pic: FRC 1771 Drivetrain

[sdcantrell56]

Im hoping I can get this drivetrain under 30 lbs. I havent made one yet that could actually function that was that light. Im working on a single speed version in case there is no need for a shifter like this past year.

[=Martin=Taylor=]

Originally Posted by sdcantrell56

Yeah I will look into cutting weight out of the frame. As for the wheels, I really want to go custom for a lot of reasons. Primarily we can get the exact size we want (5"), they are also keyed for hex shaft without a hub, and finally they are way cheaper as the material to make 12 wheels only costs ~$70. The wheels will of course be treaded with roughtop or wedgetop. I guess I am primarily asking for the durability of the actual uhmw portion of the wheel and if we go this route we will probably have a full set of spares with us at all times

I'm worried about hex-broaching plastic. Doesn't seem like a good idea to me. Might want to go with some of those Al AM hubs.... or wheels....


For the record you CAN buy 5" plastic wheels for less than $70.

[R.C.]

Originally Posted by Hachiban VIII

I'm worried about hex-broaching plastic. Doesn't seem like a good idea to me. Might want to go with some of those Al AM hubs.... or wheels....


For the record you CAN buy 5" plastic wheels for less than $70.

Yeah, I agree with Hachiban. Hexing UHMW is harsh, our capitan put ball bearings in them and it worked fine, but hexing is a different story. Where can you get 5 inch plastic wheels???

[Cory]

Originally Posted by Dancin103

Other than needing to loose a few pounds, i would say it looks good. Keep up the good work.

35 pounds is a very admirable weight for a rolling drivebase. Very few teams have made theirs lighter.

[sdcantrell56]

I don't know of any place to purchase 5" plastic wheels from other than colson wheels which are not hey keyed and which do not allow for tread attachment. Also the price of $70 is not per wheel that was the approximate price that itwould cost us to make 12 wheels, enough for 2 robots.

Has anyone actually tried broaching UHMW or any plastic for that matter? I would think it wouldn't be a problem but if that is not the case then I have to change my plan.

I agree and was under the assumption that anything under 35lbs or even 40lbs is a light drivetrain. I now have 2 drivetrains designed under 35lbs, one cantilevered and the other using plates and standoffs.

[Madison]

Originally Posted by Cory

35 pounds is a very admirable weight for a rolling drivebase. Very few teams have made theirs lighter.

Our '08 drivetrain was 35 lbs. with electronics. Making it lighter would require so much additional work that it's probably not worth it, but that doesn't mean we're not trying.

Of course, it's quite a bit easier to hit these low weights when you drop a CIM motor or two.

[=Martin=Taylor=]

Originally Posted by M. Krass

Our '08 drivetrain was 35 lbs. with electronics. Making it lighter would require so much additional work that it's probably not worth it, but that doesn't mean we're not trying.

Of course, it's quite a bit easier to hit these low weights when you drop a CIM motor or two.

...and the pneumatics.

[sdcantrell56]

Exactly. If we dropped a cim per transmission this would automatically be 5.5lbs less. Also the spur gear style transmission is heavier than a dewalt. Additionally this frame has more metal than yours. It is true we could possibly shave ~1-2lbs out of the frame, but the amount of machining might not be worth it if we know well ahead of time that we will make weight. A ~30lb drivetrain is imo very light particularly with a 2 speed transmission and 2 cims.

I am working on an updated version that uses custom hubs in the wheels and that has some more details added and Ill work on getting it up soon.

[s_forbes]

The frame looks great, nice and simple, and the bumper mounts are a very clever approach. I'd avoid cheese-holing it if I were you... It's already very light! Just put as much thought into your mechanisms as you did into this drivetrain and you won't have any weight problem at all.

And belts are awesome!

Originally Posted by rc_cola1323

Yeah, I agree with Hachiban. Hexing UHMW is harsh, our capitan put ball bearings in them and it worked fine, but hexing is a different story. Where can you get 5 inch plastic wheels???

$6-7 a piece (about $15 each if you get them with aluminum hubs):
http://banebots.com/c/WHB-HS6-498

[sdcantrell56]

Those wheels are definitely worth a look however I am going for something with a bit more traction (roughtop). I am also debating doing a finesse version of this one using custom omni wheels in the corners and a center traction wheel plus single speed. I just finished my single speed and with it I have gotten this drivetrain under 30lbs (~29.5)