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Thread: New Lathe Motor

  1. #1
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    New Lathe Motor

    I found a PMDC motor and would like to ask you guys if I should buy it so I don't waste $150 on it.

    Dimensions in inches: 6.5 (w\shaft) x 3.5 round
    Weight: 4.85 Lbs

    Motor Type: 2 Pole PMDC
    Rated Volts: 42 VDC
    Rated RPM: 4000
    Rated Power: 250 Watts
    Rated Current: 8.4 A

    I already have a 3/8 XL timing belt at 3:1 that I can throw it onto but I previously bought a 12V 15A 70% efficient motor which is 250W and it is VERY week and cant handle a tool or even spinning a large mass on the lathe.

    Should I buy it?? It looks twice the quality of the 12V one I have, thanks!


  2. #2
    Registered LeeWay's Avatar
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    That is a bit of cash for such a small motor.
    Unless you want a perm mag motor for some reason.
    My small DC motor on my lathe cost about $25 IIRC. The controller for it and heat sink was around $100. That and a DC06 board from Homann designs all works great with Mach 3.
    Less than $200 all in.
    80/20 benchtop lathe build
    Lee


  3. #3
    Community Moderator Al_The_Man's Avatar
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    I agree that is a bit steep to pay for that small a motor, even MotionTek Canada who advertise on this site have new motors much cheaper than that.
    They come in 90vdc version, so if you want to use as a spindle you can use one of the KB or Baldor SCR drives off ebay etc direct on 120v mains.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


  4. #4
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    The only other motors Ive been able to find are ones like this 1.5HP 48v 4,600RPM but its only 4" round and 4" long so I question its capabilities.

    The main problem with ebay for me is $50 for shipping kills me, anybody know of a place in the lower mainland (vancouver, british columbia area) that I can get used/new dc motors for <$100?

    As for controllers I build my own, Ive got a stock of 400V/50A fets I make H-Bridges out of that can handle almost anything and their only $2/each


  • #5
    Community Moderator Al_The_Man's Avatar
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    What size/torque are you looking for? I have a fairly large DC servo with tach on Kijiji right now, I could let it go for $75.00 shipping included to BC.
    ElectroCraft 4" dia x 7" length 5/8" dia shaft.
    Al.
    Attached Thumbnails Attached Thumbnails New Lathe Motor-dscf0002.jpg  
    CNC, Mechatronics Integration and Custom Machine Design (Skype Avail).

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    The motor I have on right now is a 1/4HP AC and I defiantly wont go lower than that, Im looking for the 1/3 - 3/4HP range.

    Doing a HP = Torque (in-lbs) x RPM / 63025 and converting (16 oz-in = 1 in-lb)

    I would like at least 500oz-in @ 500RPM (1/4HP @ 500RPM) but I do the majority of turning at 1000 to 1500RPM.

    What are the spec of your DC servo? I currently have a 48V 7.7A and 24V 25A power supply. Thanks!


  • #7
    Registered Jeff-Birt's Avatar
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    Guys keep in mind that you need a continuous duty rated motor. The stock Taig motor will produce 1/4" continuously. Many cheap motors and servo motors are rated at peak torque, the continuous duty torque is much, much lower, maybe 1/4 the peak rating.

    I've been looking at getting some custom PMDC motors made for the Taig and have to say that $150 is not a bad price for a good motor. You can of course get lucky on Ebay, or buy a cheap motor and expect to replace it often.
    Jeff Birt


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    One of my spindles is dedicated for engraving, it uses the stock Dremel collets and nut but on my own spindle with angle bearings and much higher precision.

    I dont know what kind of Brushless DC motor to get to drive it though, Ive found:

    http://cgi.ebay.ca/Aeolian-GT-Sensor...3%3A1|294%3A50

    Would spin at 52,000km @ 12V and geared down 3:1 should make it plenty powerful for all my engraving needs (the odd milling pockets into 0.080-0.125 sheet aluminum) but it might sound like a router at that speed, theirs 800kV motors but I don't know if they would be powerful enough.

    What one should I choose? My spindle is 4" long, 1.125" round and takes 1/32-1/8 bits

    Also how would I interface those types of controlers into mach3? Would i need to make a pic that outputs the 16,000Hz PWM signal and takes in mach3's pwm?


  • #9
    Registered Schweinhund227's Avatar
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    Question

    Just bumping this post !

    I too would like to know how to control a Servo Drive with Mach3 ??

    Since I just aquired "Al_the_man" ElectroCraft DC Servo on Kijiji !

    and would also need info on In Line Breaking circuits !


    Thanks in advance !

    Keep this thread going !


    Norm

    out


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