how to find gear pitch and where to buy specific gears

rwgast_logicdesign

Ok so im in a bit of a bind i just got about 35 bucks to play with and i wanna get 4 of the 5v steppers on ebay, some sr04 pings, and some passives at digikey. but i really need gears too and dont know where i can buy what i need!

im looking for specific gears i need 4 spurs 4 pinion 2 worms and 2 of the spurs that have the teeth at a 90 degree angle or bevel gears

im also working on a mini bot using the ebay steppers an attiny coin cells and i want to make it treaded i have the perfect rc belts for this but i need spurs/sprockets that fit.

all the stuff needs 5/32 holes for the axel/preferably set screw too. i have about half what i need in my erector set but id just like newer quieter gears, you cant even really find meccano gears in the US or cheaply in the uk.

i also have toms of scrap gears from electronics but most arent suitable.

if anyone knows how i can get exact gears i need at a good price thatd be awesome, especially if someone knows how i can determine the specs for the gears that go in my rc beltsai

al1970

Hi:

There are a few online places you can get gears from but they just have odd and ends. The stores that just carry gears seem to have high prices. I go to the "VEX" site to pick up the gears I need.

Al

LoopyByteloose

If you want to get gears that are sure to match in pitch, it is best to buy in pairs from the same source.

I have some junk gears, but either they require the centers to be drilled out or don't match. It would be better to just start fresh with the right sizes, matched pitch, and holes that are properly centered that can be drilled out to the right size.

rwgast_logicdesign

,so the first two pix after the youtube videos show rhe gearbox i want to copy

http://letsmakerobots.com/node/4643

hes using meccano/erector stuff, which is what im using i have the two spurs, 1 right angle, and 3 pinions but two are cracking, so i really have one. these gears are nice but due to fottimg my axels and having set screws, but there hard to source and the loud. I dont mimd going with all mee gears but vex is to much amd doesn have right angles not to mention those square shafts may be to big to re drill to round 5/32. I could find two more erector motors maybe but id also need more gears.

i wilk post the belts i have later, i bought them so i could do 4wd without the erector gears but wanna use them for a mini tank. i only have one gear from a printer that fits them

Duane Degn

Since I have a lot of Lego sets, I tend to use Lego gears. You can get them for a pretty good price at BrickLink.com.

Use the "Search Within Results" box and enter something like "40 tooth" to see a bunch of 40 tooth gears. It takes a while to figure out what the different gears are named. I think there are resources for identifying various parts. Lugnet.com has a lot Lego information.

JR brand metal gear servos and HobbyKing's metal gear servos use a 3mm screw to secure the horn. When using gears attached to servos, it can be useful to use a longer screw than the one that came with the servo.

I also like to use Polymorph to attach gears to servo horns etc.

Lawson

First off, www.sdp-si.com is usually where I go first for small gears. They also have a good gear/belt book free online. Design and Selection of drive line components. (note, $35 won't get many gears from any maker of standard gears)

To measure the Diametrical Pitch or Module of a gear you need to know two things, the number of teeth and the pitch diameter. The easiest way to estimate the pitch diameter is to average the diameter across the tooth tips with the diameter across the tooth roots. (this will under-estimate a bit on plastic gears) To get Diametrical Pitch divide the number of teeth by the pitch diameter in inches. To get Module divide the pitch diameter in millimeters by the number of teeth. Next, round the calculated Diametrical Pitch or Module to the nearest "standard" size. If this is less than a 1% change the gears will fit well together.

As this is an erector set, I bet the gears are some DP. After checking Google, it looks like they're 38 DP which is a VERY non-standard size. Hm, 25.4mm/38teeth = 0.668 Module, so not close to a metric size either. (0.66 Module should work if you can find it...)

Have fun!
Lawson

Duane Degn

Lawson's comments reinforce my opinion that it's going to be very difficult to use gears from different sources together.

If you're using Erector set gears, then you'll probably need to use all erector set gears. Same goes for Vex or Lego.

I don't like Vex's square axles nor do I like Lego's "+" axles. I usually drill out the centers of Lego gears and use my own axle. I personally haven't used Vex gears but I've used their wheels several times and I think Vex makes good quality parts. (I particularly like their Mecanum wheels.)

rwgast_logicdesign

ive been looking into Mecanum wheels how would they handel in dirt or climbing rocks. my biggest issue with them is im afraid dirt will them up and they wont work well on smooth suraces like hard wood or solid rocks due to traction.

my biggest issue wit erector stuff isnt even price it sorcing the stuff. the only site i can find is meccano man which is based in the uk and isnt even taking orders until they catch up. Im going to take a look around ebay later, for erector gears and check into lego, vex just doesnt even make what i need. im wondering if 4 gearheads is the way to go. Electric goldmine has 6v screwdruivers for 1.99 right now that gets me 4 motors with planatary gear boxes. I really like the erector motors though there about 1.5 amps at 6/9/12 vs my 9.6v battery packs make them spun so fast they blow air like a fan and leave skid marks. They also have alot of torque at that voltage with no gearing. Im just afraid i wont find cheap gearheads that even compare.

if you watch that lmr video that bot is super quick doing 4wd with two motors and and srong enough to carry a camera plus the metal erector chasis