single stage gear reduction

[Danjr1]

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

i guess thats without motors? lol

[Danjr1]

Been sketching and come up with a thwackbot running 2 eBay speed 900 motors per wheel (2wd), 125mm wheels with a ratio of 7.5 to 1 (although, according to the maths, top speed is a little low for a thwackbot at 13mph). Designed my own version of those msr gearboxes which could accommodate both motors and act as part of the chassis.

Maddox, how much do you reakon it would cost to have two 125mm diameter 25mm thick discs made? With some machining to the centre of each?

[maddox10]

Danjr.

I ment, the exchange would be 6 motors for my supply and a set of MSR 12-72 drives for you (2 motors are for you then).

If I have to buy 6 Speed 900's at the local shop, I would have to cough up ‚225.

Now, your idea of a dual motor per wheel setup, with 900's, that's a hugely powerfull drive, what will need a serious speedo. But not that difficult to build.
Speed of such a setup is depending on voltage. With 12V you get 13mph (20km/h) , @22.2V you'r thinking 23mph (37km/h)
(also, the pricetag on a Z90 mod 1 gear is £30 and weights 850 grams)
On the HDPE disks, let us discus that with PM's.

[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.

You mean Dennis? He helped design mine also.

Dennis= Inventor.

[Danjr1]

when designing such gearboxes, how much overlap should you allow in the design for meshing the gears? im using MOD 1 gears which have a diameter or 14mm and 87mm (this includes the teeth)

[Mouldy]

The overall diamater isnt important...the PCD and tooth count is what you need to know... half the PCD of each gear... then add them together that will give you your exact distance between centre's...if you dont have a milling machine or a precise way to drill it, you might find this difficult to make...Just add a tiny bit on top of the centre distances... its better to have them further apart then too close.

Look at this link to find out the PCD of you gears when you know the tooth count;
http://hpcgears.com/newpdf/spurgears_1.0mod.pdf

[Danjr1]

the design uses gears from technobots so getting the PCD is easy. Thanks for the help. Just trying to confirm that i can get the 6mm ali plate for the mounts, and that it will be able to bend to 90 degrees and what radius that would be.

[Danjr1]

The overall diamater isnt important...the PCD and tooth count is what you need to know... half the PCD of each gear... then add them together that will give you your exact distance between centre's...if you dont have a milling machine or a precise way to drill it, you might find this difficult to make...Just add a tiny bit on top of the centre distances... its better to have them further apart then too close.

Look at this link to find out the PCD of you gears when you know the tooth count;
http://hpcgears.com/newpdf/spurgears_1.0mod.pdf

Thanks for the help. The distance is 49.5mm so in the design, should i factor in 0.1mm or more do you reckon? I'm probably going to be asking Kenny to machine these parts for me as i cant trust myself with measurements this exact! i do remember from having RC cars that the gears should not be super tight together or is this factored into the design of larger gears?

[Danjr1]

Projects dead, was going to be overweight! Thanks for all the help anyway.

[Danjr1]

What would be more powerful?

Four Argos gearboxes with 18v motors, overvolted to 22.2v. Running on 75mm wheels

Or

2 speed 900 replicas, reduced down by 7.25 to 1, ran at 22.2v. Running on 130mm wheels

Both set-ups use electronize escs (if two speed 900 motors was used, could you have two speedos per motor?)

Cheers

Dan