Drill Press Motor Help

[Steve Reich]

Last night when I turned on my drill press, the motor hummed, but didn't turn the spindle, and then white smoke came out of the little connection box cover that attaches to the side of the motor. I opened the box and found the wires that connect the switch to the motor burned and melted its wire nut. I removed the wire nut and found the copper ends of the wires burned black. I've attached a picture. Before I go futzing around with this, does anybody have any guesses as to what might have caused this to happen and where I should concentrate my attention.

This is a bit distressing because I just spent the month of January fixing this machine, replacing its broken rack so that I can actually raise and lower the table, removing all rust, and repainting it. To do all of that, I had to remove the motor and then reconnect it. When I first reconnected it, it hummed and got quite hot but then it worked just fine and has been working normally for the last several weeks.

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[Charles Lent]

Are you certain that the motor is wired correctly for the voltage that you connected it to?

Does the motor have a starting capacitor (it likely does)? Starting capacitors are the most frequent cause of smoke and starting problems.

If you truly let the magic smoke out of the motor windings, it's time to go shopping for a new motor.

Charley

[Matt Day]

Charley nailed it. Check wiring, capacitor, and if they check out its time for a new motor. Luckily DP motors have common mounts, are pretty cheap, and you likely can find a used one on CL.

[Grant Wilkinson]

I, too, think Charles hit the nail on the head. It sounds like you have the motor wired for 220 input and you are only putting 110 into it.

[Steve Reich]

Thanks for the advice and diagnosis, Charley. I rewired it just as it was when I undid it when I took it apart. It had always worked fine before (I can't imagine that this thing was ever wired for 220). I stripped those wires and reconnected them, and everything is now working as before. No smoke, no excessive heat, and normal power. So, who knows? I'll keep in an eye on it, and like you say, a used 1/2 hp dp motor shouldn't be too hard to find.

[andy bessette]

...I stripped those wires and reconnected them, and everything is now working as before...

Then all you had was a bad connection at the wire nut. You don't need a new motor.

[Charles Lent]

It's not a good idea to use wire nuts on machinery. Over time the machine vibration will loosen them and if the wires aren't twisted together tightly the joint can overheat or fall apart, with a voltage carrying hot wire touching the case. I crimp ring lugs on the ends and bolt them together. Then cover the whole splice with several layers (about 3-5) of electrical tape. Then tuck them inside the case and replace the cover.

Charley

[Ronald Blue]

It's not a good idea to use wire nuts on machinery. Over time the machine vibration will loosen them and if the wires aren't twisted together tightly the joint can overheat or fall apart, with a voltage carrying hot wire touching the case. I crimp ring lugs on the ends and bolt them together. Then cover the whole splice with several layers (about 3-5) of electrical tape. Then tuck them inside the case and replace the cover.

Charley

Actually these wire nuts are as good of connection as you will find. If you install them correctly they will last forever. I know this first hand. We use them on a vibrating work head and if they stand up under the vibration they will take anything your drill press could ever throw at them. You would have to go to an electrical supply house to get them. Here is a link.
zoro.com/ideal-mechanical-conn-set-screw-10-18-awg-pk10-30-1294g/i/G2092194/feature-product?gclid=Cj0KCQjwtMvlBRDmARIsAEoQ8zRPRVhnXMBp 0PYJ_g0pL0oo_og1z2ImRRVSU3Lqp00NGJ8cWdpbOisaAg0uEA Lw_wcB (https://www.zoro.com/ideal-mechanical-conn-set-screw-10-18-awg-pk10-30-1294g/i/G2092194/feature-product?gclid=Cj0KCQjwtMvlBRDmARIsAEoQ8zRPRVhnXMBp 0PYJ_g0pL0oo_og1z2ImRRVSU3Lqp00NGJ8cWdpbOisaAg0uEA Lw_wcB)

[Steve Reich]

Thanks for the additional advice, Charley and Ronald. I will secure these wires with something much better than a wire nut. I very much appreciate the help.