The lift on our robot last year was a 6-bar. But we found that the vex drive shafts wren’t able to keep up with the torque of the motors and rather than rotating the gears and lifting the mechanism, the shafts would just twist and snap in two.
Does anyone else have this problem? How did you deal with it?
Any recommendations as to where we can buy stronger drive shafts the same size as VEX’s?
How big were your shafts??? Were they long and did they go to each side of the six bar lift??
On our team, we call this making churros 
. Normally, we just try to give the axle as much support as possible to minimize the stress on it
The shafts were less than 2", just enough to fit a motor, a gear, and a couple lock collers.
What was your gearing ratio? You could probably make some profit by selling drill bits 
The gear ratio was 1:3 - powered by a high strength motor
Similar question was recently discussed
https://vexforum.com/showthread.php?p=289792&#post289792
You can gain almost 4 years experience by reading previous 4 years of useful posts.
Stronger drive shafts than Vex would violate the intention of a level playing field by requiring that the same parts be available for everyone.
the second way is they way our robot was done.
Was the shaft that twisted attached to your motor or the gear that drove the arm? If it was attached to the arm, was it taking all of the torque of the arm (was the shaft in a gear that was being turned and then the shaft was attached to the arm via a lock bar etc)?
It would help if you posted a pic.
So there’s your problem
Just some advice…
You should always mount any structures to the gears and not the axles. If you have a 30 inch arm with an intake at the end, even using aluminum, you have a lot of torque. Too much much torque to attach the structure to the axle. The axles should only be used as pivot points for supporting your structure.
Attaching the gear directly to the arm is useful and we will implement that, but it was the shaft connected to the motor that was twisting.
Wait what…?
Motors don’t even have close to the torque required to twist as axle.
The only explanations I can think of are:
It’s a new 269 and the motor locked up, then the arm was forced into the down position.
-or-
There is another source of torque on that axle (another motor for example) that is contributing.