Mill conversion to 3 phase

[DavidR8]

Gee thanks John! Do you have a 2K by any chance?

 

[YotaBota]

Sadly my bushing has about 30 thou runout so I need to remake it or shell out for a new pulley. 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.

You could think of it as kissing a frog and the next one will be the princess.

Great of John to offer help with the pot, if that doesn't work Queale is just down the street in the same plaza as Acklands.

 

[YYCHM]

Sadly my bushing has about 30 thou runout so I need to remake it or shell out for a new pulley. 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.

What does it measure without the key installed? If that fixes the issue I'd be inclined to deepen the keyway.

 

[DavidR8]

What does it measure without the key installed? If that fixes the issue I'd be inclined to deepen the keyway.

In fact I did not. I will do that and see how it measures out.

 

[YYCHM]

In fact I did not. I will do that and see how it measures out.

Measure the shaft while you're at it. Maybe it's not the bushing that's the culprit. Were you measuring off the bushing or the pulley?

 

[DavidR8]

Measure the shaft while you're at it. Maybe it's not the bushing that's the culprit. Were you measuring off the bushing or the pulley?

First measured off the straight part of the pulley shaft, then the bushing itself, at the top and as close to the bottom as I could get.

 

[RobinHood]

Sadly my bushing has about 30 thou runout so I need to remake it

Hi David, don’t give up just yet and go buy a new pulley. As has been suggested, find out where the runout actually is: the motor shaft (not likely since it seems to be a quality, new motor), or the pulley. It could be your bushing, but I see you turned OD and ID in one set-up, so it should run true.

should it be the motor shaft, make a new bushing with OD oversize (about 50 thou or so). Install bushing on shaft. Bolt the motor onto your mill table. Put a turning tool into the mill spindle. You could use a fly cutter with the tool installed up side down - check for cutter clearance (grind if required). Lock the spindle. Turn on the electric motor and skim off the excess material (so the OD fits the pulley) by feeding the motor bushing under the tool. After you are done, the bushing will run true on the OD and a true running pulley will also run true.

if the pulley is the problem, make your bushing ID undersize. Insert it into the pulley. Mount the pulley in your lathe (use a 4J and indicate the pulley OD to run true). Bore the ID to size (so it fits over the motor shaft). Cut the key way.

You should have eliminated the runout.

 

[John Conroy]

Looks like the lowest is 5K ohms. My Teco vfd called for 5K and the Huanyang was 10k.

Sorry David.

 

[DavidR8]

@John Conroy
I just read my manual and I can use anything between a 1-5K

 

[John Conroy]

Great I'll send you one

 

[DavidR8]

Great I'll send you one

I popped you a PM with my address. Thanks again!

 

[YotaBota]

If the top of the bushing is tight and the bottom can be pushed out does that mean you have a taper?

 

[DavidR8]

If the top of the bushing is tight and the bottom can be pushed out does that mean you have a taper?

I think I I discovered the roots of the problem.
The key way was not filed flat along it’s length so the key was pushing the bushing a bit out off centre.
But somehow the bore in the pulley is not concentric. I’m not sure how that happened.

I filed the key way flat and the key now fits flat without movement.
That said I think I have to turn a new bushing because to make the pulley concentric the bore will have to be enlarged.


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[YYCHM]

I think I'll be shopping for a new pulley as the bore is 15/16" and the new motor shaft is 7/8. I suppose I could bore it out and make a bushing but I have no means to broach the keyway.

Hey, I just realise that I have a steel 3 sheave pully with what appears to be a 0.872 bore. It's currently bushed to 5/8". Sheave diameters at the root appear to be 55mm, 80mm, and 105mm approx. Strange arrangement, the pulley doesn't have a keyway but it has three set screws in the root of the smallest sheave.




Would that work for you?

Craig

 

[DavidR8]

@YYCHobbyMachinist Thanks for thinking of that Craig.

I actually 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.
Holy moly! The snout of the pulley was wobbling like a weeble! Somehow, I managed to bore the thing off-centre

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. I really hate machining cast iron.

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.

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!

 

[thriller007]

what VFD are you using?

 

[DavidR8]

what VFD are you using?

This one.

https://www.emotorsdirect.ca/item/t...ht_sourced=3.5&custcol_sca_category_sourced=3


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[thriller007]

This one.

https://www.emotorsdirect.ca/item/t...ht_sourced=3.5&custcol_sca_category_sourced=3


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What do you figure you will have into the motor and vfd project in total?

 

[DavidR8]

What do you figure you will have into the motor and vfd project in total?

Right around $600.
I had all the wire and miscellaneous bits. @John Conroy kindly sent me a 10K pot (it arrived on Friday, thanks very much @John Conroy !)

I chose to go the new route because:
a) used three phase motors are virtually non-existent where I live
b) I wanted a bolt on fit so needed a 145 frame
c) The video series by Clough42 is a step by step install of the 1 hp version of the same VFD

 

[YYCHM]

How much are you into that mill for now?

Ya, I know..... don't ever add her up cuz you'll soon discover that you're eating $10/lb venison