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rimfire1903

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#1
hello every one new guy here on the block, J.L. ( just learning), just bought a old timer clausing 8520 in the process of trying to install a variable speed controller, first strike used a cheep light dimmer switch it worked for about minute until it got hot, then speed would rev. up and down on its own, when cool it would run 600 rpm to 2400,
will attempt another pot. soon and will let you know how it went, after i get this to work im going to attempt a dro. on x,y,z
 

rock_breaker

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#2
Welcome Rimfire 1903, not sure a high priced exotic light dimmer switch would last much longer. There are a lot of variable speed technicians on this site. Hopefully some of them will be along soon. Someday a phase converter will be in my future but getting a horizontal mill and a 7" shaper up and running in addition to the household chores keeps me busy.
Enjoy the site.
Ray
 

Z2V

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#3
I see a 3 ph motor and a VFD in your future. Best way to get variable speed. It’s one of the most popular mods, probably 2nd only to a DRO.
 

David S

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#4
Welcome to the forum. If the motor is a typical induction motor you won't be able to use a cheap light dimmer to vary the speed. You can get some to work with ac/dc brushed type motors as in typical ac power drills.

As has been suggested you will need a vfd or some have used treadmill motors and controllers.

David
 

Bi11Hudson

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#5
A light dimmer, or even a high dollar router speed controller, will not work for what you're doing, Even if you can control the speed, it will vary depending on load. As in the heavier the load, the more variation you'll get. The simplest controller for your application would be a DC shunt wound motor and a thyrister controller.

The newer three phase variable frequency controllers came out(industrial) just before I retired from the business. With very little experience with them, I'll have to defer to the more knowledgable people. I don't trust 'em, but a majority of users seem to like them. So a toss-up, in their favor, there. The only application where I used them was forty(40) horsepower and up. They did work, but were very difficult to balance two running together, depending on load.

A light dimmer, and router speed controllers, trigger the sine wave internally, so only part of it reaches the motor. You have been lucky so far as the controller got hot and failed first. A heavier controller would only damage the motor first. They both work with "series universal" motors. A router, sabre saw, Sawzall, drill; things of that nature. A sewing machine motor is a good example. Motors that have brushes...... No brushes? Don't use 'em. Period.
Bill Hudson​
 

TwinDad

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#6
I'm not trying to hijack this thread however I just picked up a Sheldon EXL-56b and I'm curious if it is worth the time and effort to remove the original motor and mount a 3 phase 1.5hp motor that I have along with a VFD? Currently the machine is wired single phase with a 3/4hp motor 220v. I have a rotary 3 phase converter setup with a 7.5hp 3phase motor so that's not a problem. I'm just curious if it is that much more handy to have a variable speed machine? Thanks for any info you can provide on the subject.

Matthew
 

Suzuki4evr

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#7
Welcome to the block Rimfire.
 

Janderso

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#8
Welcome dood
 

royesses

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#9
Welcome to the forum rimfire1903.

Roy
 

Silverbullet

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#10
Hi Rimfire , welcome to the site , ac variable speed for that will be tuff to get and probably expensive to boot . But at worse it'll burn out the motor so then you go with vfd or tread mill dc. Good luck nice mill to own also.
 

Z2V

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#11
Rimfire, I replied earlier but did not notice that you had just joined H-M. Welcome aboard. There are many very smart guys and gals hanging out here and all are more than willing to share their knowledge and offer help.
We like pics here too, LOL
 

rimfire1903

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#12
thank you all for your input,, i'm going to change out the motor to the 3 ph and a vfd thanks again for the help
 

TwinDad

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#13
Welcome
 

Bi11Hudson

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#14
This will be a "theoretical" or hypothetical thought. It just struck me, not very hard, but I have zero experience in the matter. Just the theoretical knowledge of a retired engineer........ Now, it seems that every one is all wound up with converting to 3 phase motors and using the electronicly synthesized variable frequency from the VFDs.

It would seem to me that while single phase motors aren't quite as stable rotationally as a three phase, they do get their speed regulation from frequency, same as a 3 phase motor. By that thought, what would be the problem of acquiring a 3 phase VFD and running a single phase motor from it until such time as the motor conversion could take place?

There would be some limitations, I'm sure. A three phase motor would have a usable output somewhat slower than a single phase. And I assume it would be necessary to disable the phase loss for one leg. But what I see in my mind, a single phase motor should be able to run on a three phase device. Making the voltage match-up, of course. A good many of my machines will work on 120 or 240 volt. Depending on hook-up, of course. 3 phase motors will run on 240 or 480. So, 240 is the common link. For short runs, wire size shouldn't be that expensive.

I guess Sysop should move this thought to a seperate thread in the electrical questions section. It was just a thought that came up as I was thinking about this author's question.
Bill Hudson​
 

rimfire1903

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#15
This will be a "theoretical" or hypothetical thought. It just struck me, not very hard, but I have zero experience in the matter. Just the theoretical knowledge of a retired engineer........ Now, it seems that every one is all wound up with converting to 3 phase motors and using the electronicly synthesized variable frequency from the VFDs.

It would seem to me that while single phase motors aren't quite as stable rotationally as a three phase, they do get their speed regulation from frequency, same as a 3 phase motor. By that thought, what would be the problem of acquiring a 3 phase VFD and running a single phase motor from it until such time as the motor conversion could take place?

There would be some limitations, I'm sure. A three phase motor would have a usable output somewhat slower than a single phase. And I assume it would be necessary to disable the phase loss for one leg. But what I see in my mind, a single phase motor should be able to run on a three phase device. Making the voltage match-up, of course. A good many of my machines will work on 120 or 240 volt. Depending on hook-up, of course. 3 phase motors will run on 240 or 480. So, 240 is the common link. For short runs, wire size shouldn't be that expensive.

I guess Sysop should move this thought to a seperate thread in the electrical questions section. It was just a thought that came up as I was thinking about this author's question.
Bill Hudson​
Thank you bill. I have a teco vfd coming and will try it on a single phase motor I have.will update as soon as possible
Mike diedrich
 

markba633csi

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#16
Matthew/Twindad: having variable speed is wonderful, once you have it you won't want to go back
Mark
 

rimfire1903

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#17
Thanks mark. Thank you for all the help
 

markba633csi

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#18
Mike/Rimfire: You can't use a VFD on a conventional single phase induction motor. You need a 3 phase motor to go with it. Whip out that credit card and start shoppin' ! :D
Mark
 
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