I love the proliferation of COTS drive gearboxes, because the days of immobile teams were the worst.
That being said I hope VEX/WCP/AM save teams from themselves and do not offer drive gearboxes for 775 pros. This is not a trend I think is good for the overall functionality of teams. Some may execute 775 pro drives well. Many will not.
I really liked that AndyMark included spring-loaded cylinders in their EVO gearboxes. My first thought for this thread is that it’d be great if Vex and WCP followed suit.
I’m not a fan of spring-loaded cylinders in gearboxes. This year, our driver got into a shoving match with another team, and they hit a wall and disconnected a pneumatic tube, causing them to loose pressure, and somehow be sprung into neutral (I made him apologize). I’m pretty sure they’re using EVOs. We still use the old AM shifters, and although they can be rattled into neutral if you loose pressure, that’s not a very big concern.
This only happened once, I didn’t get a good look at their bot, I have no experience with EVOs, and I’m not to experienced, so take this with a grain of salt.
somewhat agreed. I don’t think this necessarily means COTS options for it shouldn’t be offered, but the community needs to find a way to warm teams about using without having the proper controls knowledge to do it. Otherwise I forsee a lot of teams running any number of 775s on their drive and smoking them as soon as they run into something.
EVOs are specifically designed with the spring-loaded pistons so they will shift into a gear when pressure is lost.
from Andymark’s website:
This cylinder extends into the selected “Ratio A” when no air pressure is supplied. This allows a robot to continue to drive using Ratio A if air pressure is lost.
Armabot already sells these: https://www.armabot.com/products/rs7-encoder
There was also a coupon for a free one in the KOP this year.
We do plan to convert all our shafts to the magnet version, if it’s not out yet it’s probably because we still have inventory of the old version, so keep an eye out.
That’s the exact opposite of how the spring extend cylinder in the EVO is designed to work. Upon loss of air pressure it will actively shift into the chosen gear. Perhaps something else broke as well.
To everyone else, we are listening!
I see at least 3 things on this thread that we were already planning to release before next season.
Keep it up!
Solenoid/Linear Actuator/Magnetic shifting for EVO/Vex/WCP gearboxes. I hate running pneumatics just for shifting.
Hmmmm, I’m guessing intake rollers and such, cots ratchet/Paul with 1/2in hex or 1.875 bolt circle and… 32dp gears from andymark in the coming months? These seem like some of the more practical items in this thread. Can anyone else guess what they might be?
Just a little one, 7/8" OD 3/8" ID flanged bearings are really good for custom gearboxes( I try and use them where possible). But there isn’t a smallish bearing for 3/8" hex. Using a big 1.125" OD bearing when using 3/8" isn’t ideal especially when designing gearboxes with plates which aren’t 1/4" thick.
A 7/8" OD bearing with a 3/8" Hex ID would be helpful.
I believe VEX used to sell a 7/8" OD bearing for 3/8" hex before iirc. I seem to remember something about them not being able to handle XXX load or having some failure issue made them go away.
Someone else can probably confirm this or correct this but that is my best recollection.
I’ve found the best solution is to generally not use 3/8" hex shaft unless absolutely necessary. Only times I’ve found I use it is when I’m using a 14T or 16T gear.
EDIT: It was actually AM who used to sell them. They would implode under certain loads as the inner race was too small.
+1 for Ratchet & Pawl set, 1/2 hex or 1.125" bore.
Would love to see some urethane and neoprene rollers (Like the Fairlanes one) which will be available also for international teams and with easy hubs option for younger teams.
Double #25 chain sprocket could be useful as well
One thing I would love to see is a proliferation of COTS parts for a 1.125" tube axle. Tube, bearings, and bushings can all be purchased online from various suppliers, but it would be nice for one of the FRC suppliers to buy them in bulk and sell them so teams can get them cheaper and easier. We already have all kinds of spacers, wheels, etc. that will fit on a 1.125" tube, since that is the same size as the standard hex and 1/2" round bearings. The biggest thing IMO would be a hub with bolt holes perpendicular to the central axis, so teams can match drill through the tube to connect to it. Without that, cleanly attaching to the tube with just a drill press (let alone a hand drill) is near impossible. It should even be possible to keep the standard 1.875" bolt circle we have standardized around. This would make it much easier for mid-level teams to design large arms or mechanisms with loads far from supports without having to worry about the axle bending or twisting.
Also, a few thrust bearings in addition to the selection of radial bearings would be nice.
To our good friends on 4613:
We’ve never tried them but I’ve been eyeing these:
Note that the CAD is wrong (shows round bore) but I called them to confirm that it is in fact hex bore
A clamping transmission powered by 2) 775pro motors.
Designed to clamp to a 1"x 2" alum extrusion.
Dave
What would that do that you can’t do with a VP and a VF mount?
A COTS Bag-in-roller intake kit would be very nice
I would love to see one of those roborio wiring guides go COTS, not everyone has access to a 3D printer to print the design available on the web. I know andymark as a wiring guide/pin saver system available but I am not a fan of the exposed contacts it has.
If I’m remembering correctly, AM used to actually sell that exact bearing, but discontinued it due to strength issues. 687 used one in our 2012 shooter gearbox, which I modeled our 2013 shooter gearbox after. After realizing it’d been discontinued, I switched over to 7/8 [in] OD x 3/8 [in] round ID bearing.
On the other hand, the corner distance (~.4330 [in]) on a 3/8 [in] hex is pretty close to 11 [mm] (~.4331 [in]). With the right tolerances between shafts and bearings you may be able to run something similar to ThunderHex using an 11 [mm] ID bearing, which should be stronger due to the lack of stress concentrators.
Woah woah woah, this exists even as a non-COTS item? I gotta see this.