bag motor on versaplanetary

[Bruceb]

I was trying to build a big reduction for a bag motor by doing the following.
Starting with 2 bag motors on the versaplanetary 2 motor adapter then plugging that into a 100:1 versaplanetary with the CIM motor output and plugging that into an AM 10.71:1 toughbox nano.
The nano would have a 1.5 inch sprocket on it driving a 4 inch sprocket which is attached to an arm that is lifting 10 pounds at 15 inches.
150 in/lbs = 12.5 ft/lbs divided by the sprocket ratio(4/1.5=2.6) = 4.8 ft/lbs on the output shaft of the toughbox / the toughbox ratio(10.71) = .45 ft/lbs on the output shaft of the VP.

I think this results in a VERY small load on the VP CIM output shaft.
I know the load rating guide says the 100:1 with the BAG is not recommended but I am not sure why.
Table 9 – VersaPlanetary Output Torque Limits states the torque load on the CIM shaft fails at 21 ft/lbs.
SOOO what do you think.
Will this work?

[Paul Copioli]

Originally Posted by Bruceb

I was trying to build a big reduction for a bag motor by doing the following.
Starting with 2 bag motors on the versaplanetary 2 motor adapter then plugging that into a 100:1 versaplanetary with the CIM motor output and plugging that into an AM 10.71:1 toughbox nano.
The nano would have a 1.5 inch sprocket on it driving a 4 inch sprocket which is attached to an arm that is lifting 10 pounds at 15 inches.
150 in/lbs = 12.5 ft/lbs divided by the sprocket ratio(4/1.5=2.6) = 4.8 ft/lbs on the output shaft of the toughbox / the toughbox ratio(10.71) = .45 ft/lbs on the output shaft of the VP.

I think this results in a VERY small load on the VP CIM output shaft.
I know the load rating guide says the 100:1 with the BAG is not recommended but I am not sure why.
Table 9 – VersaPlanetary Output Torque Limits states the torque load on the CIM shaft fails at 21 ft/lbs.
SOOO what do you think.
Will this work?

Bruce,

It is not so much about the load you are carrying, but what the BAG motor is CAPABLE of doing. At the 100:1 ratio with a CIM motor output shaft, the stall torque of the BAG motor produces enough torque to fail the output shaft of the VP. The 8mm diameter CIM shaft was meant for a motor that could produce 2.2Nm stall tourque, not 21.

The limit is based on test data and during those tests the output shaft failed torsionally. The gears and internal of the VP will survive.

If you somehow load limit the BAG motor (reduce the PWM signal or through CAN using the Talon), then you will be fine.

If you don't do that and somehow slam your arm into the floor the BAG motor can snap the shaft.

Paul

[Bruceb]

Since posting this I see AM has a pinion the right size with a 3/8 hex bore so if I use the VP 3/8 hex shaft and that pinion I should be ok, right?
Thanks Paul
BTW, I sent VEXPRO an e-mail about this as well.
Please ignore that.