single stage gear reduction

[Danjr1]

Afternoon all,

Am looking to venture away from the drill motors and gearboxes and into home-made gear reductions. What i cant get my head around is the easiest way to make such a system? i understand how to mount the motor and its pinion, and how to attach the spur onto a wheel but how to mount the wheel on an axle and mount the axle. i know it will use bearings etc but i was wondering if someone knew of a quick and simple way of building such a system.

I would want to use 100mm or 125mm robochallenge wheels, mod 1 gears, replica or original speed 900s on 22.2v

cheers

dan

[maddox10]

The Hannibalito series of robots uses the MSR gearbox. Comes in 2 flavors. 4.5-1 or 6-1 gearratio.
An example with the 6-1 gearratio.

Nothing more than a lasercut steel plate, 15mm steel axle, M8 bolts and HDPE wheels. No bearings, but bronze bushings.

Further.
Biggest gearratio you can do in a single stage is 8 to 1.

Mod 1 gears. 12 teeth gear on the motor, 96 teeth gear on the wheel. (means 98mm outside diameter). That's close to the 100mm wheel . Too close, you'll be driving on the gear in no time, and ever bit of debries will be hit. Not a good idea.

So, we drop a bit. 12 to 90. = gearratio 7.5.

Speed 900 = 550rpm/V 22.2V means =12210rpm =1744 rpm on the wheel.

100mm wheel*1744rpm= 32.8km/h

Of course, with 125mm wheels the scenario changes, but still it will be bloody fast.

[Mouldy]

Further.
Biggest gearratio you can do in a single stage is 8 to 1.

Mod 1 gears. 12 teeth gear on the motor, 96 teeth gear on the wheel. (means 98mm outside diameter). That's close to the 100mm wheel . Too close, you'll be driving on the gear in no time, and ever bit of debries will be hit. Not a good idea.

So, we drop a bit. 12 to 90. = gearratio 7.5.

Speed 900 = 550rpm/V 22.2V means =12210rpm =1744 rpm on the wheel.

100mm wheel*1744rpm= 32.8km/h

Of course, with 125mm wheels the scenario changes, but still it will be bloody fast.

Not true- why put a 12T pinion on the motor when your trying for the lowest gear ratio, if you can put on a 10T?...

It would then become;

10 to 90. = gearratio 9:1

[maddox10]

Dave, you're right. You could get a bigger gearratio. Technobots has a Z10 and a Z120 mod 1 gear in store. Combine this with a 125mm wheel and you have a 12-1 gearratio, with 1.5mm groundclearance below the gear.
You also can use the trick of the first RAF machine in RW, the very flat, triangular, torpedo armed (pneumatic spike) , if I recall correctly, Typhoon. They milled the 12mm axle of the Bosch 750 so it became a Z10 gear.
Putting this in a 6mm axle, you get a Z4,

Several reasons why I give a Z12 Mod 1 gear the preference.
Speed 900 has a 6mm axle. Some Johnson variants (the Speed 900 is a Johnson motor) have a 1/4 axle.
A Z10 has a inner diameter -for the teeth of 10-2.5mm= 7.5mm, 1.25mm or 1.1mm of steel under the teeth. Do you think that is enough?

Guideline of mechanical enginering is max gearratio with normal gears or sprockets in 1 stage is 8 to 1. Everything above that is rape.
I did find some 10-1 epicyclic gearboxes from an Italian manufactorer. But those are rated very low on imput force.

Sorry to be conservative in this respect. But I dare to say that the track record of the MSR single stage drivetrains is proven.

I know of some combat failures.

1) Hannibalito I, using an MSR 12-54 @10S NiMH, at the XFM Halloween special, after a hit on the unprotected 900 by Little Hitter, what shattered 1 magnet. (this was solved by adding 5mm of HDPE armor)
2) Kashei, what used the MSR 12-54 with 6S Lifepo4 on 110mm wheels. The low grade ali gears didn't take the strain, and shredded teeth like a maine coon cat in the Sahara.(this was solved by electronic restraints put in the TX, and the new variant will use less V, 6-1 gearatio and 7075T6 ali gears.)
3) Plofbox, after a hit from Hornet straight on the gear.(unprotected wheels.... what a surprise)

4) Satanix is a strange case (that uses another MSR drive). It wasn't dependable. Untill I had the opportunity to work on it. I still don't know what the secret was. The only thing I did was giving everything just a tad more clearance.

[Danjr1]

The replicas on eBay have 5mm axles so I'd go for the smallest sized pinion. Would like to use 125mm robochallenge wheels but I think it will be easier to make my own! I'm thinking of using 6mm Ali plate instead of the steel though?

[Mouldy]

Wasn't saying your gearboxes were un reliable... Was just saying if you wanted a lower ratio in a smaller space it can be done... I'm running a 10t mod1 on my speed 900s and so far it's been fine.

[maddox10]

Dave, don't forget I talk to Inventor on an almost daily base. He's also the inventor/provider of the MSR gearbox. I just finish those to the wishes of the user.

Oh well. I leave it to you. I won't advice a Z10 for a 6mm axle. Especialy not with an overvolted Speed 900.



Danjr, the 5mm axle replica's are much higher RPM/v motors with a lot lower torque.

[Danjr1]

http://www.ebay.co.uk/itm/300511267976? ... 1126wt_689

These ones? Bit of a shame as the real ones are 4 times the price!

[maddox10]

If you buy me 8, I'll deliver 2 fully finished MSR 12-72 with 100mm wheels in exchange.

[Mouldy]

Dave, don't forget I talk to Inventor on an almost daily base. He's also the inventor/provider of the MSR gearbox. I just finish those to the wishes of the user.

Oh well. I leave it to you. I won't advice a Z10 for a 6mm axle. Especialy not with an overvolted Speed 900.

You mean Dennis? He helped design mine also.