# Replacement Lathe Motor



## sssfox (Feb 17, 2014)

I've spent months looking for a 3/4 to 1HP treadmill motor to replace the smaller, inadequate one on my 7x lathe.  Up until the last week, I haven't been able to find anything near the price I expected.  I figured all the good deals were gone and I really didn't want to spend in excess of $100 on a new one.

Well, I finally found what I was looking for here, at a price that is very reasonable:

http://www.skycraftsurplus.com/fld-5380motordcwspeedcontrol.aspx

I have bought several controllers in the past year and the best deal I could find was around $20.  This motor includes the controller, but not the pot (They have the appropriate pot for $4.95 part# RP7871).  

I hooked mine up and it runs from 85 to 4000rpm.  It doesn't have a lot of torque below 250rpm, but for me, that's not a problem, I'm going to gear it up anyway.

At 1000 watts, even figuring loss, it should develop in excess of 1HP.
It appears to be a well built motor, with huge brushes.  It runs very quiet, with no vibration.  The description is on the listing.  I like it so much, I bought three.

Now, I just need to figure out how to mount it.  I've only had the lathe together for four months or so and it is working so well, I hate to take it apart.  I would like to figure a way to bypass the intermediate shaft without buying a new head.  The gears are really noisy.

I have no relationship with this company other than visiting their store (the adult male version of Disneyland) many, many times over the years.
They are good people.


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## chucketn (Feb 17, 2014)

I am a great fan of treadmill motors powering shop tools. I have one on my X2 mill, and one running my sand muller for my foundry. I have 3 or 4 spare motors standing by for other uses as the come up. Unfortunately, I have only 2 good controllers.
I got all of my treadmills from Freecycle. There was a period of 2 or 3 years where they were appearing every week!
What model controller did you get with yours?

Chuck


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## abby (Feb 17, 2014)

I took mine from a used treadmill and fitted it to my BCA jig borer.





It is a 5500 rpm unit rated at 2 HP ,very compact and bolts nicely on the back of the machine.
Torque is available from fly cutting speed of around 60 rpm right up the range.
I managed to fit the power supply and control circuit into the case of an old welding inverter , and was even able to utilise the welder potentiometer in place of the treadmill slider.
Couple of points though , treadmill circuits have safety in mind and cannot be started at anything but slow speed , this can be annoying , and I can't see how to get a work round .
Also the DC motor has permanent magnets so care is needed when machining cast iron or steel to avoid the small chips being attracted to the motor casing.
The shaft has a left hand thread for the pulley which was built up from the original threaded hub fitted to a new pulley of the correct size.
The set up is very satisfactory and was cheaper than replacing the blown 3 phase inverter that I had originally fitted.
Dan.


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## sssfox (Feb 17, 2014)

chucketn said:


> I am a great fan of treadmill motors powering shop tools. I have one on my X2 mill, and one running my sand muller for my foundry. I have 3 or 4 spare motors standing by for other uses as the come up. Unfortunately, I have only 2 good controllers.
> I got all of my treadmills from Freecycle. There was a period of 2 or 3 years where they were appearing every week!
> What model controller did you get with yours?
> 
> Chuck



It is a generic controller.  There is no useable data on the case or circuit board.  It has two SCRs on individual heat sinks, about what I would expect for 1000 watts.

There are some useable Chinese controllers on eBay.  Just be careful of the voltage.  I bought one that said it was for a 90v motor and it blew up when I plugged it in.  The seller said it was a mistake in the listing, it was only for 12 volts.  I've had much better luck with others.

A couple of years ago, I bought a brushless sewing machine motor with a built-in digital controller for $129.  I think it is 700 watts.  I intend to put it on my 12" Atlas lathe, but haven't had a need yet.  It is a really nice motor and came with a 1/2" pulley on it.

I have one treadmill motor I got from a treadmill.  I have the same issue with it of always starting slowly.  That's one reason I bought the motor controller for $20 from eBay.  I have no use for it, yet.  I think it is closer to 3HP.  The price was right, so I have it.

I've spent all afternoon trying to figure out how to mount the new motor on my 7x lathe.  Because of the odd size drive belt on the lathe, there aren't a lot of options.  I may have to change to a different size belt and a different arrangement.  There isn't a lot of room around the drive pulley the way it is mounted under the tumbler plate and there doesn't appear to be enough room on my spindle to mount a direct drive pulley.

From the parts diagrams, I can't figure out what I need to replace to bypass the intermediate shaft.  There just isn't enough information to be able to tell which parts are the same and which are different.


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## chucketn (Feb 17, 2014)

The soft start on the treadmill controller is intended to keep users from starting at full speed and flinging the poor sole into the wall. My SEIG mill and lathe have the same feature to prevent starting them at full speed. I got used to it and it doesn't bother me now.
I turned a v-belt pulley from the hub of the treadmill motor's flywheel where the multi-grove(correct name?) belt that drove the tread. Left hand thread, so it won't unscrew on the mill.
Chuck


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## velocette (Feb 17, 2014)

Hi try These links

http://tool20895.homestead.com/treadmill.html

Or
http://www.mini-lathe.com/Links.htm#Home_Shops

Link to an excellent controller a bit fiddly to set up. This is the units I use and very pleased with the performance.

http://www.surpluscenter.com/Electr...rs/90-180-VDC-SPEED-CONTROL-W-POT-11-2269.axd

More Info

Eric


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## abby (Feb 18, 2014)

I turned a pulley from the hub in the first instance but found that the diameter was really too small and the belt (round) would slip under load. As luck would have it I had a 3 step pulley from a scrapped Chinese bench drill on the shelf. I was able to bore this through and loctite the hub into it , slipping solved !
Dan.


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