Re: Banebots RS-775 Case Short
 

No, you're fine. I was a bit dense.

I was caught off guard by your dry sense of humor.

Re: Banebots RS-775 Case Short
 

It's just about time for some testing. Perhaps as soon as tonight. :D

Fresh out of one of my FDM machines! ;)

Re: Banebots RS-775 Case Short
 

That looks like fun. What's the polymer you used?

Re: Banebots RS-775 Case Short
 

ABS (Specifically P430) If you want more information about it check out stratasys.com or dimensionprinting.com

Re: Banebots RS-775 Case Short
 

Looks good! Are the spur gears a press fit?

Re: Banebots RS-775 Case Short
 

No slip fit with a set screw.

Re: Banebots RS-775 Case Short
 

Gearbox looks fantastic. Now I want to get our 3D printer running. I could just as easily lasercut some plates and throw a couple standoffs in there though.

Re: Banebots RS-775 Case Short
 

Same here. :) Ours should be ordered and coming in within the next 2 months. Too bad it'll be too late for this 2012 build season.

Re: Banebots RS-775 Case Short
 

We will not be using RS-775 motors this year.

It's a risk we just can't take. However, we are using 550 motors for sure this year.

-Nick

Re: Banebots RS-775 Case Short
 

Same with us.
Just need some of those p60s gearboxes...

Re: Banebots RS-775 Case Short
 

This would be sweet.

Re: Banebots RS-775 Case Short
 

Banebots called us today and asked for info on our testing, results, and motor info (printed on motors).
We found several so far that have the case shorts, yet when in use on our shooter with the CIM-U-Lator, have seen no ill effects as of yet.

Since they are willing to solve the issue and send us new ones, we plan on using them.

Re: Banebots RS-775 Case Short
 

This is a very sad day. I had high hopes for those 775s. I heard that all that was in needful in this case was to electrically isolate the motor can.

I have access to a 3D printer and some mad CAD and engineering skills, so... ...I thought I was all set.

But, two things disappoint me.

First, that what appears to be a good motor is really a ticking time bomb in many cases.

Second, Banebots. I know that they are a small company. But they just don't seem to understand what it means to a team when a their hearts are broken by something outside of their control, all the more so when the problem was known by the source of the problem.

BB has had a year to try to get to the bottom of this issue. Sorting motors is better than nothing but it hardly seems like enough given the severity of the problem.

Banebots has been a great supported of FIRST. I love a lot of their products and I love their prices (if you don't count the cost of poor quality biting you in the back when you can least afford it).

But, I am disappointed.

Joe J.

Re: Banebots RS-775 Case Short
 

This is how arms races begin.

But then I got to thinking. Brushes? We don't need no stinkin' brushes! (If only we had a speed controller that would work.)

It would be sweet seeing what you come up with, when mass-producability is thrown out the window. (Maybe not quite so sweet trying to beat you at your own game, though....)

Re: Banebots RS-775 Case Short
 

I've slept on this problem. To use the BB775s or not to use them?

I really want to use them because they should be a great motor. I think that isolating the case (from anything, including other BB775s) will limit the damage to that one motor. If I am using 2 in parallel (e.g. in a large arm application), unless both fail in the same match, I can limp through the match with only degraded performance as a result.

But... ...I don't like to go this way unless I have some way of detecting the onset of the problem and changing it at the first sign of a problem.

Has anyone tried monitoring the voltage on the case live while the robot is in action?

I am thinking that I could have put connect the case to a resistor network. For example, I could put two relatively high resistors in series between the battery and ground and tie the case to the middle of these and monitor this voltage. This monitor voltage (i.e. the case) would sit at roughly 6-8V (1/2 battery) unless a short starts and then it would start going rail to rail 12V - gnd - 12V - gnd - ...

And this is when I would replace that motor.

What do people think of this scheme?

Joe J.