How would you hold this for turning?

Technical Ted said:
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
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Ted- this is a great idea. I will try it! That's why I post here!
Randy- I have some cerrobend on hand! How would I best use it in this application?

Robert
 
Could you epoxy it to something else and go from there
 
I would turn a stub arbor the OD of the washer, this will allow easy centering. Drill & tap the end of the stub arbor, maybe 3/8-16, and secure the part with a heavy washer and capscrew. Then turn the the securing washer, the part, and the stub arbor to size. The whole process wouldn't take much more time than it took me to type this. (but I type slow at this time of night :grin:)
 
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
Keyed Washer MandrelJPG.JPGKeyed Washer Fixture.JPG

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.
 
jim18655 said:
Might be heresy but how critical is the look and finish of final part? Stick a bolt through it and spin with a drill against a running bench grinder.
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My assumption was that diameter was somewhat critical. This would imply the concentricity is also an issue. Just using a bolt small enough to fit the flats as a mandrel will not ensure concentricity.
 
RJSakowski said:
My assumption was that diameter was somewhat critical. This would imply the concentricity is also an issue. Just using a bolt small enough to fit the flats as a mandrel will not ensure concentricity.
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That's why I asked. Maybe overlooking the obvious and making it harder than it needs to be.
 
Is the hole in the washer shaped and sized for a close fit on a stud or whatever? Or is it elongated to allow side to side adjustment on a round protrusion? If the latter, concentricity may not be critical and Jim's solution might have some merit. It always helps to know the application to keep folks like me from cluttering up a thread with speculation. ;)

Tom
 
Tom, you could be right but I would expect the hole to be a slot with the rounded ends the same diameter as the width of the slot. It always helps to know what the intended use of a part is when deciding what the acceptable .tolerances are. The desired end diameter will end up with a wall thickness of about 2.5mm parallel to the flats. Any non-concentricity will reduce that thickness on one side.
 
I would take a piece of stock and face and tap it so a bolt would fit thru center of piece to be turned down . Then I would hold piece to be turned by pinching it to face of the tapped arbor with a washer and a bolt leaving it loose enough that you can use a roller bearing against the OD to true it up . Then tighten it up and turn it.
Jimsehr
 
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