# Dimmer switch speed control??



## bobalouie76 (May 6, 2010)

Hi everyone,
I picked up a "new" lathe today and was wondering if anyone has experimented with using a dimmer switch as a means of turning a normal motor into a variable speed motor?  Can this be done, can it be done with any motor?  The lathe I picked up has pulleys to adjust speeds, I was just curious if this was possible.  Thanks in advance for your advise.

Matt


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## alphageek (May 6, 2010)

bobalouie76 said:


> Hi everyone,
> I picked up a "new" lathe today and was wondering if anyone has experimented with using a dimmer switch as a means of turning a normal motor into a variable speed motor?  Can this be done, can it be done with any motor?  The lathe I picked up has pulleys to adjust speeds, I was just curious if this was possible.  Thanks in advance for your advise.
> 
> Matt



Don't do it... Best case it won't work, worst case you will destroy the motor.  Even if you can find a heavy duty enough dimmer switch, its not the right way to slow down these motors.   The 'variable' speed on a motor is done in a completely different way than dimmer switches for lights.


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## randyrls (May 7, 2010)

Don't do it.  The speed of an AC motor is determined by the frequency supplied to it and the number of poles in the motor.

Variable speed units are of several types.  The first two are electronic and the last is mechanical.
DC motors fed with a variable DC current and voltage to control the motor speed.  These have a feedback method to determine the speed of the motor and keep it constant under varying loads.

Variable Frequency Drives are 3 phase AC motors fed with a varying FREQUENCY fed to the motor to change it's speed.

Reeves drives have pulleys that change their effective diameter to change the pulley ratios and effect the speed change.  These are mechanical.


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## bobalouie76 (May 7, 2010)

Well, Im convinced. I wont try this. Thanks guys for saving my motor.

Here is the lathe I picked up, its an old craftsman. It came with a Westinghouse motor , a 15" bed extention, a 4 jaw chuck, 2 Keyless No. 1 Morse Drill chucks, 3 dead centers and a face plate ... I think it was a deal for $150.00


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## snyiper (May 7, 2010)

I have the exact same lathe. I think a router control is perfectly accaptable to use to regulate motors. Besides with the divorced motor any dishwasher/washing machine motor will work fine. Mine is a 1936 atlas sold by sears.


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## Kalai (May 7, 2010)

When it comes to moters and speed control--- DC motors can use a light dimmer as long as the amps and volts are rated to handle the hp of the motor, AC motors will not work and might even hurt the motor like was mentioned.  Aloha.

Chris "Kalai"


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## bitshird (May 7, 2010)

Nice old Lathe, those sure were better than the new Craftsman junk>>


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## jocat54 (May 7, 2010)

snyiper said:


> I have the exact same lathe. I think a router control is perfectly accaptable to use to regulate motors. Besides with the divorced motor any dishwasher/washing machine motor will work fine. Mine is a 1936 atlas sold by sears.


 
I agree with you--not sure why a router speed controller wouldn't work. Hopefully someone with chime in with a reason why not.


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## ldb2000 (May 7, 2010)

Router speed controls are like dimmer controls . They are meant for DC motors or resistive loads and vary the voltage , almost all fixed speed lathes have AC motors and starting capacitors . The lower DC voltage will just cause the motor to not start or if they do it will cause them to overheat and burn out .


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## Jgrden (May 7, 2010)

All that for $150.00 and it is 3 speed. WOW.


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## jocat54 (May 7, 2010)

ldb2000 said:


> Router speed controls are like dimmer controls . They are meant for DC motors or resistive loads and vary the voltage , almost all fixed speed lathes have AC motors and starting capacitors . The lower DC voltage will just cause the motor to not start or if they do it will cause them to overheat and burn out .


 
Are routers dc voltage? I always thought they were ac voltage, I'm confused (as usual)


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## ldb2000 (May 7, 2010)

jocat54 said:


> Are routers dc voltage? I always thought they were ac voltage, I'm confused (as usual)


Some are and some aren't . the ones that aren't will have a warning about using speed controls . The easiest way to tell is the DC ones almost always have replaceable brushes .


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## snyiper (May 7, 2010)

Also the motors were a add on from what I know of the lathes I doubt there are many still using the original motor.
The difference between AC and DC is that AC is an alternating current  (the amount of electrons) that flows in both directions and DC is direct  current that flows in only one direction; the product that is flowing  being electrons. AC power is what fuels our homes.


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## ldb2000 (May 7, 2010)

Both AC and DC motors can be powered from AC power . The DC motors will have  rectifiers to convert the AC line voltage to DC .


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## jskeen (May 8, 2010)

here's a link to a earlier thread with a little more technical description of why "that's not going to work out well for you, if you try it"  

http://www.penturners.org/forum/showthread.php?t=38947&highlight=speed+control


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## jocat54 (May 8, 2010)

jskeen said:


> here's a link to a earlier thread with a little more technical description of why "that's not going to work out well for you, if you try it"
> 
> http://www.penturners.org/forum/showthread.php?t=38947&highlight=speed+control


 


Thanks, that cleared up a lot for me.


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## bobalouie76 (May 9, 2010)

Me too.  Thanks everyone.


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