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mini 5×12 camera, part 1

April 2008

I really need a smaller, much smaller camera. Had a piece of decent cherry in the shop, started milling. Rough, oversize. Stickered for a week. Design all week. Worked out rough idea with CAD and cardboard silhouettes. Pretty effective in finding pivot points, brace lengths and extension. Need to decide on folding or non-folding WA design. I like the utility of Ebony’s non-folding models, but would miss the base tilt on both standards.

April 12-
Fabricating parts. Starting with back, to get as small as possible and still work with my existing holders. Looks like 8×15 will allow enough room for bellow pleats. Making rear box 8 x 15 x 1 1/2″. Still not sure of fold/non-fold design.
Had an idea for a reversing back. Use a platform of dovetail slides for the rear standard brackets to slide to the distinct widths needed for horizontal or vertical orientation. Will mock up some parts tomorrow.

April 13-
Using some aged rosewood for the dovetail platform. Very very hard and has a great strength/weight ratio. Cherry is a a bit too soft and I think the joints would round over and get sloppy with use. Might make final version in aluminum, but the rosewood seems quite rigid, the stuff seems to wear like iron.
I stop-slotted the platform for the brackets to slide in and out on either side. The knobs will tighten on a stud threaded through the rosewood slot into an aluminum plate that slide in a wide dado routed in the reverse side of the rosewood. The dado is mainly to let it slide easily once mounted on the rear extension carriage. I’ll have some aluminum flat stock on either side to reinforce the platform and be a bearing surface for the carriage.


dovetail slides for reversing rear standard

Needed to stop there, until I decide on an overall design. The carriage will need a rear focus-forward mechanism if I make it a folder with a large bed. On a non-folder, I’ll only need to slide the back forward enough to make it a compact and easy to store in the pack. Might just make a rigid rear standard with no base tilt, but I don’t like that idea- if you drop the bed there’s not enough center tilt on those to re-plumb the back before it interferes with inserting the film holder. Also running into dead-ends with the front- if the back switched to vertical I’ll need a bunch of front rise to get to the center of the back.

Bottom view of rear carriage. Side rails are bearing plates for rear shift and swing and also reinforce the dovetail platform. The shorter bearing plate rides in a shallow dado for clearance when finally mounted to the rear extension. When tightened down they provide the structural base for the rear standard brackets.

April 13-16
Back and forth on design, dead ends. Like a catch-22, can’t design the standards until the bed is thought-out, can’t design the bed until everything else is thought-out.
Trying some ideas for the telescoping front standard, nothing worth mentioning yet.
I did think of having a horizontal slot in the rear standard pivot bracket. That would let me side the back forward enough to store, and give some limited center tilt as well. So then I could just do a non-folder with base tilts on both standards. Unorthodox, but I like base tilt.
Played with some ideas for a short- really short- bed. I was thinking if the bed was only as long as my current cameras is wide it would still fit in my bag and be much lighter besides. I only need 14 inches of extension since I sold off my 450, and don’t really do any macro stuff with any lens longer than 250. Might be able to get 14-16 inches with a 4-stage extension on a 4 3/4″ bed. Single rear and triple front. I have some channel aluminum for plywood edges- the 1/4 and 3/8 stuff are well mated.

April 16
Made GG frame and back and front standard frame. Will cure under weight for 3 days until moisture levels re-stabilize. I had a back warp once out of the clamps due I think to the moisture from the glue and wiping the squeeze-out up with a wet rag. Not taking any chances.

*I need to THINK before just by default making everything small and thin. I made the GG frame so thin I almost don’t have enough thickness to put the ground glass in the same spot as the film in my film holder’s T-dimension. And I really don’t want to make new film holders. I also realize that I have no hope of making a folder because the front standard would have to be very short to allow it to fit inside when folded. Especially now that I made the rear platform so wide to accommodate the sliding dovetails. I guess I could make the bed longer than the rear box is tall, but doesn’t that sound awkward and ugly. No wonder I made the first one so big. It needs to be big to accommodate all the hardware. If I can’t work out an idea for a telescoping front standard I might shelve this project until I do.

rear standard and film back

April 17
Fixed the thin GG frame issue. Made a frame out of garolite to screw to the bottom of the gg frame to pad it out enough to let me recess the GG at least flush with the frame. I can live with that. I live to hack another day.

garolite shim for GG frame

Have the working idea of the bed. I’m forgoing the tongue and groove slides to save space and allow for the extra front extension. A top rail of 1/8 aluminum over the stationary rails will be plenty to hold down the extensions.
I might regret it but I’m milling slots just to keep things moving. Front and read base plates for shift, and rear sway braces and pivot brackets. I’m leaving the base plates and sway braces long and will cut when I sort out the exact pivot locations.

April 18
I have a working solution for the front standard. Well, close. The main front standard will be cherry, L-shaped in plan view to provide a bearing surface for the second stage of the standard which will be 1″ double-slotted 1/8 stock. One slot will lift a secondary standard into the vertical orientation range, and the second will allow fall and rise when in the horizontal range. The slots are close to the outside edges though, might not be strong enough. Might need to use 1 1/2 wide stuff. Also, the knobs might bump into each other when passing.

idea for telescoping front standard

Finishing up GG back. Making spring rails, aluminum housing and mandrel points. Need to order some more torsion springs.


Spring mechanism- aluminum housing with mandrels and spring arms for each side. A screw post is reversed back into the housing to leverage against the torsion spring on a mandrel- each assembly needs a left- and right-wound spring. The extra mandrel thread and screw heads are eventually filed flush. -Hard to see but the ends of the spring arms that mount to the gg frame have to be slotted a bit to allow the gg frame to lift high enough for holder insertion.

April 20-
Reworked front standard. Slotted the L cherry standard to relieve the aluminum a bit. That will help keep the knobs further apart so they don’t clip one another.
My arms are about to fall off from cranking the table on the mill back and forth! Still, beats filing those slots by hand, I remember those days too well.


Finished front standard. The knob on the telescoping stage also controls center tilt, and is mounted on a cherry spacer to clear the first stage.

Made a custom aluminum knob to tighten the rear shift and swing movement. Should hide well under the carriage with enough of an arm to stick out to tighten, and also have enough of a bearing plate to tighten the platforms securely.

April 21
All the plans and dimensions are in for the extensions and bed, so I can finally make that.
Using a breadboard deign for the base. Two solid bearing surfaces capping a thinner board in the center for the tripod mount. Running out of cherry. I boogered the first attempt- made the center part of the breadboard too short- forgot to add enough for the tenons.
Made bellows frames, cut aluminum stays for the recessed rear support. Gave light trap areas on wood parts and the stays a few coats of flat enamel.

April 22
Fitting up the base for rails and movements. Mortises in the pinions and shafts and dadoes the racks into the extensions. For the final front extension I milled slots in the 3/8 channel to for a tightening thread to engage a nut to ride in the recess there and tighten once extended.
Ordered knobs. Love the look of knurled stainless controls but they are heavy, and they are uncomfortable, especially in the cold. Any pricey. I got the Novogrip wing shaped knobs from Reid tool. Dirt cheap, light and comfortable to crank down on. Had to get a few stainless thumb-nuts and screws for several parts- not much other option in the 6/32 thread size.

Trying to keep this project under 100 bucks- I did have much of the materials on hand already, the gears and hardwood and most of the aluminum, but do need the knobs and some aluminum, lacquer, and incidentals. Should come in well under that.

Sanding and polishing parts, getting ready to spray. I’ll lacquer the aluminum as well, even though that’s not the best solution. I’ll try plating or anodizing some day. Very windy this week, spraying outside so need to wait for a calmer day.


bed fitted with spurs and shafts

bed racked in

bed at full extension

April 23, 2008
Lacquered all day. Thought I could work on the bellows in between coats but had to spray in light coats because it’s still pretty windy out.


 

(Part 2 here)