How would you hold this for turning?

If the O.D. doesn't need to be precise or exactly round, I'd walk over to the other side of the shop and introduce it to Mr. Beltgrinder, and be done in about a minute. . .
 
Hi RWM,
as a suggestion, get a sacrificial carriage bolt and center the washer on the bolt and lock it down with a nut and washer.
you could indicate concentricity as desired before locking it down.
you could center drill the carriage bolt head and use a 4 jaw chuck and tailstock center if accuracy is a necessity.
 
RJSakowski said:
An interesting illustration of the order of operations. I would guess that the washer was purchased to simplify the fabrication of a custom part which is a great way to go.

Having a lathe and mill, I would be inclined make a piece like this.
Turn a suitable piece of bar stock to 20mm or so, turn boss with a diameter equal to the I.D. of the keyed washer and slightly less height than the thickness of the washer. bore a suitable through hole and part. Move to the mill and cut the flats. Not having a mill, a little file work will suffice. The flats need not be perfect, they only serve to allow the washer to fit on the fixture. Assemble with a suitable bolt, washer, and nut. The fixture could be made from aluminum to make fabrication easier in the event that hand work was required.

This is definitely the way I would go if I had multiple pieces to modify
View attachment 243545View attachment 243544

Another option would be to solder the keyed washer to a suitable piece of round stock with acid core solder. Pre-tin both surfaces to ensure a good bond. Mount the keyed washer in the lathe chuck and turn to true the fixture to the washer. Flip it around, mounting the fixture in the chuck and turn the washer to dimension. Heat with a torch to separate and wipe the washer with a rag while the solder is molten to remove the solder.
Click to expand...
I would make a nut mandrel with a body diameter to chuck, a turned and milled part like the above writer suggests, then a smaller diameter threaded to fit a nut and washer to retain the workpiece in place for turning; trying to chuck on a nut or bolt head invites inaccuracy, as nuts and bolts are not so concentric hex to threads. Of course on need consider how many washers need to be machined; simpler, one could make the mandrel chucked with the machined flat detail and make a centered slug of steel to push the part up on the holding part of the mandrel with the tailstock, and so avoid the threaded part for the nut and washer to retain the part for machining.
 
You have not supplied the most important piece of information which will have a profound effect on the choice of work holding,
How many parts, 1, 10, 100, 1000?
 
Intended use and how many parts are often omitted when someone asks a "how do I" question. It wouldn't hurt for the OP to include the equipment at their disposal and required accuracy as well.

Perhaps a sticky post in the beginners forum showing how to effectively ask a "how do I" question would help newcomers to the HM forum?
 
Well I'd turn the hole dia a bout 30 thousandth under width. Then I'd mill the flats , then drill and tap for 3/8" bolt with a sacrificial washer I'd bolt them in the lathe turn to dia , file both edges and remove and repeat. Till orders done.
 
Wow, thanks for all the replies! Concentricity is important but the tolerance is about 0.010. I will need 4 of these. They are axle washers for my electric bike. It has a 14 mm flatted shaft.

Here is what I did: I sandwitched the part between two washers on a 10 mm bolt. Similar to what RJ showed but without the special mandrel. I then mounted it in the lathe and used my ball bearing bump center device to get the OD centered before fully tightening the nut. See Jimsehr's comment. I then took light cuts of .005 to reduce the diameter. Came out great. One is off about .006 and the other about 0.010. Two more to go later.
Robert
 
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I have a small 4 jaw chuck ( sherline ) that the part will just fit on that's how I would do it
 
Could the last two be ganged on the 10mm bolt and done together?
 
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