Arm help

[Team2339]

Rookie Team Question:
We are building an arm, 60 tooth sprocket, driven by ?
What are the best choices for the motor?
Assume CIM's are not available.

[tseres]

last year we used the window motor, and it worked, but it's realy roughed up now....

do you need finite control? if not, then i'd say use a piston.

[vivek16]

I would suggest using the fisher price motors with these gearboxes on them. Our team personally has not used these on an arm but they are some of the powerfuller motors in the kit.

-vivek

[Scott Morgan]

Originally Posted by vivek16

I would suggest using the fisher price motors with these gearboxes on them. Our team personally has not used these on an arm but they are some of the powerfuller motors in the kit.

-vivek

The AM planetary gearboxes do not provide a large enough reduction to drive an arm on their own. You would have to couple them to some other gearbox.

[colin340]

when you need power look at cims on a AM single speed or a van door
remember a piston has two positions it's really hard to any have more

[Team2339]

we would like to drive the 60 tooth sproket with something like a 10 tooth, perhaps the van door motor, but I suspect the worm gear might fail?

[thefro526]

When I came up with an arm design for my team I used the Tiange van door motor running through a 2:1 reduction and it should have has more than enough power. One of the issues with the van door motor is that it has a worm gear which means that you can't put the arm down by hand it needs to be forced down. But also that is an avantage if you wanted to used a closed loop system because then your motor does not have to stall to lock in place. Good Luck

[colin340]

Originally Posted by thefro526

When I came up with an arm design for my team I used the Tiange van door motor running through a 2:1 reduction and it should have has more than enough power. One of the issues with the van door motor is that it has a worm gear which means that you can't put the arm down by hand it needs to be forced down. But also that is an avantage if you wanted to used a closed loop system because then your motor does not have to stall to lock in place. Good Luck

yes he's right the van door can't be back driven this can be good and bad to make the motor more easier to back drive loosen the (2) set screws on the shaft that the worm gear is on, note you do not have to deassembled the gear box there on the outside

[Team2339]

If we run the van door motor to a 10 tooth to 60 tooth sprocket, it should take about 2.5 sec to raise up over the bar. Would this strain the worm gear or is it robust enough?

[MrForbes]

How long is this arm and how much weight is there on it (at the end, and the overall arm weight itself)? How fast and how far does it need to move?

this info might make a big difference in motor recommendations

[Team2339]

Pivot to center of mass of the ball is aprox 48".Arm weight about 10#, speed can be compromised for placing the ball over the bar.
A hurdle can be pushed, the end game requires it to be somewhat set in place.
We have already allowed for slower movement and durability, since this is our first year and we want to make it through 10 matches functioning.
I wasn't able to find any engineering specs for this van motor, the one 2 years ago would have worked.
How stout are the worm gears?

[vivek16]

Originally Posted by Team2339

Pivot to center of mass of the ball is aprox 48".Arm weight about 10#, speed can be compromised for placing the ball over the bar.
A hurdle can be pushed, the end game requires it to be somewhat set in place.
We have already allowed for slower movement and durability, since this is our first year and we want to make it through 10 matches functioning.
I wasn't able to find any engineering specs for this van motor, the one 2 years ago would have worked.
How stout are the worm gears?

just make sure you have a low enough center of gravity and don't tip when trying to do this.

-vivek