G'day Chris here, and welcome back to Clickspring.
In this video, I reach a significant milestone for the clock construction:
The very first tick of the escapement.
For the most part, the bits and pieces that go into making a clock
are not necessarily unique to clocks.
There's a chassis, gearing, shafts and bearings to name just a few.
But the escapement is the one component that undeniably
sets timekeepers apart from other geared mechanisms.
The purpose of the escapement is twofold:
Firstly, it releases small amounts of energy to the pendulum
to replace what it loses to friction, and so keep it oscillating.
And secondly, it effectively counts those oscillations,
and through the attached gear train keeps a running total,
that we see displayed as the time.
Now there are many different escapement designs,
each with their own pros and cons.
The one used for this clock, the recoil escapement,
is so named because it experiences a small backward recoil every time it ticks.
This recoil action is well understood to be one of its flaws,
but its relatively forgiving geometry, and robust performance,
made the recoil escapement the workhorse of the domestic clock market
for many hundreds of years.
In fact it's still widely used today.
I'm using the British Horological Institute method
to lay out the geometry for the recoil pallets,
and its a complex process worthy of an hour long video in itself,
so I won't go into the detail in this video.
Instead, you can get this publication from them directly,
and give it a read for yourself.
But it worth mentioning that in the absence of any CNC cutting equipment,
the layout lines are still only a guide.
Old fashioned trial and fit on a depthing tool is still the accepted method
to inspect the escapement action,
and decide on the required adjustments to the pallet profile.
The process of roughing out the pallets
is much like you've seen in previous videos for parts like the click and clickspring.
A paper template marks out the perimeter,
as well as the hole location on some O1 tool steel.
And in this case, I'm using a length of blued pivot steel
to ream the hole for a good fit on the pallet arbor.
It's an effective and easily made tool,
using a simple hex block to form the faceted shape.
The pallets were then roughed out from the parent stock, using the scroll saw.
The belt sander knocks down some of the perimeter closer to the line.
And if you're familiar with how this part should look,
you'll have noticed that I've drafted the pallet faces as a straight line,
between the drop point and the discharge corner.
A curved face will help reduce the recoil during the supplementary arc of the pendulum,
and I do intend to put it in.
But its positioning and radius will be a matter of judgement
once I start testing, so for now I'm simply leaving the faces oversized
with a straight line as a guide.
I used needle and escapement files to bring the profile closer to the required shape.
In fact there's probably no other part in a clock
that better typifies the process of traditional clockmaking,
than the escapement pallets.
No matter the technology at hand,
it still comes down to a clockmaker standing over a bench vise,
using a file to manually coax the part into shape.
The paper template has taken me about as far as it can,
so its time for that to come off with some solvent
And at this point the recognisable shape of a set of recoil pallets
is starting to emerge,
although there's still quite a lot of fine adjustment required to get them to perform correctly.
To do this, I need to put them into close proximity with the escape wheel,
and then examine their interaction.
Now technically this could be done within the clock frames,
but its much more convenient to remove the escape wheel from its arbor,
and then use the stable platform of a depthing tool, to get the job done.
To begin the process, I've positioned the pallets clear of the wheel,
and the adjustment screw is used to bring them closer together.
And the first thing to note is that as the escape wheel teeth clear the exit pallet,
the next tooth coming onto the entry pallet experiences a large jump or 'drop',
which would lead to much wasted energy if it were left in this condition.
So at this point the depthing of the pallets is much too shallow.
But even at this shallow depthing the teeth can't pass the entry pallet
because they're still oversized.
So I can afford to take a small amount of material from this back face,
and some from each of these faces too, to pull this apex back a little.
Now I must admit it that what follows is a rather subjective process.
But the general idea appears to be gradual removal of excess metal,
whilst incrementally pushing the pallets into closer engagement with the escape wheel teeth.
The ultimate goal is to have a minimum drop onto both the entry and exit faces,
and an easy clearance at each of the discharge corners.
While at the same time ensuring that the pallets are at the correct theoretical depth.
The amount of metal to remove is tiny,
and of course there's no putting it back once its taken off,
so I'm taking my time to get this right.
I'm using fine cut needle files, and checking the results often.
Gradually moving the pallets closer to the full depth of engagement with each trial fit,
and then responding to whatever interference condition that creates,
with more adjustments.
The end result is that the teeth are experiencing minimal,
and essentially equal drop on both the entry and exit faces.
And the recoil action is able to be accommodated
without the tops of the teeth jamming on the underside of the pallets.
Now at this point the escapement does feel just a little tight,
and the depthing is slightly shallower than the correct figure,
but I'm going to leave it like that for the moment,
so that I have a small amount of material left to work with,
when I polish the faces after heat treatment.
The next step is to drop in a threaded hole for the fastener,
which I took care of on the mill, using the pallet arbor to locate the hole position.
Like most of the other steel parts in the mechanism,
its important that the pallets be hardened to ensure they have a long service life.
And you might recall that when I made the hands,
I used a custom tray to contain the boric acid glaze during the heating.
That worked extremely well, and kept the oxidation pitting to a minimum.
So off camera I made a similar tray for the pallets,
and then put them through the heat treating process.
Boiling water dissolves the hard glaze, and the pallets are ready for polishing.
And you'll notice that I'm not tempering the part at all prior to polishing.
It's recommended that escapement pallets are left glass hard,
to maximise their service life.
It's also important that the pallet faces in particular,
have a highly polished surface, to minimise friction with the escape wheel teeth.
So I put in a fair amount of time to get all surfaces to a high polish.
Starting with abrasive paper, and then finishing with diamantine powder
on both a wood polisher and tin lap.
All pallet surfaces now have the required finish,
and I used a fine oilstone to break the sharp corners, and leave a presentable edge.
So with the pallets complete, along with a small fastener that I turned up off camera,
I can fit them to the mechanism and see how they perform.
Manually moving the crutch assembly much like the pendulum will move it,
gives me a chance to slowly examine the action of the pallets,
and confirm that all is as it should be.
And here's a closer look at just how useful that eccentric bushing can be.
In this first shot you can see that the drop onto the entry pallet is quite significant,
certainly more than it should be, wasting a lot of energy.
But with a slight turn of the bushing,
the drop can easily be minimised to what it should be for maximum energy efficiency.
The escapement feels nice and slick.
In fact a light touch on the center wheel is enough to set the pallets off and running,
and the bushing can be further adjusted so that the teeth just pass the pallets.
So at this point its all looking good,
but of course the mechanism is going to need a source of energy for it to run,
and in this case that energy source is a coiled mainspring.
I've sourced some raw spring steel stock of the correct dimension,
that needs to be annealed at each end so that I can form some holes for the spring hooks.
Off camera I've made a couple of simple tools to help me do the next part of the job.
I've made a hole punch from a hardened dowel pin and a piece of scrap steel
that I'll use to make the first opening for the hook holes,
And I've made this rough tracing template to help me mark out the shape and position.
I used needle files take care of the inside perimeter of each of the hook holes,
and quick touch on the belt sander to shape the perimeter.
In addition to the holes for the hooks,
the outer end of the spring needs to have a slight bend
to accommodate the curve of the inside of the barrel,
and the inside end needs a tighter curve to wrap around the barrel arbor.
So with the key features of the mainspring in place,
I can coil it up and insert it into the barrel, using this mainspring winder.
The steel is loosely coiled, and then pinned onto the winder.
Continued turning of the handle pulls it into a tight coil.
If I gently unwind it, you can see that the steel now has the relaxed set
of a brand new mainspring.
And that natural set of the coils makes subsequent winding a more predictable exercise.
To enable the spring to be installed, the barrel must first be separated from the main wheel.
The spring is then wound up just enough to allow the barrel to be slipped over,
and then the barrel hook is engaged with the outer hole in the mainspring.
The tension can then be slowly released by reversing the winder,
and once all of the force has been removed, the spring can be unpinned.
With the mainspring installed, the barrel arbor was reinserted,
and then engaged with the other end of the mainspring,
A few drops of oil are enough to lubricate the coils,
and will be enough to eventually cover the entire length of the spring
as it's continually discharged and rewound.
So after 21 episodes of construction,
I now have all of the pieces required to assemble a functioning clock,
so its about time I set this thing running.
There's still a lot more to be done to get this project over the line.
But there can be no doubt,
this is a big moment in the life of the clock.
OK, now that its working, I can have a go at bringing the clock into beat.
This is the condition of the clock where the tick and the tock of the escapement
are equally spaced across the pendulum cycle.
The clamping force of the crutch assembly is such that whilst it grips the arbor tightly,
it can still be rotated slightly relative to the pallets,
permitting a simple beat adjustment.
A couple of carefully judged pushes, and the pallets and crutch
are now in the correct relative position to give a symmetrical beat.
And its difficult to describe just how sensitive the mechanism is.
Despite the mainspring being quite a handful to wind,
the clock gearing reduces that enourmous force
to a barely perceptible torque up at the escape wheel.
The slightest hint of excess friction in the mechanism,
is enough to overpower that force and stop the clock.
The subtlety of these forces, and the delicate adjustments required to balance them
is for me at least, the most surprising thing about clockmaking.
OK, so after a day and a half of continuous operation,
I've managed to get the clock running within a few seconds per day without too much trouble.
But of course I can't get too excited about that result.
Its not a long enough test period,
and its unlikely that the clock could maintain this performance long term,
particularly without temperature compensation or a fusee.
But its an encouraging start, and certainly a much better result than I expected.
I'll leave it running on test over the next few weeks,
while I work on the last remaining components of the build:
The stop work mechanism, a winding key,
and of course the final polish and assembly.
Thanks for watching.
I'll see you later.
And if you've just made your way into this clockmaking series,
thanks for checking it out.
This is just one episode of a longer series,
where I show all of the steps to make a mechanical clock from raw metal stock,
so be sure to check out those other videos.
If you enjoyed this video and would like to help me bring you more project videos like this one,
then consider becoming a Clickspring Patron.
As a patron of the channel you get access to exclusive Patron only video content,
free plans for the patron projects,
and the chance to win the actual project at the end of each build.
Like for example this useful little hand vise.
Find out more by visiting patreon.com/clickspring
And finally, if you're looking for some new projects for your lathe or mill,
then take a moment to visit clickspringprojects.com
where you'll find a range of plans available for download,
including plans for some of the tools I've made to help me construct this clock.
Thanks again for watching, I'll catch you on the next video