Banebot 56mm gearbox - double D - RELOADED

[dtengineering]

While the brazing may well reduce impact loading by reducing the amount of space for "play" in the Double D, and could serve as an emergency fix, I would suggest holding off on doing it for the moment, if you can.

I would be concerned about getting proper alignment of the carrier plate while brazing... yes, it can be done, but if it is done wrong you are deeper in the hole.

I share your concern about hardening... or softening... of the shaft. You don't want to weaken the shaft, yet at the same time you don't want to make it brittle. While I can't say for sure whether the brazing is likely to affect the shaft, or whether quenching would re-harden it, I agree with you that this is an unknown of no small concern.

I would be concerned that since the braze material is softer than the steel of the carrier plate that it will deform under static load, leaving you no further ahead than you were before brazing.

If a replacement carrier plate made of hardened steel becomes available it will likely be machined to fit the double-d of the shaft... which is now brazed into the old carrier plate.

I am hoping (rather anxiously now...) that the next team update from FIRST will address an official response to this problem, and that the official response will include replacement final stage carrier plates that will be available to all teams. (I am basing this on Dr. Joe's comments that everyone at FIRST and Banebots is working hard to address this issue and the high respect I have for the FIRST organization... I have no inside knowledge on which to base this.)

So if you've got a spare transmission on which to test this fix, I'd say sure... go for it... and let us know how it works. It just might work out okay, after all. But if you can still test drive your robot, despite increasing backlash, and have no spares, then I would suggest perhaps waiting a day or two before trying this fix.

The optimal solution does seem to be in getting some proper carrier plates manufactured and distributed to teams so that the gearboxes can do the job that they were specified to do. It shouldn't be that hard, nor that expensive, particularly if it is a co-ordinated response for all teams.

Jason

[ChrisH]

Originally Posted by dtengineering

I am hoping (rather anxiously now...) that the next team update from FIRST will address an official response to this problem, and that the official response will include replacement final stage carrier plates that will be available to all teams. (I am basing this on Dr. Joe's comments that everyone at FIRST and Banebots is working hard to address this issue and the high respect I have for the FIRST organization... I have no inside knowledge on which to base this.)
Jason

I was at FIRST HQ over the weekend on a different matter and spoke with the person who is responsible for the testing being done there on this issue. They were very frustrated at the time it was taking to get the new "improved" parts delivered for what will be a much more rigorous round of testing. At that time, Sunday afternoon, the parts were somewhere in transit.

Assuming the parts were delivered yesterday, as expected, today would be earliest we could reasonably expect results. Depending on the test program, which was not elaborated on to me, it might be several days before results are ready for general release. One thing they do NOT want to do is release a fix that then does not work. That would be worse than the situation now. So they are taking the time to do it right.

Another thing that needs to be understood is the small crew FIRST has working on FRC. I was introducted to about five of them. That was the whole FRC staff. These people all have duties to perform that are related to the Regionals and are therefore time-critical. Somebody has to plan the loading of all the boxes for the trucks, make sure all the equipment gets loaded in the boxes, make sure the boxes are properly loaded into the truck, and make sure the truck leaves on time, among other things. These tasks were planned and people and other resources were allocated well in advance.

The current test program is an un-planned task. It is a very important task and FIRST is very concerned that it be accomplished successfully, but it is still something that they have to divert some of their limited resources to cover. This is also their busiest time of year and people, even robot people, need to sleep sometime. So in spite of everybody's best effort it may take some time to get this resolved.

The good news is that the failure mode is slow and progressive and the fix can be installed at a Regional if needed. That gives at least an extra two weeks to deliver a fix. (Obviously the parts would be considered COTS items and could therefore be purchased if needed during the interim between ship and competition)

So keep on building your robots, handle them gingerly during testing and watch out for the start of any failure behavior. Make sure your trannys are accessable and easily removable. If you do these things you should be OK in the long run.