it was me when on their site,,,,yes, awkward and difficult

 

[rlivergood]

mhajicek - It is a powdered metal part. I'm no die setter, but I think that they're molding way to much onto it to be machined, it would be better if it were molded as the print showed instead of the entire back side molded to the large diameter.

dandrummerman21 - That's almost exactly opposite of what I'd done for the sample batch. I wish I'd have thought of that myself, since I think that it would have worked better. But, it wouldn't be good for production. They're going to be looking for 1200-1500 parts a day, which doesn't leave much time for screws.

Zeuserdoo and SeymourDumore - I like these options. I am going to look into them.

Thanks for the feed back, all! I really appreciate it.