I'm building a 180deg rotation mechanism and am supplied a 5tpi rack that has tooth height 0.135" that is to be linearly actuated with a stroke of 3". I need a spur gear to mesh of 5-5.5" outer circumference (0.8-0.875" radius) that I will use stops to set for my 180deg of rotation.

I can make a gear (I'm newish to milling but I know what I need to do for this) or buy one if I can find it but I need specs of the gear for cad drawings for Monday.

Anyone know of a place that sells such a gear? I prefer cheap and instant delivery if possible. I'm provided brass to make a gear but a purchased one doesn't have to be brass, this is something that will be used a few times for demonstration as a part of a robotic arm.

 

Hobby stores? RC spur gears are roughly that size, and come in a variety of sizes.
You need to know the dp of the gear, or diametral pitch. Use the gear formulas to find roughly what dp you need, and bring some calipers to the hobby store. That rack is going to dictate what dp you'll need, most RC cars are around 12-16, maybe finer.

 

http://www.mcmaster.com/#spur-gears/=f6foyg

http://www.grainger.com/Grainger/wwg...N=0&sst=subset

I didn't search for your specific gear but knock yourself out.

 

Late to the party, but these guys have a bunch of neat little miniature gears and other mechanical bits: http://servocity.com/html/mechanical...cessories.html

 

Thanks guys, apparently I know a guy who knows a gear guy that likes robots that sold me one to spec at cost on the condition he's invited to the demonstration. I didn't realize most of this kinda stuff is not made in China.

We will soon be moving and stacking ceramic tiles (each with a different letter of the alphabet) that we're cnc-ing, joy!