Hi, so I need around 16 inches of linear motion expansion, but the rails are only 12 inches ling. Does anyone have any ideas on how to join two together (one having been cut to 4 inches)?
Depends, are the linear rails moving, or are the inner trucks moving?
If the linear rails are moving, you can just use an inner truck, drive shaft lock bar, or a regular steel 1x1x5 bar to attach them together. The screw heads should be going out from the bottom (flat) side of the rail.
If the linear slides aren’t the ones moving, you can just use anything on the flat side of the linear rails to attach them (c-channels preferably). Make sure the screw heads are on the bent side of the linear rail.
The linear rails are somewhat notorious for being largely unusable for their intended purpose in competition V5RC robots.
There are other ways using vex-legal parts to make implement linear motion of arbitrary lengths. For some examples, you might search YouTube for Spin Up “sling-shot” robots for inspiration.
The original kit had 17.5 (??) inch rails, not sure why that changed.
Had some use at that time.
The drive shaft lock bar looks like it will work, thank you!