I’m looking at using a 45:1 or 64:1 Banebot P60 gearbox for a parade bot. We are using a Hobbyking motor https://hobbyking.com/en_us/turnigy-trackstar-1-8th-sensored-brushless-motor-1900kv.html . It’ll be spinning about 2x the speed of a banebot motor, but nowhere near the rated torque.
The parade robot will move around 12-15 fps and weight around 60lbs
Do you think the gearboxes will last? Think we will have any problems?
First off, you should remove the parenthesis from the end of your link; it’s screwing things up.
The banebots P60s are ok, but I don’t like them as much as I like Versplanetaries. There have been problems with them in the past, and my personal experience was never super good. Noise and low-ish efficiency were problems the couple of times I sued them.
Why brushless over common FRC brushed motors like the CIM? For things like driving the CIM has better thermal performance and will last longer than a lightweight brushless motor like you’re looking at. The Sparks that came in the KOP are easily controlled just like a brushless ESC, so you can save some money there too. Brushless is absolutely fine but might be overkill for this application.
Finally, the shaft on the Trackstar motor you’re looking at may be too long, so be prepared to cut that down.
5402 used several P60s* on their robot this year, most of them stuffed with 775pros**. We had suspect assembly on many things pertaining to that robot due to a very green roster, but all of them held up perfectly through two events and demos.
Why brushless over common FRC brushed motors like the CIM? For things like driving the CIM has better thermal performance and will last longer than a lightweight brushless motor like you’re looking at.
A CIM motor’s thermal mass is an asset on an FRC robot, whose runtimes between breaks are 2:30. Chad is talking about a parade robot, whose runtime will surely be much longer–and thus denying the motors a chance to cool down. A motor that has fan blades to draw air through is an appropriate choice here, assuming appropriate debris protection and gearing options that permit the motor to run on the fast side of the curve. Pushing more air through where possible is also a good look; I’m reminded of a few teams in 2016 that used vented screws (or something to that effect) as a place to introduce more air from a compressor into the motor. I can’t see the mounting face of the Turnigy to say if that’ll help here, but if nothing else some quality fans blowing across the can will provide backup when the motor isn’t running at speed.
To OP’s question: I don’t know for sure. However, taking steps like not cantilevering loads, not exceeding maximum torque limits, and greasing it well should give you pretty good odds. BaneBots does do a lot of unique motors outside of FRC, so they can probably answer even better.
*Full disclosure, I work for and 5402 is sponsored by AndyMark which sells the P60. Being able to grab them off the shelf and run to the meeting was a significant benefit for the P60, though not the only one.
**No, being an AndyMark team doesn’t restrict us on components. We wanted the power, we got the power.
So you’d recommend the versa gearboxes over the banebots? You think they will hold up better?
Vex gear boxes have a load rating here Banebots recommend that you don’t exceed 35 ftlb. Think motor stall. I have found them both reliable when properly used. . I like the pinion gear attachment on the Vex a lot more. Banebots use a press fit that is the a little tricky to get right. Neither gear box likes an overhung load. IE the wheels will need to be supported by something other than the gear box.
I am not worried about torque or overhang. They will be driving belts that drive wheels
Also what is the difference between the vex pinion and the p60?
Vex pinion has their little clamping collar doohickey, p60s require you to press on a pinion gear.
If I’m not mistaken, the p60 pinion is press-fit and specific to the size motor being used, the Vex pinion isn’t really a pinion per-say, it’s more of a coupler that interfaces between the motor and the sun gear of the first stage, it also has the advantage of coming with adapters for a number of common size motor shafts and is secured using a set screw (no press-fitting required).
That said, if you go with the Versaplanetary gearboxes it is important to keep the size of the sun gears in mind when planning your ratios, the 10:1 reduction for example has a very small sun gear which is prone to breaking under heavy loads, in some cases it may be better to use more mid-range stages than to use fewer stages on the low or high end of the available options.
Edit - Ninja’d >_>
If I were to design a small robot for a parade, I would consider:
Cautions:
FRC wheels wear out very fast on paved surfaces.
When operating on grass or dirt, larger wheels are a plus.
Uphill travel requires more drivetrain torque.
Robots in the rain can have electrical safety issues.
Suggestions:
Parades usually last at least half an hour, if not hours. Your robot will die.
In order to not have to wait for the robot to boot up every 5 minutes, you can wire two batteries in parallel. The voltage will stay the same, but the battery life will be double as long. Then when you need to switch batteries you can unplug one at a time and the robot will never lose power.
For that matter, make sure to bring plenty of batteries for the parade because you will go through them quicker than you think.
We made a change to our 2005 robot for parades: a shelf that mounted a pneumatic caster in the back, and provided room for 3-4 batteries so we could just connect up a fresh one and go. (Mind you, this was the IFI era where boot times were stupid fast. I’d want to power my roboRIO and radio on a separate circuit if I was using them today.)
You can see an early version of it here: https://www.chiefdelphi.com/media/photos/22069 (We didn’t have the swivel caster yet, and we didn’t have a full grasp of the whole “longer wheelbase than track width means you can’t turn” thing. That was fixed before the next parade.)
That seems a bit harsh for them selling you a lower than expected efficiency gearbox.
Lying to the public is no joke. $5000 lawyer’s fees were well within 115’s budget of course.
I haven’t had experience with P80s but I hear battlebots use them. Maybe look that up and see how hard they are to destroy?
Pneumatic wheels could be a good choice for outdoors.
Billfred’s point about brushless motors and heat is spot on. Brushless motors don’t like stalling at all though, so either spec it to be larger than you need or maybe use a sensored brushless motor. Or do current monitoring. Or a score of other things you can do to stop them from stalling for a long time and melting.
LiPo or LiFePO?