G'day Chris here, and welcome back to Clickspring.
In this video, I make the sub assembly that
will show the time;
the motion work and hands.
This episode is quite a bit longer than usual,
and part of the reason is that there's a whole
lot of parts
that go into making this sub assembly.
It's essentially a reduction gear train,
that takes the single hourly rotation of the
center arbor,
and reduces that by a factor of 12, so that
the hour hand sweeps
one full revolution for every 12 hours.
Its a beautifully compact design, that uses
concentric sliding fits to great effect.
The pinions and wheels for this part of the
mechanism
were cut at the same time as I made episode 4,
but of course the wheels still need to be
crossed out,
so I'll do that later in this video
For the other parts, I'll be using these sections
of rod stock,
as well as some gound flat stock for the hands.
So lets get started.
The order in which I make the parts is reasonably
important for this part of the build,
because there are some quite close tolerances
required to make all of it work.
I'll need to have some of the parts completed
before I start working on others,
so that I can do some test fitting.
Essentially, I need to start from the outside
of the mechanism and work in,
which means the first parts to be made are
the hands.
A simple paper template marks out the perimeter
of the part,
as well as the hole positions.
I drilled out the holes slightly undersized,
so that I could use a reamer to get the precise
final dimension.
The hands were then roughed out from the parent
stock using the scroll saw.
The finger plate tool is perfect for safely
holding these awkward small parts,
and I used the belt sander to bring the edges
closer to the line.
And I should mention that this 1" belt sander
is an amazingly effective tool for quickly
and accurately removing metal.
Its easily one of the most useful machines
in my shop.
As usual, I've left a small amount of metal
outside the line,
so that I can bring the parts to final dimension
using needle and escapement files.
At this stage the profile is pretty much where
I want it,
so I used a light solvent to remove the paper
templates,
and then began preparing the parts for final
bluing.
Now I've had a lot of requests for more information
on the bluing process,
so I've used these hands as an opportunity
to make a full separate video on the subject
Click on the link if you'd like to watch that
video.
Next up is the minute hand collet,
which is a small flanged part with a square
hole in the center
for mounting on the minute pipe.
For the most part its a straight forward turning
job, to form the stepped profile.
Although one edge has a contoured shape that
provides a
great excuse for some hand turning with a
graver.
With the profile formed, the center was drilled
out,
and then it was parted off and flipped end
for end,
to turn a seating for the minute hand.
The tricky bit to form of course is that square
hole,
which needs to be dead on center, as well
as perfectly square.
Now a rotary broach would work well if I had
one,
or perhaps I could use files like I did for
the ratchet wheel,
but instead I'll be using this arbor press
and a custom made push through broach.
The center hole I drilled a moment ago is
a close fit for the pilot diameter of the broach,
and this ensures that the cut is on the axis
of the part.
With a generous coating of cutting fluid,
the arbor press is used to push the broach
through.
The result is a well positioned and dimensioned
square hole ,
with an excellent surface finish.
Click on the link if you'd like to see the
video showing how I made that square broach
Another small part required for the minute
hand is this little end cap;
again a straight forward piece of turning,
and an even better excuse to bring out an
assortment of gravers
to form the curved profile.
As for the previous part, the center was drilled
out;
although this time a little undersize, to
permit the use of a shop made reamer.
And that completes the 2 parts required for
the minute hand.
Next up is the Hour wheel pipe,
which is a sort of sleeve that carries the
hour hand on one end,
and the hour wheel on the other.
It needs to be a close sliding fit on what's
called the minute pipe,
the bit on the inside that slips over the
center arbor.
The hour hand fits on the end with an interference
fit on a short taper,
and I'm forming that taper manually using
a needle file.
Once the fit with the hour hand is confirmed,
the center can be drilled out, and then reamed
to the required dimension.
Next the part needs to be reversed so that
the wheel seating can be turned,
but often when using ER collets to hold short
parts like this,
it's difficult to get the collet to hold the
part accurately.
There's just not enough inside the collet,
and as it closes down it distorts and throws
the part off center.
I find one way to get around the problem,
is to push a small scrap of the same size
into the rear of the collet,
and then put the part in as normal.
The collet grips as if its holding a continuous
part down its center,
and gives the accuracy you expect.
The seating for the hour wheel was then turned,
so that just like the hour hand, its simply
held in place with an easy interference fit.
Now I may eventually choose to permanently
bond these parts in place,
but for now I'll leave them as is, so that
I can still disassemble them in the future.
OK, now for the minute Pipe.
And its a complex little part, that's designed
to be gently squeezed in the middle,
so that it grips onto the centre arbor.
It carries the minute wheel on one end,
and has a square to receive the minute hand
on the other.
The first job is to drill out the stock and
then ream it to be a close fit on the center arbor.
Next the profile was formed,
and the dimensions marked out for the next
operation,
with a bit of tailstock support to keep the
stock from deflecting.
The part was then transferred to the mill
to form the end square,
and remove the material from the middle.
Back to the lathe to part off, and then the
seating for the minute wheel was turned;
again aiming for an easy interference fit,
so that the wheel can still be removed if required.
A quick tidy up with needle files, and that's
the minute pipe complete.
Next up is the Intermediate wheel stud.
It screws into the front plate beneath the
center arbor,
and carries the intermediate wheel and pinion.
So it needs a thread on one end, and a nice
smooth arbor surface on the other.
I'm forming this from a length of square o1
tool steel,
so that it can be hardened and polished later.
Although I'm leaving it annealed until I've
had a chance to get a look at it in place,
and decide if I need to make any small adjustments.
I'm also leaving the arbor section a little
over length for the same reason;
I'll reduce that to the final length, once
I've put in the cross hole for the clock pin.
The wheels need to be crossed out,
and as for all of the previous wheels,
I'm using this jig to mark out the crossings.
The scroll saw was used to remove the bulk
of the waste stock,
and then I used the bench filing machine to
further clean up the cut,
in preparation for final finishing.
The final finishing was completed with needle
and escapement files,
followed by a light papering with fine grit
abrasive paper,
and then a uniform burnish of all of the inside
surfaces.
A light paper and polish brings up the other
surfaces,
and the motion work wheels are ready for assembly.
OK, so that completes most of the machining,
and some of the parts can now be pressed into
place on their respective seatings.
Next I need to depth the position of the intermediate
wheel stud,
so it can be fitted to the front plate.
And as for the wheel of the going train,
I'm using the depthing tool to do the job.
The fine adjustment screw moves the wheels
closer together,
until I can see and feel the smoothest meshing
of the teeth.
I'll be using tapered clock pins to secure
the mechanism in place,
so I can put in a cross hole for the pin now,
and also tidy up the end of the arbor.
I put in a similar hole for the intermediate
stud,
and then hardened, tempered and polished it.
So finally, after a whole lot of work, let's
put all of this together,
and see how it runs.
In the next video I'll make a start on the
pendulum.
Thanks for watching, I'll see you later.
And if you've just found 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'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.
And finally if you'd like to help me make
more of these videos,
then one of the best ways you can do that
is by becoming a Clickspring Patron.
Visit Patreon.com/clickspring for more information.
Thanks again for watching, I'll catch you
on the next video.
