Possible motor for mill

Small question: I'm working out the wiring for the VFD.
I have no problem with running from the outlet the the VFD. My challenge is what wire to use to run from the VFD to the motor. Yesterday I looked at some 14 ga, three-conductor + ground extension cord and the stuff was easily 5/8"+ thick with all of the insulation and whatnot.
I have 14 ga red, black and white THHN. Can I use the THHN if I put it inside some sort of covering?
 
DavidR8 said:
Small question: I'm working out the wiring for the VFD.
I have no problem with running from the outlet the the VFD. My challenge is what wire to use to run from the VFD to the motor. Yesterday I looked at some 14 ga, three-conductor + ground extension cord and the stuff was easily 5/8"+ thick with all of the insulation and whatnot.
I have 14 ga red, black and white THHN. Can I use the THHN if I put it inside some sort of covering?
Click to expand...

Shouldn't be any problem with using the THHN wire, I assume you're thinking of flexible wire-mold? You can also just ground the machine rather than running a ground wire to the motor from the VFD.

john
 
Thanks John, flexible wire-mold is exactly what I was thinking about... could not remember the name for the life of me!
 
Yup another bit of education in my journey :)


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I connected the VFD last night. Used 14 ga THHN VFD to motor with ring terminals. Worked like a charm.
Motor is silky smooth after tweaking some settings on the VFD.
Sady I discovered that something is wrong with my bushing as it has about 30 thou runout wobble. I think the problem is that the keyway at the bottom of the bushing is not as deep as the top so it's wedging the bottom out slightly. I think that I'm going to try and fix that or remake it before I shell out for a new pulley.
 
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Yeah, every time I've tried to use a bushing to adapt a pulley it never seems to come out right. I'm sure it can be done but for my money I'd either buy or make a pulley the right diameter for the motor shaft.

You don't have anything but time and materials to loose by trying again but don't kick yourself too hard if it still doesn't work. In the long run you'll quickly forget what you had to pay for a new pulley and be super happy about the VFD install. I know that's what happened with me, I couldn't tell you how much I paid for the pulley on my Star lathe but it works great....

John
 
I had another go at the pulley and bushing today.

I used the 4-jaw so I could dial the pulley in nice and true. I chucked it up, called upon Abom79, popped my indicator into the largest pulley groove and got it under a thou of runout in about two minutes. :rolleyes:
Holy moly! The snout of the pulley was wobbling like a weeble! Somehow, I managed to bore the thing off-centre :oops:

I remeasured the bore depth and decided to go 3/8" deeper so I could get the pulley coplaner with the idler pulley.

Commence making horrible cast iron mess. (Yes @mikey, the lathe was fully protected :))

Got it bored correctly this time. Time to make a new bushing.
Still using the 4-jaw I chuck up a length of stock. Dialed it in easy. I'm liking this chuck!
I didn't have to take much off the 1-1/8 aluminum to get a nice, slip fit in the pulley. I made sure to take light cuts to avoid heating up the aluminum and throwing off my test fits. A few passes and all done.

Time to bore. Worked my way up to the biggest bit I have, a 5/8' then back to the boring bar till I hit .0875 bang on.

I decided to not cut a key way. Instead I sawed a slot and then filed it to fit the key like a glove!

Fitted it up and gave it a test run. Smooth as butter, no wobble, no vibration!

Popped the belt on, and the only thing I can hear is horrible grinding from the idler puller.

Pull that off and discover that the bearings are completely toast. After only 30 years of service with likely zero maintenance. :p

So ordered new bearings. For reference there are two 47mm OD, 20mm ID X 14mm thick bearings.

Was a good way the end the day.
Thanks for reading!
 
It's always nice when a plan comes together. Well done. Mike
 
A bit of an update on the motor conversion.
When I fired everything back up the idler pulley bearings were making an awful racket.
I removed the pulley and pressed out the bearings. They were open cage and completely full of dirt and grime from 30 years of use.

Took some measurements and ordered new sealed, lubricated bearings which arrived today.

Just came in from putting it back together. What a difference the new bearings make. There’s only slightly more noise than from the just the motor alone. Very happy with the result.


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