Grinder Motor

[brickman]

So i bought a little 1x30 belt grinder this weekend, and it works... But i understand now why everyone uses the 2x72, That being said my forging buddy and me got a pretty decent treadmill for free and were able to pull out this little motor

We have the motor and all the electronics in still good and working condition.. Will this work well for a home made grinder? it seems to be a slightly lower RPM than a lot of the ones i see used (3400 vs ~3700) but it's 2.5HP instead of 1.5 or 2... Let me know if this will do the trick.

Thanks guys.

[RogueGeek]

Yes it is possible to get it working and I have seen some on youtube that appeared to work fairly well.
I was going to use a similar motor to build a 2x72 and ultimately gave up on the treadmill motor.
My primary reasons were:

1. treadmill motor is open to the outside air and the metal from grinding can get into the motor and will can problems. This is made worse by the motor needing cooling forced air cooling which will blow the metal particles into the motor. You will need to add a filter of some sort to keep the motor clean.

2. Non-standard shaft sizes. You will most likely have to use one or more belts and pulleys to get the RPM/belt speed you desire.  Also some DC treadmill motors are biased to running in one direction. So you may have to account for that.
The fan is part of the flywheel on most treadmills. If you take off the flywheel you will have to rig up some kind of fan to cool the motor.

3. The electronics from the treadmill control panel just didn't make for a nice looking machine. My grinder didn't need a hill climb mode.   I thought about designing a new controller but it was too much work for not enough return on my investment.  I also looked at commercial DC motor controllers and for the price, I could by a buy a 3 phase speed controller and 3 phase motor.

Ultimately I opted to go with the commercial 3 phase speed controller and 3 phase TEFC 1.5HP motor.  It cost me more than my scrounged treadmill motor, but my belt grinder is nice and compact, no wiring hacks, and everything is sealed to keep out dust and metal particles. 

 

I should also note, that while nearly infinite speed control is nice, many people get by perfectly well with a single speed motor and use stepped pulleys to change between a couple of speeds.  With a bit of engineering you should be able to get a few very usable speeds with just a couple of stepped pulleys. This is MUCH less expensive than the 3ph speed controller and 3ph motor I used.

 

-Brian

[John in Oly, WA]

Hey Brickman, take a look at the thread just below this one "Trying to figure belt speed" - it has pics of the filter (it's NOT pretty, but it works) I made for my belt grinder treadmill motor to keep it alive as long as possible (I'm cheap, what can I say?!) and has the calculations for figuring out what speed your grinding belt will be going (see Frosty's response).

 

[brickman]

2 hours ago, John in Oly, WA said:

Hey Brickman, take a look at the thread just below this one "Trying to figure belt speed" - it has pics of the filter (it's NOT pretty, but it works) I made for my belt grinder treadmill motor to keep it alive as long as possible (I'm cheap, what can I say?!) and has the calculations for figuring out what speed your grinding belt will be going (see Frosty's response).

 

I actually saw that thread after i posted. I may hit you up for some advice about using the treadmill motor with the build since you've already done it. I planned on making a housing for the motor and potentially off setting the motor from the grinder a bit and adding a pulley.. A filter idea would be cool and actually a thin mesh computer fan filter might be good, and they're super easy to clean, something like this https://www.amazon.com/Computer-Air-Filter-Polyurethane-Protects/dp/B000FJU8BC.. then just build a circular housing and wrap it around the end... i dunno it's just ideas at this point but seems like it could work.

[John in Oly, WA]

Sounds like you have a good plan. That computer filter looks like a good way to go.

Ask away, I'll give you what info and advice I can. These belt grinders are one handy tool to have in the shop.