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powering a cordless drill with PSU in drill press DIY build

Discussion in 'General Electronics Discussion' started by peterlonz, Oct 26, 2019.

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  1. peterlonz


    Feb 11, 2010
    Prompted by several DIY builds on YouTube I decided that I should build a drill press.

    All the examples on YT used a budget commercial corded drill, generally single speed typically valued at about $50.

    I happen to have a 24VDC battery drill for which batteries are no longer available. So I thought maybe a 500 Watt 24VDC PSU, if available at a reasonable price, could provide the drill torque & possibly allow me to dial up the ideal speed. FYI the chuck is 13 mm.

    I now have several questions that my experience alone can’t answer:

    1) Both speed & power of the cordless drill are not declared; is it likely that under heavy loads such as drilling steel 500 Watts may be insufficient & if that is likely, can I protect the PSU with something better than a fast blow fuse. Optmally something that can easily be reset?

    2) What options are available to regulate speed; ordinarily that’s achieved with simple trigger control. But the electronics of this are a bit of a mystery to me at this point. Can I simply use a heavy duty pot, & what type log or linear?

    3) Obviously I hope to spend no more than about $50.

    Two possible PSU can be viewed here: Scroll down to view specs.

    And here:

    Any advice, or better, how to comment, with any alternative approaches most welcome.
  2. Minder


    Apr 24, 2015
    What many have done is use an ex treadmill DC motor, this runs direct off of 120vac in N.A.
    There is two types of popular T.M. boards, the MC60 which is the simpler SCR bridge version or the PWM MC2100 version, with the latter version, a control board is needed.
    There is some out there designed around the 555, I recently designed one with a small 8 pin Picmicro.
  3. dave9


    Mar 5, 2017
    Frankly, this is madness. Even if you achieve your goal, it won't be remotely as powerful, durable, easy to use, or safe as a real drill press.

    Under heavy loads, your drill will stall and burn out the motor, but yes 500W for a 24V drill should be enough, but if it's old enough that you can't get batteries, is it really the right candidate for a new build?

    You are going to spend enough time on this that you could have just put that towards earning a real drill press.

    This is another case of "I have this widget I want to find a use for" when it isn't suitable. The best project for your drill is to rebuild the battery pack with new cells.
  4. peterlonz


    Feb 11, 2010
    Thanks for the replies.
    I did have at one time,a treadmill motor but no longer & I don't fancy my chances of getting another at low cost.
    To dave9 I think it's unlikely that a drill stall will occur, generally you'd have nouse to back off & even corded drills can stall but mostly don't burn out. In fact in my experience now over 50 years I have never myself seen a hand tool motor burn out.
    I am retired so earning to spend is not an option for me.
    Otherwise you are correct but if I can make this work it will be very useful on the few occasions that I need it.
    Are The Alibaba PSU units any good or is it more likely a case of overstated Chinese hype?
  5. dave9


    Mar 5, 2017
    ^ A drill press is a different beast than typical hand held drill work. You need either a heavy base or to have it bolted down, and the work piece often needs to be in a vice, and it is much easier to put substantial strain on the drivetrain or with a weaker drivetrain like you'd see on a cordless drill, to strip gears or stall the motor when it gets in a bind.

    Drill presses are practically never direct geared drive, without some way to slip out of engagement when the torque is too great so they don't tear apart anything more than necessary, and that's for beefier motors and gears, not the relatively tiny, fragile ones in a cordless drill.

    You should also consider that if it has any extra play, you're stuck using lower quality bits that dull far faster in order to not shatter them. Granted above a certain size, maybe 3/8" or so, a cordless drill may not generate enough torque to do that, would stall or strip gears before the shear force became too great.

    Anyway, if you're dead set on doing this, I would still (buy, if you don't have a spare and...) use a corded drill instead of buying a PSU for a cordless drill. You might find something substantial for cheap at a pawn shop (or craigslist in the US) if nothing else.
    Last edited: Oct 27, 2019


    May 20, 2017
    I doubt if your battery drill outputs anything near 500W. It's probably sub 100W and may even be closer to 50W. They get their torque by using a high speed dc motor and then gear it down a lot.
    I recently made a small pillar drill that uses a 30W motor and is belt driven with home pullies. It has a chuck of 6mm capacity. I use it for pcb's and model building.
  7. mike wax

    mike wax

    Oct 10, 2016
    it shouldn't be too hard or very expensive, and yeah you sure don't need 500W. Something like this:
    24V, 5A, that should do. Just touch it and you'll know when it's workin too hard. In fact, for lightweight drilling jobs, you could use an old laptop power supply.
    As for speed control, you'll need to bypass the trigger mechanism, which is probably some kind of chopper (PWM) with a triac. Open the drill, inspect the speed control. It will likely have only one output (one pair of wires) going to the motor. If so, then just get one of these:
    Lot less than $50
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