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I made a 2x72 ginder and I'm using a a 2.25 hp tread mill motor. 

My question is the motor will shut down when I put the belt under a heavy load for a period of time. Is there a way for this to be stopped?

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Scotty,

It's probably due to thermal overload protection.  Treadmills aren't built to be used in a dusty environment so the motors used are generally pulling air directly into the windings.  Belt Grinders typically use Totally Enclosed Fan Cooled (TEFC) motors which have radiator fins cast into their housing with an external fan blowing over them for cooling. TEFC motors cost more because they're built for harsh environments.

If I had to guess, your motor has grit and dust blocking airflow to the windings.  Heat breaks down the insulating laquer on the windings which is why vulnerable motors are generally equipped with a thermal overload protector.  If you removed the thermal overload protector, the windings would overheat until the insulation failed and the whole motor goes up in smoke.

Blowing it out with compressed air might make it worse because windings have a lot of nooks and crannies where stuff likes to get stuck.  The rotor in a motor is precisely balanced to minimize bearing wear.  Once enough junk sticks to one spot, the spinning mass starts to wallow out the bearing which often takes the end bell housing with it. 

I've torn down burnt out motors that had literally pounds  of dust compressed into the rotor. 

Given what you're working with, I'd see what could be done to put the motor into a positive air pressure situation.  Sucking in cool, clean, air with a fan that blows into a housing for the motor might help.  If you're using any kind of belt-drive you might be able to get the motor physically away from the dust. 

If you can improve the cooling and dust mitigation sufficiently to keep it from overheating, you might take it somewhere to get the bearings replaced.  While they've got it open, it's a simple matter to clean out whatever has collected in the windings.

 

 

 

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  • 3 weeks later...

This isn't something I've done myself, but wasn't there a thread a little while back where someone built a filtering enclosure around their grinder motor? Basically a frame filled with furnace filters, if I recall correctly.

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I'm in the process of putting a 2.5hp treadmill motor in my home built 2" x 72" grinder. My for now question is how much of the circuitry do I need to keep? I wouldn't mind having the speed control available and it doesn't look like the old style resister waste heat generator type speed control. This one has it's own little circuit board.

I really don't need the thumb pulse monitor or programmable workout routine and lap counter. But it all plugs into the circuit board. The transformer is separate and appears to be plug and play. Can I just lose the circuit board, run the wiring through the speed control and to the motor?

When it comes to electronics I'm a good welder.

Darned if there isn't a conversation going on while I type! :o Will wonders NEVER cease? I saw the post about using soda bottles. I'm just going to buy flexible dryer ducting. Faster, Easier, Better. I can leave it rolled and hanging on the side of the grinder stand, out of the way and stretch it out when grinding.

Thanks, 

Frosty The Lucky.

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I'll take some pictures of mine when I get home Frosty and post them up here. I built an SCR motor controller initially but then just ended up using the treadmill controls. I kept the power supply and the controller board that allows you to adjust speed. Most of them are MC-60's but mine was an MC-1200, I think. It is what provides the variable speed.

EDIT*** To bypass the magnetic safety key on the treadmill control board, I just wired the three wires together. I'll take pictures. 

If you don't want that big treadmill control board you can build an SCR controller for around $25 that will work just fine. Like this: 

Anyway, I'll post pictures of what I did for a cost of 0$ using the existing treadmill parts. If yours has an MC-60 board and can solder, you can do it this way: https://hackaday.com/tag/mc-60/

15 minutes ago, JHCC said:

This isn't something I've done myself, but wasn't there a thread a little while back where someone built a filtering enclosure around their grinder motor? Basically a frame filled with furnace filters, if I recall correctly.

Here is the two liter fan enclosure I was talking about: http://bbs.homeshopmachinist.net/threads/47611-Cooling-off-a-hot-treadmill-motor  Pretty nifty!

 

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Well O-K-A-Y! Browsing through a few videos I can make a speed controller with a bridge rectifier and a wall plate dimmer switch? No transformer necessary, that's what the rectifier does. Yes? What do I need to know about the rectifier?

Any traps or things I need to know before heading to Home Depot and the local electronics supply.

I'll double check the voltage rating on the motor and adjust as necessary. 

I can just lose all the circuit boards and junk. Cool. :)

Frosty The Lucky.

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1 minute ago, Frosty said:

Well O-K-A-Y! Browsing through a few videos I can make a speed controller with a bridge rectifier and a wall plate dimmer switch? No transformer necessary, that's what the rectifier does. Yes? What do I need to know about the rectifier?

Any traps or things I need to know before heading to Home Depot and the local electronics supply.

I'll double check the voltage rating on the motor and adjust as necessary. 

I can just lose all the circuit boards and junk. Cool. :)

Frosty The Lucky.

The wall plate dimmer switches burn out faster from what I read but people use them and they work. Better to get an SCR controller and bridge rectifier then change out the pot in the SCR controller to one with lower resistance. That's what I did first then I ended up using the boards from the treadmill when I burned up my controller. Make sure you get a rectifier with a heat sink or make one. Those little boogers get hot!

Now as for the drive wheel on the treadmill motor, I welded on a steel pot that was about 3 inches deep and slightly smaller than the flywheel on the motor. I have since started running my belts right on the flywheel and it works fine though it will deform some of the super thin belts being only an inch wide. I saw a guy on youtube just using the flywheel and it worked for him so I tried it. 

I think this is the controller the guy uses in the video: https://www.amazon.com/Yeeco-Electronic-Regulator-Thermostat-Temperature/dp/B00MLZ1AT2/ref=sr_1_1?ie=UTF8&qid=1496262867&sr=8-1&keywords=scr+controller+10000w 

You're in for a fun and rewarding project!

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The motor I salvaged appears to be the same one shown in the how to video you linked Cedarghost, as close to exactly the same as can be seen from the spec plates. That makes things easier and I'm a fan of easier.

Darn, I just spent a couple hours trying to find an electronics shop here in the Mat Su Valley but since Radio Shack closed a couple years ago they all did. Closest is in Anchorage and I really don't like driving in Anchorage anymore, folk here in the Valley are crazy stupid enough behind the wheel for me. Yeah, I know I'm an old fogey but I like buying in a brick and mortar store, look at it, hold it, talk to someone about it. ESPECIALLY when I'm stepping outside my skills sets.

Of course I COULD use the speed control from the treadmill but the SCR and bridge rectifier control is so much cleaner. I'll see if I can talk Deb into letting me take the SUV tomorrow or just grit my teeth and  buy one through Amazon prime. I'll have to make some calls tomorrow and see first but there are a couple restaurants I haven't tried. The Gumbo House and the Bombay (something) a new to me place to feed makes a drive to Anchorage less onerous. Just going to depend on availability and price of the components I need.

Frosty The Lucky.

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11 hours ago, Frosty said:

I'll see if I can talk Deb into letting me take the SUV tomorrow or just grit my teeth and  buy one through Amazon prime.

You can buy an SUV through Amazon Prime?

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19 hours ago, Frosty said:

I'm in the process of putting a 2.5hp treadmill motor in my home built 2" x 72" grinder. My for now question is how much of the circuitry do I need to keep? I wouldn't mind having the speed control available and it doesn't look like the old style resister waste heat generator type speed control. This one has it's own little circuit board.

Frosty, show some pictures and if you have any info on the grinder (model number etc) I'll see what I can do to help. 

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Michael: Cedarghost posted links to easy, inexpensive speed control for DC treadmill motors. The motor in the video is exactly the same motor as I have, at least as well as I can see the spec plate on it. 

The grinder is one of 13 our club built in a crazed 2" x 72" belt grinder spree. Scrounging and adapting treadmill motors is an inexpensive way to power the things. One of our guys found a relatively inexpensive source for 2hp. ac motors that come in about $200 with shipping and you still get to wire a speed control.

It's not so much I think a grinder needs a speed control but I like a slow start, there's a lot less stress on components without the sudden application of torque jumping from 0 to 7,000 rpm. and these motors do it in a split instant.  

Been calling local electronic suppliers and it looks like online is my option. <sigh>

I'll post some pics as I go.

Frosty The Lucky.

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