Box Channels

Occasionally, as I am building with VEX, I find myself wanting more torsion resistant parts. Even 1x5 C channels are pretty easy to twist.

Box channels, on the other hand, are VERY torsion resistant, so even small ones can take very large torsion without bending. Accordingly, I box in critical C channels after bolting to them to give my robots stiffness.

Easy demonstration: take a 1x5 C and try twisting it (easy). Now take 2 1x5’s and bolt them together along the sides to make a box (I can’t cause a noticeable deflection if I get the screws tight). The more places the better: 3 points/side is minimum, 5 is good.

Does anybody else use this technique, and if so, what methods do you use to bolt them together (it’s a huge pain to get the middle screws in)? My current best technique is to use Keps nuts, slide them down inside the channel to the right point, put an axle through from the other side to push into the top of the nut to keep it flat while starting the screw, and then use the natural lock of the Keps to tighten.

You could use a 1/4" standoff between the faces of the C channels. Many teams use standoffs to improve the rigidity between parallel planes.

If I am understanding #Iwilsonp correctly, he would need 1 inch standoffs because both C-channels are .5 inches deep. If making a box, the two would close in on each other making it 1 inch between the planes.

We have done this in the past and using 1 inch standoffs work great because they are threaded all the way through. This allows you to use a screw all the way through the standoff giving you some pretty good strength and keeping the C channels lined up.