G'day Chris here, and welcome back to Clickspring.
In this video, I depth and plant the train of the clock.
Planting the gear train is a big milestone in the clock build.
Up until now I've been constructing mostly separate parts, but for the first time the
wheels will be positioned and rotating in their final locations within the frames.
Before I can get onto that task though,
I need to finish off a few parts of the build that I skipped previously.
One is the task of fixing the great wheel to the barrel,
and the other is the insertion of the barrel hook.
A common way to make this hook is to use a screw,
cut off the end, and then contour the inside.
The features of the screw are as you'd expect,
although a slight difference is that I've turned off the threads at the end,
to make it a little more convenient to insert it from within the barrel.
I drilled and tapped the barrel, and after forming a screwdriver slot,
the hook was ready to be put in place.
The tool I'm using to insert it is a right angled screwdriver,
click the link if you'd like to see the video showing how this was made.
The insert is nice and secure in the barrel, and I can now trim off that end and give it
a file and light rivet to further secure it in place.
I took the barest of whisper cuts on the lathe to trim off what remained after the riveting,
and I used some emery paper to help blend the surface in with the barrel exterior.
And finally I completed the barrel hook by using a grindstone,
to trim and contour the inside face of the insert.
So with the hook complete, I moved on to fitting the great wheel to the barrel.
And for the most part its fitted in much the same way
as the other wheels were fitted to their collets in the previous video.
First off, the hole positions were marked out on the wheel.
Then I drilled a tapped a single hole, and used a commercial screw
to keep everything fixed in place, while I drilled out the other 3 hole positions.
I also put in a pair of register pins to ensure that the wheel can only go on the one way
when it is re-assembled after servicing in the future.
After the pins were inserted, I trimmed them back to stop them protrude into the barrel
and connecting with the mainspring, and then chamfered the edges with this chamfering tool.
A quick touch with a file and some emery paper,
and that upper surface of the pins has blended nicely into the surrounding metal of the wheel.
And then to complete this part of the build, I turned up a set of custom screws,
polished and blued them, and then used them to fasten the great wheel in place.
Ok so after all of that catch up, lets now move onto the main focus of this video,
which is getting the gear train into place.
Now "Depthing" and "Planting" are the terms clockmakers use to describe the process
of correctly positioning the gears relative to each other within the mechanism.
There are some specialist tools required to get a good result,
and one of those is this depthing tool I made in a previous video.
A wheel and pinion pair are positioned on the tool,
and the correct operating distance apart is determined by observing how well the gears mesh.
The center distance is slowly varied, using the fine adjustment screw,
and after each change, the meshing of the gears is assessed.
Once the perfect distance is established, that dimension is transferred to the frames,
using the points on the other side of the tool.
Now it's most common to see the central arbor as the starting point for this process,
but in this clock the the third and escape wheels are the starting point,
because the design of the frames means there's really only one place they can go,
so I started with those two wheels first, and lightly marked the top plate.
Next I made a start on forming the pivot holes.
A small pilot hole establishes the position, and also removes some of the waste stock.
Then an oil sink is put on the outside end of each hole, starting with a standard twist drill,
and then following with one of these roller cutters.
but it's worth noting that at this point the hole is well under the size required to let
the pivot pass into the frame.
The rest of the hole is formed by hand using these tapered clockmakers broaches.
Now you might be wondering about the need to form tapered pivot holes;
why doesn't a standard straight hole do the job?
And the reason is that compared to general engineering, clocks need a lot of free play at the pivots.
Mostly this is so that they can deal with the angular misalignment caused by flex in the plates,
wear, or even a bent pivot, but it also helps them cope with dirt and oil
gumming up the pivot holes over time.
A straight pivot in a straight hole that experiences misalignment or contamination might bind,
and stop the clock.
A tapered hole though, combined with some side clearance,
gives a pivot the necessary angular freedom to cope with quite a lot, and continue to rotate.
Many clockmakers use a rule of thumb, that says
if the arbor can tilt about 5 degrees off its axis all around the hole,
then the pivot hole has the required freedom, so that's what I'm aiming for here.
Once it looked about right, I gave it a test it in the frames to see how it ran.
It's coasting gently to a stop, and there's a nice click as the frames are tilted from side to side.
That click is an indication of what clockmakers call end shake,
another required clearance between the arbor shoulders and the plates.
Now each of the wheels was depthed and then the arbors let into the frame in a similar way,
although there were some slight differences in each case.
The center wheel was depthed as before,
but in this case a trumpet runner used to mark off the dimension from the existing pivot hole.
The actual broaching is as simple as twisting the broach in the hole until it reaches the required clearance,
whilst taking care to keep the broach vertical to the plate.
It is easy to remove too much metal though, so I took it nice and slow.
The last arbor to be let into the frames was the barrel arbor,
again using the trumpet runner to offset the distance.
All of the twist drills I use on this clock have been modified to make them suitable for drilling brass.
Click on the link if you'd like to see a video about that.
But even with that drill modification, this hole is at the upper end of what I'm comfortable
with holding the workpiece as I drill.
I really don't want any mistakes this late in the game, so I'm not taking any chances,
instead I've got the plates strapped down nice and firm to the table,
and I'm picking up that hole location with a wiggler.
And now that I'm dealing with the larger holes, I can show you a bit more of the detail of the broaching.
You can see the cutting broach cuts long flaky chips from the interior of the hole.
When the arbor will just enter, the smoothing broach is used.
Its surface must first be given an fine grain either with some emery,
or in this case a diamond lap.
The smoothing broach does remove a small amount of metal,
but its main job is to distort and work harden the surface,
to leave a hard burnished bearing surface for the arbor to rotate in.
These particular pivots only rotate when the clock is being wound,
so in this case I'm aiming for a fairly snug fit in the plates.
And before I put everything together, the plates themselves need a bit of a tidy up,
the thick end of the register pins will be getting in the way from here on,
so they need to be trimmed back flush with the surrounding metal.
I also bonded the pinions in place with loctite 603,
washing the excess off with a some lighter fluid.
So with most of the parts from the previous 12 videos on the bench,
its time to put it all together, and see what we've got.
After so much time and effort, It feels great to see the structure of the clock finally starting to emerge.
With the lightest of pressure on the great wheel, and the whole gear train starts to rotate.
In the next video I'll make the ratchet click, as well as the channel namesake, the Clickspring.
Thanks for watching, I'll see you later.
If you've just found you're 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 stock,
so be sure to check out those other videos.
I also post project videos on making some of the tools I need to build the clock,
and you can also find some more toolmaking info on the clickspring projects website.
Thanks again for watching, I'll catch you on the next video.