I've been working flat out for several days on an old (1936) Brunton's marine gearbox. It suddenly hit me that I was going to have a problem assembling the thing, the main shaft assembly is held together with a
1 3/8" Whit nut, recessed into a gear and with 3" of shaft projecting through it. When I've dealt with these before I've made do, as have many others before me, with a hammer and punch to tighten the nut. Having spent a lot of customer's money sorting out 70 years of wear & tear and abuse, and having made the reducing gear pinion an interference fit on the shaft, I reasoned that this wasn't good enough this time. I'd made a decision after work the previous evening to sacrifice one of my 3/4" drive sockets for the job, boring it out, turning down the outside, and welding on an extension tube. In the cold light of day, I realised there wasn't a socket big enough in the set, so they were spared! Next option was to ring round the local tool shops to find something suitable for me to butcher in this way. Then the lamp above my head lit up - I could make one with the new toy! Quick drawing of a hexagon 55mm across corners on the computer, transfer it to DeskCNC for the machine. Find a piece of suitable (2 3/4") round bar (all I could find was a 'tool special' I'd made years ago for the 2-sided nut in a Lister Blackstone gearbox, I used the other end so it's now a double ended 'tool special'). Bore out the bar & turn it down to be a neat fit in the gear recess, then set it up in the CNC mill (old Bridgeport revamped), then 2 series of cuts with 3/8" & 1/4" endmills, hey presto! A tool for the job in less time than it would have taken to go out & buy a new socket, never mind the expense and the time taken to convert it to a useable form. Yes, I know it's not model engineering, but it felt good to be able to do the job successfully in this way ;-)Cheers Tim
Tim Leech Dutton Dry-Dock
Traditional & Modern canal craft repairs