Slowing down a tile saw's RPMs - Contractor Talk - Professional Construction and Remodeling Forum

ksskss · 10-04-2009, 12:05 PM

Can you slow down a tile saw to a lower RPM?. I'm not sure if a rheostat would work or burn up the motor. Ideally I'd like to just plug the motor into this device and plug the device into an outlet. Also it's a Rigid saw, which probably has a motor similar to a Dewalt, rather than a continuous use type motor like a Baldor motor. I'd also be interested to know if anybody has done anything to slow down a Baldor too, so let's make the topic more general than just my needs, but please specify what type or model motor or tile saw you either got this to work on or messed up.

Another question is if the GFC circuit would interfere with doing this and trip if it gets a lower amount of signal (voltage).

Why would I want to do this? I'm told that a slower speed may help me reduce chip out and particularly reduce shattering when cutting tempered glass - another question I asked on a separate thread.

Another approach I'm probably going to use is to use a smaller blade - smaller circumference instead of lower RPM to reduce the feet per second going by the material being cut. I'll probably do both tricks if I can.

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Ken

neolitic · 10-04-2009, 12:35 PM

Quote:

Originally Posted by ksskss

Can you slow down a tile saw to a lower RPM?. I'm not sure if a rheostat would work or burn up the motor. Ideally I'd like to just plug the motor into this device and plug the device into an outlet. Also it's a Rigid saw, which probably has a motor similar to a Dewalt, rather than a continuous use type motor like a Baldor motor. I'd also be interested to know if anybody has done anything to slow down a Baldor too, so let's make the topic more general than just my needs, but please specify what type or model motor or tile saw you either got this to work on or messed up.

Another question is if the GFC circuit would interfere with doing this and trip if it gets a lower amount of signal (voltage).

Why would I want to do this? I'm told that a slower speed may help me reduce chip out and particularly reduce shattering when cutting tempered glass - another question I asked on a separate thread.

Another approach I'm probably going to use is to use a smaller blade - smaller circumference instead of lower RPM to reduce the feet per second going by the material being cut. I'll probably do both tricks if I can.

---
Ken

You can't cut tempered glass.
You can shorten the life of the motor.

bwalley · 10-04-2009, 12:38 PM

Quote:

Originally Posted by ksskss

Can you slow down a tile saw to a lower RPM?. I'm not sure if a rheostat would work or burn up the motor. Ideally I'd like to just plug the motor into this device and plug the device into an outlet. Also it's a Rigid saw, which probably has a motor similar to a Dewalt, rather than a continuous use type motor like a Baldor motor. I'd also be interested to know if anybody has done anything to slow down a Baldor too, so let's make the topic more general than just my needs, but please specify what type or model motor or tile saw you either got this to work on or messed up.

Another question is if the GFC circuit would interfere with doing this and trip if it gets a lower amount of signal (voltage).

Why would I want to do this? I'm told that a slower speed may help me reduce chip out and particularly reduce shattering when cutting tempered glass - another question I asked on a separate thread.

Another approach I'm probably going to use is to use a smaller blade - smaller circumference instead of lower RPM to reduce the feet per second going by the material being cut. I'll probably do both tricks if I can.

---
Ken

A rheostat is not the proper way to reduce the speed of a motor, you need to alter the cycles, it can be done, but it is not as cheap as a rheostat.

No matter what speed your motor is, tempered glass will shatter when you try to cut it.

mikeswoods · 10-04-2009, 04:41 PM

Ken-Talk to a glass shop. I've watched an auto glass shop"cut" tempered glass using a piece of string dipped into a flammable liquid,arranged on the glass,then lit. For the precise cuts you are after, you may need to have them made to order.

Slowing the speed on the saw you own will likely cost more than it's worth.

Tread mills frequently have 1 and 1 1/2 horse Baldors with a speed control.Check garage sales/Craigs list .------------------------------------MIKE---------------------------

ksskss · 10-05-2009, 03:56 AM

Guys, Thanks for helping me reduce the number of dumb things I could be doing. Much appreciated. I'm going to check one last source tomorrow before I throw this whole line of reasoning in the trash and just accept the fact that there's no way cutting tempered glass is happening on a tile saw.

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Ken

JeffeVerde · 10-05-2009, 09:49 AM

On the motor speed question (cutting tempered glass is a different matter) Yes, you can, and No, it won't damage/shorten the life of the motor. You want a PWM (pulse width modulated) Motor Speed Control. Rather than reducing voltage (which reduces torque and shortens the motor's life), a pwm speed control provides full voltage, but not 100% of the time. Picture riding a skateboard on level ground - kick frequently and you go fast, kick occasionally and you go slow, but fast or slow, the kicks are done with the same force.

Rockler Woodworking has one for routers that will probably work for you (3HP/20a max) for $50. I don't have link-posting rights yet, but go to rockler.com and search for "router speed control". You can also find a 20A controller in kit form (assembled circuit - you supply a case and the AC cords in/out)for as low as about $30 dollars, if you wanted to build it into the saw housing.

shanekw1 · 10-05-2009, 09:53 AM

Just push harder, that will slow it down.

I jest.

ksskss · 10-06-2009, 12:35 AM

Well, I think I'm going to go with a smaller diameter blade utilizing a 5" diameter blade. Since circumference is 2 * Pi * Radius, so going from a 5" radius to a 2.5" radius effectively halves the feet per second to a workable range for what I want to do - as opposed to pushing harder

Jeff thanks for a clear explanation. I might go to this too and just vary pulse widths to control RPMs. Very good! Now will this work with a GFC circuit or will the pulses trip the GFC?

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Ken

Railman · 10-06-2009, 09:06 AM

As long as it's a universal (ac/dc brush type) ,motor, you can get what you need with a cheapie Harbor Freight variable speed control. I have a couple that I caught on sale for about $10. Running a universal motor on lower voltage will only do damage if you run it at high loads, which I doubt will be your case. An example of a universal motor running at low voltage would be variable speed drills, sewing machines, etc. A pulse width control would be better, but in my opinion, not necesary for low torque loads.
Joe

JeffeVerde · 10-06-2009, 02:35 PM

Quote:

Originally Posted by ksskss

Jeff thanks for a clear explanation. I might go to this too and just vary pulse widths to control RPMs. Very good! Now will this work with a GFC circuit or will the pulses trip the GFC?

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Ken

I've never tried one on a GFCI, so I couldn't swear to it -- but it shouldn't be a problem. A PWM is like flipping a light switch on and off really fast.