Gearbox incorporated into frame.

[sanddrag]

I'm looking for pictures of gearboxes that are incorporated into the frame sturcture kind of like this http://www.firstrobotics.uwaterloo.c...etrains133.jpg

I'm looking for pictures of where the gearbox is really integrated with the frame, not built in separate modules. Thanks.

[Ken Patton]

Sanddrag-

We have done this since 2001. We started out with 1/4" plate on the outside, 1/8" plate on the inside, and a 3rd small 1/8" plate for a bearing support.

Over time this has evolved to two plates, 3/16" and 1/8".

I uploaded a picture of our 2003 robot (actually its the "mutt" made from spare pieces) to the CD picture gallery, year 2003, section "robots."

Advantages:
1. The two sides can be identical, so machining multiple pieces is easy.
2. You can put extra motor mount holes in the inner plates to be ready for a motor swap with different gear sizes (say FIRST decides to replace the F-P motor halfway through the season... never know it might happen).
2.5 If you pay attention, you can make access holes to do very quick motor swaps when those F-P's start to fry.
3. Stiff as all get-out. Don't get carried away though or it will be heavy as all get-out. With stiffness comes well-supported shafts, which leads to low friction.
4. Frame x-members can be very lightweight aluminum or steel thinwall tubing with welded flanges on the end. We use 1" OD 0.065" wall chrome-moly.
5. Can machine cool designs into the sides - 7075 aluminum works best for both machining an polishing, but get out your wallet. We typically use 2024 or 6061.
6. Good mounting surfaces for components - eliminates the added mass of a lot of brackets. We often "trampoline" control boards off the tubular x-members.
7. Very little welding required (we weld simple flanges on end of x-members).
8. East to assemble - disassemble.

Caveats:
1. Think ahead of time where you want to put x-members - pay attention to torsional stiffness when you place them.
2. It is easy to make the plates bigger than they need to be, which means you might carry around too much weight.
3. If you want to mount a horizontal platform (say for a turret) you have to think ahead about how it will get securely mounted to the frame. If possible use the mountings for your appendage(s) as x-member(s).
4. We always seem to have trouble with bumpers - think about what you put in the front and rear center of the bot (where there are no plates) cuz it will get banged up.
5. Mounting things to the tubular x-members can sometimes be a pain.

hth,
Ken

[sanddrag]

I'm still looking for more pictures of robots whose transmission is closely integrated with the frame, sort of like this one http://www.firstrobotics.uwaterloo.c...etrains005.jpg If you have done something similar please post pics and details. Thanks.

[RogerR]

well, our 2004 robot was inspired by 25's evil machine.

originally, it had 4 motors (2 drill, 2 CIM) with the drills geared to run in the same direction. the drill gearboxes had mounting holes, output shaft, output gear, and output speed identical to that of the CIMs, so the 2 motors could be switched at will. it was driven by solid steel gears directly from the motors to the wheels (no chains, belts, etc.) it used (6) 8.5"x2" beadlok wheels modified to climb the steps, with the center wheel dropped 1/10". it was geared for 16 fps, and achieved about 15~15.5 fps (according to 494's dynometer). it was extraordinarily maneuverable, but because of weight concerns, the drills where removed, so over-all power was somewhat lacking.

the wheel wells where made from 1/4" thick Al plate machined on a CNC mill, and connected using 1/4-20 bolts and aluminum stand-offs. the wheel wells where connected to each other (and the spine plate) by 0.5"x1.00" Al bars on the bottom and supported by (3) 1.75" ENC tubes on the front and back. while the body had the ability to flex a little and roll with the punches(more so after some of the ENC tubes were removed) the wheel wells construction kept them stiff and rigid and we never had any problems with mis-alignment.
this drive-train was heavy, but extremely robust, maneuverable, efficient, and fast.

[techtiger1]

25's gearbox is very cool. We were allied with them at Palmetto. The whole thing is gear driven and runs beautifuly and smoothly. All very nicely laid out inside the frame. I can see why someone would be inspired by it. This is one of the most original desgins as far as gearboxes go I have seen in FIRST. One thing I would like to point out is that comming out of there main gearboxes the output gear is easily accessible and interchangeable. All in all a very slick design.