Bag Motor Tips

[craigboez]

Hello all

Because the Bag Motors had issues last year we steered clear of them and used 775s instead. It sounds like the Bag Motor issues have been sorted out, so I'm interested in using them for 2014. We haven't used a VersaPlanetary either, which appear to be the only real easy way to use the Bag motor. I'm interested in hearing tips, tricks, and other feedback from teams who have paired these two items up and used them.

[AdamHeard]

Hello all

Because the Bag Motors had issues last year we steered clear of them and used 775s instead. It sounds like the Bag Motor issues have been sorted out, so I'm interested in using them for 2014. We haven't used a VersaPlanetary either, which appear to be the only real easy way to use the Bag motor. I'm interested in hearing tips, tricks, and other feedback from teams who have paired these two items up and used them.

Especially with their new motor mounting plate, using a BAG motor with a versaplanetery is pretty darn easy.

Vex has multiple pdf's on their site about the vesaplanetary, and that's all the information you really need.

[DampRobot]

Hello all

Because the Bag Motors had issues last year we steered clear of them and used 775s instead. It sounds like the Bag Motor issues have been sorted out, so I'm interested in using them for 2014. We haven't used a VersaPlanetary either, which appear to be the only real easy way to use the Bag motor. I'm interested in hearing tips, tricks, and other feedback from teams who have paired these two items up and used them.

We've found that BAG motors really don't like being stalled. If you stall them, they will smoke. I believe 1678 has had similar experiences too.

Personally, if the difference in mass or size isn't absolutely critical, I'd use a MiniCIM instead. Unless the rules change next year (and I certainly hope they won't) you're better off using the extra power and robustness of a MiniCIM.

[AdamHeard]

We've found that BAG motors really don't like being stalled. If you stall them, they will smoke. I believe 1678 has had similar experiences too.

Personally, if the difference in mass or size isn't absolutely critical, I'd use a MiniCIM instead. Unless the rules change next year (and I certainly hope they won't) you're better off using the extra power and robustness of a MiniCIM.

Are you saying they "don't like being stalled" compared to a miniCIM/CIM, or compared to a 550 type motor?

[T^2]

We've found that BAG motors really don't like being stalled. If you stall them, they will smoke. I believe 1678 has had similar experiences too.

Personally, if the difference in mass or size isn't absolutely critical, I'd use a MiniCIM instead. Unless the rules change next year (and I certainly hope they won't) you're better off using the extra power and robustness of a MiniCIM.

They're okay with stalling for a few seconds at a time. The first time we used one in competition, we put way more stress on it than we should have, for around half a minute. This led to the worst smell you'll ever experience in your life.

[DampRobot]

Are you saying they "don't like being stalled" compared to a miniCIM/CIM, or compared to a 550 type motor?

Compared to a CIM. Which they can be exchanged for, according to the rules. I'm sure that the BAG is better than a 550 when stalled, although I'm not sure about a 775.

[magnets]

The biggest advantage of the bag motor and versaplTe art , IMO, is that you don't have to wait for the stupid p60 gearboxes to ship. If your team has experience with 775s then just use those. They're a great motor, especially if you don't use the p60 gearbox.

775s are super durable. They've been around forever too.

[craigboez]

We've had good luck with Banebots recently. Shipping times have been good and the P60s have done their job.

[AlexH]

treat the bag motor like a 550.

versaboxen are probably my favorite smaller gearbox out there.

[roystur44]

Anybody have any BAG motor specs

At a comfortable output speed we are looking for the desired gear ratio for the VersaPlanetary to drive a 4-5 inch wheel on a shaft at 20' per sec.

Can somebody make a spreadsheet?

[AdamHeard]

Anybody have any BAG motor specs

At a comfortable output speed we are looking for the desired gear ratio for the VersaPlanetary to drive a 4-5 inch wheel on a shaft at 20' per sec.

Can somebody make a spreadsheet?

The circumference of a wheel is pi*Diameter. Rotations per minute can be converted to rotations per second by dividing by 60. Gear reduction divides RPm by the gear ratio.

Give it a shot.

[Cal578]

Anybody have any BAG motor specs
...
FIRST posted this on their website:
2014_Motor_Information.pdf (http://www.usfirst.org/sites/default/files/uploadedImages/Robotics_Programs/FRC/Game_and_Season__Info/2014/2014_Motor_Information.pdf)

And this is on Vex's website:
217-3351 (http://www.vexrobotics.com/vexpro/motor-controllers/217-3351.html)

[roystur44]

Adam

Look right?

[craigboez]

Are you sure about that 20 ft/sec number? Seems pretty fast, though I don't know what you're attempting to do with it.

[Short Stuff]

Are you sure about that 20 ft/sec number? Seems pretty fast, though I don't know what you're attempting to do with it.

That does seem a little bit extreme unless you are attempting to throw the ball across most of the field. For our robot last year, we used bainbot motors to shoot the frisbees and they worked really well.

[roystur44]

Ball pick up at full speed.

[T^2]

Ball pick up at full speed.

Use a MiniCIM in a VersaPlanetary instead. Will save your bacon at your first regional.

[AdamHeard]

Use a MiniCIM in a VersaPlanetary instead. Will save your bacon at your first regional.

I fail to see how a bag motor isn't robust enough for an intake roller. MiniCIM is more robust for sure (based on it's power/weight ratio), but that doesn't mean the bag is a bad choice.

[T^2]

I fail to see how a bag motor isn't robust enough for an intake roller. MiniCIM is more robust for sure (based on it's power/weight ratio), but that doesn't mean the bag is a bad choice.

We burnt out one on an intake-related mechanism last year. Granted, part of this was to suboptimal friction within the system, but we ultimately just needed more power. Because the motor allowances are the way they are, MiniCIMs generally carry more advantages this year.

[roystur44]

Have you checked out the dual motor input for the VexPlanetary? The BAG motor runs much cooler than a Banebot motor. We have had to fan cool the Banebot motors being used in a high torque on/off process.

A cool design would be to use one transmission to ready the catapult, shift and lower the collector arm then run the roller.

Anybody ever build a 3 speed with neutral dual motor PTO transmission?

[R.C.]

Have you checked out the dual motor input for the VexPlanetary? The BAG motor runs much cooler than a Banebot motor. We have had to fan cool the Banebot motors being used in a high torque on/off process.

A cool design would be to use one transmission to ready the catapult, shift and lower the collector arm then run the roller.

Anybody ever build a 3 speed with neutral dual motor PTO transmission?

Roy,

Why do need a 3 speed? A 2 speed with a neutral/3 position would work for almost any first application.

[roystur44]

RC,

Just thinking out loud.

Engage gear to arm the launcher,
turn gear to bring launcher arm back
at load position lock the arm with cam
shift to engage intake arm gear, two belts are driven at 15:1 to hit the sweet spot for the bag motors.
to forward roller arm, and turn the roller . The belt for the arm is on a clutch once the hard stop is reached it clutches the belt but the roller keeps rolling to intake.

Two motors + 1 transmission=cool design

PS> RC the Versa blocks are super cool. Great idea. You could extrude the design to reduce the manf. costs. All you need to do is obround slot the tubes and teams wouldn't even need to cut holes into the tube. I could have a tool made to progressive punch the slots.