Hello. My team has used either a tank drive or a mecanum drive for previous competitions, but have decided an x drive would likely be best for this year’s competition. I’m having trouble finding detailed images/build guides on x-drives, and was wondering if anyone had some good posts I could reference to build an x-drive. I know there’s a few different designs, so feel free to debate which is best.
If you look on Wingus and dingus’s YouTube channel, there are a bunch of videos showing theirs. 10q during skyrise also had a x drive. Also, look through the pictures on the 8059d thread for this year.
Beyond what Turbo Tech said, it’s really just 4 wheels at 45 degree angles. If you’re doing a 4-motor drive, that should be really simple. Use the 45 degree angle gussets with some c-channels and just put omni wheels on each corner.
There’s a very informative thread about X-Drives right here 
Snaps of a CAD we have on file…you would probably need to add more support, but this gives you the idea.
Th bracing can be tough at times with the motors wanting to bend in a cantilever manner and then the holes don’t line up. Small bits of polycarb can help or drill a new bigger hole.
From experience, the 45 degree brackets are a pain. You really have to brace everything so it’s perfect first, then tighten the brackets. Because the amount of play in the brackets
I can second what @NattyMan0007 says above. In our X-drives, we always build them with two “layers” so that the wheel modules are supported better, which means there are a whopping 16 angle gussets involved.
We had 32 last time
So its said, you can make an X shaped base rather than and octagonal base. Depending on how you do it, there is less of an issue with twisting and more open space on the perimeter of the bot.
Some examples:
https://s32.postimg.org/ig3vvg5t1/x_base_flat2s.jpg
The cross shape/X shape has three main disadvantages though to be aware of. It’s still really cool though and can be very successful.
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The size of the opening for a manipulator is harder with a big old wheel in the way - if you stay with the holes for the top part of the robot. You can make the top of the robot offset 45 degrees, but getting it attached nicely can be a trick. It can be done like 80Y Cypher did in skyrise or 81M Mystique in sack attack. 80Y shortened the one wheel in front a bit to make room for the lifter arm to come completely down.
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With more rigidity comes the ability for a wheel to lift off the floor a bit easier. This reduces torque quite a bit! Arm position can tilt the robot a bit so in one position you are OK and another you lose some traction on one wheel. So center of gravity across all arm configurations must be looked at.
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Going forward and backwards has less torque. 45 degrees offset has the most wheels driving in a cross. But most people don’t naturally drive that way.
@Team80_Giraffes Perhaps it’s not clear, but the open side of the build sketch is at the top of the drawings. The superstructure is at 45 degrees to the base as you describe in your issue one. The holes that align are circled.
As such, issues one and three are exactly the same in an X or octagon build. The 3d sketch above has constricted space between its “front” wheels as well. Issue two is a general concern for all drive bases: maintaining as even traction as possible when your intake/scoring mechanisms are in motion.