Banebot 56mm gearbox - double D - V3 - It's Show Time.

[Joe Johnson]

I am sorry to keep closing old threads and starting new ones, but I am doing it again.

This is the thread that started the discussion: Banebot 56mm gearbox - double D related

This is the tread that continued things: Banebot 56mm gearbox - double D - RELOADED

A new chapter is about to begin and I thought it was time to start from scratch.

Bottom line first: Banebots has come up with a plan to get harder plates to teams that need them. Expect details in an update soon (today perhaps).

It is not ideal in that we don't have a genie to make the parts with a blinking her eyes nor do the parts magically install themselves, but given the constraints associated with living in the real world, I think that Banebots has really done a great job pulling this off.

Now for my two cents. In order have any chance of meeting timing constraints, Banebots has had to commit something like $30,000 to solving a problem that has not yet been shown to cause a robot to stop driving.

Think about that. The only total failure of the DD joint that I can document is the destructive torque to failure test that I did on a bench not on a real robot. We have had a handful of reports of Bowtied carrier plates, which I admit is not good, but we have had no reports of transmissions that have stopped working due to that time.

In short, to date no testing by FIRST or testing by teams we have recruited for this purpose have been able to cause a DD joint failure to the point that the robot will not still drive (and drive quite well).

Test results to date:
Data point #1: FIRST
FIRST tested these transmissions (1-CIM and 2-CIM) last summer and found no failures -- not even bowtied carrier plates.

Data point #2: Team Testing
1-CIM, 16:1 ratio
We have done 500 hard full forward, full revevse cycles with a 6WD with roughtop conveyor wheels on a 115lbs robot. Result: "noticeable wear, however I think it is nowhere near the point of failure."

Data point #3: Team Testing
2-CIM, 12:1 ratio
We have done 350 hard full forward, full revevse cycles (test is still in progress -- they ran out of batteries) with a 6WD with roughtop conveyor wheels on a 115lbs robot. Result: "noticeable backlash"

I expect pictures and a completed 2-CIM test results by the end of the day. The other team I have testing should be able to get us results today or at latest tomorrow. But that is all we have for now.

So, here is what I would like to see. I want every team that is using the 56mm gearbox and can drive their chassis to load it up to competition weight and do some evaluation for us.

If possible, help us with as much data as you can give us

1. approximate weight of the robot
2. the type of wheels you have (size and surface type)
3. the ratio from 56mm shaft to the wheels,
4. the number of CIMs (1 or 2),
5. the ratio of the Banebots Transmission (12:1 or 16:1)
6. tell us if you are using support on the output shaft or if not, how far from the bearing plate is the sprocket
7. if possilbe the angular backlash at your wheels before and after testing/driving.
8. If the backlash increases signficantly from start to finish, give us a picture of the carrier plate
9. if possible, give us pictures of your robot chassis so we can judge your traction etc.
10. tell us what kind of driving you were doing (climbing stairs, crashing down brick walls, starting and stopping, pushing around old robots, etc).

I know that Banebots is committed to a addressing this issue regardless of whether it is a real or theoretical problem. Even so, I would like to know that the money they are spending is going for more than just public relations.

So, It's Show Time!!! Show me some robots that actually stops driving because of this type of failure. Heck I would even settle for seeing a bunch of bowtied carrier plates. It is Show Time... ...so show me.

Joe J.

Update: Had to split pictures into two files because they were so large. JJ