Everyone else was posting up there crab modules so I thought Id post up the one Ive been working on. It’s made from all .090 sheet metal. The wheel is custom machined from uhmw. 4" diameter and 1.5" wide. Power is transmitted via timing belt. All shafts are hex. Everything will be attached by bolts and pem nuts. Total weight for everything pictured is 2lbs.
I like to think this is what happens when 111 meets 1625 and its all put together with some 1771 flair!!!
By the way I also do not ever foresee us building a swerve/crab drivetrain as it does not, imo, offer enough performance gain to justify the weight penalty, as well as machining time and motor cost. Of course who knows, maybe next years game will be perfect for it…but I doubt it.
Thanks guys. I have had this one designed for at least 2 months now. It also can fit a 4" colson as is right now. The custom wheels is much much lighter though. I believe the wheel pictured is right at .2 lbs.
RC…dont worry. I have no intention at all of using this during a season. It was more a study of how I could design a swerve to take advantage of our sheet metal capabilities and to do it as light as possible. You’ve seen the 6wd that I’m leaning towards
Akash: I have a wood frame designed right now for it just as a mock up but it looks complete. I need to look more seriously into properly selecting the thickness of each piece of wood for the application and weight reduction of the frame.
If I do single speed, I am pretty certain I could pull of this swerve right at 30 lbs.
Looks really good, nice and compact. One question though, it looks like it might be a little tough to get that cog belt on inside the module, dot you have a method for doing that?
I like the design though. Is this design intending to use cables for steering?
That’s really cool how it’s all sheet metal, great work.
By the way I also do not ever foresee us building a swerve/crab drivetrain as it does not, imo, offer enough performance gain to justify the weight penalty, as well as machining time and motor cost. Of course who knows, maybe next years game will be perfect for it…but I doubt it.
Ha-Ha-Ha, famous last words.
My son sometimes reminds me how back in 2002 I said we would never again use 4-wheel crab. We struggled so much with turning with the 2002 design. So what did we do, we used 4-wheel crab on our Championship robot in 2003. And have done so 3 more times since then. The 2003 design is pretty much what we have used ever since, with only slight mods.
In some games, including this year, crab/swerve gives you a distinct advantage if you know how to use it.
HAHAHA I was hoping you or someone from 1625 wouldn’t come on here and tell me something like that. I can definitely see times when I would definitely push for a crab drivetrain, and I am extremely close to having it light enough and easy enough to build so that those aren’t significant hurdles.
I guess mainly my point was that unless the game truly calls for crab drive…which many have not, I will not build it. I do think that this past game it could have been advantageous, as well as 2007, although certainly teams did well both years without it. It seems like everyone is jumping on the crab banwagon because its cool without realizing that its only advantageous in certain limited situations and its exponentially more difficult and time consuming to do.
And Raul, your modules have definitely been a huge inspiration for this design.
nice design! But really I’m going to have to agree with you: it’s not worth it. I keep telling our freshman over and over again, “tank drive can do anything”, and then I see them giggling over crab modules. They are cool, REALLY COOL, but not worth the time that could be put into a more refined everything-else-on-the-robot that will go a lot farther towards success.
I couldn’t agree more, my team has done swerve the past two years, they were both fairly efective, but if I could do it again, I’d have done 6 wheel skid both years.
