How to cut the groove?

BradS · Oct 20, 2004

Hi,
I'm building a 4x5 view camera and am presently working on the design of the back. I've built one prototype already and I'm stuck on how to cut the groove to match the raised feature on the film holder -- the one that runs the length of the short side about two millimeters in from the film window...any suggestions? How have others done it.

My back is made of wood.

wfwhitaker · Oct 20, 2004

(there was a url link here which no longer exists)

Loose Gravel · Oct 20, 2004

If you don't have the other features on the back yet, then it can be made as a saw cut. If you want or need to, you can cut it too big and then fill it back to size by molding the film holder into the groove. You don't want an exact fit, but snug.

I think, too, that I have cut this groove with an exacto knife or utility knife.

Another way to get a back is to buy an old camera and steal the back off. My first homebuilt had a graflex back on it. It had that nice little door and the springs, too. Made life much easier.

127 · Oct 20, 2004

I just cut the film window larger than it needs to be, so the top window lined up with the groove. Then I just used a jigsaw and widened the top 1mm of the window - the "groove" goes all the way through.

There's plenty of other light proofing, so it didn't really matter that the hole was a little larger than it needs to be.

Ian

BradS · Oct 20, 2004

Thanks all...

Thanks to everyone who graciously contributed. I had not thought of simply using a saw...should have been obvious.

On my prototype I ended up "building up" instead of "cutting out" -- but this is certainly not optimal as it adds another (albeit small) distance between the lens and film plane.

William, I looked at your previous answer (supplied in the link) to this question...photos are certainly helpful. I like the leaf springs too...

Thanks.

scootermm · Oct 21, 2004

I had to just recently remove the velvet light trap material on my empire state 8x10 I in turn had to cut the groove you are talking about into the back so it would better seal out light leaks. I used a dremel and a rounded point attachment and had a straight edge set up to keep it completely parrelel.
worked like a charm. I then got some velvet and replaced the material and was in business with no more light leaks.

barryjyoung · Aug 2, 2005

I use a 1/8 inch Marples Blue Chip chisel. Makes beautiful flat bottomed grooves. But they must be sharp enough to shave with. Careful now, shaving with a 1/8 inch wide chisel is very tedious business.

Calamity Jane · Aug 2, 2005

On both the cameras I have made this year I simply put a cut all the way across the back - a plywood blade in the table saw is a perfect match for the lip on a 4x5 holder. I then cut a sliver of wood and glue it in each end of the slot. If done carefully, it's almost invisible.

Murray@uptowngallery · Aug 9, 2005

Is the groove for light trapping only, or is it part of filmholder retention too?

noseoil · Aug 9, 2005

Easiest way is to use an 1/8" saw blade (table saw) and make the pass. This will make a larger than necessary groove. To get a good tight fit, usa a film holder and cover the raised light trap ridge with masking tape, a layer or two, and then use paste wax as a mold release on the tape. Do the same thing on top of the saw kerf, but don't trim for the groove until the wax has dried completely. Trim the tape with an exacto or razor knife to expose the groove from the saw cut. Mix a little bondo, apply it to the groove (just enough to fill it nearly full), press the holder in place and when the bondo goes off, remove the holder and peel the tape. You will have to sand gently, but a shot of balck spray paint and things will be snug, light tight and nice.

Second best is to use a saw blade which is the exact width, depth and profile, but I have yet to find one. tim

argus · Aug 9, 2005

Murray@uptowngallery said:
Is the groove for light trapping only, or is it part of filmholder retention too?

Both, but I can't tell you what is te most important one:
- the ridge will make sure that the filmholder sits at the appropriate place in the camera back, i.e. compared to the ground glass on which you compose the image.
- since a filmholder without the ridge feature an open end at the side you insert it in the camera back, it would be prone to light leaks, even with velvet light trap.

G

Joe Symchyshyn · Aug 9, 2005

What about a slot cutter in a router table with a fence?

joe

RichSBV · Aug 9, 2005

The router table w/fence is a perfect idea, but not witrh a slot cutter, which is essentially a saw blade with 2 or 4 teeth. And you'd need a horizontal table which very few people own.I would recommend a spiral bit with a downward cut. That keeps the edges from tearing up... Same thing can be done with a Dremel...

How to cut the groove?

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