Treadmill Motor of Destiny: The Arbor Factor

[Not Steve]

Hi, still kinda new at this. Can you help with a 2x72 build? I liberated the motor from a treadmill…its destiny is to power a grinder.

The motor has a threaded 1.25” arbor, and I can’t find a drive wheel for it. Everything seems to be 3/4, 5/8 or 7/8.

• Can I get a drive wheel that fits?
• I found an adapter…are there downsides to using one?
• Is destiny unavoidable?

Thank you for your time and expertise. A 2x72 would allow me to blame my lack of other tools for my failures.

 

[Britt_Askew]

are there downsides to using one?

That is an open construction motor, most people want a tefc (totally enclosed fan cooled)motor. Difference is an open motor will not last unless you can keep it clean, dust from the steel you grind will kill an open motor. People use them and are happy but I would look for a tefc motor so when I go to the trouble of building a grinder it will last.
If you get a 3 phase motor you can then use a vfd and will have variable speed - a big plus when grinding knives.

 

[Not Steve]

That is an open construction motor, most people want a tefc (totally enclosed fan cooled)motor. Difference is an open motor will not last unless you can keep it clean, dust from the steel you grind will kill an open motor. People use them and are happy but I would look for a tefc motor so when I go to the trouble of building a grinder it will last.
If you get a 3 phase motor you can then use a vfd and will have variable speed - a big plus when grinding knives.

Thank you - I wasn't aware. For now, I'll need to use the motor I have—but I've got a new motor on my list, now.

 

[JTknives]

The big problem with that motor is not that it is just an open frame motor it’s that it’s open and a permanent magnet motor. It has 2 large magnets inside of it that will attract every bit of steel dust in your shop. I guess the good thing is you will have a shop air filter of sorts. The gap between the magnets and the rotor is very close and once that gap fills with grit you are SOL.

 

[Not Steve]

The big problem with that motor is not that it is just an open frame motor it’s that it’s open and a permanent magnet motor. It has 2 large magnets inside of it that will attract every bit of steel dust in your shop. I guess the good thing is you will have a shop air filter of sorts. The gap between the magnets and the rotor is very close and once that gap fills with grit you are SOL.

Thank you for more information on this - I wouldn't have even known why the motor was covered!

What do you all think: I could put the motor at the back of the grinder, so the magnetic field is too weak to attract dust—unless there was direct contact. Then, the motor goes in a box with with a 0.20 μm (or less) nitrocellulose barrier. Add a PC cooling fan. Happy motor.

 

[12345678910]

Thank you for more information on this - I wouldn't have even known why the motor was covered!

What do you all think: I could put the motor at the back of the grinder, so the magnetic field is too weak to attract dust—unless there was direct contact. Then, the motor goes in a box with with a 0.20 μm (or less) nitrocellulose barrier. Add a PC cooling fan. Happy motor.

No, it could be 10 feet away, the dust gets everywhere.

Don't spend any time or money on making treadmill motors work.
Junk all the treadmills you can get for $ .15 a pound until you can get a motor.

Just get a NEMA framed TEFC motor.

 

[Stacy E. Apelt - Bladesmith]

You would need a custom bored drive wheel or pulley ... which may or may not run smoothly on a threaded shaft.
You will have a very short life on the treadmill motor, and when it goes up in flames and smoke the custom drive wheel/pulley will be useless.
You will have to make some sort of way to mount the motor to the grinder, which will not be of any use when you get a proper motor.
The HP ratings on treadmill motors are not the real HP compared to normal motors. It may not even be equivalent to a 3/4HP regular motor. It will probably run a grinder, OK, but won't necessarily deliver the rated power. (If it plugged into a 15 amp wall socket it isn't 2.65HP)

Do yourself a favor and use a TEFC C-face motor. If you can't afford a 3 Phase motor and a VFD right now, use a regular single phase motor for the time being. They can be found for very little or even free.

Fill out the location info in your profile. Someone in Shop Talk might be near you and they may offer a motor for free.

 

[Drew Riley]

Keep an eye out on Craigslist, Facebook Market Place, eBay, or there may even be a local/semi-local motor repair shop that has a few rebuilds on the shelf for cheap. They're not always an everyday item, but I've pretty regularly seen 3 phase TEFC motors in the 1 to 2 hp range for $50 to $100. You can then get a VFD for about the same price from eBay, though it'll be open frame, so you'll absolutely want to stick it inside an enclosure, and/or wrap some filters around it and keep it clean. That's a lot easier to do that keeping dust out of a treadmill motor though.

I know the treadmill motors are tempting (decent power, variable speed, often free), but by the time you start buying or machining shaft adapters, rigging up some kind of mount, and getting the controls setup to be half way usable, a lot of guys will have already spent most of what a cheap VFD and used 3 phase motor would have cost them (if not more), and at the end of the day, you still have something that's likely to self destruct within the first 90 days of use anyway. It's a false economy. If you still have a usable treadmill, put the motor back on it, sell it for what you can get, and put the money towards something that's going to last.

 

[Not Steve]

No, it could be 10 feet away, the dust gets everywhere.

Don't spend any time or money on making treadmill motors work.
Junk all the treadmills you can get for $ .15 a pound until you can get a motor.

Just get a NEMA framed TEFC motor.

I wish I could…things are just too tight right now. I appreciate the advice.

 

[Not Steve]

You would need a custom bored drive wheel or pulley ... which may or may not run smoothly on a threaded shaft.
You will have a very short life on the treadmill motor, and when it goes up in flames and smoke the custom drive wheel/pulley will be useless.
You will have to make some sort of way to mount the motor to the grinder, which will not be of any use when you get a proper motor.
The HP ratings on treadmill motors are not the real HP compared to normal motors. It may not even be equivalent to a 3/4HP regular motor. It will probably run a grinder, OK, but won't necessarily deliver the rated power. (If it plugged into a 15 amp wall socket it isn't 2.65HP)

Do yourself a favor and use a TEFC C-face motor. If you can't afford a 3 Phase motor and a VFD right now, use a regular single phase motor for the time being. They can be found for very little or even free.

Fill out the location info in your profile. Someone in Shop Talk might be near you and they may offer a motor for free.

Thanks for your detailed reply. (I've filled out the profile.) I recognise and appreciate the proper way to do this—I'm just not in a position, yet, to buy anything. If I could ask a few more questions…

Could I use an adapter? I found one [ here ]. I'm planning to use it with a [ 5" drive wheel ] connected to a vanilla [ Origin kit ].

Why do treadmill motors have a short life…is it the dust, or maybe the demands are different for a grinder? As I understood, at least when powering a treadmill, a motor lasts 7+ years and runs almost continuously without overheating.

I'm not surprised on horsepower, and thanks for the info. For treadmill motors, I'm probably interested in the peak duty, which looks to be 1.6 for this one.

 

[Not Steve]

Keep an eye out on Craigslist, Facebook Market Place, eBay, or there may even be a local/semi-local motor repair shop that has a few rebuilds on the shelf for cheap. They're not always an everyday item, but I've pretty regularly seen 3 phase TEFC motors in the 1 to 2 hp range for $50 to $100. You can then get a VFD for about the same price from eBay, though it'll be open frame, so you'll absolutely want to stick it inside an enclosure, and/or wrap some filters around it and keep it clean. That's a lot easier to do that keeping dust out of a treadmill motor though.

I know the treadmill motors are tempting (decent power, variable speed, often free), but by the time you start buying or machining shaft adapters, rigging up some kind of mount, and getting the controls setup to be half way usable, a lot of guys will have already spent most of what a cheap VFD and used 3 phase motor would have cost them (if not more), and at the end of the day, you still have something that's likely to self destruct within the first 90 days of use anyway. It's a false economy. If you still have a usable treadmill, put the motor back on it, sell it for what you can get, and put the money towards something that's going to last.

Cheers for all the info. Yes, I've been able to find some good stuff locally, especially at a used tool store. True about a false economy - the treadmill economy is all I can afford now, ha…I'm not disagreeing.

Good point about the mount - I just went back to the treadmill wreckage and discovered there were mounting brackets.

I'm planning/hoping to simply use the treadmill's controller…seems to work OK. It's waaaay too big and looks ridiculous. But…it has 10 programable speed buttons, big ol' start/stop buttons…and I get to know how many calories my knife worked off. Even the fan works!

View media item 10947

 

[Stacy E. Apelt - Bladesmith]

He is in Cape Cod, Mass fellows. Anyone up there able to help him with a motor?

It is the powerful magnets in the motor that will attract the superfine steel dust from the air in the shop and build up in the motor. The motor needs the openings for cooling, so you can't tape them shut or cover them up. Did you keep the driver wheel that mounted on the motor? If so, it may work as a way to use the motor.
Show us a clear photo of the old drive wheel, motor shaft, and verify the shaft diameter.

That adapter converts a M10-1.25 metric angle grinder to a 5/8"-11 thread. It isn't going to work with a 5/8" bore drive wheel.

You said the motor has a 1.25" threaded shaft. If that is correct, you will need a drive wheel with a 1.25" hole.
If you can't use the old drive wheel in some way, your best bet for using the motor is to get a friend with a small lathe to take the wheel and bore out the center to 1.25"

That grinder frame is the bare bones. It will require the motor to be perfectly aligned in three planes to run smooth. You will need to mount the motor with the ability to make fine adjustments.

The controller for the treadmill will work ... maybe. It isn't going to like the metal dust in the shop either.

 

[Britt_Askew]

Why do treadmill motors have a short life…is it the dust, or maybe the demands are different for a grinder? As I understood, at least when powering a treadmill, a motor lasts 7+ years and runs almost continuously without overheating.

A treadmill is kept in a clean environment , either in the house or garage and may see a little dust .... that dust is NOT metal dust. Using it as a grinder motor it WILL see metal dust.
When I first started I had a question about my shop stereo, I've had it in my woodworking shop for 20 years but when I started making knives I was told it wouldnt last long near the grinder and I couldnt understand why? I mean it had survived for many years in my shop already but Stacy pointed out that wood dust covering a circuit board will not short it out but when that same circuit board has metal dust on the little soldered connections so they make contact with each other POW ... When your treadmill motor dies you will hate the fact that you spent money making things work with a treadmill motor and to get your grinder going again you will either need to get another treadmill motor that also may not last or throw away the stuff you bought to make the treadmill motor work and buy a TEFC motor and drive wheel anyway. Like I said some people use them so... its your choice.

 

[12345678910]

A treadmill is kept in a clean environment , either in the house or garage and may see a little dust .... that dust is NOT metal dust. Using it as a grinder motor it WILL see metal dust.
When I first started I had a question about my shop stereo, I've had it in my woodworking shop for 20 years but when I started making knives I was told it wouldnt last long near the grinder and I couldnt understand why? I mean it had survived for many years in my shop already but Stacy pointed out that wood dust covering a circuit board will not short it out but when that same circuit board has metal dust on the little soldered connections so they make contact with each other POW ... When your treadmill motor dies you will hate the fact that you spent money making things work with a treadmill motor and to get your grinder going again you will either need to get another treadmill motor that also may not last or throw away the stuff you bought to make the treadmill motor work and buy a TEFC motor and drive wheel anyway. Like I said some people use them so... its your choice.

That's it.

OP, you're trying to save $ ?
We're trying to learn ya.

 

[J. Hoffman]

That adaptor is not going to work. The motor will burn up quickly. Find another option. You're trying to make lemonade using bananas.

 

[Hubert S.]

I'm not going to try to talk you out of doing this (but I agree that it is not a good idea). Just one thing to consider if you proceed is the direction of rotation. Depending on the cooling fan and whether the drive wheel is threaded onto the shaft, it might not be a good idea to reverse it. Your motor says clock-wise, and I believe that is when looking at the end of the shaft. If that is right, the motor would have to go on the opposite side of what the grinder is designed for. Depending on the size of the wheel and where it has to be placed, this might make belt installation anywhere from tedious to near impossible. Maybe you can put the tracking wheel on the other side of the tension arm, but there is no telling whether that is possible from the picture. If you want to reverse the motor direction, you will have to make sure that the fan still cools the motor sufficiently and somehow lock the drive wheel to the shaft.

 

[Stacy E. Apelt - Bladesmith]

Folks, I don't think Not Steve is going to listen to us. If he had acknowledge that he needed to change his plan I might have mailed him a motor.
What I think what we should all do for now is let him make his grinder ( almost surely doomed to fail) and hope he posts photos of the build.

I will point out to the members posting here that his info does not exactly seem to match his posts about equipment levels and budget. He posts no age, either ( I thought that was a requirement when signing up?) This is his personal info:
I'm relatively new to forging. Starting with a coal forge, I moved to a home-built propane forge, and then bought some commercial ones. There's a lot of tools in my shop, but not many that are ideal for forging. I'm hoping to get some better tools, such as 2x72 and press. At the same time, I'm also working to build a real shop…that one is getting close. Still need a ventilation system…are shops ever done?

My last question to Not Steve is - Is your shaft like this? If so, everything that Herbert said about direction of rotation is going to be a problem (left-hand threads). You would have to get a custom made drive wheel ... which could cost more than a proper motor. There is a lot more I could add, but I don't think it will change your mind.

 

[3fifty7]

 

[Drew Riley]

Not to beat off a dead horse (is that the saying?), but a couple more minor points:

Those motors are not only open frame, but externally cooled, usually by a fan on the shaft end (often incorporated with the drive pulley/flywheel). You'll be removing this if you choose to adapt it to your grinder, so you'll already be at a disadvantage from a temperature control standpoint.
Also, you're very likely not going to be seeing 2.25 "real" horsepower from that motor, but probably something closer, on average, to 1 hp.
In other words, even if you were to swap it out for a 1hp 3 phase motor and a 110V VFD, you'll still be at an advantage with the VFD.

Trust me, I get shopping on a budget, and I'm the king of Macgyvering things to work on the cheap, but sometimes it's just really not worth it. Save a little bit more cash, sell a couple of things, and have a little patience, and before you know it, you'll find a good deal on the perfect motor.

And for all the guys on these facebook groups swearing that they've run their grinders on a treadmill motor for years without any problems, color me suspicious. Either they're grinding little to no steel, they're using their machine very little, or their treadmill motor happens to not be an open frame (TEFC DC motors certainly exist, but they're not often seen in consumer grade treadmills). For every guy saying they got a treadmill motor to work (for now), there's 50 more makers who burned out their motor, or are already on their 2nd or 3rd control boards, or their "free" treadmill ended up costing as much to make work as the better options mentioned above.

 

[ChristoDart]

Yea, I think you added one too many words to that idiom.

Not to beat off a dead horse (is that the saying?), but a couple more minor points:

Those motors are not only open frame, but externally cooled, usually by a fan on the shaft end (often incorporated with the drive pulley/flywheel). You'll be removing this if you choose to adapt it to your grinder, so you'll already be at a disadvantage from a temperature control standpoint.
Also, you're very likely not going to be seeing 2.25 "real" horsepower from that motor, but probably something closer, on average, to 1 hp.
In other words, even if you were to swap it out for a 1hp 3 phase motor and a 110V VFD, you'll still be at an advantage with the VFD.

Trust me, I get shopping on a budget, and I'm the king of Macgyvering things to work on the cheap, but sometimes it's just really not worth it. Save a little bit more cash, sell a couple of things, and have a little patience, and before you know it, you'll find a good deal on the perfect motor.

And for all the guys on these facebook groups swearing that they've run their grinders on a treadmill motor for years without any problems, color me suspicious. Either they're grinding little to no steel, they're using their machine very little, or their treadmill motor happens to not be an open frame (TEFC DC motors certainly exist, but they're not often seen in consumer grade treadmills). For every guy saying they got a treadmill motor to work (for now), there's 50 more makers who burned out their motor, or are already on their 2nd or 3rd control boards, or their "free" treadmill ended up costing as much to make work as the better options mentioned above.