I just found a site that sells compound gears.

Gizmo's Zone

I haven't had a chance to completely check things out, but this might be a great source for off-the-shelf compound gearsets!!

They also sell planetary gearmotors and gearboxes.

THANK Mlnielsen........
Very good site for those seeking gears to improve the torque of their crawler.

YELLOW-CRAWLER has a 34x10 more in each differential .. Torque = 120 / 1 ..
http://www.youtube.com/watch?v=sQ8C-eMH6Fc

loulou, nice vid.
do you have a build up of what you have don eon this rig?
what tires do you run? that is very impressive traction on a flat board!! unless there is sandpaper glued to it

As much as I like the products that "Gizmo" has they are in " Hong Kong " - I wonder what the chances of getting such a small package over here is ( no offense intended ) - if it arrives at all.. just wondering.. anyone ever ordered anything from there ?

( not Gizmo per se,, Hong Kong )

I ordered some stuff from Dinball.com in Hong Kong without a problem. I've never bought anything from Gizmo. They are "Paypal verified", if that has any meaning.

I just checked, to order 8 compound gears, the shipping is $4.30. Very economical!!!

what size did you look at ? - the closest I saw to what loulou mentioned was 10x32 or 10x36....

it is a nice find by the way - I hope that shipping is good ( 'cause it sure is cheap )

I just picked a randome compound gear.

For 8 gears it was $18.00 + $4.30 in shipping.

I think it would be best to change-out all the gears. This way there won't be any mismatch between metric and unknown NB gears.

phatchantz ..my gears is 34x10 :-)

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Change all the gears would be a good decision.

I was lucky to find these two gears (war tank) and which have adapted to the newbright.

These 34x10 gears had, which I give a torque of 120 / 1.

I was very pleased with this finding. I had to install them in the wake of three others.




(( A crawler is made for climbing ))

This message has been edited. Last edited by: loulou,

For future reference, I measured our gear center distances:

0.670" (17.0mm) = pinion to 1st compound gear
0.750" (19.0mm) = 1st to 2nd compound gear
0.805" (20.5mm) = 2nd compound gear to spur gear

Gizmo has the following gears:
Pinion : 8T - 18T
Spur : 20T - 60T
Compound: 8T - 14T pinion
24T - 60T spur

All Gizmo gears have a Module of .5 (metric pitch).

Here's the formula to find center distance from module and number of teeth:
C = (M(N1+N2))/2

To solve for number of teeth you get:
N1 = ((2C)/M)-N2
or
N1 = (4*C)-N2

This means you multiply your metric center distance by four to find the total number of gears required for that ratio.

For the first set (pinion to 1st compound gear):
N1 = 4*17-N2
or
N1 = 68-N2
That means we need a total of 68 teeth between the pinion and 1st compound geart.
We could/should use a 8T pinion and 60T compound spur.
That is the exact ratio as the Flapding 70:1 gearset!!!

So, here are the number of teeth we need for each gearset:
68 teeth = pinion to 1st compound gear
76 teeth = 1st to 2nd compound gear
82 teeth = 2nd compound gear to spur gear

Unfortunately, the widest ratio compound gearset Gizmo sells is 8T pinion and 60T spur.
This means we cannot get to 76 or 82 teeth without more teeth on the compound pinion of spur.
I have an email in to Gizmo to see if they have more gears available.

I think my measurements and calculations are correct, but I might have made some errors.

I would appreciate it if someone would double-check my work.

This is why I had to change the diametral pitch on the pinion and first spur to 48. It was the only way I could get a pinion small enough to make a difference.

OK, so Gizmo doesn't sell compound gears with the correct pinion/spur combo.

They do sell individual pinion and spurs that could be attached to each other.

The correct pinions/spurs could be match-drilled, pinned, and epoxy bonded. It would require the purchase of five gears per axle instead of four and a bit of labor. In the end the best ratio using 60T spurs will be 77:1.

All their gears are acetal (think Delrin).

Also, the Gizmo bores will need to be drilled out to accept our shafts and the hex axle.

That's how I make my sets.

The pinion is a 48 pitch 8 tooth helicopter gear. The next gear is an RC18T 60t spur gear, with a 32 pitch, 8 tooth gear glued into it. I take the 2nd stock gear, and cut the outer part off. Last, I take another 32 pitch spur gear, I think it's 34 teeth, cut a hole in the center, and glue the modified stock gear into it.

It results in a final ratio of around 90:1, compared to the stock 40 or so :1.

It isn't very expensive, but takes some time and a decent lathe. I have had to make several fixtures to hold the various gears for machine work, and to align them for gluing.

Mr Burton (Flapding)

Would you perhaps be willing to share a picture of your fixtures? I am an apprentice machinist and certainly have access to a decent lathe. I have my RC18T gears, and 8 tooth pinions on order at the LHS, but I'm not sure of the best way to hold delicate plastic gears.

I usually work with fixtures of a somewhat larger scale.

Found more compound gears:

E-Clec-Tech.com

If you poke around their website they've got other cool stuff.

A bit pricey though...

These gears are more accessible than my (war-tank)

..thank .. minielsen ..

Tamiya makes a 6-speed gearbox with a Mabuchi 260 motor. The compound gears can be configured to give you a gear reduction from 11.6:1 thru 1300.9:1

If you look at the Tamiya diagram, these gear ratios are configured with only 3 axles. Interistingly, the NB also uses 3 axles...

If we could add a pair of compound gears to our axles we could increase our gear reduction.