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View Full Version : Millrite won't run at high speed.



Commander_Chaos
10-28-2013, 09:09 PM
My mill has a pair of stepped pulleys to change speed but the motor won't turn the spindle at anything more than 1/2 speed. When I disconnect the belt and turn the spindle by hand it feels like it's moving smoothly, but I don't know what the problem could be other than bad bearings.

Any other ideas before I tear into this?

dalee100
10-28-2013, 09:22 PM
Hi,

I would suspect the motor. Are you sure that you have it wired properly? Correct voltage? A three phase on single phase? Perhaps the motor needs repair. A step pulley setup can't help but run at proper speed.

dalee

Stepside
10-28-2013, 09:22 PM
I would check out the motor. Will it do better when cold? 220V, 3 phase with a dead leg? When my rotary Phase convertor popped a fuse it would still try to make the mill motor run. My furnace blower, 120V would work until the motor got warm and then it would run real slow. How about some more details. See previous post

Don Young
10-28-2013, 09:54 PM
In these cases it always helps to know what was going on just before the problem started. If it is a new setup, that is important also.

This is a common problem if the motor is wired for 480V and is being operated on 240V or the motor is wired for 240v and is being operated on 120V.

Commander_Chaos
10-28-2013, 10:12 PM
Fair enough. It's a new setup, but I wasn't inclined to blame that since the old setup wouldn't turn at speed either.

The motor's new with a new static phase converter (I had another thread on this not long ago). Plenty of variables, I guess.

JoeLee
10-29-2013, 08:08 AM
It sounds like you have either a dead leg or one that is really low on out put. More than likely it's the third leg or the one created by the phase converter. I've seen this same thing before. Some motors will run but run slow with loss of power and my not be noticeable until they come under a load, you might get away with light milling. Changing the belt to a higher speed will put more load on the motor especially off the start and the motor may not start or it may jump, or make noises. Does you phase converter chatter or make any strange noises???

JL...................

EVguru
10-29-2013, 08:42 AM
What happens if you let it run for say half an hour at low speed and then try high?

DR
10-29-2013, 09:34 AM
The static converter is my first suspicion.

jlevie
10-29-2013, 12:21 PM
I agree that the probable cause is the static phase converter. I had a similar experience with a 2hp spindle shaper motor when using a commercial static box. I was able to work around the problem by tuning the system with run compensation capacitors. But even then you are limited to not more than 2/3 or the motor's rating.

A better choice would a quality VFD in the case of only one 3 phase motor. When the shop will have more than one 3 phase converter a purpose built rotary phase converter makes more sense.

Commander_Chaos
10-29-2013, 12:32 PM
I agree that the probable cause is the static phase converter. I had a similar experience with a 2hp spindle shaper motor when using a commercial static box. I was able to work around the problem by tuning the system with run compensation capacitors. But even then you are limited to not more than 2/3 or the motor's rating.

A better choice would a quality VFD in the case of only one 3 phase motor. When the shop will have more than one 3 phase converter a purpose built rotary phase converter makes more sense.

The VFD was the advice I got in the other thread, too. Unfortunately I already had the converter, so I hooked it up to see what would happen. Guess I'm back to square one. Bummer.

Commander_Chaos
10-29-2013, 04:32 PM
Would it be a good idea to buy this?

http://www.automationdirect.com/adc/Reviews/Catalog/Drives/DURApulse_-_GS3_%28230_-z-_460_VAC_Sensorless_Vector_Control%29/DURApulse_-_GS3_Drive_Units_%28230_-z-_460_VAC_SLV%29/GS3-21P0?showReviews=true

kitno455
10-29-2013, 06:27 PM
There are lots of options. I have a Teco JNEV from dealerselectric.com, and a Hitachi WJ-200 from driveswarehouse.com (thru ebay). They are both good, and support three wire control hookup, but I slightly prefer the Hitachi.

allan

MrSleepy
10-29-2013, 06:36 PM
Have you made any phase to phase voltage measurements to see if you have a supply issue or a motor problem.

Throwing money at a fault rarely works if you don't know what the fault is.

Removing all the existing control gear and refitting a VFD gets complex quickly..make sure you know what you're in for

hth Rob.

lakeside53
10-29-2013, 08:46 PM
Pretty a hard to see why an unloaded mill would not be able to power up on a static phase converter. Even on the upper speed ranges, the load is low. Heck, you only need to kick the motor in the right direction and it will run on single phase (which is what a static converter does!). I'd be looing at the motor wiring - wrong voltage, bad/wrong connections etc.

rohamm
10-29-2013, 09:04 PM
my 3-phase Millrite runs off automation direct's GS2. A Warner sc4000 drives w/my Rockwell 11, and I have another autodirect GS1 unit shared by two shop-made grinders. Heck, I even converted my table saw to 3-phase so I could use a vfd to spin a metal-cutting blade as well as use a variety of blade diameters.

Obviously, I think it's the way to go and each of these cost me less than $100 on CL and ebay.

I've never had to endure Chinese manual torture so in my experience these devices are pretty easy to set up.

Commander_Chaos
10-30-2013, 11:15 AM
Ugh. I'm totally out of my depth on this. I'm going to look for someone I can pay to sort this out.

EVguru
10-30-2013, 12:26 PM
Ugh. I'm totally out of my depth on this. I'm going to look for someone I can pay to sort this out.

But then you'll be poorer and won't have learnt anything :)

Royldean
10-30-2013, 12:38 PM
Where in Philly are you located?

Commander_Chaos
10-30-2013, 04:00 PM
But then you'll be poorer and won't have learnt anything :)

I will have learned who to call to fix stuff.

I'm in the East Falls section of Philadelphia, near Manayunk.