View Full Version : Spring Back Sprung Out?

matthew blais
19-Jan-2004, 19:32
I just recieved my "new" 8x10 Korona today ...what a monster yet surprisingly "light". All the parts are there (all knobs, ext. rails, good workable bellows, glass, back, etc), some looses joints but I plan on tearing it apart (you know what I mean) and restoring. I also am half way through a 4x5 Korona I picked up a few weeks back. (More parts than I thought, but I'm a competent woodworker/handyman/masochistic/anal retentive type) and so far so good.

Question: The spring back tension on the 4x5 seems fairly tight, but the 8x10 seems to have less tension (floppy-ish). I know you can sometimes find a replacement set, but my thought was I could just drill a new hole a half inch or so further up and add another screw, which will add tension. Is this a good alternative if need be?

However, I like "original" as best I can. I talked to two machinist friends today, both said though it looks simple, spring steel is a bitch to work with (their way of saying "I don't want to do that" ??). I believe this would be better, but how difficult for even an experienced machinist/fabricator?

So, my first option would be to find new or new used replacements, (if so, from where beside a parts camera on ebay?) Second would be to fabricate new ones via my friends or other fabricator, and last option, the extra hole/screw.

What might your thoughts/experience be regarding this?

Also came with a Unicom shutter...ain't those cool things! Thanks all

19-Jan-2004, 19:44
spring steel is a bitch to work with (their way of saying "I don't want to do that" ??)

Or their way of saying the price just went up.

My suggestion is to leave the springs as they are. To add another hole or set of holes for extra screws would limit the amount the back will open up and possibly make getting a film holder in or out more difficult. It may not be necessary either. Try using it first and see how bad it really is. If it's so loose that you get light leaks, then you'll need to do something. But it may be OK. In the meantime keep an eye on Ebay for a parts camera.

John Kasaian
19-Jan-2004, 20:53

I don't know what I'm saying here---just a guess really---but how about "helper" springs? pieces of stiffer spring steel material supporting(on top of, I guess) the weaker spring(sort of like the suspension on my Uncle Al's 54 Chevy Pick up.) It seems like a piece of spring steel maybe 3/8" wide to a little shorter than the original spring's length should work. Maybe a gunsmith or clock repairman could help you find suitable spring stock. Good Luck!

Tim Curry
19-Jan-2004, 21:13

The cheapest spring steel I know of comes from old band saw blades or the hanging file folders used in an office (Pendaflex folders). Both are readily available, free and can span several sizes. The band saw blades will need to have the teeth ground off, but a bench grinder will do this in short order. Try not to overheat the steel or it will lose its temper. With a drill press and a cobalt or carbide bit it drills well enough. Make sure to use a slow speed and a drop of oil to keep it cool.

I would second John's suggestion to use "doublers" which are shorter in length than the original springs. The back I have on my old B&J 8X10 uses just this type of arrangement and it is a very snug fit with the film holder in place. You can put too much pressure on the back, so try a few lengths to get the right amount and you should have a good fit.

Bill Jefferson
20-Jan-2004, 03:27
Matt, I used a couple small bungie cords, and small eye screws found in a crafts store, to give a little extra tension to hold a Polaroid 8x10 film holder in place.

Larry Gebhardt
20-Jan-2004, 06:46
Tim, my bandsaw blades would not make strong enough springs, do you mean hacksaw blades?

matthew blais
20-Jan-2004, 07:29
Good advice all;

William, I know I'm jumping ahead anticipating they will not be light tight, which they may be, but just in case! Thanks John & Tim, I'd forgotton about the layered leaf spring option...and the use of bandsaw blades. And where would be without bungee cords! Thanks Bill, another option. And Mini, i think in short piece, bandsaw would be fine, though cheaper to cut a hacksaw blade too.

Thanks guys.

Tim Curry
20-Jan-2004, 19:18

I did mean bandsaw blades, not hacksaw blades. Bandsaw blades are readily available from any cabinet shop or lumber mill in used condition. They usually snap or become dull and are then thrown away as they are of no use (free for the asking). They are ideal as spring stock because the temper is such that the teeth are very hard, but the blade itself is supple. Once the teeth are ground off, they can be used as soft springs and layered or shaped for use with proper heat treatment. They are available in various sizes from narrow to wide and different thicknesses.

Hacksaw blades tend to be very brittle, as they are tempered differently and tend to snap due to their hardness. In this case, too much of a good thing.

The older Pendaflex hanging file folders had steel very similar to band saw stock which was hardened. They are good for narrow spring stock.

Piano wire, as sold in hobby stores, is also available in various diameters and will make good springs.