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#1




JVNDesign Calc Question
When using the JVN calculator for linear motion, should you include the diameter of your sprocket(s) as the pulley diameter to get a better estimate of speed and amps? Example: Put 5.4" in the pulley for an elevator with #35 15t at the bottom to a #35 44t at the top. Or, is there a better choice/method on the JVN to estimate this? Thanks for any help!

#2




Re: JVNDesign Calc Question
Use the pitch diameter of the sprocket you're driving with your motor as your pulley diameter.
If you're driving the 15t sprocket with your motor, use 1.79" If you're driving the 44t sprocket with your motor, use 5.257" Note: Current estimates in JVN's calculator don't seem to take efficiency of the gearing into account. So for elevators that experience significant amounts of friction or binding, your current draw may be above what JVN estimates. 
#3




Re: JVNDesign Calc Question
You would use the pitch diameter of the driving sprocket attached to your gearbox. I assume the 44T sprocket is just an idler at the top of your system? The PD of a #35 15T sprocket is 1.790", so that is what you input for your drum size. Those numbers can be found in this document.

#4




Re: JVNDesign Calc Question
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Friction is pretty great, except for when it isn't. A lot like gravity. 
#5




Re: JVNDesign Calc Question
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#6




Re: JVNDesign Calc Question
Thanks to all the responders! It's awesome being. A rookie team in a competition like FIRST! Hope to see some of you at competitions this season.

#7




Re: JVNDesign Calc Question
The direction of the static friction (helping or hurting) depends entirely on how your control approaches (and behaves at) the static position.
You have to build the smarts into the controller to "back off" and let the static friction help hold the load. 
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