We’re planning on teaching new students design skills by having them build laser-cut drivetrains. We’re using Denso throttle motors for the drivetrain as we have a number of them and we’d probably never use them for a “real” robot. However, we probably need a few more. Does anyone in the CA Bay Area (specifically the peninsula) have any they’re not using and don’t want?
@asid61 great, let me know if you can and I’d be happy to drive over at a time that works for you. Thinking 4-6 motors per chassis, not sure how heavy they’ll be yet (we’re still in early-ish planning) but the drivetrains will be max 24" x 24" because that’s the longest side of our laser bed. They’ll also be made out of 1/4" plywood, and we’ll be getting some lithium batteries. So not super heavy in other words. We’re going to make some gearboxes out of plastic, probably acrylic, to gear them down. We don’t know how many new students we’re going to have yet, so that will dictate how many drivetrains will be built.
I sent a chat to the person in charge, I’ll let you know when he replies.
24" x 24" seems way too big for a chassis made of throttle motors. IIRC they have a max output power of 20w, which is 1/15th the output of a CIM.
2 cims can make a 120lb chassis go at 8fps easily. If we follow that, then we need 30 throttle motors per 120lb, or 1 throttle motor per 4 lbs.
I’m disregarding a lot of factors here, but you may want to make a much smaller chassis on the order of <30lbs just to be safe. Will you be running FRC control systems or just RC?
We haven’t decided whether we’re doing RC or FRC control systems—the appeal of the former is that everyone can drive their robot at the same time, but we like the idea of the latter b/c we could have a swappable electronics box that teams would have to design to easily connect and remove from their drivetrain (we don’t want to buy each team a full control system for the obvious reason of $$). But yeah, we’re not thinking more than 30lbs, hence the lithium batteries, and we don’t expect the robots to go very fast. JVN DesignCalc seems to tell me I can get 5-6 fps with 3 CIMs on each side, which is good enough for this. We’re planning on building a test drivetrain and seeing exactly how much we can get, however.
We designed a gearbox for the Denso Motor that gives it a 7.5:1 reduction and a 1/2 hex output shaft. We manufacture these gearboxes ourselves and have donated them to new and inexperienced teams in 14 different countries.
There were many teams at the Australian Regional who utilised Denso Throttle motors to power intakes through the gearbox. One team using the motor/gearbox on their robot ranked 13th in their Division at the 2016 CMP.
Although it is only a low power motor, it is actually very useful once you give it an adequate gear reduction and give it an output shaft that can interface with other FRC specific COTS parts.
This sounds like a great training exercise, PM me if you require any help finding gears to interface with the motor pinion or for the mounting hole spacing etc.