Craftsman drill press resto-mod

[PDBreske]

My first build thread!

A few months ago, my wife and I were doing a little garage sale-ing and found an old treadmill in the heap of stuff for sale at one of our neighbor's homes. I asked what they wanted for it and they said I could have it if I wanted to haul it away. They said it didn't work and they couldn't fix it. I know a steal when I see one, so I took it home and started parting it out right away.

This is the part that I wanted: a permanent magnet DC (PMDC) motor with electronic speed controls from the treadmill.

I didn't know then what I would end up using it for, but I knew it was good to have.

A couple weeks later, I found a Craftsman drill press on craigslist for $80 and drove about an hour to pick it up. It needed a little TLC and I'm just the guy to supply it. This is the day I brought it home (I removed the motor to load it into my Jeep):

My profession is photography, but I'll admit now that I don't always set up my progress photos as if they were for a paying client. But I do usually take a lot of photos. In the background here, you can see a gray piece of rectangular section steel that was part of the treadmill stand. That will come in handy later (and while we had been living here for over a year, I still hadn't made anything of the garage, so it was a mess—forgive me):

 

[PDBreske]

Beginning the disassembly process:

The spindle taper was pretty beat up (and crooked). I had planned to have it converted to a screw-on mount for a new chuck, but had a helluva time finding a local machine shop that would do the work. Eventually I did find a place, but more on that later.

 

[PDBreske]

I cleaned and degreased everything with Purple Power (my first time using it and it did a pretty good job) and alcohol and used a twisted wire cup on a cordless drill to clean up the worst parts. Then I masked and painted all the cast iron bits with Rustoleum Hammered Metal in Verde Green. I love the color.

The motor mount rods were ugly, so I chucked them in the cordless drill and spun them in sandpaper and steel wool. If you do this, be careful not to spin up the drill too quickly or else you might whip the sandpaper and your fingers around the rod and in the blink of an eye you'll think you've broken your hand. Don't ask how I know this. After and before:

A tip on getting the rods back into the mount plate: Stick them in the freezer for an hour before you attempt to insert them into the plate and they will go in a lot easier. In fact, mine needed only to be lightly tapped with a soft hammer and they went right in. Once they warmed up they were solid as a rock.

Undersides, too!

I took the main post over to my dad's to clean it up on his belt sander. It could be better, but it's lots better than it was.

Starting to look like someone knows what they're doing :

 

[PDBreske]

Next was to mount the new motor on the original mounting plate and get it to work with the V-belts instead of the treadmill's flat serpentine belt. The motor has a threaded mount white the DP's pulley uses a set screw against a flat on the motor shaft. Also, the treadmill motor shaft is thicker than the bore on the DP pulley, so one of them needed to be modified.

I mounted the new motor in the vise and clamped up a system of brackets and boards to brace a file against so I could turn down the shaft diameter as it spun on the vise. Basically, I used the motor as its own lathe. This worked amazingly well. Unfortunately, I didn't take any photos of this setup and I'm sorry. I think it would be helpful to a lot of people who may need to do something like this themselves.

Anyway, I mounted the pulley onto the newly turned-down shaft and filled the end around the threads with JB Weld. While this worked well enough to hold the pulley in place, the mount was slightly eccentric and wobbly. I decided I wouldn't need the biggest pulley diameter anyway, so I used the file trick again to remove the largest pulley from the stack:

The DP pulley doesn't have a built-in fan like the treadmill pulley, so there may be some heat buildup in the motor with extended use. A DP typically doesn't run continuously for more than a minute or two while a treadmill may run under load for up to an hour, so I think I'll be okay.

Very smooth cut after cleaning with sandpaper:

Bought this plastic housing on Amazon for $20 and installed the treadmill electronic speed control inside:

Remember that gray rectangular steel channel from earlier? I cut it up and made four angle brackets that go between the new motor and the motor mounting plate. They give me flexibility for the motor mount location as well as a place to hang the new control box:

With the belt in this position, the spindle speed was roughly equivalent to the motor speed and the motor can spin up to 4900 RPM. This is far too fast for anything I'd do and the slowest speed was still too fast for some work and there was still a bit of vibration when it was running. I will need to fix this. More on that later.

I'll add more tomorrow. Need sleep.

 

[larryq]

Remarkable work, and you're right, the verde green looks fantastic on that press.

Definitely interested in learning more about the speed control setup, and how you finally got the taper converted to a screw-in type.

 

[softailgarage]

Having restored 5 of these, I have to say your doing a great job. I like the Verde Green too. I've seen photos taken at Sears stores in the 50's and that color looks like the original color. I always thought it was a greyish color, but I think at one time craftsman equipment leaned to the green, which wasn't out of the ordinary for industrial equipment, although it was usually an olive drab.

 

[larry4406]

Nice job! I like that color as well.

 

[PDBreske]

Next, I wanted to convert the tapered chuck mount to a ½-20 threaded mount. Using my tricky hand file method (again, no pictures and again, I apologize), I turned the spindle shaft down to .495". It doesn't look like it in this photo, but that shaft is exactly cylindrical. I was very proud of this:

Alas, it was not to be. I bought a set of taps and dies just for this occasion and my limited experience showed greatly in the final result. I guess I managed to get the die started just slightly askew and it ended up being totally screwed up.

Now the spindle needed a professional's touch. I called every machine shop I could find and no one was willing to take on such a small job. I posted an ad on craigslist asking for anyone with a lathe to help out, eventually hearing from a guy who works in a machine shop on the other side of town. He said he'd build up the threads with weld and recut the threads to my specs for $50. Great! I dropped off the spindle and picked it up a week later. When I went to the shop to get it, I asked if we could chuck it up and check the runout with the drill chuck I had brought with me, but they already had other jobs in the machines and couldn't stop for me, so I paid him and brought it home. Once I had it in the drill press, the runout was ... pretty bad. At least an eighth of an inch. I called the shop and they told me that no drill press is going to have zero runout and that was the best they could do. I asked if they used a three-jaw or four-jaw chuck and he admitted they had used a three-jaw. Now, I'm no machinist, but I do know that you can't expect to get perfect concentricity from a three-jaw chuck. If you create a new part and part if off after turning the diameter, you do get a perfectly round part, but if you are cutting on an existing part and expect the new machining to be concentric with the existing center, you need to mount it in a four-jaw and fine tune the jaws until it's perfect. Ugh. Fifty bucks to learn that Ocala is not the place to find competent workers.

It turns out that threading the spindle may not have been the best idea. A tapered mount has the benefit of being correctly aligned to the spindle and having virtually no wobble if machined and installed correctly, and it's probably easier to machine and install properly than to get the threads perfect without the benefit of testing the fit over and over as the part is being machined. At least, that's how I rationalized my decision to machine the taper myself.

So I built up the end of the spindle with JB Weld over the threads and let it cure for a few days. Then I used the hand file to slowly and carefully shape a JT33 taper into the epoxy while the spindle turned in the drill press. This not only was easy, but it assures the center of the taper is perfectly concentric with the spinning center of the spindle while installed. Obviously, the epoxy isn't as hard as the steel shaft, so the machining process was quick. If I encountered a void in the epoxy, I could just fill it with more JB Weld and start over. I would test fit the new Shop Fox chuck and check the wear marks on the epoxy for high spots and low spots. By the time I was done, the taper was perfect.

How long will this setup last? I have no idea, but the total runout now is about 1/64th of an inch (maybe less) and hasn't shown any signs of loosening during use. In fact, since the initial installation, I haven't had to adjust it or reseat it or anything.

 

[gilbo]

Very very nice, great write up too.

 

[PDBreske]

This is the treadmill motor. You can find one of these (or something similar) in just about any treadmill. If you see an ad for a cheap or free treadmill, get it! The more basic the controls, the better.

Before I found the drill press, I rigged up the treadmill controls with some scrap parts and deleted anything that wasn't needed to control the motor. There is a lot of stuff inside the treadmill that is specific to that device, but the parts that control the motor speed are pretty simple and easy to figure out. Plus, there are plenty of YouTube videos that explain how to scavenge these things for other uses.

Inside the control box, I mounted a piece of plywood with screws through the back of the box. This gave me a place to mount anything I wanted to use for the speed controls or anything else I may add in the future.

I added a switch to the circuit for the potentiometer that allows the motor to be turned on at the last-used setting. All treadmills have a safety circuit that will not allow the motor to ramp up to its set speed without starting over from zero. This prevents people from turning on the power and having the belt move under their feet without warning. You always have to return the speed dial to zero to get the belt moving. Obviously, it would be better for a tool to start at the same speed you last used it without having to dial it up every time, so you can add an interrupt in a specific circuit that allows this. While it doesn't cut power to the motor, it does stop the controller from sending a speed signal to the motor. The end result is the same. I used an aircraft-style switch with a cover that forces the switch to OFF when closed, so it's easy to see that it's off from a distance and impossible to turn on without conscious effort to lift the cover first. There is about a one second delay from turning on the switch before the motor starts turning. Not sure if this is a PMDC motor thing or if there is additional circuitry that causes the delay, but it's not a dealbreaker when using the tool.

Also added a digital tachometer so I could see the spindle speed. This was an easy install, although I couldn't figure out how to wire the power supply for the display to the existing treadmill components (electronics is not my strong suit), so the tach is powered by its own AC adapter that plugs into the wall outlet. The green LEDs are on all the time when powered, so I added a switchable power strip to the wall for this bench which includes the DP, tach, and a lamp.

Hall effect sensor for the tach magnet mounted under the bottom spindle pulley on a piece of aluminum secured with JB Weld:

On the front door of the box, I made a label with the speeds of the spindle on two of the spindle pulley positions. The other pulleys are so small that the speeds would be ridiculously high, so I ignored them. The label just gives me a way to quickly spin the dial as the motor turns up to speed. And it looks cool. Although not pictured, I did add some white paint to the notch in the dial so it's easier to see.

 

[PDBreske]

A few artistic photos of this (mostly) finished project:

 

[The KickStand]

Fantastic! I’ve scrapped two treadmills for the same reasons! Just waiting for the right reboot! Was planning on a small cast iron band saw and maybe a similar era belt sander. Thanks for the great write up!


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[PDBreske]

Remarkable work, and you're right, the verde green looks fantastic on that press.

Definitely interested in learning more about the speed control setup, and how you finally got the taper converted to a screw-in type.

I hope I was able to answers any questions you had. If there’s anything else you need to know, don’t hesitate to ask.

 

[187 speed]

I knew I was going to enjoy your posts!! I have had a the idea to build a bead roller using a treadmill motor for a few years, this may be the fire under my **** I needed to start collecting parts!!

 

[Ole Slewfoot]

The green even looks great in B&W!

I'm working of a packaging conveyor system, but the CL tool who said my free treadmill works forgot to mention the control board is failed. Motor is good, power supply is good, human interface works, but the SCR output doesn't go. Its an MC-1000, in the same heat sink as yours. Still going to take a couple stabs at fixing it before I buy a DC drive.

 

[KillNThrill24]

That's a rad build!! I love the old school blue you went with too.

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[PDBreske]

I knew I was going to enjoy your posts!! I have had a the idea to build a bead roller using a treadmill motor for a few years, this may be the fire under my **** I needed to start collecting parts!!

Get to work! Can’t wait to see it.

 

[PDBreske]

The green even looks great in B&W!

I'm working of a packaging conveyor system, but the CL tool who said my free treadmill works forgot to mention the control board is failed. Motor is good, power supply is good, human interface works, but the SCR output doesn't go. Its an MC-1000, in the same heat sink as yours. Still going to take a couple stabs at fixing it before I buy a DC drive.

Keep an eye out for those treadmills. I found another on Craigslist, but the seller still hasn’t responded to my inquiry.

 

[PDBreske]

That's a rad build!! I love the old school blue you went with too.

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Thanks!

 

[eric.holmslice]

Great build! I’m looking for another old drill press and plan on making a similar motor / controller combo.


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[PDBreske]

Great build! I’m looking for another old drill press and plan on making a similar motor / controller combo.


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Let me know if I can be of any help when you do. Good luck!

 

[KMinAF]

Is torque an issue? I saw a You Tube (I think it was Mr Pete 222) that expressed concern that the smaller motor wouldn't have the capacity of the original motor.

 

[PDBreske]

Is torque an issue? I saw a You Tube (I think it was Mr Pete 222) that expressed concern that the smaller motor wouldn't have the capacity of the original motor.

I suspect it might be, but I haven't had any problems yet. Of course, I haven't attempted any intensive drilling yet, so I really have no idea. These little motors are quite powerful, they can run a treadmill steadily with the pounding footsteps of [an adult human who needs to do more exercise] all day long.

I'm sure you've also seen YouTube videos of idiots getting tossed around by a treadmill when they try to do something dumb. I've never seen a treadmill stop or slow under those conditions.

EDIT: Also, I'm running it around half the speed of the motor with the pulley arrangement, so that should double the torque rating at the spindle, right?

 

[PDBreske]

Just wanted to add this: I replaced the v-belt with a link belt and the difference is night and day. SO much smoother and quieter. Highly recommended.

The color even matches the drill press!

 

[JoCoSawdust]

Very cool! Thanks for sharing the journey.