Do y’all think it’s necessary to use pneumatic wheels to get over the tubing around the rendezvous point? I haven’t found too many recourses regarding how big a bump higrip wheels can take.
It depends on how fast you plan on going over the bump this year. If you plan on full sending it over, then in the long run pneumatics might be useful. The plastic hub wheels might crack over the course of the season.
If you don’t use pneumatic wheels, you should definitely use wheels with metal hubs. During 2018 when my team used the Andymark HiGrip wheels we had issues with them cracking after 1 competition.
It’s a good year to test stuff. Colsons have an earned reputation for durability and a little bit of cushion.
We plan on full sending. Team agrees pneumatics are the way to go.
Here’s what you can do with 6" pneumatic wheels - www.skylinerobotics.org
They were so much fun last year!
We tested drivetrains this past weekend. The 2018 chassis with 6 inch hi grip wheels struggled when stopped on top of the metal tubing. When it had some momentum it could get over but not without a lot of shaking. The 2019 chassis with 8 inch pneumatic wheels went over easily with minimal shaking/shock to the chassis.
We decided Pneumatics are the way to go this year with the 12.75:1 gear ratio and 4 Falcon 500s.
The team @sagefrom4572 and I are on will be using the 10.71:1 gear ratio with CIM motors, and I think we will get the desired speed and traction for our robot this year. We always thought we were a little bit slow last year when we had the 12.75:1 gear ratio with our mecanum wheels, so this year we have bumped the ratio down a notch to get a bit more speed and sacrificed a bit of the torque. The pneumatic wheels will probably make up for that lost torque in terms of traction and shock absorption though.
Does anyone know a good place to get 6 inch pneumatic wheels. Andymark doesn’t have them in stock, and the cost of the WCP versions are going to quickly add up.
I would like to point out that the HiGrip wheels included in the 2019 and 2020 KOP have significant strength improvement over the older ones.*
We still have (and can re-stock quickly) the hub (the real FRC specific thing), and it should work with any tire and tube that claim to be “6 x 1 1/4”
Obviously I can’t guarantee that that every tire you find claiming to be that will work, but that’s the spec of the one we pair with it.
*Full disclosure, I worked on the design and testing of said improvements.
To counterpoint, we tested a robot with the 6 inch white higrips, and had no concerns over getting over the berm, and had no visible damage after 30 full speed (13 ft/s) crosses. Robot weight was approximately 135.
Just to clarify - I think the difference is probably weight distribution. If you think you will have a relatively centered center of mass, I think you will be fine. Our problem probably came from our center of mass being between a center and outer wheel (8-10 ish inches back wards from center.) When we stopped on top of the bar, with the light side above the bar, and the heavy side behind on the ground, we couldn’t get enough torque to get the robot over. Only with a run up and a lot of momentum would it work for us.
I think if your center of mass is roughly centered, you will be fine. As always, I’d recommend everyone test this for themselves and make their own decisions.
We started out using 4" aluminum wheels with blue nitrile tread, but had second thoughts and decided to go with 8" pneumatic wheels. Overkill? Yep, but we’ve used them in the past and we know what to expect. That said, 6" is probably the sweet spot for any type of wheel, pneumatic or otherwise, but we have a lot of 8" mountainboard tires around the shop.
Anyone have experience with any of the AndyMark pneumatic upgrade kits (6" vs 8", SD vs HD)? I know they’re having stocking problems right now so we might have to cobble it regardless. But people also talk about issues turning with pneumatic wheels and needing specific drop center distances?
Do the AM pneumatic wheel upgrades even turn well? (I’d be floored if AM overlooked this, but I have to ask.) Any other pros/cons besides weight and price (and stock)? Any specific Kitbot on Steroids upgrades for them?
We’ve currently got 3CIM Evo Slims 11:1, probably low (low goal trench bot/defense) centered CG if it matters.
Our team is planning on going pneumatic tires this year as well. It has been a number of years since our team has used them, prior to my time on the team, and so I wanted to get some insight on using them. We opted for the 6" WCP Pneumatic Tire with Centipede tread. We use a 6 wheel WCD and are planning for a 1/4" center drop. Until the mystical Falcon 500’s bless us with their presence, we are opting for a 10.4:1 gear ratio 2 CIM gearbox. Our wheels are spaced 10 3/8" apart, and we are considering inflating the tires to about 25psi. Does anyone have any experience with a similar drivetrain, or insight regarding probable turning ability/current draw? Also, hooray for finally posting after a couple years of lurking.
If we decide to use pneumatic wheels, should we drop the middle wheel? Our team is considering dropping the wheel 1/8" to help with turning.
On any all traction wheel drive, I’d say yes and drop the wheels. 1/8" is enough, 1/4" is plenty and max you should go.
With pneumatic wheels a drop of 1/4" or more is critical to being able to turn. The wheels are grippier than standard hard wheels anyway, and can compress enough depending on inflation that you will have all of your wheels on the ground with an 1/8" drop. When that happens you will be having a bad time.
From my team’s experience last year, an 1/8 inch center drop with pneumatic wheels is not enough. We had 0.140 last year and had major issues with being able to turn (browning out because it drew so much current.) It is still incredibly hard to turn that robot manually. I think a 1/4 inch center drop is the minimum for pneumatic wheels. I’d go closer to 1/3 if we went full traction pneumatic wheels. This year, we are going to try an Omni on one side and a stronger (more torque, 10.71 vs 12.75) gear ratio which will hopefully reduce scrub and current draw. We will see how it goes tomorrow.