Treadmill converted to homemade variable speed grinder

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drlozier

Joined
Jan 4, 2010
Messages
158
I wanted to step up from my HF 1 x 30 sander and stone bench grinder but have a budget so I built this 2 X 72 grinder from the remains of an exercise treadmill. The treadmill motor is 2.5 horse and the electronic controls from the treadmill gave me variable speed at the turn of a dial at not much cost. I should have photo'ed as a WIP but was not sure how it would turn out. It will win no beauty contests but it works great. :D Happy to share my experiences (frustrations) with anyone who wants to go this route
 

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I have not checked that yet but I too am curious to know and will try to figure that out and report back. The beauty to me is that I can run it slow and am not limited by a few settings from a step down pulley. Thanks for looking !
 
Man I have so much respect for you guys that are so mechanically inclined. I think it looks way cool. I think in it's current state it's missing some attachments, but it looks like you're mechanical enough to construct those too.
 
ok, so, 15' per second. 6 total feet in a belt. 2.5 belt lengths per second. x 60 seconds in a minute = 900 feet per minute. I think without the diameter of the main drive wheel it would be hard to figure out RPMs
 
AWESOME!!! I'm gonna have to see if I can find an old tredmill myself now. :D It almost looks like a professionally made rig. All it really needs are cleaner welds. It looks like there is a speed readout on the consoll so I don't see how hard it would be to figure out the belt speed. It would have to be the same as on the original tredmill.
 
Everyone, thanks for looking ! I have to go run an errand so I can't run the numbers right now but here are the variables for speed (some of whcih are irrelevant ) if anyone wants to calculate:
Max Motor RPM is 7100; digital speed read out on the console at max speed is 10 MPH; motor shaft drive belt pulley is 1 inch diameter; drive belt pully on drive shaft has diameter of 3.25 inches; belt drive shaft diameter is 1 7/8 inches; contact wheel diameter is 10 inches. All I know is it works, I can dial it down to snail pace, and its a step up from the tools I had for not much money...next question is what can I do with it ?? As a newbie, I did order my first "known steel" thanks to the collective wisdom of this forum and I am anxious to get after it. Thanks again for your input !
 
I love it! Variable speed and a grinder for anyone with the time, will, and basic tools. I may have to make one of these as my first 2x72" grinder. Currently I use a 4x24" craftsman belt grinder and i bite it in the vice. Thanks for the Idea.
 
Thanks everyone ! Dr thunder asked about changing belts. There is one adjusting bolt on the drive cylinder I need to remove to put a new belt on and the contact wheel is mounted on a pivoting arm with spring tension so it is pretty easy to change belts. I could probably pick up the speed by changing out the drive belt pulleys but for now, it pretty much matches my knife making experience and I am ok with that...the best part from my perspective is I can slow it down without a stall...some day when my skill justifies it, I will get a better grinder...that's the beauty of this knife-making experience...we keep learning and stepping up from where we were. Its a great journey and this forum keeps us all pressing forward. THANKS AGAIN EVERYONE !!
 
Very good ingenuity.
The only problem will be in the fact that the motor is open framed, and will be very likely to draw in metal dust. Most treadmill motors used for grinders have shortened lives.
Vacuum it often, and blow it out with the air hose regularly.
 
That's awesome!

I'm gonna send you an old Nordic Track and a couple of dumbells. See if you can make me a hydraulic press out of 'em. :D
 
Fashion a case to keep the motor in with 2 vents w/ filters to keep the dust from being drawn into the motor. You could easily make the case out of plywood.
 
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