In September 2010 I visited the steam rally at Henam as I had done the year before. You can find photos of that trip elsewhere. This time I was quite taken by an old Burroughs adding machine. It is a class C and probably dates from around the 1920s and most likely built at the Strathaven plant in Scotland. It is a 14 column machine with a maximum register value of £9999999999/19/11¾d. Built long before UK decimalisation it is a victory of engineering being able to cope with columns that need to carry using multi base arithmetic. Base four for the farthings, base twelve for the pence, base two for the tens of shillings and base ten for all the others.
When I acquired it, it was completely locked up. Nothing would move. I did hope it would be a simple matter to free it and get it working again but once I got it home and opened the case I found that almost all of the moving parts didn't.
Practically every gear, wheel shaft, crank and cam were corroded into an almost solid gray brown lump.
Although I never worked on these machines when I was a Burroughs field engineer I thought "how hard can it be"? Writing this some four months later I think the answer is "really quite hard".
I had to strip it down into each of its individual parts and using various oils and degreasing agents and an old toothbrush I managed to free up and clean every part. Re-assembly was something of a problem. I had to make my own specialist tools and jigs to hold things together as I put the parts together.
But hardest of all was working out how to align all the parts which involved working out how it works from first principals.
Sadly I didn't have the foresight to take photos of it before I started re-assembly but some of the photos here may give an idea of the effort and time put in to bring this machine back to working order. Although I probably still don't have it all lined up correctly.

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p1040009 This is the rather sturdy wooden box it has been kept in.
p1040010 As you can see it has cleaned up really nicely.
p1040011 Out of the box and on my desk.
p1040012 With the case off the inner workings can be seen.
Note the complex carry gears between the ten shilling and the one pound columns.
p1040013 Sorry I tried for a close up but the camera refuses to focus so close.
You can see there is one wheel still not replaced. The teeth on the gears are very worn and I'm trying to re-build them.
p9210002 Here you can see about half of the key-stems replaced.
Good job you can't hear my language as I struggled to re-fit the faceplate.
p9210003 Each of the key-stems only needed a light polish with very fine emery cloth to get the corrosion of. Of course, this is very hazardous as every part is coated with cadmium which is highly toxic.
p9210004 Once again partial replacement of the key-stems.
Although it can not be seen here, all of the wheels on the front were corroded into a single solid piece. Once I was able to get them off, cleaning revealed that many were very worn.

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