Speed 900-gear ratio

I get my gears from technobots but if they dont have what i am after then HPC gears always does. Bit more pricey but the service is very good and you can get them to carry out various machining operations (at cost) on your gears.

ok so i just had the size of gears the wrong way around?

No i think it was right. Small gear on the motor, large gear on the wheel. it is a reduction, not an accelation you need.

hi leo could you reply to the email on my profile with your reply to my pm i sent to you?

thanks alex

just had a thought probably wont be suitable but, are there any tools which contain suitable gears which could be salvaged?

Alex, 100mm wheels will be WAY too fast for matts ratio. They are 5:1 and he just wanted the fastest he can get without burning the motors out and in a single stage.
The way you have drawn the gearbox will work, but with a 10:1 reduction on a single stage is quite alot and might not fit it in. I personally would build a 2 stage gearbox.
You havent stated what sort of speed you want so these ratios are just guesses. Do you want it really fast, real slow for easy control of in between?
Ploughbot is a fast featherweight with a theoretical speed of 9MPH, people say all these fancy speeds but they arent quite real.
Work out the sort of speed you want, it depends on the type of robot it is. I would Aim for the 8/10mph unless it needs to be really accurately driven.
Easy to work out the ratio you need.
Speed of motor divided by the ratio used. That gives RPM of the wheel, then work out the circumfrance of the wheel (diamtre x 3.124) that will give you the distance travelled in mm per rotation, turn that into metres.
Multiply that by the RPM at the wheel which will then give you metres per minute. Divide by 60 to get m/s. Then multiply that by 2.237 to get MPH.
Its worth making a note of that and tring to learn the rough workings out of ratios/velocities as it will help you alot.

hi grant

thanks for that, i will try it out to more i just used the technobots calcuator and did what you said start witht the mph (10) and found i would need 13.47:1?

alex

That sounds about right to me. I use 15:1 gearboxes on ploughbot to get 9mph and will soon be moving to around 16.5:1.
The higher the ratio the less your motor will have to work, so 13:1 sounds a good figure and shouldnt draw too much current. You will need a 2stage gearbox for that though. Not sure on the sort of money you have but I am making some more gearboxs for ploughbot, and a few other people will be using the same design so a few will be made if you were interested 16:1 ratio gearbox in a VERY lightweight package, but they will cost around the £250-£300 a pair mark.

you gettin ed to cnc them or makin em by hand grant?

Not sure yet - My gearboxes are different to eds so maybe by hand. Kenny might use some the same so he might cnc some.