Vincent's Film Slitters

Pictures presented in stereo are for parallel eye viewing.
Minox Film Slitter
This slitter allows the slitting of 35mm film into two rows of 9.3mm wide film for minox cameras.
(actually, the two rows produce four to six rolls of film)
This design is similar to the many designs on the web that use razor and like blades.
However, by slitting in a light tight box, the film can be slit in daylight.  The film is then rewound into the
the 35mm cassette for latter loading into Minox cassettes.  I used a plastic camera
I pick-up at a garage sale for $5 as the base for the slitter.  This provides a cheap
light tight box as well as the film transport mechanism.
Front view of the camera.  Notice the beefy film wind crank I added.  (aluminum
with African Rosewood knob)  Slitting film requires alot of PULL!
 
Side view of the slitter.  I built a wooden box to enclose the knife blades from
light leaks into the film chamber.  (oak actually, sealed to the camera
with lots of RTV silicone)  The knob at the back allows the knives to move back and
forth into (or out) of the film plane.
 
Here's an assembly view.  The blades are mounted on a pair of UHMW plastic blocks,
which can slide back and forth on pins.
 
Four brass pins are screwed into two aluminum blocks glued onto the back of
the camera.  These four pins fit into four holes in the blade block.
 
Three craft (or safety) blades are used to cut the film.  These blades are much
stiffer than standard razor blades, and thus can permit closer tolerances.
Two UHMW polyethelyne blocks provide the proper spacing and allow easy
sliding of the blocks on the pins.
 
Here's the rear door of the knife box with the draw bolt attached.  The draw bolt
is used to move the blades back and forth into the film.  Notice the
felt along the lip to light seal the box.
 
There are a few modifications to the camera.  A large square hole was cut into the
rear door of the camera to allow the blades to pass through.  A stronger crank
and shaft (shiny brass) can be seen passing through the film take-up reel.  As well,
a piece of matte board has been placed in the lens cavity.  The tips of the
blades press into the board, keeping them from wavering.  It also prevents the
film from being pushed into the lens cavity.
 
Here's the original film pressure plate.  Because its plastic, I easily machined
three slots for the blades to pass through.  The pressure plate ensure that the
film is flat while being slit.
Final Notes:
My first design actually had the blade block bolted directly into the back of the camera.
However, as the film is drawn backwards into the 35mm film cassette after slitting, the back of
the blades would still cut, leaving shavings in the camera.  Thus I devised the draw bolt to move
the blades in and out of the film plane.
 
Punching the "Keyhole"
Some people have asked how I punch the "keyhole" shape onto the end of a minox film roll  so that it may be attached to a minox tank reel.  I use two different punches, in a wood base to stamp a "figure-8" shape onto the film.  Slots in the wood make sure that I punch the holes in the correct location.
Here's a close up of the resulting film.
The figure 8 allows the film to be "locked" onto the peg at the bottom of a minox film tank.
 
Results:
Here's a "contact" sheet of a strip of negs.  (I acutally project the negs.)
Notice how close the image comes to the edge of the film.
 
A stereo picture using the minox with the cha-cha method.
 
 
 
127 Film Slitter
This slitter cuts down a roll of 120 film for use in cameras using the old 127 film size.
I can actually get 12 shots instead of the usual 10, if the camera has enough space to fit
the resulting fatter roll.
I used an old Kodak Bownie camera.  It's really designed for 620 film, but with a few
modifications, you can fit a 120 film roll into it.  (I can still use it as a camera
if I take out the blades.)
 
Here's a rear view.  Notice the matte board pads that the knives press into.  These
pads are light sealed onto the camera with big gobs of RTV silicone.
 
Two razor blades are bolted to an aluminum block, machined to the correct
width.  The block itself is the bolted onto a cross member, which is bolted
to the side of the camera.  (the two shiny bolt heads visible)
 
Two square holes cut into the back, for pads which are used to hold the knives
steady.  (I used regular razor blades, which can wiggle side to side while cutting
if not held)
 
Notice the brass pins that I installed in place of the small chrome ones.  Due to the
larger hole in the middle of a 120 roll, the smaller 620 pins get jammed.
 
The 127 film width is actually narrower than the paper backing.  However, as the film must
eventually fit into my developing tank reel, I cut both the film and paper, at the same time, to
the film width (about 1.8").  This results in the film roll being shorther than the film reel,
allowing fogging along the edges.  A little care in loading, and keeping the film in the dark until use
helps to minimise the amount of fogging.
 
Here is the resulting 127 negative, taken with a Coronet Stereo camera, in
downtown Toronto.
(f11, meniscus lenses)
 
Close-up of the light leak along the edges.
 
As the film is cut along both sides, the numbers still appear in the middle
of the paper backing.  Thus the little red window can still be used to
help advance the film.
 
 
 
 
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