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electronic speed control for drill motor

Discussion in 'Sensors and Actuators' started by DougR, Feb 21, 2016.

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  1. DougR

    DougR

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    Feb 20, 2016
    Hello all,
    My first post other than intro. After spending time through the first twenty pages of threads I realized that being past 70 years, I have a finite amount of time left. If a prior post exists and I missed it, I will plead stupidity and beg forgiveness in advance. Short and sweet!! I have a project in which I wish to use an existing Milwaukee HD gear head drill. It currently has a trigger switch for on/off and a reversing switch. Milwaukee has other models that offer variable speed control and I am checking to see if I can modify mine with one of those component pieces. My preference would be to breadboard a circuit which would halve the speed from 450 RPM down to 250. Don't need variable speed just slower.Maybe not as complicated to build. Any thoughts or suggestions.
    Regards,
    DougR
     
  2. Minder

    Minder

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    Apr 24, 2015
    If it is a Universal motor (has brushes) then you can get a $25-$35 speed controller for power tools, other than that, Google Triac controller to build one.
    M.
     
  3. DougR

    DougR

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    0
    Feb 20, 2016
    Thanks for the reply. I have considered using one of those but have seen some remarks regarding performance especially in the mid to lower adjustment range. Loss of power and erratic speed control. Loading on the motor will not be linear, It will used to power a pitman arm wheel. Therefore, it will see minimum loading through 300 degrees of rotation with power requirement rising to maximum at the 310 thru 340 degree arc and reducing to minimum until 360 where it will start the cycle again. I'm just not sure the units I have seen on EBay, etc. will cut the mustard. Any comments?
     
  4. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    A Universal motor has a wound field so the motor will operate on AC or DC. It is also a high RPM motor, such as in a Vacuum Cleaner.
    A motor in a power drill is a 3-pole motor.
    To reduce the speed you need a PWM circuit capable of handling about 30 amps. It all depends on the wattage of the motor and the voltage.
    There are plenty of these circuits on the web.
     
  5. duke37

    duke37

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    Jan 9, 2011
    Give us details of the motor. If it is an induction motor either single phase or three phase, then you have no chance without a complicated drive system.
     
  6. DougR

    DougR

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    Feb 20, 2016
    Thanks for your response. Yeah, it's a universal wound field motor, [email protected] A quick look on Milwaukee.com will give you a peek at wiring arrangements for the straight on/off/rev I have (mod#1660-1) and mod1663-20, on/off/rev/var. spd. Without being overly wordy, my plan is remove handle and mount drill motor to it's new use using the mount pad. Reroute all the electrics to an isolated J-box. Take the controls from the variable speed unit so that I have the factory speed control. Better, right?? The only rub for me is getting it right when I switch wiring configs. Givens are don't need reversing capability although I would wire for std. CW rotation. Don't need variable speed, just half of rated 450 RPM. If I build a unit myself, I would install a known value resistance (equal to pot value at needed speed). Am I being overly simplistic, just plain dumb? I seem to be hung up on not having the pot in the circuit when that is not needed. I tend to overthink things. Maybe a straight swap of controls is best. Does any of this make sense? Opinion, please. Don't spare the criticisms.
     
  7. Minder

    Minder

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    623
    Apr 24, 2015
    You can either feed it from a home made 555 based PWM controller or if you can find one with high enough rating on ebay, these run around $5 to $10 just needs a bridge rectifier on the AC feed.
    http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm
    A universal (series) motor operates in a run away condition, the max rpm is controlled by the load presented with poor rpm regulation performance unless feed back controller is used.
    M.
     
  8. Externet

    Externet

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    Aug 24, 2009
  9. Bluejets

    Bluejets

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    Oct 5, 2014

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  10. DougR

    DougR

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    0
    Feb 20, 2016
    Thanks, everyone for your comments/replies to my questions. However, I have been able to speak to one of the "older" engineers at Milwaukee. He was most helpful and actually intrigued with my problem. He totally researched the history of the drill motor, it's field windings and other associated components and determined that the new model speed control circuitry would adapt to my proposed use with no problems. I have therefore ordered the current model speed controls and will install them for use with my old motor. What could be better than factory made!! I just love it!!! A little research by him found that this drill is in fact one of the earliest manufactured in it's current package. It has more than earned it's keep and proven that old is just old - nothing more.
    Thanks for your interest in my project/problem.
    Regards,
    DougR
     
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