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.