Globe transmission with other motor(s)

[billbo911]

Forgive me if this has been addressed elsewhere. Searching did not seem to address my exact question(s). If this has been addressed, please point me in the right direction.

With the huge delay in getting P60 transmissions from Banebots, we are looking elsewhere for a rugged solution for transmissions to use on a roller claw.
There are a couple options already posted, but many of these alternatives seem to all have issues with reliability. Stripped gears seem to be the biggest culprit. Here is an example.

With that lead in, here is what we would like to do. We have several Globe motors from previous years. The motors may not be legal this year, but I believe the transmissions are. Additionally, the transmissions seem to be quite robust. If we can interface a 395/540/550 to the traansmission, I think we will have a nice solution.

Here is the issue we need to overcome: The pinion that is currently on the globe motor has an ID that is noticeably larger than the shaft on the three motors listed.

Option 1) Make a sleeve to go between the motor shaft and the pinion.
Option 2) Locate a pinion that will fit, or can be drilled to fit, the motor shaft and drive the transmission.

Has anyone successfully performed either of these options?
If not, what other options might we have to solve this problem?

[Dad1279]

What target rpm are you shooting for?

We geared up a window motor with a belt. Simple, reliable, easy to mount to flat side of our gripper.

[billbo911]

Originally Posted by Dad1279

What target rpm are you shooting for?

We geared up a window motor with a belt. Simple, reliable, easy to mount to flat side of our gripper.

Definitely an alternative we are considering. We will be using two, so weight is now becoming an issue.

[Dad1279]

Originally Posted by billbo911

Definitely an alternative we are considering. We will be using two, so weight is now becoming an issue.

Does your design need 2 motors? We change direction for the lower roller by crossing a belt. Can also be done with gears.

Back to your original q., If you have the machining capabilities, I would make a sleeve for the pinion. I don't think globe pinions will be easy to find.

Off hand I don't know what material the pinions are, but if they are brass of steel, you could probably have the center holes brazed/welded closed, and re-drill.

The best solution really depends on the machining capabilities of your team.

[billbo911]

Originally Posted by Dad1279

Does your design need 2 motors? We change direction for the lower roller by crossing a belt. Can also be done with gears.

Back to your original q., If you have the machining capabilities, I would make a sleeve for the pinion. I don't think globe pinions will be easy to find.

Off hand I don't know what material the pinions are, but if they are brass of steel, you could probably have the center holes brazed/welded closed, and re-drill.

The best solution really depends on the machining capabilities of your team.

Our desire is to have two motors so that we can re-align a tube if it is not tilted the way we would want it.

We can definitely make a sleeve for the motor shaft, I just wasn't sure if that would be a good solution. I calculated the max torque and we should be well under .25 ft lbs at the motor shaft with a RS540 and under .4 ft lbs with a RS550. I just want to make sure we don't have a failure at that point because of a sleeve design. I guess with enough of an interference fit, we should be good.

[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.