Thanks! What you say makes a lot of sense. It looks like you used MDF for the septum, and lightened it by removing some material.
My own camera will be made with much less precision because I'll be using inexpensive shop tools. But as you said, the film holder needs to be precise, as does the ground glass holder. I got a few sheets of ruined 14x17 inch x-ray film today, and I can start building around them, and then outward from there.
Thanks again!
The septum is actually also Garolite XX, .125" thick. The beige color was cheaper than pure black. The machined concentric circles were an effort to relieve the stress in the material and flatten it out (the raw sheet had a slight bow to it).Originally Posted by Paul Kinzer
Good luck with your build.
Super job! Exceptional set with a lot of details looks just great!
Ah, I see now! Did the circles work?
As I've mentioned in another thread...this is so very breathtaking! I'd love to see it in person sometime!
I do have one question regarding your choice of dark slide material. In the photo of the film holder laid out flat...it looks as though the dark slide bows downwards, to the point where it looks like (to my eyes) like it actually makes contact with the septum. I'm guessing that if this is indeed the case, then it would only be a "problem" while loading/unloading films - in that there may be some potential for scratching an emulsion. Perhaps this is a non-issue, but if I were you I'd look very carefully at your processed negatives, and if you see axially located linear scratches, then maybe a very fine polish on the dark slides leading edges (maybe you've already don this?) would alleviate any tendency for such scratching, and if not, then perhaps you might think about using a thicker dark slide material. Then again...not all scratches actually show up on a print!
Actually it did take care of about 75% of the bow, and the straight and rigid walnut stiles did the rest.
The slide definitely does flex to the point of touching the septum. The leading edge there is rounded and sanded smooth to facilitate the entry into the bottom flap. I have not checked my negatives for faint scratches in that area, but surely will do so now. Thank you for the heads up.
A 1/16" thick dark slide would be a lot stiffer for sure, I just wasn't comfortable with it during the design phase and quite frankly, don't really regret my choice either. The squeaky folding mechanism and sagging bellows are infinity greater issues for me to worry about ;-)
Perhaps if you could find a way to carefully hold the middle of the slide above the film's surface as you close the slide?
For saggy bellows support, I'm wondering about those ringed tabs I often see on photos of the bellows on older LF cameras, especially those really long ones. Like those seen here. They are meant to have a rod slipped through them, like this (though the camera in that image doesn't seem to have the tab actually being used) in order to hold up the bellows. Something like a telescoping radio antenna would be ideal for the rod, though not really heavy-duty enough. A brass tube sliding within another would look nice, and I know my nearby hobby shop has brass tubes of varying diameter.
...actually, from Radii's photos, it looks like an elegant solution to bellows sag is already in place underneath the bellows (wondering about the fore-and-aft adjustability of this?)...although perhaps one location might not be enough for certain situations.
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