|
|
|
![]() |
|
|||||||
|
||||||||
![]() |
|
|
Thread Tools | Rate Thread | Display Modes |
|
|
|
#1
|
|||
|
|||
|
RS775 Gearboxes
It seems strange that banebots wouldn't have these available by now.
I'm looking to use four S775 to lift a ten pound arm thats about 60 inches long. Is this overkill, or would it allow me to maximize the speed of raising and lowering the arm? Any suggestions for a gear ratio/gearbox and where I might be able to get it? The goal is to turn all four output shafts from the banebots motors into a single pivot to move the arm. Thks in advance! |
|
#2
|
||||
|
||||
|
Re: RS775 Gearboxes
Quote:
I think 4 will be complete overkill. Our calculations allow us to lift an arm double the size and weight (i.e. 4x torque), running them at only 1/4 of their stall torque with just 2 motors. Last edited by rahilm : 17-01-2011 at 01:17. |
|
#3
|
||||
|
||||
|
Re: RS775 Gearboxes
4 is complete overkill. They're roughly 240W motors if I recall correctly - think the equivalent of a 2010 FP motor.
|
|
#4
|
||||
|
||||
|
Re: RS775 Gearboxes
I think we're going to get away with one for our lift...
Then again, we might just use the FP. |
|
#5
|
|||
|
|||
|
Re: RS775 Gearboxes
Thanks for the fast responses. If I go for two RS775, what typ of gear ratios should I be looking for? It will be a parallel lift with a diagonal surgical tubing assist. I'm looking to making the arm raise and lower as quickly as possible without worrying about the motors not being able to handle it.
|
|
#6
|
||||
|
||||
|
Re: RS775 Gearboxes
Quote:
Also, the 2010 FPs had roughly 190w. This year's have 290w. (Both figures from the FIRST motor curves) Quote:
Last edited by rahilm : 17-01-2011 at 02:19. |
|
#7
|
||||
|
||||
|
Re: RS775 Gearboxes
I think you took the stall current at 18 volts instead of 12 volts.
|
|
#8
|
|||||
|
|||||
|
Re: RS775 Gearboxes
Quote:
Banebots suggests a maximum torque output of 85 ft-lbs for the P80 CIM gearbox. If your mechanism is actually going to require anything close to 576 ft-lbs of torque, you'd destroy a P80 gearbox rather quickly. And P80s are tougher than the P60, which is smaller with an aluminum ring gear. BB doesn't list the max recommended torque for the P60s, but it's going to be less. At least half, possibly a quarter. So I strongly urge you to look at the maximum safe output of your gearbox and make sure you plan your gear reductions accordingly. You may want to decrease the reduction in your gearbox and add an additional reduction stage of sprockets. 256:1 gear reductions provide surprisingly little torque once the gears have failed. |
|
#9
|
||||
|
||||
|
Re: RS775 Gearboxes
I was under the impression that the P60s were counterintuitively stronger than the P80s. If the P60s can output less than 85 ft-lbs of torque, they're pretty much completely useless to me.
|
|
#10
|
||||
|
||||
|
Re: RS775 Gearboxes
Remember - if you have a 15 lb end effector at 4 feet from your pivot, that's 60 ft-lbs. If you then have a 2:1 sprocket and chain reduction leading into your P-60, then it will never seen more than 30 ft-lbs of torque statically. Dynamically is dependent on the speed you move it of course.
|
|
#11
|
||||
|
||||
|
Re: RS775 Gearboxes
Yeah - this is what happens when you do math in inch pounds and are too tired to remember to convert. The gearboxes should be fine for me.
|
|
#12
|
||||
|
||||
|
Re: RS775 Gearboxes
Quote:
|
|
#13
|
||||
|
||||
|
Re: RS775 Gearboxes
Be sure not to just model for torque but for speed as well. An arm that rotates 180 degrees in 1 second is not very useful.
|
|
#14
|
||||
|
||||
|
Re: RS775 Gearboxes
Based on our prototyping, watching some old 2007 videos, and current consensus on design, we've found that speed close to optimal. Of course, it's only week 2, and there's a lot more testing to do, so our plans may change quickly.
|
|
#15
|
||||
|
||||
|
Re: RS775 Gearboxes
Quote:
Then try to precisely place a tube on a rack with that rotation rate. I haven't done it, so maybe I'm talking out of my butt here... but that seems pretty darn fast! ![]() |
![]() |
| Thread Tools | |
| Display Modes | Rate This Thread |
|
|