Rear Standard box joints
The creative slump continues. Rather than waste gas and film, I thought I would make some improvements on the 5×12>5×7 conversion I made last year. Except I’d really rather just start over.
I like much about the 5×7 conversion. Well- no; it’s heavy, the back design is among the worst I’ve made or seen, and the movement hardware is bulky and heavy without being especially rigid. But I do like the bellows- I’ll keep the bellows. Actually if I had more thin bellows cloth I’d redo the bellows, but I don’t so I like the bellows. Actually, I just remembered that I ordered some Deardorff bellows cloth. Whatever. I wasn’t sure if I would like the format before I made it, so I didn’t spend a lot of time or effort on it.
I’ve actually been kicking ideas around for a few weeks. Not much inspiration to speak of. So I started to mill some wood to rough dimensions. Maybe I’ll think better when I’m working in the shop instead of sitting in front of a CAD program.
CAD doodles. Planning pivot points for folding, general stock dimensions, gear placement, movements; swings, tilts and shifts. I still can’t decide if I want it to be light, or capable. I like the simplicity of single point lock downs in build and use, but they tend to be less rigid unless you use massive base plates for the standards’ turntables. The rear turntable has a separate stage for shift and swing, but it will be fussy to implement. Since I have a working camera, I might take my time making this one. I don’t have a lot of time to work on it since I’ve been working 50-60 hours weeks at work, but hope I can string together at least a few hours each weekend to work on it.
March 9th- Some lumber left over from projects that never materialized. Peruvian Walnut, Honduran Mahogany, Santos Mahogany. I’m a bit burned-out on mahogany, and and not a fan of exotics in general. I’d rather just use cherry, but didn’t feel up to the 3 hour round trip to Edensaw in Port Townsend, so used the walnut. Interesting wood, it seems like a genetic blend of mahogany and black walnut.
Freshly milled to general dimensions. 4 board feet of 4/4 walnut goes fast. It’s different from domestic walnut, not as hard but also not as heavy, which is a plus. It’s very stable and similar to mahogany in grain structure. There is a sort of an sickly purple cast to the freshly milled surfaces that will warm and darken considerably on exposure, judging from the appearance of the seasoned board I milled it from. Everything ripped fairly straight and true, no hidden tensions. Anyway, pretty much all the wooden parts are represented here (that’s the nice thing about a general CAD plan- cut lists are easy to generate and double check). Back, GG frame, rear standard, breadboard base parts, guides and rails, and front standard. I like to use a ‘granite’ slab as an inspection table of sorts, to see how flat part and assemblies are.
The bed of the camera will be bread-board style. A solid 3/8″ plank the length of the bed joined perpendicularly to 5×8″ stock with tongue & groove joints that the rails will ride on. Above- after edge joining the two boards, the are stacked together on edge and sighted down to insure they will glue up flat and true.
March 10th- I had a mental meltdown and trimmed the panel in the wrong direction, then not catching that screw-up, set up the router and milled the tongue in the direction of the grain, so that he load axis runs down the center of the board, directly on the glue joint. I actually almost glued it up before I realized what I’d done. So much for thinking better in action.
I was worried the walnut would chip out a lot cutting box joints, so I clamped the pieces face to face, and made a new box joint jig so there would be a fresh zero-clearance cut around the blade. I like using a table saw and sled instead of a router- I don’t like routers very much and avoid them whenever possible. A flat-top grind saw blade make a nice clean square cut. The joint is super-strong and it looks like it took all day to make, but it really only takes about five minutes to cut. Glue-up, however is a bit stressful with all the tiny joints to coat. Especially with open grained woods- the glue squeeze out is a bitch to get out of the pores, so I mask off the pieces before gluing them. A scrap of plywood is cut to the ID of the standard to make sure it stays square during glue-up.
I like using a lamination method to make the ground glass back. Re-sawn parts are planed to 1/8″, and the frame is built in layers. I started doing this when I made my first camera and wasn’t sure how thick the back would need to be and have since stayed in the habit. Also, it’s a little easier to arrange the parts so tensions counter each other, if needed. And it also makes milling slots and inside rabbets in the separate layers a little easier. And, even after 5 1/2 cameras, I’m never sure what sort of attachment hardware I’ll use. I like the corner pins -a la Deardorff- but the back needs to be a bit thicker to have enough wood around the pins to support them. The perimeter slot I used on the last camera worked well, but I worry about the durability of it over time.
The bottom of the back and the middle are glued up first- they are first glued to make the 1/4″ thick components with half-lap joints, then glued into a frame. Once cured, the light trap slot that engages the film holder rib is milled, then the final 1/8″ layer is glued on top of that. After that has cured, it’s planed to size and the relief for the secondary light trap is routed with a little extra finger room to extract the holder after the shot. I wish I’d taken a picture of the parts because it’s difficult to describe. Essentially, once assembled, the corners are full brindle joints, the the parts are cut and alternated so the corner joints will be build up in layers.
Once the frame assembly is done, it’s planed to size and the perimeter light trap rabbet is cut to inset in the standard.
Update 11/7/14- I really should have thought to bevel the back opening’s inside edges when I was making this. The opening as built was too close to actual film size. Which means that with extreme front movements (when the lens projection is off-axis), the edges of the back opening will cast a shadow into the image area of the film. It took me forever to figure out what was causing random ghostly lines along the edges of the film. Beveling the opening with a 45° router bearing bit fixed the problem.
March 16th- Measuring T-dimension for the ground glass frame
Ground glass frame. Walnut was milled to 7/16″ stock. Next time use 9/16″- I will have to pad the bottom out with a garolite frame or wood lamination. By the time the bottom of the gg frame is routed to nest into the film-holder recess, the frame would have been too thin to add spring hardware. I ran into this problem with the 5×7 conversion but forgot about it until I was about the cut the joints- on the old 5×7 I had to screw strips of aluminum alongside the frame for the spring pin pivots. This time I took into account the extra 1/8″ thickness of the garolite shim when setting up to cut the T-dimension.
To glue this little frame up, it cut a flat piece of melamine a hair smaller in OD than the frame to support the weight of the clamps. I also cut a scrap of melamine the same size as the ground glass recess, then screwed that to the melamine below to help hold it flat. Wooden clamps were used on the joints to hold the corners to the melamine to make sure the stub tenons weren’t stressed too much when the bar clamps were tightened. It’s sort of funny to see the clamped assembly, bristling with 20 pounds of clamps to hold this tiny 5×7 frame.
Haunched offsest mortise and tenon joints for the GG frame. Yes, the pictures are godawful- I often get so absorbed in the work that documenting it is a bother. But I wanted a reference to this joint because I always seem to forget the particulars of it. Milling the mortises on a router table with a 1/8″ bit. I used double-sided tape to attach a block of wood to the parts while milling, to give the part extra mass for a cleaner cut. The parts are very small so it’s hard to put hold downs and featherboards around the bit, and the extra block makes it easier to hold onto as well. The Rhino carpet tape I used for the bag bellows worked well, it rolls off and leaves no stains or residue.
March 17th- For the bed, I decided to save a little weight by sectioning the breadboard panel. Still plenty of room in the front and back for the gear shaft channel, and in the middle to inlay an aluminum tripod mounting block. I salvaged the early breadboard panel goof by ripping the stub tenons off the sides and routing them cross-grain on the ends (like I should have to begin with). I planed down some extra stock to use for the front and back. The center panel’s tenons are haunched a little on each end to allow for cross-grain movement, but probably an unnecessary precaution considering how small the panel is. Some spacer blocks were glued in the groove between the panels to reinforce the thin edges. Glue up was similar to the GG frame, clamping the corners to a slightly undersized scrap of melamine to keep the assembly flat when bar-clamping everything tight.
Trimmed GG frame. Made a 1/16″ rabbet around the bottom so it will nest in the film holder recess. I drilled holes with a forstner bit at the ends of the ‘horns’ and connected the dots at the router. Trying to do the entire thing on the router is tricky, the bit will want to blow out the short grain as it climbs at the end of the cut. I tapered the underside of the gg frame with a tenon jig on the table saw and cleaned it up with a block plane.
Trying to keep an ongoing record of weight. Just over 2lbs so far, without hardware, front standard, bellows, extension rails… Still lots missing, but I hope to be able to keep it under 6 pounds.
A little more progress. The extension rails milled and cut to rough length. Lensboard frame and rise/swing frame
Ordered some parts from McMaster-Carr. Some aluminum bar stock and various stainless steel screws and sundry small parts. Got some bronze sleeve bearings for pivot points and shafts. Even trace amounts of slop in pivots points can make a camera feel very sloppy.
I ordered a 3’x’4 sheet of 1/32″ garolite; seriously thinking of making some wood 5×7 film holders out of the left over walnut stock after the camera is done. I like wood holders much better than the plastic ones.
Also got a dovetail endmill. Toying with the idea of machining a dovetail slide for shift in the rear turntable out of 1/4″ aluminum bar stock.
Made the lensboard frame. Made a swing stage for the front standard. It will nest in the standard and move the swing function off the base turntable. I’m exceedingly tired of having multiple movements controlled by one knob in one plane. My plan is for the front standard base to have shift and base tilt, for the front standard stays to have separate controls for rise and axis tilt, and for a nested frame between the stays and the lensboard stage to have swing. The front axis tilt will have an off-axis knob for extra rigidity. Ideally, the pivot for the axis tilt will be the same point for tightening the rise and fall.
More CAD doodles. Left: plan view of nesting front standard frame to control swing. Haven’t decided if the slots will go in the stays or in the frame. Shows 45 degrees of swing for proof of concept, but will make it have that much- the frame would interfere with bigger lenses and WA lenses would likely see the axis tilt turntables, if not the frame itself too. Also, the stays are too long and too shallow of an angle to resist twisting forces. I intend to move the stays’ locking points in closer to the pivot axis, or move the stays’ pivot points further away. Less swing, but that will solve many of these problems. Which is fine, I doubt I’ve ever used more than 5 degrees of swing in my life. Center: Elevation view of front standard with axis tilt turntable and off-axis locking knob. The on-axis knob will control rise and fall. I pilfered more ideas for the front standard from the Gandolfi Variant- I’ve never handled one, but from web pictures it looks like an extremely well-though out camera, especially the gimbal-style front standard movements. I really like the front shift design on it as well. Right: Cool, I’ve invented the square. 1/8″ aluminum swing frame and nested lensboard stage. Reminds me of The Hudsucker Proxy- ‘You know, for kids!’
Fun with basic geometry. Spending the weekend making squares and circles. I suck at metalworking and with every project make big plans to improve at the craft but then get impatient and do something stupid, sloppy, or dangerous. To bend the aluminum, I marked out where the bends would be and heated them with a propane torch. I made a caul out of white oak, radius’d the corners, then bend the bar stock around it. I made a sort of cam follower and used a cast iron wing from an old table say for leverage. Mostly was a matter of clamping one side, bending the corner a little, moving the clamps, bending a little more. It took a long time, but turned out nice- flat and square. To cut the seam, I overlapped the ends, wedged the sides out the width of the hacksaw blade, then cut through both pieces at once.
Top- centering the workpiece with a center finder. The bit is not used for boring, just for centering. I finally bought a decent vise, some hold down clamp, parallel bars, setup blocks and this indispensable center/edge finder. Center- The centering bit is removed when the punch is centered and a center drill is used to drill the pilot pivot hole. I lucked out- the a bit the same diameter as the sleeve bearings I’m using used. In the bottom shot, a billet of 1/2 aluminum was used to make a mating hole for the bearing to fit into. Bottom- Yes, yes- the workpiece is rotated by hand to cut the radial slot. I don’t have a rotary table, so took like a million micron-thin cuts. Actually, it worked better than I expected. Some mills marks, but not a lot of chatter considering. But definitely not recommended- the bit can still wedge in the slot and dangerously spin the piece around at the speed of the bit.
Milling the front standard slots. One of the trickier parts of milling slots is getting the width just right. There needs to be enough clearance around the thumbscrew threads, too loose and the movements get sloppy and you have to crank down on the the thumbscrews more to lock the movements in place. Easier to plan to cover the thread that rides in the slot with a small nylon sleeve bushing. This really reduces friction to allow for a much tighter fit, protects the thumbscrew threads and slots from binding damage, and makes movements such as rise and fall a lot smoother.
I cut longer slots it in segments, since the vise face is narrow, leaving a small bit of aluminum in the center of the slot for support. Then I put a wedge in the slots on either side to finish off the bit in the middle. I’m still getting a lot of chatter in these slotting cuts, even with the added mass of the screw vise. Even more chatter that cutting the radial tilt pieces freehand. Have tried faster and slower speeds, shallower cuts, cutting fluid. Maybe there’s just not enough mass to the rig. The table’s dovetail gibs are adjusted well, there’s no vibration during the cut….maybe the bit is just dull. Anyway, not too difficult to clean up with a file, but it would be great to get a nicer finish straight from the bit.
Note- parallel blocks support the stock from underneath during milling.
After both sides were milled I ganged them together to file the mill marks out. Good idea to reverse the pieces occasionally to make sure the slots are staying square to the faces.
Assembled. The radial tilt slots have a tightening screw that feed through the standard and tightens with a thumb-nut. The slot is stepped to give clearance for the screwhead- a pan head screw with the sides filed parallel so that is will ride in the counter sunk slot and not spin. For enough clearance the mating parts of the frame have to be recessed as well.
Recesses are cut for the axis tilt slot screwhead. My first try at routing aluminum. IT actually worked well, but I was scared to take of any more than 1/64th at a pass.
I haven’t had much time to spend on the project lately, but what time I do have has been dedicated to squinting at what I’ve done so far. The front standard especially is bugging me- too bulky, and I really hate that joining plate on the bottom of the frame. I heated up some 1/2 aluminum and used the brake at work to bend a tighter frame with smaller-radius’d corners.
The frame is made of two pieces and is seamed along the radial axis plates, instead of being a single piece joined at the bottom of the frame with a mending plate. I made a cutting jig to make sure the pieces are symmetrical and square
I’m using bronze bearing for pivot points wherever I can. This isn’t exactly a pivot- but I bored for the 5/16 sleeve before thinking it through. Instead of making the frame over, I filed flats on the bearing sleeves and mortised them into the frame to keep the bearings from spinning as the rise/fall knobs are tightened. In the spirit of making the best of a goof- and I’m getting much practise with this- I’ll use the the bearing’s center as the receiver for ball plunger detents mounted in the lensboard frame. This will zero-out the swing.
The new radial plates are made in the dame way as the last, but to shape them I clamped the pieces down and used the mill to trim them parallel. I actually like using the plywood backer- seems to absorb more vibration that metal plates, and set-up sure is a lot easier- no holes to tap.
Back where I was last weekend. Still more filing to do, but I like it a lot more. The radial tilt slots are stepped as before, and a recess is cut into the frame as well. I used the same pivot bushings, filing flats on the flange and mortising them into the frame to lock them in place.
Spent the weekend cranking. The @#$&! mill that is. Made the dovetail shift slides for the front and rear. The rear dovetail shift took about 8 hours to make, no kidding. Since my table’s travel is so short, I made a jig with a fence that let me clamp the work independently so I could do half at a time and flip it without loosing registration. 8 hours of cranking that tiny wheel. 2- 11″ mating pieces, 12 passes per edge, 8 edges, & .001″ per turn..but I’m way too tired to do the math. Or take a picture of it. Most of the metal parts look like crap until they’re polished up anyway.
Also finished a few nagging items- cut the base and extension to final dimensions, attached the garolite base to the ground glass frame, milled the shaft slots in the base and the gear rack slots in the extensions.
Garolite base brings T-dimension to correct depth, plus provides a durable wear surface for sliding film holders in and out of the frame. Yeah, I over-did it on the screws.
Test depth for the gear racks. Fussy- needs to be just right to avoid backlash-too low and the teeth wont mesh fully and there will be slop front to back, as well as excessive stress at the tips of the teeth. Too high and the hub will bear on the extensions.
Slots for the gear racks
A really bad set up for re-boring the pinion hubs- thankfully I thought better of clamping the rack in the ‘V’ section of the vise before actually drilling; clamping down the vise would flex the rack enough to throw the hub off center. Parallel bars hold the gear, well, parallel and square to the drill bit. The scraps of rack allow the gear to be clamped in the vise without damaging the teeth. I step up 1/64th at a time from the factory-bored 1/8″ to the 3/16″ I use for the drive shaft.
Checking shaft depth. Pinion should roll easily without bearing on the straightedge above. Not the final position of the gear obviously, but good for judging the depth. I still need to mortise recesses along the shaft dado for the pinions to spin in. Correction 4/27– goofed here, actually this needed to be 1/32″ deeper to account for the distance between the bottom of the spur’s teeth and the hub.
Shine, Cosmo and Lonnie. Cosmo will be a year old in May. Haven’t been able to get a picture, but he’ll stick his head through my shop window to see what I’m up to. He’s seriously challenging my apathy towards horses.
Finishing up back while waiting for parts to arrive. I bought some traditional Deardorff leaf springs to use for this camera, but after seeing how weak they are and how limited the travel, I decided to make this sort of torsion spring back again. For the last 5×7 back, I made a double-arm spring for each side, but that restricted the travel too much and it was difficult to remove the film holder after the shot. A single arm is longer, so it can lift further away from the back.
Assembled springs. I tapered the nesting battens to lighten the weight and look a little.
Spring arms and springs. Left and right-wound springs are housed in a small peice of 1/4 aluminum channel. The mandrel for the spring is the pivot for the spring arm, and the small screw post engages the spring leg inside the channel. More about that here-
Lots of room to get the holder in and out.
Inserted holder. Still need to make the rear part of the nesting frame. Will help help direct sunlight off the end of the holder so I don’t have to shade it.
Milled dovetail for front shift. I milled this a few weeks ago and have been thinking about how to implement it. As pictured, it’s upside down. The 1/4 aluminum bar will be the base for the front standard brackets, and the dovetail key will be mounted on a 3/16″ ‘table’ that attaches to the slide extension. I milled it deep for a UHMW glide, but goofed- it should have had the space on the fat part of the dovetail, not the narrow. Oh well. I can trim a little more off the width to flush it up if needed, but the extra space makes it adjustable by tensioning the screws
Countersinking screws to attach dovetail key. Tape keeps the parts in registration, so that the dovetail key will get partially drilled at the same time. Then the components are disassembled, and the key is pilot drilled the rest of the way then tapped for 6/32 machine screws.
Assembled front shift. Still need to slot the top piece for the locking knob. The slot will be in the front (left as pictured), that’s why the dovetail is offset. The dovetail is mainly to resist racking/lifting forces so I can probably get away with a single locking knob for shift. The locking knob (maybe a lever) will be underneath, like an Ebony camera. If the front is racked out, the dovetail ‘gib’ screws will be adjustable from underneath as well with a screwdriver, if needed.
Weight check #2- the metal in at 2lbs. Still on pace for around 6lbs. The big offender is the rear dovetailed turntable- 1 lb just for that sandwich at the bottom. Most over the parts are oversized, so trimming those will shave a few ounces off.
Finished the weekend finishing. The open grain of the walnut has really been bugging me, so I tried filling the pores on a test scrap with grain filler, tinted with aniline dye. First sealed the crap with dewaxed shellac so the filler wouldn’t stain the wood, buffed that out, then added the grain filler. After that was dry I sanded it and used a lacquer top coat. Looks really good, but I should have let the filler it cure more, so I went ahead and finished sanding all the wood pieces and sprayed them with a sealer coat of shellac. I’ll fill the grain tomorrow after work so it’ll have plenty of time to cure before next weekend. The parts I ordered should be here by then so hopefully I can start putting everything together over the next few weekends.
Got the sealer coat and the grain filler on the wood parts after work this past week, but thought I should better start the rough assembly before putting the final coats of lacquer on. Still lots of finishing to do on the metal components. Still need to install the racks and drive shafts, but since I’m planning on robbing my current camera of those, am putting that off as long as possible to keep a functioning camera available.
Initial assembly- installed the extension guides, front shift base, and the rear extension channels for rear standard forward-focusing.
Front shift. I had a lot of clearance, so I decided to inlay the front plate into the extension rails about an 1/8″ of an inch. Now the shift just clears the guide plates and looks cleaner, less bulky. The outside channel piece in the foreground is for the rear standard bracket to ride in for forward / wide angle focusing.
Standard brackets and standards installed. I notched the standards so thy would lay flat on the bed, to help with nesting. Still need trim the standards to length and install a crossbar at the bottom, connecting them to help keep them aligned and rigid. Will probably use a 1/4″ x 1/2″ piece of walnut, and maybe crosscut a dado in the standards to house it and make it resistant to twisting. And the stays, need to add the short strut stays as well…
Nest test- spend a lot of time trying to making sure the swing stage would nest properly between the standards into the bed, and have been anxious to to test the fit. It was a great relief to find that everything fits properly. Yeah, the swing knobs are mismatched. Leaning towards the style on the right- sort of a fancy low profile thumb nut with a large, thin knob to tighten with.