Variable speed DC motor for Delta Lathe #1: Modernizing a 1950's Delta Lathe

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Blog entry by Bluepine38 posted 03-04-2015 06:52 PM 6096 reads 3 times favorited 7 comments Add to Favorites Watch
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The lathe was powered by an old 1 HP Craftsman motor run through a jackshaft and a 4 step pulley, the
speed was somewhat variable. I had read about people adapting treadmill motors to lathes and decided
to attempt it. The first free treadmill was not operating because the controller was bad, but had a $300-
according to the owner- motor, the second had no controller and the third had a controller I could not
adapt. I bought a rebuilt MC-60 controller for $50.00 and my core and started down the slippery slope.
I could not find a V-belt pulley to replace the serpentine belt pulley, so I took the pulley off a second DC
motor and bored it out to 3/4” to fit on the jackshaft I used with my old motor.

The motor had a 16mm (.6295In) shaft with the pulley/flywheel held on by a 1/2” 13tpi left hand thread.

The cross slide rest is one reason I want to keep this old lathe, I can do light machine work with it as well
as wood turning. A local machine shop broached a 3/16” keyway in the pulley for $15.00 and I was ready
to start assembly.

The only problem is the V belt drive is on the left side of mounting setup so the drive motor has to set on
the left side. I would have to make the mounting plate extra wide or reverse the DC motor. Wanting to
save space I decided to reverse the DC motor by switching the motor leads, but the left hand mounted
pulley would want to spin off, so I drilled a hole, half in the drive shaft and half in the pulley and threaded
it 1/4-20, inserting a 1/4-20 set screw with blue lock tight eliminated the problem of the pulley coming off.

I now have the motor mounted to the special adapter plate and driving a serpentine pulley that will turn
the jack shaft that will turn my lathe. The plate is fastened to a sturdy piano hinge that will allow the
weight of the motor and drive assembly to provide tension on the V-belt. The DC motor had a tensionilng
bracket that I used to tension the serpentine belt.

The controller might not be damaged by wood chips and dust, but I decided to enclose it in its own box.

I made the back from sheet metal, but wanted to be able to see the lights on the controller so the front
is plexiglass. The controller sets behind the head of the lathe. I wanted to use a regular electronic box
to mount the controls for the lathe, but Radio Shack closed its store in Missoula last month, so I adapted
a double gang electric box.!!

The fuse is from the original treadmill, and is a 12 amp ceramic fuse. the red light and the potentiometer
for adjusting the speed also came from the treadmill. I used a heavy duty toggle switch from my supply.
here is the drive unit in place.

Looking at it, it is a little Rube Goldberg, but it does work. The electric power comes through an outlet
on the lathe that is controlled by a special paddle switch that I can shut off by bumping it with my leg
just in case I get careless and need an emergency shut off. It works good so far and my only problem
is that I just got another free DC motor that has a keyed shaft that is 17mm (.6693in). If I redo my
adapter plate, I could build a V-belt pulley that would fit on that motor and mount it directly below
lathe head. That is for another day. I want to thank Rick M. / Woodknack and Sawdustonmyshoulders
for the help and pictures that made this project a lot easier.

The DC motor is rated at 21.5 Amp and 2.65 peak HP, but the AC fuse is 12 amp so I am getting a
lot more power at a lower cost thanks to that electronic control box. There may just be a few more
DC motor projects in my future.

-- As ever, Gus-the 80 yr young apprentice carpenter

7 comments so far

View Sawdustonmyshoulder's profile


489 posts in 4234 days

#1 posted 03-04-2015 07:37 PM

Here is the blog of my ‘journey’ to the same planet. Hope it helps. My lathe working great and it has about 5 gallons of African mahogany dust underneath it right now. 8-)

-- The more skilled you are at something, the worse you are at it when someone is watching.

View LJackson's profile


295 posts in 2200 days

#2 posted 03-04-2015 08:23 PM

I’m envious of all of you who have done this conversion.

View JoeinGa's profile


7741 posts in 2613 days

#3 posted 03-04-2015 08:55 PM

I’m envious of those of you who have found free (or nearly free) treadmills so you can DO this conversion!

-- Perform A Random Act Of Kindness Today ... Pay It Forward

View nkawtg's profile


294 posts in 1857 days

#4 posted 03-04-2015 09:04 PM

I m envious of those of you who have found free (or nearly free) treadmills so you can DO this conversion!

- JoeinGa

Exactly, it’s like those who are “given” an a/c furnace blower so they can make a dust filter.
Envy doesn’t quite describe it enough.

View Bluepine38's profile


3387 posts in 3691 days

#5 posted 03-05-2015 09:55 PM

Got a PM from Shipwright asking about the possibility of converting a shopsmith to this type motor. I grabbed
my Shopsmith book and gave a longwinded possibility scenario. Then thought, when he writes he gives a
lot better explanation. First the J series micro-V belt is the same on the treadmills and the shopsmith. There
is room to run the micro-V belt from the motor to the powered quill, that is what they do with the Powerpro
headset that is the Shopsmith update, but this might mean getting rid of the lower accessory drive shaft.
If you are going to do this, I would recommend that you do have the newer double bearing quill, not the
older single bearing quill-that is just my opinion, and it is worth what it cost you. The DC motor would take
up a lot less room in the motor compartment, but I do not know if there would be room for the controller
in there. Shopsmith does not show a parts diagram for the Powerpro headstock, but I am guessing they
use the lower drive unit as a jackshaft and run two micro-v belts. If you do this, you could get rid of the
reeves drive system and that would give you plenty of room for your controller and switches in the top
of the headstock. The MC-60 controller is the easiest I have found to work with, the choke coil could be
mounted behind instead of beside the controller to give you more room.

Shipwright did mention that he would not want to mess up his newer pristine 500 series headstock, but
there are plenty of used ones available you could use for this project. The Powerpro headstock lists for
over $1000, even if you bought the motor and controller from someone like Treadmill Doctor this project
would cost less than $400. The belts would have to be ordered from a Gates or other belt dealer. Gates
had the only catalog site I could find the J series micro-V belt drives on and shows them available in 4,6, and
10 rib widths and in length increments from 18 to 98 inches in 1 inch increments. Hope this helps some
one, but it will probably not be in my future projects list for a while.

-- As ever, Gus-the 80 yr young apprentice carpenter

View Bluepine38's profile


3387 posts in 3691 days

#6 posted 03-05-2015 10:06 PM

Joe and nkawtg, I am indeed blessed in being in an area where there are a lot of available free and low
cost machinery such as the $100 Delta Cabinet saw I bought and rebuillt, but I have also put a few miles
on my pickup looking for and at items that were not worth looking at, much less picking up or buying.
It does not cost much to check craigslist and other scources, I hope you too will find what you want
and/or need.

-- As ever, Gus-the 80 yr young apprentice carpenter

View Woodknack's profile


13014 posts in 2986 days

#7 posted 03-07-2015 06:13 AM

Sounds like you had a time of it but things worked out in the end.

-- Rick M,

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