Motor & sprocket Help please

Hi all,

Im in need of some help and links if possible, i have currently been kindly donated 2no 18v drill motors. I plan to mount these centrally in my robot and run a chain to a front and rear wheels on both sides making it 4wheel drive using only the 2 motors. To make this a bit more helpful what i have been donated is just the motor no Gear boxes. I have measured the spindle on the motors and i believe them to be a 6mm or 1/4 in old money (correct me if im wrong:) ) Can a Sprocket be mounted direct to the motor and then geared up at the front and rear wheels?? Is there a preferred method for achieving this? My bot will be running on 4inch wheels so i will also be needing sprockets to fit to the wheels then to work out what the best way of mounting them will be. I'm probs getting out of my depths here but i prefere a bit more of a challenge.

Any help and advice would be brilliant


Thanks all

If they don't have gearboxes you'll struggle to get enough gear reduction using chain and sprocket. You will probably need about a 24-1 reduction so even if you used gears and managed to fit a 10mm diameter gear on the shaft then you could only get a 10-1 ratio with 100mm wheels and a single stage reduction. I'd suggest getting some drill or Gimson gearboxes or banebots (I don't think these are available individually) to do the reduction then use a straight 1-1 ratio on the chain to run to each wheel.
Hope that's helpful

6mm ain't 1/4". 1.4" is 6.35mm, and that's a huge difference concerning axles, gears and sprockets.

And, as Max says, it's a problem with drill-motors and more common RC motors, to get the gearratio good, as those motors are fast running.

Thankyou all for the feed back i think i maybe stretching my skills with the idea somehow, think i may settle for 4motors with gear boxes hahaha go for the 4wd method that way,

Thanks everyone for your advice

I`ve done it with chains/sprockets, apart from the gearing issues (I`ve got away with about 10:1 before) there is the weight to consider and also the failure rate. I`d go for four Gimsons or similar if I were to do it again.

With a 6mm shaft your motor is likely to be bigger than a standard drill motor, probably similar to a speed 900, in which case you could get away with either a single stage gear option or sprocket however it would take a bit of knowledge when it comes to the motor itself.

hands on im pretty competent that way, but as for knowledge on the motors its a no no. Ive only at this moment measured the shaft with a tape, so far from accurate but its it around the 6-7mm mark, i presume when you mention the single stage gear that would be a (sorry for my terminology) a small sprocket on the drill shaft to a larger sprocket on the wheels?

Would you advise for someone like myself who is just starting out to run for example 4no cheap 12v drill motors over volted (i have 2no already) and just run them trough a set of bot bitz 85A esc's?

I'm inclined to say go for the 18v drill setup, purely to be different. Though many (ourselves included) start out with four drills overvolted. Done right it makes for a nice powerful machine, but no matter what you do, it will be dogged by reliability problems. Reliability will be greatly improved without overvolting.

Can you get a picture/any manufacturing numbers from the motors? Chaindrive is perfectly possible, but if the motors are fast-running (quite likely unless they're really quite big), you get into needing two or more stage reductions for it to have the power to drive the machine, and that gets pretty complicated (and heavy). Single stage means, yes, from the motor directly to wheel.

In short, if you can, pictures please!

Hi ELLIS,

i Will try get some photos taken over the weekend as currently all my gear is neatly (cough..cough) packed away due to moving house in a few weeks time, i wanted it to be slightly different like you said, as i have a set of four 12v motors with gear boxes and luckily enough in a few more weeks time i will be getting 2 more 18v ryobi drill motors this time with Gear boxes.So not sure whether to hold out until i pick them up and run them with gear boxes on and run a chain straight to back to a set of wheels as wouldnt need to worry to much or gearing them.

Whats your thoughts