The axle is friction fit into the roughed-out knob then
installed in the chuck mounted on the lathe while the live center is installed in
the lath’s tale stock. In the photo
below you can just see the cone peeking out from the end of the knob and the
hole in the live center.
Here you can see how they come together. The cone inserted into the live center will
keep the knob centered and provide support while I finish turning it. Some reference lines have been added to the
knob. The dotted line on the left is the
depth of the axle hole, the next line is the shoulder of the side and the
far-right line is the final length of the knob.
In this photo the turning is almost done with just a tiny
bit of the cone remaining attached.
Going forward it gets cut away the tailstock pulled back and the final
sanding done.
The last bit of turning is to add three friction burned
grooves. Below on the far right is the
pencil line where a groove goes. The
center shows where an awl has been used to score a fine line while the far left
shows the finished friction burned groove.
To burn the groove a fine wire is pressed into the scored line while the
lathe is running at a fairly high speed and it literally burns the groove.
Here you can see how the knob assembly and the film
take-up spool goes into the dry fit camera body. Now all I need to do is exactly duplicate the
second knob.
Making one knob was not to hard but making a duplicate is
quite a bit more challenging. The
turning is no harder but making them both look the same certainly increases the
difficulty. Anyway, here is the pair.
After both were finished it occurred to me that I needed
to add a reference mark on them that can be used when winding the film so it’s
easy to see how far the knob has been turned.
It’s a simple drilled spot that gets blackened with a permanent marker. The knob is set in a cradle that holds it so
the drill is aligned with its center line.
Next is to fit the steel washer up into the underside of
the knob. In a perfect world I would
just go get a 1” diameter washer that has a 5/16” center hole. Unfortunately, that combination was not to be
found. What I did find was a 1” diameter
washer 1/16” thick with a 3/16” diameter hole.
The fix is to drill the existing hole out to the required 5/16” but
that’s not as easy as it sounds because when drilling through 1/16” thick steel it’s almost guaranteed that
the bit will catch, rip the washer out of your hands and leave a nasty looking
set of burrs. It won’t do your finger
any good either. That can be fixed by
hand filing but trying to keep the hole perfectly round is a pain. An alternate is to grab the washer with a set
of vice grips but its jaws will mess up the washer’s finish. My alternate method is to make a small wood
jig that holds the washer securely in place.
That’s shown below along with a before and after washer. The jig itself consists of two pieces, one of
which has a shallow 1” diameter recess for registration.
The other has a hole that lines up with the center of the washer and a
couple of screws that go into the first block.
When the screws are really tightened down the washer is
captured between the blocks holding it in place ready for the drill to enlarge
the hole. This photo shows the setup
clamped to the drill press fence. With
this setup I don’t really need to hold the jig in place. Having my fingers away from the jig in case
there is a catch makes me more comfortable.
Now that all the pieces are done for the knobs I will set
them aside and start on the film box.
That’s the piece in black below.
It is sized for the typical 24 x 35 mm image. If all goes well, I may make second one for a
wide-angle panorama image. A channel cut
into it will be where the film rides during the exposure and the edges will
cutoff the light from getting to the rest of the film.
The box starts by ripping material close to the finished
width on the table saw then to rough thickness on the bandsaw. That’s followed by running it through the
thickness sander to get the three different thicknesses needed. Here the final two blanks are coming out of
the sander.
After that the blanks are cut to final width on the table
saw. To cut them to final length a stop
is set on the chop saw for repeatable results.
Here is the top piece of the film box. As you can see the caliper reads out 35
millimeters. It’s nice to have a caliper that
can switch between millimeters, fractions or ten thousandths of an inch. This also gives a closer shot of the stop
setup on the chop saw. There are three
layers. The bottom is a scrap that’s
been cut so its right edge is flush with the blades cut. Next is a thin layer that acts as a spacer so
there is a free space that keeps sawdust from getting trapped against the
length stop which is the larger oak piece.
Without the thin spacer sawdust could get trapped against its face and
the cut piece would be too short.
This is the stack of pieces for the film box plus some
extras in case I mess things up along the way.
Once the stop block is set on the chop saw it’s easy to cut another
piece rather than taking the time to reset it up later. If you look at the drawing you can see the
channel that I will be cutting later. It
would be nice if it was centered top to bottom but that’s not the way it worked
out.
Now at last I can start gluing pieces together. The film box is glued up in two steps so I
can take my time and get the pieces aligned perfectly. This photo shows the first step where each
half is glued up. The cam clamps being
used to hold them together are ones I just finished making. If interested you can see how they were made
under Cam Clamps.
After the two halves glue are cured they can be assembled
into the final sub-assembly.
Next Up – Body Sub-assembly, Assembling the Film Boxes,
Milling the Front & Back
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