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  1. #1
    Frank R is offline Hot Rolled
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    Default Using a treadmill DC motor

    I am looking at a very early little flatbelt Rockford lathe. Someone made a cheap motor bracket and put an old washing machine motor on it. I would like to replace the bracket because it looks bad. I would also like to put a better motor and belt on it.

    I have heard you can scrounge good DC motors from used treadmills. This allows variable speed control.

    Has anyone done this? Any pointers?

  2. #2
    Frank R is offline Hot Rolled
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    Default

    Never mind. Google is my friend.

  3. #3
    ray french is offline Titanium
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    I put a 1HP treadmill motor on my drill press along with a DC driver and it has worked great for 3 years now.

  4. #4
    tom_boctou is offline Cast Iron
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    If the treadmill motor doesn't work out, look for some inexpensive phase converters - I got some from Surplus Center for $50/each, 110V in and 208 three phase out, with reverse, slow start, dynamic braking, etc. Small things (and much simpler than the Allan Bradley ones), and they'll run a 1 hp motor.

    This assumes, of course, that you can lay your hands on a three phase motor for cheap. There are a lot of extremely high quality old motors that can be had for scrap value, usually a bit on the large side, but if you can fit it then it's a good way to go.

    I'm sure there's a lot of variation in treadmill motors, but I tried one a few years ago, and it was a odd size with an odd size shaft, and the speed ramp was designed to keep the user from being spit off the treadmill. One thing I'm not sure of is how the torque of a DC motor (like the treadmills) vs. the AC motors drops off as the speed drops. An 1100 rpm 3 phase motor sure doesn't have any torque left by the time it gets down to 60 rpm!

  5. #5
    MarcD is offline Aluminum
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    Quote Originally Posted by Frank R View Post
    I am looking at a very early little flatbelt Rockford lathe. Someone made a cheap motor bracket and put an old washing machine motor on it. I would like to replace the bracket because it looks bad. I would also like to put a better motor and belt on it.

    I have heard you can scrounge good DC motors from used treadmills. This allows variable speed control.

    Has anyone done this? Any pointers?
    Frank,

    The suggestion of using a 3 phase motor is very good but I would use a VFD. I have a 1HP 3PH motor powering my wood lathe. The motor was free and very easy to overhaul. The VFD offers variable speeds, forward and reverse emergency stop etc. With a stepped pulley you move the belt only when you need a bit more torque.

    One added benefit: the 1 HP motor is a BEAST so the added weight makes a very smooth operation.

  6. #6
    doc
    doc is offline Hot Rolled
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    fiwiw...base on postings of others experience , you will still need a counter shaft for gearing down , since w/ a lathe as opposed to a shaper ,( my 150 yr old shaper runs just fine on VERY slo speeds w/ a DC mtr & controller) when you slow it down , you are still asking it to do the same amt . OF WORK ...& the lower speed of the constant torque results in less HP ...one normally goes to slower speed for for larger od cutting , but the larger circumference takes off same amt of metal as smaller circumference at higher rpm ..
    best wishes
    docn8as

  7. #7
    Frank R is offline Hot Rolled
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    I have wired up a VFD in the past so I am familiar with them. I was hoping to not spend the money on one. I wanted to get a cheap motor and controller for this little lathe.

    My understanding is the DC motor is pulse width modulated so you do not lose power as it is slowed down.

  8. #8
    L Vanice is offline Diamond
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    In general, you get constant torque with either DC or a VFD below 60HZ. Above 60HZ, you get constant power with the VFD. So with either type motor and control, at 1/10 of the normal RPM, you have 1/10 of the power and the same torque as at full speed. A lathe will be more satisfactory if you have full power available at low speed. That is why variable speed belt and gear drives have been used on lathes for decades. The modern lathes with built-in VFD or DC drives start out with oversize motors so they still have decent power at lower speeds.

    And I have bought several good VFD drives for very low prices on eBay. You don't have to pay retail, though prices have dropped quite a bit since they first came out.

    Larry

  9. #9
    JunkyardJ's Avatar
    JunkyardJ is offline Titanium
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    Arrow I put a 1.5hp treadmill motor on my mill drill.

    I have a 1.5hp DC treadmill motor on my mill drill. I got it and the speed control dirt cheap from surplus center. They don't have any more of either the motor or the speed control in stock, but you can still scrounge treadmills from craig's list. The speed control and the motor were about $120 together, so it worked out well. It's just a cheapo SCR based speed control, so it doesn't provide as much torque as a mosfet based PWM. It works well though, I took an idler pulley off my mill and basically have 3 mechanical speeds with the pulleys. Usually I just use it in medium speed, up to 750 rpm.

  10. #10
    ray french is offline Titanium
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    I got my motor out of a treadmill that had been trown in a dumpster.Had a Minarak DC drive on hand and that was all it took.I think most DC drives now-a-days are PWM.

  11. #11
    Frank R is offline Hot Rolled
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    There is a nice article on one of the Logan Yahoo groups about using a modified router speed control from HF to inexpensively run a treadmill motor.

    I tried to attach the pdf but it is too large.

  12. #12
    Frank R is offline Hot Rolled
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    Quote Originally Posted by ray french View Post
    I got my motor out of a treadmill that had been trown in a dumpster.
    This is what I had in mind.

  13. #13
    AiR_GuNNeR is offline Plastic
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    One of my lathes is a Smithy Granite 1324 that uses a 90 volt, 1.5hp DC motor. It is geared down via a belt but worked great. I have since upgraded to a 2hp Brushless DC motor.

  14. #14
    Frank R is offline Hot Rolled
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    Hey AiR_GuNNeR: I have sent you a couple of emails and a couple of PMs. Please contact me, I need your help on that lathe you looked at. No pressure, just need you to help identify some parts.

  15. #15
    wippin' boy is offline Diamond
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    way to go
    now every time i see a junk treadmill i'm gonna have to talk myself out of hoarding it away

  16. #16
    Joe in NH is offline Titanium
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    Post Heart Attack (I was 40 at the time) I scrounged a treadmill from the dump. As expected, the treadmill had "issues" this particular one being the power board. As luck would have it, Surplus Center had the power supply for sale. Power board was $25. I've since examined Surplus Center and they seem to do this a lot: buy up a manufacturers excess supply and put it on the market.

    The treadmill is gone but I still have the operable motor and power board. Motor is 2 HP and 125VDC. Anybody local want it? Freebee. I'll be at the Dublin, NH Engine Show on September 11th.

    Joe in NH

  17. #17
    ray french is offline Titanium
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    Women love excercise equipment and the treadmill seems to be at the top of the list.Only problem is most won't use it but a couple of months and then it sits around until better half carts it off.Another good place to look is The Salvation Army and GoodWill.They're cheap,at least around here.I think because the women go into one of these stores and they see one and thing "that looks just like the one I used to have".Even The second hand stores don't want to sit on this stuff for to long.Takes up space.

  18. #18
    paul39 is offline Stainless
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    I bought a working treadmill at a junk store for $10.00.

    Took out the motor and controls, used the belt to cover my fire wood, put the square tubing on my steel pile.

    Take lots of photographs of the wiring when you take it apart. Mine had wires running through small places, but it all unplugged.

    With luck you can mount the motor and control panel, replug everything and play.

    I also found a lightly used 1 hp 3 phase 120 volt and a new in crate 3 hp 3 phase 240 volt at a junk yard. I paid 50 cents a pound for them. These were small modern Baldor motors. I put a constant torque VFD on the little one.

    Paul

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