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What should I do with a treadmill motor?

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by jawilder, Jun 21, 2012.

  1. jawilder


    Jun 27, 2006
    My brother was throwing out his old treadmill, so I salvaged the 1.5hp motor and controlls before he scrapped it.

    The problem is that I really can't think of anything to do with it.

    I already have a 2x72 and upgraded motor on my 2x42. I have a 10" HF Disk grinder but can't find any 10" disks at a fair price, so I'm thinking I might make a 9" DG. I suppose I could use this motor for it, but would rather hear some options.

    What would you do with it?

    FWIW, it has a 17mm shaft with 12mm left hand threads.
  2. timgunn1962


    Apr 1, 2009
    Any data on the rated speed?

    I've not played with treadmill motors myself, but most of the specs I've seen, show rated power at pretty high speeds. I was considering one rated 2 HP at 6000 RPM and another rated 1.5 HP at 3250 RPM, some time ago. Shaft torque seemed pretty low on both, with the lower-powered but slower motor looking much more useful.

    In the end I went AC instead.
  3. jawilder


    Jun 27, 2006
    If I recall, the speed is 4000 or somewhere around there. May not be useful for much. Maybe I can rig it to work with a foredom


    Apr 25, 2010
    BUFFER ,Pully it down may be useful there ,I have one ,,I bought a housed bearing twin ,L/R at harber freight and BELT pullyed it with a 3 stage set up , slows and speeds up ,the other end I stuck a 6 in. grinder wheel on it.. TAKES MORE ROOM BUT WORKS..mine was a 2 stage motor.. Was an old singer tred. machine ...
    Good Luck ..
  5. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    You can run a VS buffer with it.

    One regularly overlooked place for a VS motor is the drill press. Just fit it with a pulley and make a mounting bracket. The drill press is now VS.

    Other places;'
    VS band saw
    VS mini lathe or mill
    VS disc sander
  6. daizee

    daizee KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 30, 2009

    I have one of these, but it's rated 2+hp, or something nuts. Not sure what that will translate to in real terms, but I was hoping to use it for a grinder. That way I could push the speed control up to 'fat burn' when I really want to hog some metal.

  7. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    The HP ratings on tread mill motors is about as silly as those on shop vacs. I have a "5HP" shop vac that draws 11 amps. The best way to get an idea of the real power of any motor or tool is to look at the wattage.

    In theory, 750 Watts is 1 HP. Motors are not 100% efficient, so if the plate does not have an efficiency rating, figure it at 75-80% so that makes a 1HP motor draw closer to 1KW. At 120 volts, that is about 8 amps. In the real world, motors that are rated at 1HP can draw from below 8 Amps to over 12 Amps. The smaller/lighter/cheaper the motor, the higher the current is a good rule of thumb.

    The shop vacs and other tools with crazy HP claims are rated in "Peak" horsepower. That is derived by calculating the inrush current needed to start the motor. If that current was drawn for more than a fraction of a second two things would happen. One would be smoke and sparks from the motor, and the other would be a blown circuit breaker.
    A 5HP shop vac has an inrush current of about 40 amps. That only lasts for a split second, and then the RPM rises and the current drops to about 10 amps. What you have is an inefficient high RPM 1HP motor that they sell you as a 5HP motor. Inrush current is what causes the lights to dim when you switch on these motors.
  8. daizee

    daizee KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 30, 2009
    This is what I've got:

  9. timgunn1962


    Apr 1, 2009
    Honesty demands that I point out that I've not used a treadmill motor myself, so my input is much less useful than those that have....

    My thoughts, for what they are worth:

    The thing that really bothers me is the open frame construction. This, combined with permanent magnets, would seem to make it totally inappropriate for anywhere that ferrous metal dust might be present (even if the machine it will be running does not itself make ferrous dust).

    The "dual fans required" suggests it will need a fixed-speed fan in addition to the shaft-mounted one (if fitted; I assume it's part of the drive/flywheel that I'm guessing is just off the right-hand-side of your photo?), in order to provide cooling at low speed. It's not rocket science, but it should be considered.

    Other thoughts:

    2 1/2 Hp at 130V is 1865W at 130V, assuming 100% efficiency (1 HP = 746W from memory).

    Rating is 17.2 Amps at 130V, giving 2236W input.

    1865W / 2236W = 83% efficiency

    It's high efficiency, and the permanent magnet description, suggests it will need a purpose designed controller. This shouldn't be a problem, but a quick-and-dirty lash-up with a rheostat isn't likely to work well, if at all. On the upside, a quick google suggests the torque curve should be quite nice, with maximum torque at low RPM.

    7099 RPM is fast: about twice the speed you'd get from a 2-pole AC motor. Unless you are specifically after high speed, you can probably put a reduction belt drive on to sort this, but it needs a little thought.

    If the reduction ratio is large, it is sometimes necessary to have quite a long distance between the motor and driven axes to get enough "wrap" round the motor pulley to transmit the power. It's worth making this distance as long as you reasonably can from the outset, but if modifying existing equipment, you may be stuck with the original centre-centre distance.

    This may mean that it may be more hassle than it's worth for things like drill presses, bandsaws, etc. if your main objective is a lower speed range than stock.

    On the other hand, if you want a higher speed range than the stock motor gives you, it may be close to ideal.

    There are plenty of guys on the 9x20 lathe forum who have successfully used treadmill motors on small lathes. It's probably worth checking out. They have certainly come up with solutions to some of the potential issue.
  10. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    You don't need to gear it down a lot because it is VS. I would use a 2:1 pulley ratio and let the controller do the rest.

    What you say about the open frame and cooling fans is valid, and that probably makes the uses much more limited.
  11. daizee

    daizee KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Dec 30, 2009
    Oh, I salvaged all the electronics AND the control panel. When I said I'd push the speed up to 'Fat Burn' I wasn't kidding one bit. That's how it's labeled!

    Ironically, I accidentally bought the wrong motor for something else today at the used tool store.
    Ended up with a fully enclosed continuous duty 115/230 1.5HP 5/8" shaft USA-made Delta motor for $50.
    Think I just solved the enclosure & fan problem....

    Now to sell a couple things and buy a damn grinder chassis.
    Which brings me around to the OP's question again (and Stacy's answer): what ELSE to do with a spare VS treadmill motor? :D


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