Expanding Mandrels - How well do they work?

[Nelson_2008]

When I first learned of expanding mandrels (and saw some low resolution pictures), I incorrectly assumed that there must be some inherent mechanical means of drawing the sleeve over the arbor to expand it.

So just sliding the sleeve over the arbor by hand expands the sleeve and generally grips the work with enough force to machine it without easily coming loose?

Sorry if this is a stupid question.

[marcel beaudry]

Hello Nelson

Yes this is how they work, but do not take heavy cuts or you will damage the taper if it slips.

alway's machine toward the larger end that is in your chuck

Marcel

[Nelson_2008]

Hi Marcel,

Thanks for the reply.

Let me see if I understand your recommendation: I should always cut toward the larger end of the tapered body (i.e., mandrel), which would be towards the headstock? Is that right?

Also, since I can't seem to find the proper size lathe dogs for my setup, I'm thinking about using some cheap set-screw type shaft collars, with the short set-screw replaced by a longer screw which is driven by a bolt mounted in one of the slots on the faceplate. Does that seem workable?

Lastly, I just got a set of five expanding mandrels, supposedly covering the range of 1/2" to 1"; and the diameters of the drive ends of the mandrels all correspond to "standard" shaft sizes, except for one mandrel, which is 21/32" diameter. So here's my question: If the shaft collar idea will work, should I bore out a 5/8" shaft collar to 21/32", or would 0.03" of clearance on the diameter be ok, allowing me to use an 11/16" shaft collar for the 21/32" mandrel? Thanks.

Regards,
Nelson

[marcel beaudry]

Hello Nelson

Yes the collar would work ,
yes alway's work toward the larger end of the taper taking small cuts.
if the mandrel expands to the size you need it should hold your part ,
remember you must force your part on the mandrel usually i hold the mandrel and the bushing holding the part and just tap it on a wood bench to hold everything together

Marcel

[Nelson_2008]

Do you think a shaft collar with an ID of 11/16 (0.6875) inches would have too much slop to work as a lathe dog for a mandrel with a diameter of about 0.653 inches, or would it be ok?

Also, do you think aluminnum shaft collars would be ok, or would you go with steel? Thanks.

Regards,
Nelson

[marcel beaudry]

Nelson

It all depend on how heavy the cut you take as long as you take small cuts you will be fine

Marcel

[Andre' B]

Arbor or mandrel press.

http://books.google.com/books?id=FUp...YPES#PPA148,M1