Drill Motor pinion

We are TRYING to build team 116’s transmission… and after much much hair pulling out I have found everything but the little oddball .7 module 55 tooth gear that is listed as msg25-55 (55 tooth). pic has no record of this gear, however they do have an msg25-56(56 tooth) listed. Was it a typo that 55 was used insted of 56. could an 7.5(edit ment 7.5) module gear be used to mate with the drill pinion? and does anybody know of a gear manufacturer that could supply one that can ship faster than 2 weeks (which i think is rediculous SP). basically im tired of fooling with this ordering stuff and I want to get to building this thing. I have look for the gear at mcmaster,grainger,msc, boston, martain, brown, sdp, small parts, berg, motion industries, everywhere… any help would be appreciated… pulls out last of hair (/rant) :frowning:

(guess I should have also said that the plans call for an 55 tooth gear, whereas there is an 56 avaliable… i think were just going to order the 56 tooth, and if it comes in soon then we will use it… if not… well run drills alone and have it for next year)

I was not aware that 7.5 was a standard module… I assume that you mean 0.75. In that case, the short answer is “no”. A 0.7 module gear is only designed to mate with another 0.7 module gear and no other. The long answer is “maybe… but only if you know what you’re doing”. Technically, if you mount gears at a non-standard center distance, the “effective” module changes and this may allow you to use a 0.75 module gear. There is a lot of things to think about when doing this though, so I would only recommend it if you are a gear expert… since you’re asking the question, I think it’s a safe bet for me to recommend you not try this…

FWIW: a few years ago I was on a team that tried to build a custom transmission like this and we needed that oddball drill motor pinion. We couldn’t find anyone to sell it to us, but we could find a machine shop with a wire EDM machine that was willing to make us one for free. That was pretty cool… You might see if you can find anyone in your area who could do the same…

Justin -

For that design, a 55-tooth gear is correct. If you order the gear through the PIC Designs web site, just enter “msg25-55” instead of “msg25-56” (the “standard” part number that is on the list). The order will be accepted, and they will ship the 55-tooth gear.