G'day Chris here, and welcome back to Clickspring.
In this video, I go through the process of making a set of screws to fasten the chapter ring to the inside of the bezel.
My main priority with these screws is to make them look unobtrusive as they do the job of holding the chapter ring in place.
They don't have to deal with a great deal of load,
so a simple overhang of the screw-head should be enough to do the job.
But to make them look consistent with the bezel, I'm keeping the profile quite slim.
There's also not a lot of depth in the bezel to drill and tap, so I need to keep the thread quite short too.
So lets get started
The first step was to turn the basic profile of the screw.
Next I formed the thread, and it was these bezel screws, as well as the other screws
for this clock that motivated me to make the tailstock die holder for my Sherline lathe.
Click on the link if you'd like to watch the videos showing how that tool was made.
The die holder keeps the die both on centerline, and square with the work,
making it much easier to consistently form a true thread.
The ends of the screws need to be reduced a little in length, and then domed,
which is another great excuse to bring out the t-test and do a little hand turning.
With the thread complete, the next job is to form the screwdriver slot.
The work was parted off a little over length, and then re-chucked the other way around.
Now in a previous video I formed the screwdriver slots using a slitting saw on the mill,
so in this video I thought I'd do it by hand, using some fine cut files.
of screws like this, I think it might even be quicker to do it this way, rather than
For a small number to set everything up on the mill.
With the screwdriver slot formed, the head can now be trimmed to length,
and I can get the screw prepared for heat treating.
One of the things I that I'd like to avoid is the build up of black scale that usually occurs during the heat treating process.
So I'm enclosing the screws inside this small wire basket,
and then coating them in a mix of boric acid and denatured alcohol.
The boric acid forms a protective coating over the metal and reduces the oxidation to a minimum.
Once the screws have been quenched, that coating can be either chipped off,
or simply washed off with boiling water.
Now the screws need to be tempered before I start the polishing.
Which means I need a fresh metal surface to monitor the color change,
so I took care of that on the lathe using this tailstock polishing tool.
The temper color I'm aiming for is blue, but at this stage, I'm not overly concerned about the quality of the color.
I'll put a better quality blue on the surface as the last step,
after the screw has been polished.
OK , now for the part that certainly takes me the most time - the polishing.
The screw was re-chucked by its head.
And of course initially its running well off center.
But I just love this attibute that lathes have. That with just a gentle touch, a part can be set to run true.
Its so effective, yet beautifully low tech.
I started polishing with oilstone paste on a piece of sharpened pegwood.
A quick clean off with some paraffin, and then I followed up with some of this extra fine diamantine, also on pegwood
The screw was then reversed, and the same process used on the top face.
And again I'm using the circular lap, to make sure I grind the face flat with crisp corners.
I'm starting with oilstone paste on an mild steel lap.
And then I followed up with diamantine on a tin lap for the final polish.
The edge of the screw was treated in a similar way, first with emery paper, followed by diamantine on a brass polisher.
I also brightened up the screwdriver slot with diamantine,
and then gave the edges a very light bevel with a triangular shaped slipstone.
So with all of the surfaces polished, the final step is to give the screw a nice blued appearance.
As before I'm using a butane torch and brass shavings,
but this time I'm being a lot more careful about how the color turns out.
The screw surface is as clean as I can get it, and I'm keeping an eye out for any parts that change color too rapidly.
And that's the bezel screws complete.
The bezel will need to have some pillars turned and then fitted at a later stage,
to enable it to be connected to the frame of the clock,
but I'm going to leave that until later in the build.
In the next video, I make a start on assembling the wheel work.
Thanks for watching, I'll see you later.
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Thanks again for watching, I'll catch you on the next video.