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Thread: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

  1. #11
    8x20 8x10 John Jarosz's Avatar
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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    Having done it, making the leaf springs are the most difficult aspect of making the back. I got my material (Spring temper brass) from McMaster. That material works well but is very difficult to work. The other really tedious work of making a bellows I sidestepped by luckily finding a used one online. My 8x20 is not fine furniture. It's what I would call 'workman like'. Making fine furniture should be reserved for furniture.

  2. #12
    LF/ULF Carbon Printer Jim Fitzgerald's Avatar
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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    Michael, nice to see your steps for the build. I used the same methods when I built the 8 x 20 years ago. Having built 5 cameras now I have me head around it.....I think. Bellows are the only thing I have not tackled yet. One day maybe. When I retire later this year maybe I will try. I have some studio cameras that could use a new bellows so just need to find the material and give it a go. If I build another camera it may have to be for someone else and I have all of my formats covered. I even have two 14 x 17's! One for the studio and one for the field.
    I'll try to get the latest build photos of the 14 x 17 together and post them in a separate thread. May be of interest to some.

  3. #13

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    Thanks Jim--that would be great!

    I'll post some more pics of work in progress and finished backs later today...

  4. #14

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    Here are four pics of the 12x20 spring back I am working on. For this back, I used 1/4" cherry for the base layer. The 1/8" thick runners for the film holder, the 1/2" x 1/2" surround, and the 1/8" thick light trap on back are all basswood. No staining or flat black paint on back yet.

    Pic #4 shows the trap for the filmholder rib.
    Attached Thumbnails Attached Thumbnails 003 (600 x 450).jpg   005 (600 x 450).jpg   006 (600 x 450).jpg   007 (600 x 450).jpg  

  5. #15

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    These photos show a 7x11 back for an 8x10 camera. The back is made from 1/2" balsa wood covered in 1/32" mahogany.

    I'm terrible at fabricating metal, so don't look at the springs. I plan to replace them with real brass springs scavenged from orphan vintage parts....

    The view screen is 1/16" acrylic covered on the inside with translucent film.
    Attached Thumbnails Attached Thumbnails 010 (450 x 600).jpg   009 (600 x 450).jpg   011 (600 x 450).jpg   012 (600 x 450).jpg  

  6. #16

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    These photos show a 5x7 back I am making to replace the back on a vintage camera. The base is two layers of 1/8" basswood. The top layer is 1/32" mahogany.

    Unfortunately, I've decided the stain is too light to match the camera, so I plan to sand off the poly finish and do a darker stain.

    I'll talk about gg frames and post some related pics next.
    Attached Thumbnails Attached Thumbnails 013 (600 x 450).jpg   017 (600 x 450).jpg   015 (600 x 450).jpg   016 (600 x 450).jpg  

  7. #17

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    The 5x7 extension back for my 4x5 Nagaoka is a work of art, but any lens longer than a 210mm casts a shadow and reduces it to 5x6.5" (like Paul Strand). The whole thing only weighs 3# 4 oz.
    Wilhelm (Sarasota)

  8. #18

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    Bill, what you need is a spacer between the camera and the 5x7 back; like this: http://www.largeformatphotography.in...7x11+expansion

    If you add a 1-2" spacer, you should be able to focus a 300mm lens w/o any vignetting.

    Michael

  9. #19

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    Love this thread! I need to fashion an adapter to attach my Graflex 8x10 FP shutter to my V8. I think I have the dimensions down, but really basic questions: where would I go in the US to buy the right wood for these? Also, where can I get the pins and the spring lock to keep the back in place? Thanks!

  10. #20

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    Re: fabricating wooden camera backs, reducing backs, expansion and enlarging backs

    A couple of hints: You can make bends in spring steel by carefully applying heat to those areas. Solid cobalt drills can do holes in most spring steel, but you may want to use a bit of cutting fluid for this.

    When you glue up the back "frame" (and ground glass frame) - don't just clamp the joints to themselves, but clamp the entire assembly to a surface of known flatness. Then, to ensure tight joint seals, mix some black pigment with epoxy. Loctite also makes some black glue which I used awhile ago, but I forget what it is called. Come to think of it, Loctite makes some pretty amazing adhesives!

    Make sure to measure for just a bit of space between the edges of your film holders and the frame into which they will slide - to allow for variances in film holder external dimensions and slight changes in the frame itself due to expansion/contraction.

    The most critical measurement in film back assembly is that between the surfaces of the film holder runners and the surfaces of the ground glass frame upon which the "ground" portion of the glass will rest (you will need to modify this if you place a fresnel lens on the lens-side of the ground glass, with the fresnel rings contacting the ground glass - I can help you with this, or contact Bill Maxwell). To get this measurement, load an assortment of your favorite film holders (of known flatness) with your favorite types of film, place a straightedge across the holder apertures with dark slides removed, and using the depth gage of a caliper, measure down from this straightedge to the surfaces of the films in different locations (five measurements each along centerlines, one third to edges, and near edges). Note if the films need to be pressed downward to make contact with the inside plates of the holders, and back off from this just a bit. Do all of this and take averages from all of your data to get an accurate reading. I've found this method to be more reliable than using the "established standard measurements."

    When determining ground glass frame spring tension, make sure to do this with the ground glass frame hanging downwards, to make sure that the force of gravity does not overcome this tension. Actually things should be a bit tighter than this to account for what will be a slight weakening of these springs over time, but not so tight that when a holder is inserted you risk moving the camera and/or its set adjustments. If you don't go with a "pickup bail" design for lifting the ground glass frame, you should at least consider beveling and polishing the underside of the ground glass frame on the loading side, to facilitate smooth insertion/removal of holders. You can also cut some air relief channels into part of this surface - but you only really need to consider this if your ground glass does not feature cut corners. Otherwise, these corner cuts do a good job of letting the air in and out of the bellows as you change focus.

    You may want to very slightly bevel the bottom edges of the ground glass frame - to minimize the possibility of these edges catching on the upper edges of the larger frame in which this sits when in the focussing position.

    At any rate, just a few hints, and remember that none of this is rocket science. Good luck!

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