Globe transmission with other motor(s)

[clayman]

Although we only had it on our robot for three matches, our roller claw worked without a hitch using the 395 and Black and Decker electric screwdriver combination.

[billbo911]

Originally Posted by clayman

Although we only had it on our robot for three matches, our roller claw worked without a hitch using the 395 and Black and Decker electric screwdriver combination.

This is good to know. I never have heard if the BD's were solid or weak.

So, why only three matches?

[ratdude747]

Originally Posted by billbo911

This is good to know. I never have heard if the BD's were solid of weak.

So, why only three matches?

i can attest that the cheapo 18v firestorm trannies are so-so at best. if you are going to use drill trannies, go dewalt.

[clayman]

Originally Posted by billbo911

This is good to know. I never have heard if the BD's were solid or weak.

So, why only three matches?

I was troubleshooting the type of belting I was using for the majority of my free time at the Detroit regional at Wayne, and the roller claw was only ready to put on for the last three matches. Lesson learned: never buy thick, pre-sized belts.

As far as the sturdiness, I only had issues when I put the motor into a situation that I couldn't turn by hand easily, in which case the gears in the box would pop out of place (they can easily be put back). I mounted it with a couple of screws through the casing and electrical tape onto an long angle bracket I made. As far as the drive connection, I hammered a regular locking screwdriver bit into one of our rollers (1/4" hole), the hex of the screwdriver bit holds it in place. The roller-screwdriver bit combo then just clicks into the BD.

As you can guess, this was a lot of trial and error.

[billbo911]

OK, I may have found a solution.
Today I finished a mash-up of a RS-395 and a Globe transmission. It actually fits together fairly well, but I did use a lathe to trim down the motor mounting plate.

It runs quite smoothly. I also see no reason that a RS-540 or RS-550, and maybe even a RS-775, couldn't be mated up as well.

I will post up pictures tomorrow.

For now, here are some specs:
With RS-395 132RPM 7.8lb ft max torque.
With RS-540 143RPM 18.5lb ft max torque.
With RS-550 164RPM 32lb ft max torque.

These values are based on the following:
117:1 reduction.
76% Efficiency.
Max Torque Spec. 12.5lb ft. (This is an odd spec because from the same sheet, the factory motor produces 16.6lb ft )

[EDIT]BTW, I forgot to mention, with the RS-395, this mash-up saves 130 grams compared to a window motor. You gain 45 RPM and maintain the same torque![/EDIT]

[Don Wright]

Avoid the 775's...

[Kevin Sevcik]

Ahhh, too late for suggestions, then. Still, I suspect you've discovered that a press fit is easily enough to hold your pinion in place. I was going to suggest you make it easier on yourself and get the pinion nice and hot with a torch before you press it, but you've apparently managed.

Other option is hunting up the gear, as you've said. The tricky part is determining whether it's inch or metric, not finding the DP or a supplier. Suppliers are easy: SDP-SI or WM Berg

[Brandon Holley]

Originally Posted by Don Wright

Avoid the 775's...

...at all costs...

[billbo911]

Originally Posted by Don Wright

Avoid the 775's...

Originally Posted by Brandon Holley

...at all costs...

Agreed!

[MrForbes]

775 motors would be good candidates for students to disassemble to see how motors work inside. Make sure they destroy them in the process.

[billbo911]

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.

[JesseK]

/favorited

[PAR_WIG1350]

Originally Posted by squirrel

775 motors would be good candidates for students to disassemble to see how motors work inside. Make sure they destroy them in the process.

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)?

[Doug G]

Originally Posted by PAR_WIG1350

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)?

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?

[billbo911]

Originally Posted by Doug G

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?

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.