High Speed X- Drive

Does anyone know if an X-drive with 4 high speed motors will stall very easily?

an x drive with 4 speed motors on 4" wheels will stall very easily on robots heavier than 20lbs
an x drive with 4 speed motors on 3.25" wheels can work
an x drive with 4 speed motors on 2.75" wheels will not stall easily, and is good for extremely heavy robots

an x drive with 4 torque motors on 4" wheels will not stall easily, but you will move slower than speed motors on 4" tank

an x drive with 4 speed motors on 3.25" wheels will be faster than a 4" tank drive on speed motors

An X-Drive is a type of Holonomic drive, not sure what you’re asking.

I prefer tank drives over x-drives and tend to not use them.
In most situations (not all) tank drives are superior in competitive match play.
Why?
-X drives rotate, and move diagonally slower, this means if you have to move from point A to B not in a straight line, the tank drive will do so faster or as fast as an X drive.
-They are highly vulnerable to defence, they are stressed when pushed from the side while moving forward, and you can not place traction wheels to counter side pushing.
-They use more space, and are difficult to get appropriate drive ratios, especially when using more than 4 motors, however if you are investing 8 motors in the drive, it becomes a viable option
-Ramps just got a lot harder to climb, when they were already difficult with high speed tank drives

The bottom line is, manueverability is better achieved using a high speed tank drive. For this game, the only times an X drive would be better than a tank drive is in autonomous, and when you have 8 motors on the drive and intend on pushing those 8 motors to make the robot as fast as possible.
The reason why a high speed robot would be better using an X drive, is that you can put all 8 motors on direct drive with the wheel, resulting in very little slop.
If you were to achieve the same speed as the above X drive with a tank drive, you would have to add gearing and couple the motors together using lots of gears or sprockets etc. and that results in large amounts of slop that will affect automous accuracy.

With this mentality, my preffered x drive configuration would be 8 motors on turbo with 4" wheels.

I definitely agree with Stanley on this one. Early in the season we tried using an X drive as well as a plus drive (really the same thing), only to find major thermal fuse issues. The tank drive has been very beneficial for us, especially considering the amount of defense that has been played in FL.

Thanks for all the help, I am planning to go towards another iteration. Do either of you have a suggestion for a tank drive, I would like to use 4 motors at most on the drive. Also I have high speed and turbo options with a recommended external gearing.

One other question I found that it is easy to adjust your robot for Mid and Full field shots if you are off. How is the tank drive for a user control adjustment?

I tend to stay away from using anything but standard speed motors. I personally prefer to gear externally. And user control adjustment has been fine, takes driver practice just like every other design.

Refer to this recent thread to find the perfect drive ratio: https://vexforum.com/t/drive-top-speeds/31849/1

X- drives were definitely useful last year, but this year you want a fast tank drive for more gears, sprockets or space so you can’t be blocked by an opponent like you guys did with 2Z. There is also a disadvantage with tank drives because you can be pushed from the side if you are using omni- wheels.

Simply place traction wheels inbetween the front and rear omni wheels, and you can’t be pushed sideways anymore.

Our drivetrain is all omniwheels, we hope to change this soon but we’ve noticed the mere weight of the bot makes it extremely difficult to push ours sideways, although it is still possible.

I guess, but if you have omni-wheels in the front and traction wheels in the back, your front will be pointing somewhere else and your back will stay.

The robot will rotate around the solid wheel

Use 6 wheels in total. 2 traction wheels in the middle, two in the front, and two in the rear.

So… all traction wheels?

the front and back should be omnis XD

Is that what he is saying?

I believe so… all traction wheels makes no sense XD

When i say 2 tractions in the middle, 2 omnis in the front, and 2 in the rear i mean this:
http://puu.sh/mbW97/939177b23b.jpg

It would make sense, but you will be terrible at turning.