# adding variable speed to one speed biax



## LEEQ (Aug 2, 2014)

I'm thinking about picking up an older biax. Has anyone remodeled these to have variable speed?


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## Kernbigo (Aug 3, 2014)

a router control may  work, can buy them for under $20


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## LEEQ (Aug 7, 2014)

I'm not super up on all the ins and outs of motors and controllers. Have you hooked one up? I can't afford to fry a high end tool with maybe/probably. I need expert help. Anybody that can shed light on this would be greatly appreciated.)


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## Kernbigo (Aug 7, 2014)

They are a brush type motor, it will work, i used them to scrap ways for years and also had them apart it will work


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## LEEQ (Aug 7, 2014)

I'm guessing the neutral leg runs to the motor unbroken and the hot leg would have the device added to it with the power going from the control to the motor. Does this sound about right? Would a small angle grinder work the same and be a good crash test dummy? Thanks)


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## Kernbigo (Aug 8, 2014)

all you have to do is plug the scraper in to the speed control and plug the control in to the wall  it is a no brainier


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## LEEQ (Aug 10, 2014)

That could not be more perfect. Would it work on the grinder too? Do they have the same kind of motors?


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## Andre (Aug 10, 2014)

When slowing AC motors, especially on a mice machine like a BIAX, try to use pulse with modulation instead of lowering voltage like the common router speed controller.

If the motor whines, it's struggling and trying to suck amps. This is bad for the motor, so if you have to slow it down don't slow it till it whines.


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## LEEQ (Aug 11, 2014)

Are there readily available pwm devices to plug into? Something that would be a simple project that won't burn up a high dollar tool? I can handle basic wiring, I just don't have much of a knowledge base when it comes to motors and controllers.


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## Andre (Aug 11, 2014)

LEEQ said:


> Are there readily available pwm devices to plug into? Something that would be a simple project that won't burn up a high dollar tool? I can handle basic wiring, I just don't have much of a knowledge base when it comes to motors and controllers.



Don't know, I'm not any better at electrical stuff than you! I call myself electrically challenged.


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## JimDawson (Aug 11, 2014)

If it is a brush type AC motor (Universal motor), then a router speed control will work just fine.  A router speed control is pretty much a light dimmer with a little more circuitry.  The technical term is Phase Angle Control.  On the low end, about $15 from HF.  The speed control is OK, but not great.  I have used these on my router and other universal motors without problem.  I did a quick search, and was not able to come up with a plug in 120V PWM controller.

If you want to spend the money, then a DC motor controller is a true PWM controller and will have much better control and torque characteristics than a router speed controller.  Around $100 - $150

A good paper on the subject can be found here: 

http://www.komel.katowice.pl/ZRODLA/FULL/84/ref_02.pdf


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## Kernbigo (Aug 11, 2014)

If you are referring to 4 or 4.5" grinders it will work


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## Andre (Aug 11, 2014)

Kernbigo said:


> If you are referring to 4 or 4.5" grinders it will work



A BIAX is a power scraping tool, not an angle grinder.


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## Kernbigo (Aug 11, 2014)

read my first post!


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## LEEQ (Aug 12, 2014)

We can all ). I was thinking try the device out on my 4" cheap angle grinder if it has the same style of motor. It is much cheaper than a biax if all does not go well. I have not yet heard from anyone at all yet that claims to have actually added variable speed to a power scraper. As such I will not risk it. Poor folks have poor ways. I could invest in this rather cheap control and risk the grinder, making the decision then as to whether or not to buy a single speed power scraper. I would also love to know more about the pwm set up. Even this rather expensive control on a used single speed biax would be much cheaper than I'm finding the variable speed ones. I looked at the paper, but must confess it gets too deep for me. I understand that the router control is the cheapest route with the poorest performance. I like the simplicity though. I could wire the pwm and other components with a lot of hand holding. I'm trying to avoid all that. Or if I knew how /where to shop and could pick up a proper single unit with Crayola simple directions I could cut a cord and wire it up. Love to hear what everyone has to say.


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## Kernbigo (Aug 12, 2014)

I worked in machine repair for 25 years and did a lot of power scraping with a biax, and for life of me don't know why you want to go variable speed. You have the stoke adjustment and that is the control you can use. I have also had a biax apart and they are a brush motor so a router control will work. I just plugged my Makita recipro saw into the router control and it worked fine.


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## LEEQ (Aug 12, 2014)

Why do they make them variable speed now? Smarter folks than myself decided it was worth doing. I'm not ashamed to steal a page from their book.)  Good to know there are folks out there that like the old ones too, though.


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