Re: Globe transmission with other motor(s)
 

As promised, here is a breakdown of what was done to mash-up an RS-395 and a "Globe Motor" transmission.

The first steps are fairly self explanatory, and I don't have pictures of those steps.

Start by knocking the three roll pins in to release the transmission from the motor. Once the pins are in, just wiggle the two halves apart. For now, set the transmission aside, preferably with the output shaft down so the gears don't fall out.

At this point, you need to remove the pinion from the motor shaft. I settled for the double screwdriver prying method. This will most likely kill the motor for any future use. But once you remove the motor mounting plate, you will realize the motor mounting plate is an integral part of the motor too. So, that motor was going to be useless anyway.

Once you have the pinion off, remove the two torx head screws. The right tool is best, but careful use of an allen wrench will do the trick.

OK, now turn the mounting plate over and remove the retaining clip that is holding the bushing into the plate. It pops right out with just a little tug from some needle nose pliers.

Now the real fun begins. It's time to decide if you need to turn down the back side of the mounting plate or not. It will all depend on the length of the mounting screws you choose to use and how long the motor shaft is.
I chose to turn the plate down so the entire back was on the same plane as the outer rim.



The next step will also be based on how far you turned down the back of the plate. If the center section of the motor prevents the motor from mounting flat against the plate, you may need to drill the plate out to allow it to fit correctly.

While you are drilling the plate, add two holes for your mounting screws.



OK, go ahead and mount the motor on the plate, I know you want to.

Also, take note of the difference in diameter of the motor shaft and the pinion's ID. You will most likely need to make a sleeve to mate the two together.

Start by turning a piece that is .002" larger than the ID of the pinion. Now press the pinion onto that piece. Press it in until the shaft is flush with the surface of the pinion. Cut the other end of the shaft so it extends about .050" out of the pinion. Now you will need to drill out the center of the shaft to about .002" smaller than the motor shaft. (These press fitting measurements work well with 6061 aluminum and the RS-395 motor, YMMV.)

Now line up the motor and the pinion. Make sure everything is square, don't forget to press against the back of the shaft, not just the motor. Press the pinion on until the face of the pinion away from the motor is approximately .375" from the flat surface of the motor mounting plate.



OK, align the holes in the transmission to the holes in the mounting plate and wiggle the two together. Once it is together, knock the roll pins back into the holes and make them flush with the outer surface. It should now look something like this.



The best part of this is that the transmission is bullet proof. This rig is 130 grams lighter than a window motor. It gives you the same torque and 45 RPM more, too.

Re: Globe transmission with other motor(s)
 

/favorited

Re: Globe transmission with other motor(s)
 

:eek: I feel like I missed something. Any explanation (videos preferred if epic failure is involved) for such resentment towards the RS-775 (which I have just decided to rename the RS-sev sev)?

Re: Globe transmission with other motor(s)
 

Many folks are finding the rs775s case shorted. You must check em out thoroughly, burn them in, before using them.

@Bill, great job! I saw some other teams at sac doing the same thing. We too are using rs 550s and p60, 64:1 gearboxes on our roller claw and haven't noticed any problems. When did your original gearboxes start showing wear and tear?

Re: Globe transmission with other motor(s)
 

Somewhere on CD there's a long thread about the problem with "case shorts" on the RS-775 motors. I disassembled a motor that showed about an ohm resistance between the case and the terminals. The problem that I found was that the insulation on the armature failed and allowed the winding to short to the armature. This is an unacceptable condition in a motor, and many teams have found that their motor(s) are shorted this way. Banebots has not offered to replace them.

Re: Globe transmission with other motor(s)
 

The case short issue is definitely annoying, but it is no reason to completely avoid the sevsev. It is still the second most powerful motor we can use.

Re: Globe transmission with other motor(s)
 

If your robot design needs them, then go for it. We figured out how to do what we needed with window motors. No hassle at all.

Re: Globe transmission with other motor(s)
 

Wait, FAILED? As in NOT a factory defect? If a motor is not shorted out now, assuming the possibility of developing a short is a significant issue, what are the chances of it shorting out during the season?

Re: Globe transmission with other motor(s)
 

The motor I took apart was shorted right out of the box. We never applied power to it, aside from an ohm meter.

Read the thread, see what you think. Check the resistance of your motors after using them for a while.

http://www.chiefdelphi.com/forums/sh...ad.php?t=91733

Re: Globe transmission with other motor(s)
 

Thanks, I know that and they have already been checked, only one bad one:) . I just wanted to make sure they would stay the way they are.

Re: Globe transmission with other motor(s)
 

Doug,
The RS-395 and Globe transmission actually an experiment. We wanted to test it out to see if it would be a workable alternative for a roller claw we are building to take to St. Louis. As it turns out, it is .25 inches too long. Instead we will be direct driving rollers with window motors on "Claw 2.0".

We got burned by Banebots not delivering on time. Then after hearing about the failures the P60 is experiencing, we wanted to avoid them like the plague. With the minimal load a roller claw sees, the RS550 P60 combo should be fine. But, if it would be used in a heavier load situation, then the P60 is out and the Globe is in.

This bad-boy may not see any use from us this year, but it's good to have as an alternative in the future.

Re: Globe transmission with other motor(s)
 

Very nice modification! It's great to see a planetary gearbox alternative that a lot of veteran teams already have laying around.

Seems a little blurry to me on the rules though this year... Is this considered modification of a COTS item? I didn't think that anyone sold these motor/gearboxes anymore.

R29 is a neat rule this year that allows use of past robot components and COTS items that aren't sold anymore, but gives the impression that you can't modify them if you intend to use them on your robot.

Re: Globe transmission with other motor(s)
 

Steve,

It must be in an unmodified form before kickoff (it can not have been modified in a previous season). However, I believe that modification during the season is permitted under <R29>...

JMHO,

Mike

Re: Globe transmission with other motor(s)
 

Good catch on the rule question. I think you're right; if not commercially-available any longer, <R29A> says they must be unmodified—which they aren't—and <R29B> says they must obey other rules—of which the motor rules <R46> and <R47> seem to be pertinent. (There is some question about whether modifying a motor such that it is incapable of being used as a motor renders it permissible for use this season.)

I'm not sure what the GDC was intending with this rule. Is there something special about formerly-COTS parts that necessitates their being left unmodified? Perhaps a concern that teams would re-use particular fabricated items from old robots? (Not that I think this rule would be the logical response to that; I'm just speculating.)

Re: Globe transmission with other motor(s)
 

We installed 775s that did not show any issues right out of the box and after running them for a short while, the short presented itself. I would not feel comfortable with 775s on my robot at all. At any point the short can occur and cause huge potential issues.

We use 2 servos to release our minibot. One to release the deployment system and one to actually launch the minibot. The 775s would cause grounding issues throughout the entire robot because they were directly interfaced to the frame. We tried completely isolating the motor and gearbox from the frame by adding thin electrical tape in between and also switching to plastic screws, but this did not work. The pinion is still directly connected to the frame through the other gears.

When we would run our elevator at full speed it would cause the servos to move around as if they were getting a dirty signal. If we ran our elevator full speed from ground to top peg it would drift the servos enough to release our deployment system. Needless to say this is an extremely frustrating problem.

We are removing the 775s from our robot for Boston. It's simply too big of a risk/headache to continue using them.

Your mileage may vary however.

-Brando


/sorry for thread jack