How would you hold this for turning?

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Robert
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I need to turn down the OD of this specialty washer. It seems to be mild steel. I am not sure of an easy way to hold it. I could make an expanding mandrel to fit the hole but that will be somewhat complex. Is there a simpler idea out there???

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The OD of the washer is about 24mm and I need to take it down to 21mm.
Robert
 
If the I.D. across the two rounded sides was close a common size I would probably grind two flats on a bolt and use that as an arbor. The non-flattened sides would still have threads enough to use a nut or pair of nuts to hold the part.

Might have to use a narrow parting tool to sneak in between the nuts to make the cut, but if you only have to do one part it wouldn't be bad. Multiples might want a better solution, though.

-frank
 
If it were me, I'd probably try to super glue it to a faced off piece of material and take fairly light cuts. Acetone or heat will loosen the super glue when done. You might have to use a four jaw chuck to line it up unless your glue job is spot on center.

Worth a try!
Ted
 
1+ with the suggestion from Technical Ted.

I had parted a thin disc from a piece of steel and as "Murphy" would have it the part I wanted had an uneven face on the parted side.

I used CA glue (super glue) to affix this to a piece of aluminium so I could face off the piece. If I had needed to fix the OD, this would have been easy.

The part can be removed by either a good tap, or applying heat. A hair dryer on High setting may be sufficient.

Whatever is used to mount the work needs to be sacrificial.
 
Thanks all! I have not had good luck using CA glue to hold parts. It may be my glue. Who makes the best CA glue?
The center hole is 14mm. I think a mandrel is the best option so far.
Robert
 
Another idea is to find a bolt that will fit through the hole and then clamp the washer between two nuts. Chuck up on the bolt and go to work. You could even us a 3 jaw chuck and then tap the washer to line it up before clamping it tight for final turning.

Edit: Or if the bolt is threaded all the way, just use one nut and the head of the bolt to hold it. Whichever works out better for you...

Ted
 
I agree with Ted. I do this quite often for small & thin parts except I use 5 min epoxy. Epoxy releases easy with heat & in my case I need parts to be free of any glue residue. Since heat will loosen epoxy, careful not to get it too hot.

I never tried CA so I'm not sure which holds better. My guess is the CA may hold better but CA won't always come off clean on many materials.

In this case since it has a through hole I'd probably go with the mandrel route. You don't necessarily even have to make something with the 2 flats. You can just use a bolt that will fit inside the 2 flats. Drill & thread a hole in a piece of stock for the bolt. Then slightly snug it, if you have one of those ball bearing pusher tools you can use that to get it centered up well enough, then tighten down the bolt. Or use a 4 jaw.
 
I would use a rod with an OD smaller than your 21mm and turn a short section the size of the rounded part of the ID of the washer. The length of the short section would be just shy of the thickness of the washer. If you have them, use collet blocks to cut the flats. Then drill and tap for a bolt or screw to go in the center, slip a washer on the bolt and lock it all down. If you have many washers to do, this would be the fastest, simplest way to securely hold them.
 
If you can deal with this cost, Cerrobend or one of its cousins are made to solve such problems.
Randy
 
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