ARM GEARING ON ROBOT
 

I've been looking at many of the robot pictures that have been posted at CHIEF DELPHI and noticed that many teams had arms as a medium of stacking tetras. I would like to know some of the torque your team expected to come across wiht your robot's arm, the motor(s) you used for the arm, and the gear reductions you did for the arm. Here's a picture of TEAM 696's shoulder joint. We expected max of 265.5 in-lbs of torque on the joint...with a 1 to 20 reduction of the VAN DOR motor...we were able to do this. Our elbow also went through a 1 to 20 reduction with the globe motor with an anticipated max torque of 219 in-lbs.

I KNOW U LOVE OUR ROBOT:
pic 1
pic 2
SEE US AT THE LOS ANGELES REGIONALS!!!!!!!!! GO TEAM 696

Re: ARM GEARING ON ROBOT
 

oopss sorry about that:

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PICTURE # 2
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Re: ARM GEARING ON ROBOT
 

I'm not sure on the torque calculations for our arm (I'm on the drive train team) but for the lower joint of our arm we used two FP motors locked to a common shaft with a 16T sprocket on it. This sprocket "walks" along the OD of a semi circular, .500" thick piece of lexan with #25 chain around the OD seated in a groove. As for the upper joint we have a van-door motor fed through a modified KOP gearbox with a 4 foot (pneumatically telescopes to 5 feet) arm on the output shaft.

Re: ARM GEARING ON ROBOT
 

Since we hate underkill (i.e as in "oh no it doesn't work) and love overkill (as in "haha we can pick up the center goal") ... we ran 2 FPs geared 1700:1 (w/ sprocket) lol... so much torque we actually ripped one arm in half after a day of practice (the peeps at the jesuit scrimmage kno what i'm talkin bout...) ... so we went back and made one out out of 1/8 box + a jacket of 1/8 X 1.25 X1.25 and guess what we bent it! so we slapped a piece of quarter inch plate on ... it looks bad but oh well...

Re: ARM GEARING ON ROBOT
 

Yeah I hear ya with the insane torque Salik. We accidentally pile drove our arm into the ground during practice and it effortlessly picked up our robot. Our arm has more than enough power to lift anything we need......or don't need....hmmm how about some "curling" competitions at Nats? :D

Re: ARM GEARING ON ROBOT
 

Hey, that looks pretty front heavey... having any problems with maneuvering?

Re: ARM GEARING ON ROBOT
 

The reduction on our arm gearboxes is roughly 1:520 from the CIM motor to the sprocket on the lower joint, resulting in about 2800 in-lbs at the joint, at 27 amps.

Re: ARM GEARING ON ROBOT
 

pppssstttttt....chea right...this thing handles like a beauty...my blood pressure goes up everytime i see it in motion. jp...haha

karo

Re: ARM GEARING ON ROBOT
 

we use one of our past gearbox designs slightly modified. It is ~ 75:1 reduction with 2 CIM's powering it. The teeth pop sometimes, but not enough to warrent rebuilding it. Due to the elbow joint breaking, this thing will lift a tetra and an 8' arm from the ground to verticle in a few seconds.

Re: ARM GEARING ON ROBOT
 

I won't give everything away yet because when people see what we did I think a lot of teams will copy it next year. I will say we scared people at the UTC scrimmage and those who saw our robot sitting in the pits and asked "What size chain is that?". We used No. 40 for good reason. For those of you at The UTC NE regional or Philly regional stop by and we'll show you what we did. The entire assembly was designed and built in an afternoon using only 1 machined part. Oh and we're using the 6V FPs. they barely even get strained lifting 3 tetra's.

Our motto on arm design is "Too much is just enough, so drive straight beyond overkill just to make sure."

If I can find a good picture I'll post it after the UTC New England regional.

Re: ARM GEARING ON ROBOT
 

Our arm is powered by a CIM reduced by a DeWalt transmission in 1st (12:1)and a 50:1 worm gear reduction. This yields a total reduction of 600:1 on the CIM. We were trying to get enough torque necessary and still retain speed so that we can cap quickly.

Re: ARM GEARING ON ROBOT
 

Wow. That sound similer to what we did. We have 2 FP in the gearboxes (12V) together turning those 2 oversized drums they give you. This pulls on rope to move our arm. I don't know what the torque is but it could (if they were taped up there or somthing) about 3-4 tetras I think. Maybe more With no sign of giving up.