# Speed Control for the Harbor Freight (34706) Wood Lathe



## MMuntz (Oct 17, 2011)

*Speed Control for the Harbor Freight (34706) Wood Lathe*










I thought I would share one of the most useful modifications that I have made to my Harbor Freight wood lathe. By adding a lower range of speed control to my lathe I am able to turn large, out-of -balance bowl blanks.

The factory speed range for this lathe is 600 to 2400 RPM. Trying to turn even small, out-of -balance bowl blanks at the slowest speed of 600 RPM can be quite unnerving. This modification allows me to adjust the speed from 0 to 2200 RPM.

I replace the factory ¾ HP AC motor with a ½ HP 90 Volt DC motor. I wanted a motor with more horse power but I could not pass on the price, it was free.










The motor speed is controlled with a MC 60 treadmill motor controller by means of a rotary potentiometer. I've added a push button on\off and forward\reverse switch. I purchased the controller on EBay.










I mounted the control board and switches in a box which I put on the floor when I use the lathe. This allows me to use my foot to turn the motor on and off.










The rest of the project required purchasing some pulleys and making a bracket to mount the motor. I replaced the reeves adjustable speed pulley with a standard pulley. The outboard side of the lathe spindle is 24mm in diameter. In researching this project I found that this same spindle is used by a number of different lathe manufacturers. Jet, Grizzly and others use the same reeves pulleys and spindle in some of their wood lathes.

I'm very happy with how the project turned out. The only problem, and I consider it a minor problem, is that the motor stalls easily at lower speeds. I have less stalling as the bowl balances and I increase the speed.

Thanks for reading.


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## Michael1 (Feb 12, 2011)

MMuntz said:


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That is a really neat idea. Just last week I was talking to a friend about this very thing. He sells these types of motor and controllers and I was talking to him about building a shop built lathe that would have variable speed control with out having to stop and change belt positions on a stepped pulley. He explained this set up to me but your post has made what he was talking about allot more clear. Thanks for posting


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## rance (Sep 30, 2009)

MMuntz said:


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Very inventive. Thanks for sharing.


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## exelectrician (Oct 3, 2011)

MMuntz said:


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All good and very much a move in the right direction. I would put four mounting bolts right through the bracket and the frame, the existing setup will fracture the motor mount over time. I hope my constructive advice is taken with a pinch of salt.


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## DavidBethune (Feb 9, 2009)

MMuntz said:


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Great project. I just purchased a 2 1/2 hp Treadmill motor to do the same thing with.

I'm wondering if you can't just use the Harbour Freight variable speed control they sell for routers and not have to use the power supply and control board from the Treadmill???

This is the one Harbour Freight has..
http://www.harborfreight.com/router-speed-control-43060.html

If you could let me know if you think it would work I would appreciate it?
Thanks
David


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## EEngineer (Jul 4, 2008)

MMuntz said:


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I'm wondering if you can't just use the Harbour Freight variable speed control …

I don't think that's going to work! The very first line on the speed controller description at HF:

This router speed control works with any universal AC/DC brush-type motor …

Although the manual for the lathe doesn't explicitly say so, that sure looks like an induction motor to me. They spec a 1700 RPM motor speed which is right for a 4-pole induction motor. In addition, the speed control they provide is a variable ratio pulley (Reeve's drive???) that I often see with constant speed induction motors. That motor won't work with that speed control.


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## FrankSpillman (Jan 10, 2011)

MMuntz said:


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I am trying to do the same thing with a 2 hp motor. Has anyone successfully used the MC-60? Does anyone know the voltage and amp limits on the MC-60?

Thanks


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## wkerr (Jan 12, 2011)

MMuntz said:


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I'm fixing to do the exact same thing to the exact same lathe, do you mind to tell me what pulleys you used and what if any other issues you might have ran across? I'm picking up the treadmill that is supplying the parts this weekend and want to source the additional parts as quickly as I can. I broke the factory drive pulley (hand pressure) and figured I might as well gain the additional functionality that this would afford while fixing it, plus as you said the motor, control, and power supply are all free.


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## FrankSpillman (Jan 10, 2011)

MMuntz said:


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Wkerr, what size motor are you going to use? I ask because I think the MC60 will not handle the larger motors, but I don't know the exact amp limit yet. You might just want to look at the voltage and amp requirements on your motor.

In any case I would be interested in sharing experiences.


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## crank49 (Apr 7, 2010)

MMuntz said:


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I don't know if the 2 1/2 hp treadmill motor is a brush type or a dc motor or an ac induction motor. Why not use the controller from the treadmill as well? Then you would know the motor and controller match.

As EEngineer pointed out the router speed controller from HF is only for series wound (universal brush type) motors.

Muntzie, I'm curious why you removed the variable speed belt drive? Especially since you had to drop down from a 3/4 hp to a 1/2 hp motor.

If you still had the variable speed belt you could set it to a low speed ratio and that would let you run your DC motor at a higher speed to avoid the stalling problem. Kinda like a granny gear on a truck.

Then when you have the workpiece rounded and balanced you could shift the belt back up to a higher speed ratio and have all the variation you want with the DC controller.


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## FrankSpillman (Jan 10, 2011)

MMuntz said:


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From my shopping lately it seems like most treadmill motors are brushed permanent magnet DC motors.


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## MMuntz (Oct 17, 2011)

MMuntz said:


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Sorry Guys I haven't been around in a while.

WKerr, the motor has a max RPM of 1800. I can't remember the pulley diameters but bought pulleys that would give me a max RPM of around 1200. Good enought for bowl turning. I bought the pulleys from McMaster-Carr. Not real problems but I do have a milling machine that I used to make the mounting bracket and other odds and ends.

Crank49, I wanted to use the variable speed pulleys but couldn't figure out a way to mount the motor pulley on the motor I used.


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## wkerr (Jan 12, 2011)

MMuntz said:


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I've been away from this project for a while as I had trouble getting my hands on parts and I've had to put "woodworking" on the back burner for a while. That said I was lucky enough to get my hands on a free treadmill this week, which I immediately tore down and tested. I was able to get my hands on a 2.5 hp dc with mc-60 controller. Everything works good in my tests. I'm looking at putting a taper lock v pulley on it and utilizing the variable speed pulley on the spindle side to allow for a high and low range.

Any thoughts or concerns feel free to let me know. I'll post during or after the process.


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## BobBlarney (Apr 17, 2015)

MMuntz said:


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I'm late to the party, but you can add a DPDT switch between the controller board and the motor so that the lathe can run in reverse - just be sure to use a chuck that has a setscrew to keep it on the spindle. Put the switch somewhere away from the regular on/off switch so that it takes a deliberate action to flip it.

Also, I used the treadmill's flywheel pulley. Both it and my Delta midi-lathe use the polyj-vee belts, it's just that the lathe pulley has 3-4 grooves and the flywheel pulley has 7-8 grooves. I ordered a belt to fit from beltsforanything.com

Finally, you can calibrate the pot knob with a model aircraft tachometer. Paint a white dot on the spindle or chuck, darken the room, and illuminate the dot with a flashlight or tungsten bulb (NO fluorescent lights). Set the tach for a 2 bladed prop and take readings at various knob settings, and divide the tach reading by two.


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