Update!
I did some stress testing tonight! I weighed down my sled with 75 pounds of weight and put the chains at 124Ëš internal angle (emulating a near-top scenario). I measured (and double checked with math) 80 pounds of tension in each chain!
I used inline spring scales on the chains and got 80 pounds.
I then did the math to double check that: 75lb x 0.5/cos(124Ëš x 0.5) and got 79.89lbs
There were zero breaks, cracks, or problems with the linkages! I think this proves that not only will the linkages handle the normal forces (which will max out at around 30-40 pounds per chain assuming a 20 pound sled) but that this system can handle rogue spikes in the system and that they hold up fine well past the forces the motors are even capable of (which is about 66 pounds per chain).
There are some on the forums who think the chains will regularly see 66 pounds of force, while I haven’t been able to get anyone to prove that to me this should still help alleviate fears even for them. The motors should stall long before the linkages break.
I had planned to stress the system to it’s breaking point but I was not ready for 75 pounds to come crashing to the floor. I still may break things to find their failure points but I think I will do it one component at time in a more controlled setting.
In other news, the first batch of linkage kits is in the mail! I’m waiting on some of the specialty hardware parts that should get here later this week to send out a second batch. The demand for kits was a little higher than I expected so I didn’t order enough parts the first time. Also, my wood supplier ran completely out of 1/4" baltic birch, this was the first time I had seen that happen in 5 years buying wood from them! I bought more wood yesterday but have quite a bit of laser cutting to do now. So, needless to say I am a little behind the curve but I am catching up and will get things finished and in the mail asap!
One more conclusion from the evening: I probably would have loved taking trigonometry…