#jacot tool

[fishstickmonkey]

Watchmaker's jacot tool

the Science Museum

[joyofprecision]

Jacot Tool Rescue

I recently acquired very rough looking jacot tool for cheap enough that I didn't mind a bit of a gamble.  I bought it with basically no description of the tool, and a few poor pictures.  Here is the tool as I received it (this picture is actually from the auction):

I assumed it would have a broken lantern, if it was even present at all (it was tough to tell from the pictures).  Even though it appeared quite corroded, most of the working surfaces (specifically, the burnishing beds and one of the centers) looked like they had a chance of being in good, honestly used condition.  After receiving the tool, and inspecting it, I found that the burnishing beds were all in good usable condition with the exception of #5.  #5 was worn past being usable.  The lantern, as suspected, was chipped and corroded, but still had many of the smaller size holes present.

I set to work cleaning things up.  After disassembly, I started by cleaning up the steel indexing post protruding from the body.  Being a critical working surface, I took great care to only remove the surface corrosion.  The rest of the cleaning and polishing of the body was purely cosmetic, no working surfaces were affected.  I started with very fine crocus cloth coated in light oil, to remove the corrosion.  I followed that with a bit of an experiment that worked really well.  I used some shavings of buffing compound mixed with WD-40, applied to a Selvyt cloth, and polished by hand.  In this picture you can see the tool disassembled, with the body cleaned and polished:

Next I tackled the gibs that are screwed into the body.  The large brass screws on top of the tool tighten down the gibs to hold the runners in place.  The gibs were a little bit fiddly but I used the same cleaning/polishing method on them (the outer surfaces only - the inner portions that go into the body and clamp against the runners were not touched).  The other miscellaneous parts were given a quick cleaning/polishing as well: the protective cover for the lantern and the small set screw that holds it in place, the large brass gib screws, and the small steel screws that hold the gibs in place.  The small steel gib screws looked poor, so I cleaned and polished them, hardened them, re-polished them, then tempered them to a nice purple.  Finally, I worked on the runners.  Nearly every surface of the runners is critical so this took a lot of time and patience.  The bed surfaces did not need any attention - they were already clean from being regularly used.  Likewise for one end of the center runner.  The other end of the center runner, as well as the outer diameters of the bed runners were given just enough attention with crocus cloth and oil to remove the surface corrosion, and nothing more.  Here is the tool after everything was reassembled.  Very attractive!

In the photo above, the protective cover is in place over the lantern.  The lantern has not been cleaned yet, I am going to try soaking it in a product called Evapo-Rust (I have heard excellent things about it), and then pegging out the holes.

I'm looking forward to trying it out!