Gallery, Projects and General > How do I??

How do I cut some rings?

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John Hill:
Thanks Stew, John

Now why didnt I know that the accuracy question could be solved with money? :D

Actually, I thought I had the solution when I made a mandrel for the MT3 but thats not very repeatable either and I dont know why, maybe my taper is not at good as I thought it was. :(

Alan Haisley:

--- Quote from: John Hill on March 04, 2009, 01:06:01 PM ---Actually, I thought I had the solution when I made a mandrel for the MT3 but thats not very repeatable either and I dont know why, maybe my taper is not at good as I thought it was. :(

--- End quote ---

John, if your MT3 mandrel is not repeating, depending upon how you made it, it is probably dirt or chips inside the bore or on the taper. The mandrel SHOULD be made from oversized stock. Drill and tap for the drawbar first. Then cut the taper. Now, clean the bore, really clean, make sure there are no imbedded chips or dirt or oil in it. Put the new taper in the bore and fasten it in with the drawbar.
Do the rest of the turning to size and facing operations with it held that way. So long as your spindle is not worn out and is rotating true, you should end up with a very repeatable arbor.

Alan

John Hill:
Thanks Alan.

I think I found the reason why my mandrel is not as good as I would have liked and that is that the face I press the work up too is not of a big enough diameter and has too little area to locate the work,  I think that face should have been turned a little concave too?  I usually pay good attention to the chips and dirt issue and have a 'special' rag that is used only for wiping our tapers and the bits that go in them.

Alan Haisley:

--- Quote from: John Hill on May 18, 2009, 10:36:37 PM ---Thanks Alan.

I think I found the reason why my mandrel is not as good as I would have liked and that is that the face I press the work up too is not of a big enough diameter and has too little area to locate the work,  I think that face should have been turned a little concave too?  I usually pay good attention to the chips and dirt issue and have a 'special' rag that is used only for wiping our tapers and the bits that go in them.

--- End quote ---

John,
There may be a small radius where the face meets the mandrel. A little undercutting just at that point may make a world of difference. The face shouldn't really need to be concave, just make absolutely sure it's not convex instead.

Alan

John Hill:
Yes Alan, a little undercutting does describe it better.   Hopefully, armed with what I have learned on this thread I will have more success next time I need to use a mandrel.

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