Friday, August 16, 2013

Mr. Lecount Gets Fitted For A Bonnet

Le Count Ready For Fitting
I have spent several days this week fitting the Lecount works to the case, which is assembled without the bonnet.  I prefer to make the bonnet last, as I don't work from plans, and need to see where the works end up to actually put the top together.  It is important the bonnet fits exactly right, since its primary purpose is to keep the dust away from the works, and it needs to be a relatively airtight fit.

As I said in earlier posts, my method for making tall case clocks is to start with the back board. This becomes the spine of the clock and all measurements are taken from its center line.  Then I build a lower case (just a box) and fit it onto the back board.  That allows me to cut and fit the sides and front frame, which makes it easy to fit the large door properly.

The door itself has a wide overhanging molding around it, which needs to be carefully measured so the the edge of the molding clears the case when it opens.  That is why these doors have a unique type of hinge that has an offset pivot.  Also the door has an opening, the "lentical" which allows the owner to see the weights and pendulum from a distance.  In my case I am having a glass blower make a bullseye glass oval to fit in this space.

The last job for the lower case is to make and fit all the molding.  In these early cases the molding is short grain, so it is usual to cut and glue sections of short grain wood (olive) onto strips of beech or oak and make the molding lengths this way.  I am also using cherry molding which is ebonized to provide contrast, like the original clock.
Initial Fit 

Now that the case is assembled, I set up a thick piece of wood on the floor and make it absolutely level.  Standing the case on this floor allows me to properly fit the works.  I have lots of lead weights on the floor to keep it stable.  Placing the works on the cheeks of the case, I can then adjust the fit and set the crutch to make the beat even.  That means that it works perfectly in an ideal flat and level location.

However, not all homes have that ideal flat and level place for a clock.  I have made a special modification for this clock, which is not original to the 17th century.  The works are old and some of the gears are worn slightly uneven, so the beat is not always regular.   Also, the works are designed to run for 30 days, so when the weights are low enough to reach the pendulum bob, it sets up sympathetic vibrations which can act to stop the clock.  That took about 2 weeks to happen when the works were running on my test stand, which is not that stable.

I solved this problem and also the problem of making sure the case is level with a modern solution.  The round feet are turned from cherry around a large bolt.  This bolt is set into the bottom of the clock with standard "T" nuts, so the feet can be screwed up or down slightly to fit the floor.  At the same time, I made a large hollow space above the bottom board and covered it with a second "false" bottom board.  Inside this hollow space I added a fair amount of lead shot.  When you look inside the case at the "false" bottom, it looks fine.  You cannot judge the distance easily so it just looks like a standard case.  However, the addition of lead shot provides stability for the case and the loose shot absorbs any vibrations which may affect the operation of the clock.

As soon as I put the works into this case, standing on the level floor, they ran perfectly, even though the weights were all the way down into the case.  Problem solved.

Today I was able to glue together the basic bonnet, which fits nicely to the works.  During the next week, my attention will be to add all the veneer and molding which will dress it up.  I expect that the clock itself will be ready for the finishing process in a couple of weeks at most.

I cannot wait.  Either can Mr. Lecount.

The Bonnet Assembled


Jeremy said...

Masterful work as always but I have a question, wouldn't it be better to have the glass for the door before you construct the door since the glassblowing process may not be as accurate as desired?

W. Patrick Edwards said...

Actually I have a lot of antique window glass from houses which have been demolished. I use it for restoration of antique furniture as well as my new creations.

For the normal glass areas it is easy to cut the glass to fit the wood frame.

However, on this clock I needed a blown bullseye glass oval for the lenticle in the door. I made a pattern and got the glass blower to fit the bullseye to the pattern. Then I installed it with putty.

Worked great.