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pixpop 18th March 2006 06:51 PM

Removing puleys
 
I'm experimenting with small motors for TT drive. I have motors salvaged from tape decks, VCRs, etc, and many have pulleys (usually plastic, but sometimes brass) that are press fitted, or perhaps fitted while hot. Is there a tool I can get to remove these without wrecking the motor? I want to remove the pulley, so I can add a new one, of course.

These are all small shafts, up to about 1/8 " diameter.

dnsey 18th March 2006 08:01 PM

Take a loop of fairly strong thin cord, pass the shaft and pulley through it, and twist the cord so that it supports the rear of the pulley. Continue twisting until there's a small loop at each end of the cord. Pass a screwdriver through both loops, and use it to pull the pulley off. Works with tight pushfit knobs too!
An alternative method is to drill a hole slightly larger than the shaft through a metal bar, then split the bar lenghways through the hole. Place the halves either side of the shaft behind the pulley, hold them together, and use in the same way as a corkscrew.

EC8010 19th March 2006 08:08 PM

Hmmm. Although I see what the previous poster is doing, I'd be a bit uneasy. You see, you're effectively pulling against the rotor on the motor's shaft. I think there's a very good chance of damaging the motor and not even shifting the pulley. A minature pulley puller might work, but if the pulley has been heatshrunk on, then I think the only solution would be to cut the thing off. You then have the problem of doing that without damaging the shaft and not filling the motor with swarf. Not trivial...

dnsey 19th March 2006 08:42 PM

I'm sure that some pulleys are shrunk on, but most seem to be a very light interference fit, and secured with locking compound. A sharp tug will usually break the joint without too much trouble.
It may help to put the entire assembly in the freezer overnight first, depending of course on the shaft and pulley materials.
Don't forget that once you've found a suitable motor by experiment, a new replacement (of the cassette, VCR etc type) can usually be obtained inexpensively if there's any doubt regarding damage.

peace brainerd 19th March 2006 08:51 PM

Sounds like the pully you want to remove is expendable? Cut the pulley to within a few millimeters of the shaft(so that you don't actually damage the shaft) with a dremel disc, or very very slowly with a small piece of hack saw blade, and then put the blade of a screwdriver in the slot you've just created. Turning the driver will crack the remainder and allow the pulley to be easily removed.

If the motor works are sensitive to debris, keep a vacuum cleaner attachment near to it as you work.

poobah 19th March 2006 09:41 PM

You know... the plastic pulleys could likely be removed with a soldering iron... might stink a bit.

:xeye:

pixpop 20th March 2006 12:30 AM

Hehe, yeah, I guess I could remove the plastic ones with a little creative use of ordinary tools.

I think I'll try to find a small gear puller... now that I know such a thing exists ;)

EC8010 20th March 2006 07:55 AM

Quote:

Originally posted by pixpop
I think I'll try to find a small gear puller... now that I know such a thing exists ;)
Oh dear, I do hope you weren't taking my words to mean that they do exist. I was thinking that one could be made - a stainless steel M3 (or whatever) hex screw to bear onto the end of the motor shaft would be a good starting point.

dnsey 20th March 2006 10:02 AM

They are quite readily available - this was the first that I could find on the 'Net, but most decent modelling shops sell them.

EC8010 20th March 2006 11:33 AM

That's excellent - I shall bear that in mind for the future.


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