Clausing 8520 DC motor w/ MC-60 controller

[gajunkie]

Recently started a DC motor conversion on my 8520. Treadmill motor with an MC-60 motor controller, 10k Ohm pot for variable speed, and an RPM sensor with a display.

I wasn't able to figure out a power source (8-12 VDC) for the RPM display, so I just used a 9-volt battery and wired it up with a momentary switch. I don't feel like I need a constant display of the RPM and can hold down the button whilst setting the speed, then letting go. Should last a long time like that. Works pretty slick...maybe somebody else knows how to tap into 8-12 Volts out of this setup??

Found a box on Amazon to stuff it all into, and made a mounting bracket for the control box, where my drum switch used to be. Speaking of switches, I wired this one up with a DPDT toggle for forward and reverse.

I'm still experimenting with motor placement and deciding whether or not to use the idler pulley or go direct drive. I only have one pulley for the motor so far...had to modify a pulley by boring it out to fit on the motor shaft, and also had to mill a keyway slot in the motor shaft that fits a grub screw through the pulley to prevent slippage. Probably not the best setup, but I don't have a way (at least a quick way) to cut a keyway in the pulley.

Right now the pulley is a 1-3/4", and trying to figure out how to make the mill run as fast/slow as originally intended without having to move belts around. The DC motor has a range of 0-6000 RPM so about a 2-to-1 ratio is needed to get it down to the 3200 RPM range...not sure how often I'd use that speed but at least it can do it! Seems to have good power and doesn't bog down under a load like my last setup did (smaller SCR controller)

Nothing specific to ask just yet, but if anyone has done this and has some good advice pleas share at will! Some pictures of the setup:

 

[Nutfarmer]

Would a wall wart ,a plug in charger for electronics , work to power the tach?

 

[gajunkie]

Good idea! I’ll look into that. Still don’t have the actual sensor mounted yet, working on a spot for it. Hesitant to mount it through the brake hole because i want to fix the brake someday. Currently just have a magnet stuck to the quill…damn thing holds on at 3500 Rpm

 

[mattthemuppet2]

Very cool! I have a similar set up on my 6x26 clausing copy, same controller but a 4k rpm motor instead. I reused the original motor pulley but dumped the intermediate pulley. I rarely use the upper or lower pulley range, but it's good to have when needed, especially the lower range.

For the rpm sensor mine is mounted up under the spindle pulley with the magnet glued to the bottom of the pulley. I use a 130vac>12vdc wallwart stuffed inside the control box and wired downstream of the main power switch

 

[Zertsman]

I have no brake parts, so I stuck my sensor in the hole where the brake lever mounts. It was also already aligned with the pulley.

Since you have a brake, and that's good, the retainer screw for the lever has lots of exposed threads behind it. I bet with some work, this already threaded position is a good place to mount it without drilling anymore holes in that nice machine.

I bought some small magnets with holes in the center and mostly countersunk one in the bottom of the pulley. Move it away from the edge so you do not interrupt the V groove for the belt. My magnet was about 5/16 OD and 1/8 thick or so.

Before you mount the magnet, make sure the right side is facing the sensor. The sensor will likely only read one side of the magnet

 

[gajunkie]

I’ve made a little bracket today out of sheet metal that hopefully will work. It sandwiches between the head cover and the head. I think I’ll try the magnet idea first like mattthemuppet did…a little less invasive in case it doesn’t work out.

 

[Zertsman]

That's great! will remember that if I ever get around to making my brake parts.

Be sure to get the magnet right way down.. I did a bench test to make sure my harness and powersupply was all sorted.. worked great. Drilled the hole, flattened the bottom with an endmill, epoxy for the magnet, 12hr wait to cure.. and NOTHING!

Had to chip and drill it out and sink another one in there.. second one held with a screw.

 

[gard]

Nice work, I will be interested to see how this works out for for you, I have a treadmill motor, have messed around with some cheaper controll stuff off amazon but could not get good control. Electronics are not my strength. Did you consider some kind of variable control for the existing AC motor? My understanding is they work much better with a 3 phase motor.

 

[wa5cab]

Variable speed with a single-phase AC motor isn't practical. But a variable frequency controller and a 3-phase motor will be much stifferthan the variable speed DC motor.

 

[Zertsman]

I'm just a hobby user in my garage. I'm not making myself any money, but I have spent some.

I have made several cuts in aluminum with a 1/2" 2 flute endmill, and am able to do the same sort of things I was doing on my round column mill. So far, I'm happy. The first passes with my amazon purchased flycutter, probably from littlemachineshop went well. Plenty of torque as far as I can tell.

There is a cheap speed controller on amazon with a switch and knob in a small box.. DC something or other is it's name. This does not have the torque for a mill. It may be good for the rock tumbler. Pass on this for a Mill or Drill or Lathe.

Again, I'm in no hurry, I take light cuts and have only broken taps I turn by hand. I'll prolly never power tap.

The treadmills I bought (3 of them) were all under $50 each. This 20 dollar treadmill and ammo can is getting it done for me just fine. I'm using the same motor and controller that were paired together on the treadmill. (I believe)

If you were doing this for money, then you'd prolly have money for a 3phase motor and VFD which is for sure a way more elegant approach, prolly last longer and provides some braking and things.

However, I have a knob I turn to go faster and slower along with a digital readout to tell me how fast it's turning. Much better than switching belts for my budget. So far so good.

I made an adapter to go from the motor to the cone pulley, eliminating the flywheel and fitting under the stock guard on the 8520. My mill now coasts to a stop quicker than with the flywheel. It's another small step in the right direction.

I will incorporate the choke from the treadmill at some point to see if it quiets the motor a bit. It's way quieter than my round column which prolly needs spindle bearings. The segmented belt makes most of the noise I hear, but I can hear a hum/groan from the the motor as well. I like to leave the garage door open to the house in case I need help, the family is usually within ear shot, but I try to keep the noise down. It'd also be nice to hear my Pandora playing.