| ~ IN THE SHOP ~ |
| October 2011 |
| Boardman & Wells Wooden Works Shelf Clock |
| A Monthly Sample of Clock Repair Projects |
Like last month, we are working on another early American
"mass-produced" clock. Eli Terry was the first to streamline the
basic design of this "wood works" movement; Seth Thomas, Silas
Hoadley and dozens of other enterprising Americans (including
our subject, made by Chauncy Boardman & Joseph Wells)
followed with similar type wooden geared movements. >>>>>>>>>
Why wood? Because it was plentiful and cheap. Why not brass?
Because it was not plentiful, nor was it cheap in America at that
time. Around the late 1830's brass became easier to procure for
the clockmaker and from then on wood works clocks were strictly
novelties.
The plates are almost always quartersawn oak while the wheels
are of oak or cherry and the arbors and pinions are usually
maple. There are brass and steel parts also, but it's pretty
minimal: our subject has a brass escape wheel and bridge as well
as brass bushings which are a press-fit into the wood (it's
amazing how well they press-fit into the wood - particularly 180
years after it was built!!!!!!)
"mass-produced" clock. Eli Terry was the first to streamline the
basic design of this "wood works" movement; Seth Thomas, Silas
Hoadley and dozens of other enterprising Americans (including
our subject, made by Chauncy Boardman & Joseph Wells)
followed with similar type wooden geared movements. >>>>>>>>>
Why wood? Because it was plentiful and cheap. Why not brass?
Because it was not plentiful, nor was it cheap in America at that
time. Around the late 1830's brass became easier to procure for
the clockmaker and from then on wood works clocks were strictly
novelties.
The plates are almost always quartersawn oak while the wheels
are of oak or cherry and the arbors and pinions are usually
maple. There are brass and steel parts also, but it's pretty
minimal: our subject has a brass escape wheel and bridge as well
as brass bushings which are a press-fit into the wood (it's
amazing how well they press-fit into the wood - particularly 180
years after it was built!!!!!!)
Our subject is in pretty good shape overall. But with wood gears,
it's not surprising to see broken teeth when initially inspecting the
parts. And sure enough - here, on the strike side great wheel a
previous broken-tooth repair has failed again>>>>>
Because the meshing of gears occurring here (with the pinwheel
pinion) is the closest to the power source (the weight) you can
imagine the pressure put upon these teeth. But this is strange:
why did the tooth in the middle of the repair fail and the 2 teeth to
the right fail, but not the tooth in between? My guess is that the
middle may have had a weak spot along its grain which sheared
itself off the top of the tooth. When the tooth broke the force upon
the teeth must have been multiplied since the weight had a
sudden (but short) freefall which broke - not only - 3 of the great
wheel teeth, but 2 of the pinwheel pinion leaves as well. Perhaps
the surviving repaired tooth was filed too low and it passed
through the pinion teeth unscathed.....maybe? I don't know...
But here you can see the 2 broken leaves on the pinion that the
great wheel teeth mesh with. >>>>>>>>>>>>>>>>>>>>>>>
These broken teeth must all be replaced properly before the clock
will strike again.
it's not surprising to see broken teeth when initially inspecting the
parts. And sure enough - here, on the strike side great wheel a
previous broken-tooth repair has failed again>>>>>
Because the meshing of gears occurring here (with the pinwheel
pinion) is the closest to the power source (the weight) you can
imagine the pressure put upon these teeth. But this is strange:
why did the tooth in the middle of the repair fail and the 2 teeth to
the right fail, but not the tooth in between? My guess is that the
middle may have had a weak spot along its grain which sheared
itself off the top of the tooth. When the tooth broke the force upon
the teeth must have been multiplied since the weight had a
sudden (but short) freefall which broke - not only - 3 of the great
wheel teeth, but 2 of the pinwheel pinion leaves as well. Perhaps
the surviving repaired tooth was filed too low and it passed
through the pinion teeth unscathed.....maybe? I don't know...
But here you can see the 2 broken leaves on the pinion that the
great wheel teeth mesh with. >>>>>>>>>>>>>>>>>>>>>>>
These broken teeth must all be replaced properly before the clock
will strike again.
First we'll deal with the great wheel teeth. I cut out the portion
which encompassed all of the broken teeth. I leave just a bit of
undercut so as to create a slight "dovetail" which adds strength to
the repair. I lay it out on a piece of band-sawn oak (even though
the wheel is made of cherry - we're a bit low on cherry this month
unfortunately) and trace the dimensions onto the blank making
sure to keep the grains somewhat orientated (in the bottom photo
it doesn't look it, but they actually are in the end).>>>>>>>>>
which encompassed all of the broken teeth. I leave just a bit of
undercut so as to create a slight "dovetail" which adds strength to
the repair. I lay it out on a piece of band-sawn oak (even though
the wheel is made of cherry - we're a bit low on cherry this month
unfortunately) and trace the dimensions onto the blank making
sure to keep the grains somewhat orientated (in the bottom photo
it doesn't look it, but they actually are in the end).>>>>>>>>>
The oak blank was cut out with a jewelers saw then filed to fit
the gap (I used a modern wood glue for additional strength).
The individual teeth were then carefully cut with a jewelers saw
and then filed to shape.>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
the gap (I used a modern wood glue for additional strength).
The individual teeth were then carefully cut with a jewelers saw
and then filed to shape.>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Now for the pinions: this is a touchy area....we must insert new
teeth, precisely formed and situated - firmly, and that is the
critical part - firmly in place. As you can see from the photo>>>>
there is not enough glue-able area to ensure a strong bond for
the new pinion leaf in it's present condition.
So what can be done? One method is to remove the entire
pinion, cut a new one and fit it back onto the arbor. Another
method, however, is to keep the existing pinion, but cut
lengthwise channels where the pinions sheared off; these
channels will act as a seating for the new pinion leaves once
they are glued into place. Please note, however, our
forefathers warned against fitting new pinion leaves in this
situation. But.....they were not lucky enough to have the Dremel
or Foredom rotary tools which and, with great care, can form
very nice channels - by hand - in very awkward places like this.
With channels cut, the new leaves were formed, fitted and
finally glued into place. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
The result is satisfactory and meshes very nicely with all of the
great wheel teeth (both old & new)
teeth, precisely formed and situated - firmly, and that is the
critical part - firmly in place. As you can see from the photo>>>>
there is not enough glue-able area to ensure a strong bond for
the new pinion leaf in it's present condition.
So what can be done? One method is to remove the entire
pinion, cut a new one and fit it back onto the arbor. Another
method, however, is to keep the existing pinion, but cut
lengthwise channels where the pinions sheared off; these
channels will act as a seating for the new pinion leaves once
they are glued into place. Please note, however, our
forefathers warned against fitting new pinion leaves in this
situation. But.....they were not lucky enough to have the Dremel
or Foredom rotary tools which and, with great care, can form
very nice channels - by hand - in very awkward places like this.
With channels cut, the new leaves were formed, fitted and
finally glued into place. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>
The result is satisfactory and meshes very nicely with all of the
great wheel teeth (both old & new)
