This particular Instructable isn't so much a step-by-step guide - it's really an overview of the steps I went through to design and manufacture this prototype. I hope some of you find this useful.
Step 1: The Brief
I try to scrounge logs for my woodburning stove whenever I can, and frequently end up with odds and ends and awkward sized branches to cut up.
Cutting these logs up into suitable lengths for storage and burning can be problematic: a chainsaw is needed to do the work, and these are very dangerous tools - more so when the branch you're cutting is no longer attached to a tree! It's awkward to position a log on the ground (particularly if it's small-ish diameter, and relatively light). I've seen logs being held in position with one foot while being cut to length - a dangerous idea without chainmail socks! On top of this, bending to ground level while holding the saw doesn't make a repetitive task like this any easier.
I was considering buying a 'Superjaws' type work clamp with purpose designed log gripping jaws, when I hit upon the idea of using my trusty Black & Decker workmate. I've used this before to grip small logs (the max opening width is about 130mm / 5"), but maybe I could design something to widen the clamping capacity and offer better grip on the log? A quick browse around the internet showed that it had been done before and I could buy a set for around £20 - but the only options out there look a bit flimsy, and log size is limited by the travel of the workmate jaws. So I decided to design my own.