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Tapping arbor to add bolt instead of pulley

jordanirvin

Plastic
Joined
Oct 27, 2019
Hey all,

I"m trying to make a sanding mop, so I need to clamp the sandpaper from both sides. I'd like to use an existing motor, but it's arbor is set up for a pulley and woodruff key or set screw. However, I want to use all-thread, but this isn't compatible with the motor's setup. Has anyone tapped an arbor to accept a bolt/threaded rod?
Are there any issues with strength of a 5/8" arbor if I tap in for a bolt ~1" deep? I'm thinking I need to have a machine shop do this, since I'm not going to be able to drill straight into the arbor, and would probably booger up the threads too. However, if people have suggestions for a low tech and/or low cost option, I'm all ears.
 
Many years ago I used to buy threaded arbors that mounted on a motor shaft. While they increased the distance from the mounted buff.flap wheel etc. to the motor housing I never found it to be a problem re bearing wear but your results may vary. If you check around someone probably stills sells them. If not you could easily make one on a lathe. Bore most of the length for a snug slip fit on the shaft and drill and tap for a couple of setscrews. Cut female threads in the remainder for your allthread.

Edit: Yup, they are still sold.

Clesco AS-4FS 1/2" Motor Arbor to 1/2" Threaded Shaft Adapter - - Amazon.com
 
If you try to put a 5/8 bolt into a 5/8 arbor or motor shaft there will be a problem. ;)
1/4- 20 and no worry.
Most of these are not hard, a skid test with a file tells you.
Ideally one makes a sleeve to hand drill it straight. In the field you just eyeball up/down, right left and drill by hand.
You clamp the arbor/shaft and try not to wobble. Then you just tap it, same try to align as best possible.

If you have a lathe and lots of time you make guides, bushings or just an adapter, otherwise you just make a hole and thread it.
As Scottl has said is there nothing you can just simply buy.
What I would do at my cabin is much different than what I would do in my shop.
Bob
 
Many years ago I used to buy threaded arbors that mounted on a motor shaft. While they increased the distance from the mounted buff.flap wheel etc. to the motor housing I never found it to be a problem re bearing wear but your results may vary. If you check around someone probably stills sells them. If not you could easily make one on a lathe. Bore most of the length for a snug slip fit on the shaft and drill and tap for a couple of setscrews. Cut female threads in the remainder for your allthread.

Edit: Yup, they are still sold.

Clesco AS-4FS 1/2" Motor Arbor to 1/2" Threaded Shaft Adapter - - Amazon.com

Thanks for the link to the shaft extender. I was hoping for something longer, but this isn't too expensive and might work. For the other replies, I'm glad to hear that you all don't think this is too crazy of an idea. I was worried about not getting the initial hole and the subsequent threads straight leading to a lot of wobble on the end of the threaded rod. Cutting the female threads on this will be done with a hand tap, but I can use the drill press to keep this straight. I think I'm going to try that, and if the run-out on my all thread is too great, then I haven't really done any damage to the shaft itself.
 
What is the speed of your motor and what is the length & diameter of the all-thread you're considering?

It seems unlikely to me that your rod will run true, and if it starts to wobble at high speed you could have a serious disaster.

Saw the aftermath of an S&D drill in a drill press that was started at high speed. Bit shank just bent at 90 degrees and smacked into the column, welding itself on. Luckily no injuries.
 
Thanks for the link to the shaft extender. I was hoping for something longer, but this isn't too expensive and might work. For the other replies, I'm glad to hear that you all don't think this is too crazy of an idea. I was worried about not getting the initial hole and the subsequent threads straight leading to a lot of wobble on the end of the threaded rod. Cutting the female threads on this will be done with a hand tap, but I can use the drill press to keep this straight. I think I'm going to try that, and if the run-out on my all thread is too great, then I haven't really done any damage to the shaft itself.

Just a couple of quick notes about your plan, in case this is foreign territory: 1.)Make sure to countersink the tap drill hole before tapping, to approximately 10% over the major diameter of the thread you are tapping. Helps greatly to center and and start the tap properly. 2.) Use a good-quality HSS tap, not a hardware-store "carbon steel" tap.
 








 
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