Home made expanding mandrels?

A

Aaron_W

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One of my main interests in getting a lathe was for making small scale model truck wheels. Looking around and seeing how rings are made, I'm thinking a small expanding mandrel would be very useful. These seem to have a very limited range for holding, but also seem fairly easy to DIY allowing for the exact size I need for a project. I've found a few tutorials for making these, but none seem to give a recommended size for the expansion slits. I'm probably looking at a couple mandrels to cover 5/8"-1" in diameter.

For the price of a set of expanding mandrels I could get myself a slitting saw arbor and a couple sizes of saw. I know I want a 0.01" for another project, but not sure how large I should get for making a mandrel. Sherline carries the 2" saws for their arbor in thicknesses of 0.01" to 0.057"

Maybe I'm over thinking this, the slots allow the "fingers" to separate so does the slot thickness even matter?

Assume I should do these from an easily worked steel rather than aluminum, any recommendations for material?

Thanks
 
Hallo Arron.

I did a thread on expansion collets I made and they work very well. I got the idea from the guys of this forum so you can check that out. In my experience,the size of the slit does not matter at all,I would say that the thinner the better 0.7mm or so is fine. Aluminium is good for this application and would machine and cut easily, but 12L14 or EN1A(1112) would work well. I made mine out of EN1A. The main thing is to expand the arbor a bit and machine the outside diameter to the final internal size of your ring or bush so that when you clamp your workpiece it will clamp evenly. Hope this helps.

Michael
 
There was just a You tube video done on expanding internal and external arbors, Joe Piesinsky ( SP ) Advanced Innovations is who posted it. Worth taking a look.
 
There is a good video posted in the Tool junkie section under bushing internal clamping tool, that I posted and,I can't remember who,posted that video and it helped me alot.
Good luck.
 
David S said:
Yes I think that Joe's video is a very good one. He shows how to make them without the conventional slitting, by using O-rings instead.


David
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Yes I think that is the one. Very informative.
 
I was just going to suggest Joe Pi's videos. I've made a couple. Its pretty simple. The real trick for good mandrels I thought was to expand them amd then machine them back to size so they are a more uniform fit with more uniform clamping pressure. That is something I would not have thought of.
 
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I for one can be extremely fussy about wheels, handles and such that wobble when rotated…extremely fussy! And to make a wheel, handle and such to turn true when mounted on its end result is NOT an easy task! Using an expanding mandrel is one way but maybe not the best in all applications. You want to duplicate the mounting exactly from machine making (ie: lathe) to final use…Dave
 
One thing you might want to consider is the screw . Many life times ago I was told that using a flat head screw was not the best choice . I was instructed to make a screw that had more of a Morse taper on it and I was given some matching C'sinks to use for the mandrel . I was working in a shop that was building a 35mm motion camera , we were making lots of egg shell thin round parts . Anyhow I made up a few screws that had different lengths and diameters to work in mandrels of various shapes and diameters .
 
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westsailpat said:
One thing you might want to consider is the screw . Many life times ago I was told that using a flat head screw was not the best choice . I was instructed to make a screw that had more of a Morse taper on it and I given some matching C'sinks to use . I was working in a shop that was building a 35mm motion camera , we were making lots of egg shell thin round parts . Anyhow I made up a few screws that had different lengths and diameters to work in mandrels of various shapes and diameters .
Click to expand...

I used M10 countersink hex screws. Screw lengtes was in accordance to the collet lengths.
 
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