Question about motors and gearboxes

[Vertik]

Okay, firstly I have Never built a robot before. I have a decent understanding of physics but the two things I am unsure about are the motors.

1. Do you need a gearbox to be able to work (propel a robot sufficiently)?
2. Are cordless drill motors brushed or brushless?

By the way I know the difference between brushed and brushless so i don't need an explanation of that; but a way to determine either from the drill or the actual motor itself.

Thank you very much for any help.
Vertik.

[maddox10]

Unless you have a very strange electric motor, you'll need a gearbox to get any decent torque and useable speed. Like George Francis said during the tech check of Project One "It's an arena, not a runway".

Batterydrills. Some of the latest models have brushless motors, Milwaukie has a series of those. But most are 540 sized brushed motors.

[overkill]

To identify the type of motor, brushed motors have two leads and brushless motors always have three leads. If a drill has a brushless motor, it will be mentioned as its a big selling point. At the moment, only up-market drills have brushless motors and they are much more expensive.

[shakesc]

The sort of drills people buy and disassemble are http://www.argos.co.uk/static/Produc...er/7112946.htm

Have a look at http://www.instructables.com/id/Hack...oxMotors-for-/ for how to dissemble

[john_frizell]

You can often get cordless drills dead cheap by going to a boot fair and looking around. Most will have their battery in very poor condition (try out the drill - see how fast it spins). Bargain with the seller. A crap battery makes a drill almost useless for work but it makes no difference to a robot builder since you aren't going to use the battery. Ask your friends - someone might have an old drill lying around that they no longer use because of the battery You can buy wheels that screw directly onto the output shaft of the gearbox, once you get the chuck off, elsewhere on this forum. Good luck!

[daveimi]

Be wary of mis-matched second hand drills that spin at different speeds.

[mrsam]

I wouldn't bother going second hand with drills, i made that mistake and had all 3 pins on the carrier plate shear at once, the life of these things is very short when used in the way that we do and buying second hand when a brand new once from Argos is only around £15 seems a bit pointless.

[john_frizell]

The no load speed of every drill is printed on its casing. I've done a lot of second hand drills and rarely had them fail on me. If they do, I keep the good part [motor or gearbox] and if one gets damaged in a fight I have a spare motor, or gearbox, to use in repairs. If you have lots of money, by all means buy new [although I think Argos cordless drills are more than £15 each, but that might be just my store - 18 V drills start at £26.] but new drills can also fail when they get hit hard.