(Reviving a very old post here, but it's the logical place to put the information)
I've been using this machine quite a bit recently, and decided that there were a few improvements I'd like to make to make use a little easier. When I re-built it, a few things got left off the list due to time, and not being able to source materials - mainly the various locking devices.
Most on the planer hold downs, fence, and rip saw guard were male 3/8" Whitworth square headed bolts. OK they work fine, but I find I'm everlastingly looking for the square hole spanner - I would have liked to replace them with 'Adjustable Clutch Levers' as I did on the planer in and outfeed table locks. Those were 1/2" Whitworth Female that I did find a source for but were very expensive.
Also the 'locking bar' for the cross cut saw had be badly bent at some time in the past and was beyond straightening so a new one was needed.
So then I had a flash of inspiration - Metric versions of these adjustable levers were available very cheaply both on eBay and from WDS - I got them from WDS as I suspect their quality is slightly better. So what was the flash of inspiration - make up a double ended stud - metric one end Whitworth the other, and Loctite the stud into a female metric lever converting it into a Whitworth Male - easy peasy