The wonders of modern science

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
Reply to
timleech
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Our fathers used box-spanners :-) regards
Reply to
Roland and Celia Craven
In article , timleech writes
(Snip tale of making a tool with a CNC mill)
Nice job Tim! I still get a big silly grin watching my little Taig chewing away at a lump of metal all on its own.
One of the strap buckles on my melodeon broke last week. I let the Taig make me a new one... :^)
Cheers
Reply to
Nigel Eaton
Some of us still do.... :-))
Peter
-- Peter & Rita Forbes snipped-for-privacy@easynet.co.uk Engine pages for preservation info:
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Reply to
Peter A Forbes
Maybe so, but the biggest one my father has is about 1/2" W. Have you tried buying off the shelf or making a 1 3/8" Whit box spanner recently
I have made up box spanners for 'very' large nuts in the past, I considered it for this job but didn't fancy it. I think this method was actually quicker given that i would be starting from scratch.
Cheers Tim Tim Leech Dutton Dry-Dock
Traditional & Modern canal craft repairs
Reply to
timleech
Hallowed be thy hammer,
............. any more?
Reply to
Mike Whittome
Give us this lathe, our daily thread,
Dave Colliver.
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Reply to
Dave
: 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 Forged tube spanners are good, cherap and quick to make wit little waste! Perhaps not so much fun! ChrisR
Reply to
Chris
I did consider this, I've made them in the past, but apart from finding the right size of tube I would have had to spend some time sorting out a former. I couldn't use the gearbox shaft to screw the nut onto to use that as a former (Not after all the work I had done on it!), so it was a choice between making up some sort of mandrel with a 1 3/8" W thread or, better, machining up some hex bar the right size. No doubt it can be done with the nut alone, but I didn't fancy trying, especially as it's castellated. I'm also a bit doubtful about tube spanners, having split at least one (commercially made), as I noted earlier this one had a bit of work to do pulling the gear into place and tightening it firmly.
As an aside, trying to get a 7 tpi castellated nut into a position where it's appropriately tightened and with the slots lined up with the split pin hole can be very time consuming (especially working on my knees with limited visibility & access :-( ), as there's so little 'give' in the assembly relative to the thread pitch. However carefully I tried to take just the right amount off the face of the nut, it took a long time to get right!
Cheers Tim
Tim Leech Dutton Dry-Dock
Traditional & Modern canal craft repairs
Reply to
timleech
In article , timleech writes
Yeah, and a 3/32" thick nut's going to be *fine*, no problems.
Reply to
Nigel Eaton

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