So I am looking into a long term project of a completely scratch built tank. So I'd like to get some information regarding gears and ratios that are currently out there...

So for an example, I have downloaded a Gearbox calculator (excel spreadsheet) which has a variety of details and data regarding ratios and teeth, etc...
According to the chart a standard 3:1 HL gearbox (3:1 = 3 reduction gear system) has an overall reduction factor of 39.326 : 1
None of them actually show or callout the DP/Module of the gears. (I am also assuming that they all have a 20 degree Pressure Angle).

Does anyone know of a source for aftermarket double gears and such for making a custom gearbox?

try these guys, they are decent people
https://www.robotgear.com.au/Category.aspx/Category/36-Motors-and-Gearboxes
or these guys
http://www.robotshop.com/en/gear-motors.html

Hmmm.... I need to relearn electrical calculations from 25+ years ago...
I recall reading that Clark boards and such have a max current draw of about 20A with the drive motors, which you would want to be well below with stall torque of the motor (Example, Graupner Speed 400, 6V, can draw 25A @ Stall torque, @ 7.2V that drops to 21A).

In the links you supplied, would you be better to select a 12V pololu gearbox vs a 6V, to run at a standard 7.2V? (higher V on the 6V = higher RPM and more heat?)

I've never been able to figure out the pitch of gears our tanks use, the hobby shop guys had no idea and the standard pitches used in cars / helis weren't even close. I've been on the lookout for pinions for years, no luck.

the gear pitch is 36 yep, 36. I took a set of gears to an industrial gear shop that is a customer of mine and they worked it out for me.
The key is to try and find 36 pitch gears. I have found a few places but not small quantity joints by no means

lol Jarlath wants us to do math, I don't even do math when I get paid lol

Freakydude wrote:

lol Jarlath wants us to do math, I don't even do math when I get paid lol

Now, now... My expectations have not yet been formed... Don't give me preconceived notions...

I've been looking up gears and such and it is amazing how many places do NOT list pitch diameters (Or module for the metric ones)

my post was in gest only, i agree and there is even less places that you can go to get pinions.

Freakydude wrote:

my post was in gest only, i agree and there is even less places that you can go to get pinions.

Yup I knew it was

Guess RC'ing and custom gear-crafting is not as common as it used to be...

Unfortunately there is alot less science and way more trial and errors in this hobby than you think......... Half the time I just put something in and see if it works. If not, try something else............  :-)