|Project by horologist||posted 06-01-2013 12:09 AM||2384 views||0 times favorited||4 comments|
Next in the series, a fairly basic project that started out as an exercise in decorative carving. As you can see there isn’t much carving.
This vise is one of my all-time favorite ebay purchases and came with an interesting rounding up tool. (Yet another vise mounted tool that is laying on a shelf and soon to be the subject of another shop project.)
This is a Prentiss patent vise, (sold for $4.50 in 1880) and is a little lightweight for most of the clock work I do so would be a poor replacement for the bench vise I currently use. Instead I have been using it as a fixture for repairing broken teeth on early American wood works clock movements. The vise came mounted on a scrap of pine visible in this photo.
I started with some mahogany offcuts and used the high tech layout method shown in the photo. This lack of planning will cause some trouble later on…
The base is a fairly simple thing, essentially a wooden hockey puck. I was careful to make sure the sides were square to the top surface. The 3/8” hole in the center is to provide a reference for installing the bearing and to help keep things concentric. I finished it with Liberon Woodturners’ Lathe Polish, never used the stuff before but so far I’m happy with the results.
The next part is where things started to go wrong. I failed to notice the cracks in the end of the board when I cut out the rough blank and of course they were deep enough that they weren’t removed during the shaping. Originally I had planned on carving a rope pattern around the edge of this piece but realized I didn’t get the geometry quite right for this and then the cracks were the last straw. I have a big project which involves a fair amount of carving and I thought it would be sensible to learn on smaller more expendable projects. As you can see, I decided that saving the carving exercise for another project was better than scrapping the base. Anyway, I think I like it better without the carving.
I modeled the bearing after one used in my engraving vise and made a brass cup to fit closely over a steel peg. The best way to get an accurate hole is to drill undersize and then bore out the hole to the correct diameter. I wanted a tight fit so the disk wouldn’t wobble, there is a little less than a half thousandth of an inch of clearance between the two. Sorry, no real detailed photos here as I tend to forget to stop and take pictures also it doesn’t take very long before my hands are too dirty to handle the camera.
The peg is ½” in diameter and has a base turned to fit into that 3/8” reference hole I mentioned earlier. The brass cup has the end turned to 3/8” also and both are press fit into matching holes in the wood. No need for fasteners or glue.
Bearing components installed and ready for final assembly.
For those who may wonder why anyone would need such a gadget…
It is very common for teeth to break on American wood clock movements. Typically the teeth come off in one piece with clean breaks so whenever possible I prefer to reattach the tooth than to replace it. This makes for a nearly invisible repair. I like to set the wheel in the vise and rotate the assembly around so I can verify the tooth is fitted in properly before the glue sets. The pine scrap was perfectly adequate but I felt the vise deserved better.
Three broken teeth.
-- Troy in Melrose, Florida