Hi all!
Just curious what everyone thinks the best turret motor / gearing / connection / control combo is.
We have never built a turrent before but we did CAD one,
I think the best (cheapest and simplest) way to rotate the turret is with an open timing belt and a timing pulley connected to a motor, similar to what triple helix did in 2012 but with timing belts instead of chain
Depending on the size of your pulley and where you tied your open timing belt you should get ~100:1 reduction in speed. Defiantly use an encoder on your motor. I’d prefer a 775pro with versa planetary gear with the integrated SRX mag-encoder
Edit:
This design allows a maximum rotation of ~300 degrees, its more than enough for most cases
It depends entirely on your design, and what kind of performance you want. A good place to start would be to look at the greyt turret on west coast products. It isn’t perfect, but it is a pretty good example of how to get a proper drive system and gear reduction.
One that is fast enough to meet your requirements, has enough torque to move things without stalling, and can be precisely controlled through a closed-loop feedback system. Personally, I want to be able to gear a motor to be twice as fast as I ideally want - that way the motor can be run at half power, which means it’s a smaller load on the battery and I have additional power that can be delivered if something doesn’t work quite perfectly.
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775pro is a solid motor to use for a turret; gearing wise, 300-500:1 ratio
NEO and Falcon 500s also great motors for a turret application; 90-110:1 ratio.
As for the NEO550, not sure about it’s turret capability just yet, but I’m sure if done right, can be a great alternative from a 775pro; 200:1 on that for gearing.
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Using a redline on the Armabot Turret 240 it moved at around 220-260 degrees/second with a 20-pound load on top. It is also only rotationally limited to the length of your wires. The ratio is 462:1 with an encoder geared 1:1 with the turret. If you are inexperienced with turret designs, I highly suggest you go with this. (Plus it only took two days to assemble!)
Thanks for the suggestion. If you do go with this turret, the digital encoder is having issues communicating with the Talon SRX, so the analog version may be an easier path right now.
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We did have problems with our encoder values jumping all over the place; I believe we might switch over to a mag encoder depending on what our programmers require.
That is another good solution. There is a mag encoder mount solidmodel in the other Armabot turret CD thread, that we also got permission to put it on the turret product page. In addition, I took the existing encoder mount and modified it with a Dremel to fit the mag encoder in about 5 minutes.
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What about using a continuous rotation servo for this? You could mount a small 3D printed gear to the horn and print a slice of a much larger gear to attach to your turret. It should have enough torque assuming that your turret doesn’t weigh a ton. You would have to get feedback from a separate encoder, or perhaps a multi-turn potentiometer.
That would be a fun experiment. Just thinking about it, the continuous rotation servos I’ve seen are probably under powered for this size of turret. Most servos also rotate a little to slow to have such a large ratio to the big ring.
How did you assemble that in two days? There are several places where you have to apply retaining compound and then let it cure for 24 hours.
So the retaining compound will hold fairly well in 10 minutes, but you don’t get full strength until 24 hours. I thought it would be better to ensure that teams didn’t have issues to wait for full strength before operating the turret.
We didn’t power, or even rotate the turret until we let the retaining compound cure for more than 24 hours. We added the compound and waited around half an hour before continuing assembly.
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