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Need Some Custom Machining Work Done

mrdbdigital

mrdbdigital

The TBS Archives
Hi!

Does anyone here have access to equipment and the capability to enlarge a 0.159" center hole in a pulley to a 0.195" size?

I'm experimenting with some DC servo motors in the attempt to find a cheaper replacement motor for the Pioneer RT-909 and other machines that use the same motor.

Also, where would I go to get some custom sized pulleys machined out of brass for experimenting?

Thanks for any and all information.

Dave :music:
 
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A correctly set up drill press in skilled hands will work for enlarging holes with great accuracy. If you need absolute perfection, you need to move to a lathe that is perfectly set up.

As for custom pulleys- better to use off the shelf pulleys and make a motor speed control. But if you do not mind spending a couple hundred dollars for a one- off piece, just talk to a local custom metal shop.
 
I'd chuck it in my lathe, drill it slightly under, then use a reamer to get to the final size.

Oops, you said it's for a tape deck? Need a pretty decent lathe to keep the center hole concentric, I might be able to keep it within a couple of thousandths but I'm guess you would want half a thou.
 
mrdbdigital said:
Hi!

Does anyone here have access to equipment and the capability to enlarge a 0.159" center hole in a pulley to a 0.195" size?

I'm experimenting with some DC servo motors in the attempt to find a cheaper replacement motor for the Pioneer RT-909 and other machines that use the same motor.

Also, where would I go to get some custom sized pulleys machined out of brass for experimenting?

Thanks for any and all information.

Dave :music:
Click to expand...

Probably just about any full service machine shop could help you out.
 
Almost all small motor shafts are metric. It sounds like you want to go from 4 to 5 mm. That's probably too much to just ram a 5 mm reamer through the existing hole. It needs to be drilled and then reamed. Best done on a small lathe. Any machine shop could do it cheaply enough. As for making pulleys, it takes more time than you'd think and a commercial shop will charge maybe $50-$100 for a single piece. Find a hobby machinist. I do that sort of thing, but only in warm weather- my garage is pretty much the same temperature as the outdoors right now!
 
I guess it would be best to take the motor to someone along with the pulley and just let them do the measurements to get it right.

I don't actually have the motor yet. It is on order and should be here in a few days.

I might be able to use an off the shelf pulley. Does anyone know of a good company to source such an item?

I'm still working on the pictures. The pulley in question is about 3/4" in diameter and about 1/2" inch wide with a rounded contour where the belt runs.

Thanks for the offers and advice.

Dave
 
If the rounded contour is convex, then that's a little harder than the standard concave shape of, say, a clothesline pulley. The convex surface will need to be cut with a "ball-turning" attachment on a manual lathe, a custom-ground cutter, or possibly even just filed to smoothly match the contour. If convex, the bulge is just to keep the belt on and centered. There is likely somewhat of a range of acceptable radii.

Chip
 
Crowned pulleys, I'm thinking like the old AR XA, usually have a lip on each side, so a custom ground plunge cutter is the only practical way on a manual machine. On a CNC machine, the cut can just be programmed in and a narrow tool used.
 
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