Omnibot 2000 , Rad 2.0 Vacuum Bot

jstarne1

USA

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#1697  

Hey Josh, you could just epoxy a nut on the end of the plastic tube that matched the threads. Just a thought.

#1698  

i think thats what he is doing with that design

#1699  

Since its a worm gear (depending on how tight the pitch is) it may hold its grip when the servo is released. If thats the case, why not close it until stall. Use the stall sense idea DJ mentioned a few months (or year ago). For the multiturn pot, try to do like I did and use a standard pot near the shaft.

#1700  

only problem with stall sense is that the mosfets (h-bridge) will burn up only way to do it is have a circuit that senses stall condition and remove the power from the servo easy way to test is simple get super cheap servo and apply stall torque for over a 1 min,and check the h-bridge for high heat or smoke

here is info on stall torque Electric motors [1] continue to provide torque when stalled. However, electric motors left in a stalled condition are prone to overheating and possible damage since the current flowing is maximum under these conditions.[2]

#1701  

I remember somone had a 6 turn pot that would.be.ideal right?

#1702  

need a multiturn pot,more turns better the accuracy

#1703  

I was thinking of using the original screw , but I guess I could make a completely new one. A new one would be stronger.

Current sense can stop the servo if it sees a certain amount of current drawn. It's logical to say if full stall is 5 amps , and free turn is .5 amps then setting the stall sensor to release the servo as soon as it sees 2 amps that would protected servo.

#1704  

Ok yeah, it WAS an H-bridge design. Over a year and a half ago. Feb 2011