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I'm trying to use this super-cheap PCB drill that I bought recently, but it's too weak for human convenience (takes about 10 seconds to get through standard 1.6mm FR4).

The drill uses a small DC motor (40 mm length, runs off12V, RPM unknown, my PSU shows < 100 mA current draw), which is clearly of concern.

Luckily, it's very simple to detach the drillbit collet from the original motor shaft, by simply releasing the black set screw in the photo.

So I wanted to substitute a more powerful motor. I'm supposing I can just use any standard DC motor to replace the original one.

What motor specs should I look for, if I want to achieve more powerful drilling? Also, should I ideally go for non-geared (higher RPM) or geared (higher torque, but at the cost of rotation speed)?

pcb drill

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  • \$\begingroup\$ I read somewhere that PCB drills should probably be made with stepper motors running at around 300rpm. Your motor appears to be a brushed DC motor, which will be very weak. \$\endgroup\$
    – DerStrom8
    Commented Apr 7, 2016 at 16:41
  • \$\begingroup\$ @derstrom8: I googled a bit and I couldn't find any application of steppers for such purpose. Regarding brushed DC motors, surely there has to be a range of speeds and torque, given that some brushed motors are used in heavy-duty machinery? Agreed that this particular motor is weak though! \$\endgroup\$
    – boardbite
    Commented Apr 7, 2016 at 16:49
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    \$\begingroup\$ Drill bit <1mm should be running >10000rpm, probably 30000rpm. If the motor IS really fast, check the bit isn't blunt, and is rotating in the right direction! Carbide drills are commonly used because the glass in FR4 blunts steel bits rapidly. \$\endgroup\$
    – user16324
    Commented Apr 7, 2016 at 17:27
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    \$\begingroup\$ After a quick perusal of the forums, it seems that people recommend very fast speeds (as Brian said), and vaccum or compressed air for chip removal. It is common for people to have problems with ruining tooling due to the hardness of the glass in FR4. I would not try to drill a small hole with a handheld drill, though. You will just break bit after bit. I think you need some type of micro drill press. If you are not drilling a lot of holes, then I guess it is OK. But buy extra bits. They are consumables. \$\endgroup\$
    – user57037
    Commented Apr 7, 2016 at 17:38
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    \$\begingroup\$ The reference to stepper motors is for POSITIONING the drill in cnc drill machine. not the drill it's self. \$\endgroup\$
    – Spoon
    Commented Apr 7, 2016 at 19:39

1 Answer 1

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For PCB drilling you want high speed. < 100mA current draw indicates that you have a very 'weak' motor which has low rpm and torque at 12V.

A '380' size brushed motor which produces 25,000-30,000rpm at 12V should be sufficient. For example the Mabuchi RS-380PH-4045 is rated for 3-12V, draws ~0.5A free running, and does 25,000rpm at 12V.

Many manufacturers make similar motors, and these are commonly used in PCB drill systems. Here is an example on eBay:-

VANGEL--mini pcb drill Press tool 380 motor

Power: 3-12 V DC
Diameter: 2.8CM
Length: 5.2CM
Weight:65g
Rated wattage: 20
Rated torque: 600G.CM           
3V    6915Rpm    0.52A
6V   14395Rpm   0.66A
9V    21095Rpm  0.68A
12V  29326Rpm   0.80A

enter image description here

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