We are looking to get a sonic shifter gearbox (or maybe 2) . What gear ratios do most people get when ordering them? How are they being utilized on your bots?
Gear ratios are really on a per use case basis. I’d recommend using the JVN Calculator to calculate the gear ratio for your use case. Also I recommend taking a look at EVO Shifters they are a more modern 2 speed gearbox.
I really don’t know what we’d use them for. I just noticed they are on clearance, and figured they’d be a good thing to have.
You’re going to use them if there’s a game where 2 speeds is going to give you an advantage in what your robot is designed to do. For example, this year if you designed your robot to work on the cargo ship and play defense, you might consider a 2 speed gearbox. In my experience, you want ratios that will give you ~5 ft/s for the low gear and ~12 ft/s in high. The low speed gives you the torque to move robots around and then higher gives you enough mobility to be fast without losing control.
Ok, so these are mostly used on your drive base or could they be used for other purposes?
Drive train is the primary reason. However, it would also make sense to use this for a combination elevator/climber for either of the past two years, so it can go faster as an elevator but put out more force as a climber.
I haven’t used a shifting gearbox since 2012, but the 2.4:1 ratio between the speeds is more common for drive trains; 4:1 ratio would be more likely for the elevator/climber scenario.
Personally, I would avoid using a COTS shifter for an elevator. They are expensive and heavy and generally difficult to mount on anything that’s not the drive train. If you have the capacity, design a custom gear box or use a faster motor (775 pro or Redline) in a VersaPlanetary
Was more common. These days, especially with the EVO Shifter letting teams choose whatever ratios they want, it’s much better to calculate the best ratios for the needed sprint distances (say, 5/15/25/50 feet) and make a decision from there. And you may find that in the age of modern motor rules you don’t even need to shift for every game. This year, 1293 designed for half-field (25-foot) sprints and it would’ve made zero sense to get them when we could throw six Mini CIMs at a single-speed 3CIM4U and call it a day. A game like 2017’s would’ve been a comparable slam dunk for shifting, since you really were sprinting across the full field often.
(Full disclosure, I used to work at AndyMark.)
Four bolts in a rectangle is difficult to mount?
That won’t get you the variation in speed and torque that a shifting gearbox can; if you make it fast, you can’t get the torque unless you use several motors and lots of current.
Totally concur with both, but here OP doesn’t have a specific use case identified.
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