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barnacle
21-Mar-2016, 08:48
I'm investigating materials to make bellows from, and found the following at a UK supplier: Point North/Profabric. In the photos below, the outer shell of the bellows is their NN1-09 neoprene coated nylon, and the inner is BTM-09 polyester microfibre. Both of these are two-layer fabrics with a flexible coat and the NN1-09 is completely light-tight (I don't know about IR). The BTM-09 is *nearly* light tight but I selected it because of the slightly brushed inside face; no specular reflections.

The 'bones' of the stiffener: this is just 90gsm printer paper and it's not stiff enough, so I'll try again with 160gsm for the next one.

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Five segments: the outer two will be overlapped somewhat.

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The position of the bones marked with a silver sharpie on the inside of the outside - the smooth side goes out.

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The outer shell cut to size.

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Neil

barnacle
21-Mar-2016, 08:57
I forgot to photograph the bones stuck to the centre three segments, but stuck the top on directly. The two outers I left unstuck (mostly!). The adhesive is Evo-stick spray contact adhesive.

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The inner is marked to allow for a slight overlap at the corner, and cut to size. I should have moved it further from the corner... made the corners a bit tricky. The outer side definitely shouldn't be at the corner. The smooth side of the inner goes toward the outside to leave the soft side inside the bellows.

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The bones then get added to the remaining side - the greaseproof baking parchment allows the bones to be rolled flat without sticking to the glue.

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Neil

barnacle
21-Mar-2016, 09:05
The outer shell is folded to match the overlap and glued; the baking paper stops the sides sticking together. Then the inner is stuck together at the flap along with the bones.

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The bits of dust from the cutting board brush off.

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Neil

Jim Fitzgerald
21-Mar-2016, 09:17
Nice job, thanks!

barnacle
21-Mar-2016, 10:23
Hmm. The picture thingy doesn't want to let me upload from the computer for some reason; I just get an empty window. I'll try again later to try and get the last four pictures in.

Neil

RSalles
21-Mar-2016, 13:09
Great Neil, keep updating the bellows making, I have heard that it's a task that can be accomplished by a "normal" human being, but it's better to see it then to hear about,

Cheers,

Renato

barnacle
21-Mar-2016, 13:22
Aha! The system allows me to post images again.

The tube is turned right side in.

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Then the folds are started, using the stiffeners as references. The tiny bulldog clips hold the folds in place.

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And finally, it sits under a weight for a few hours to set the pleats.

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So there it is. Not perfect, but usable. The next one will have some slight changes: I'll use a solid frame to support the outer before sticking the bones on. That will guarantee the thing comes out square and the right size; this one is about a quarter inch rectangular at the fat end, down to not lining the bones up correctly. It will also mean I can move the seams further from the corner, which will simplify and neaten the bottom corners. If possible, I shall also find somewhere that can cut the bones by laser or something similar, and they'll be about twice the thickness for extra stiffness. However, I don't want to get too thick in the multilayer pile.

As an aside - I got a sample of the equivalent red NN1-112 but it turns out to be quite transparent. Shame. However, there is a heavyweight coated fabric here http://www.profabrics.co.uk/collections/heavy-weight-water-resistant/products/1000-denier-cordura?variant=8358970883 which might do the job for those who want technicolour bellows - though it's half as heavy again.

Neil

chris_4622
21-Mar-2016, 16:09
Neil, I've found it better to have the seam on an angle from the back to the front. That way the seam doesn't stack up thickness in the folds.
I've looked at this product before for making my next bellows but I wasn't sure about the thickness, if it would be thicker or thinner than curtain liner material.

chris

barnacle
21-Mar-2016, 16:23
Yes, Chris, the next one will have an angled seam. I couldn't do it on this one because it lacked an obvious reference point and place to stick the bones.

I've just measure the thickness of a pleat - i.e. two layers each of the outer, stiffener, and inner - and it's as near as the callipers can measure 1.0mm. Using thicker paper would raise that perhaps .05mm. I used curtain liner material for a previous attempt and it was much thicker: 2.1mm

Neil

chris_4622
21-Mar-2016, 16:39
I followed this method:
http://web.archive.org/web/20100327160815/http://www.cyberbeach.net/~dbardell/bellows.html

If you scroll down 3/4 of the way you'll see how he figured the angle. Hope this helps.

BetterSense
21-Mar-2016, 18:55
I have done it. Getting the right fabric is 90% of the battle. Mine was for a 6x9 and I used regular printer paper, not even construction paper, and it seemed to do fine.

barnacle
24-Mar-2016, 01:22
I made another bellows... this one turned out rather better as I used a wooden frame to build it on. Although the bellows are square, the frame isn't - it needs two sides the size of the outside of the mounting frame, and two sides the size of the inside, so the folds work. In this case, I had a large frame at 160x160mm and a small frame at 130x130mm. The thickness of the frame borders - 15mm - defines the depth of the pleat. So in this case, the frame was 160x130mm at the wide end, tapering to 130x100 at the narrow end (all external dimensions).

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Sanded smooth to avoid any snags, and baking paper fixed for added slipperiness.

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The fit of the bellows outer is less critical; it just needs to be big enough to cover the frame though too much overhang might be an issue. The outer seam will be on the bottom of the finished bellows, and uses a nice wide diagonal to distribute the thicker result.

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And then this is glued to the other side; I used more of the baking paper to ensure that the glue went only where it was needed. I'm not sure that spray adhesive is the best option.

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Neil

barnacle
24-Mar-2016, 01:32
Apologies for these photos, taken in the dark, of a light-absorbing material, with the camera flash... oh well!

The inner skin is cut with a seam opposite the outer skin and temporarily taped in place:

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It's then unwound but left attached while the bones are glued, first to cover the seam in the outer (so the bottom of the bellows).

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The inner is then refitted and glued to the bones just fitted. It is then released from its temporary place to allow the bones on the two sides to be glued, and finally the top bones.

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Everything is rolled nice and flat, then allowed to set. The excess material is trimmed and the complete bellows slides off the frame.

Then, as in the earlier attempt, it's turned right side in, the pleats folded, and it's weighted overnight to set the pleats. The final thickness is only 25mm so I'm rather pleased with that. I still need to find some stiffer bones, though; thicker paper or a thin plastic perhaps. It's also important to ensure that the bones on the four sides line up with each other, or the creases won't align. That needs a little marking on the build.

Neil

chris_4622
24-Mar-2016, 05:59
Neil,

What is the purpose of building it right side out instead of just starting with the inside fabric first, then the bones, then the outer shell? That way it wouldn't have to be turned right side out after you slide it off the frame. I must be missing something...

barnacle
24-Mar-2016, 07:34
Good question... I think it gives better control of where the glue is going. The outside is always protected from sticky fingers, I suppose. I got the idea from a link on the web somewhere which did it that way, and I don't think I reason was given, and to be honest I didn't ask!

The outer shell though is the most robust in terms of sticking things to it.

Maybe I'll do the next one the other way in!

Neil

Sean Mac
24-Mar-2016, 16:00
25mm is a good result. The Profabric material is a great find.

Neoprene is used for wetsuits and inflatable boats and they seem to have specialised glues for it.

Thanks for sharing, I will definitely have a go at this.:)

barnacle
24-Mar-2016, 16:39
That 25mm does not include the frame thickness, so that would be needed too.

Neil

Sean Mac
24-Mar-2016, 19:01
I am thinking about using FR4/G10 sheets for frames.

http://www.presspahn.com have it in black. Not really a traditional material for cameras but neither is neoprene:)

Thanks again....

barnacle
25-Mar-2016, 00:40
I've thought of FR4 but unless it's quite thick it's not usually light-tight. Don't know about black, though; that might help. 5mm ply should do, unless you absolutely need the precision machining you could do with FR4.

Of course, if you want to make leather bellows, Tandy is your man: http://www.tandyleather.eu/en/product/assorted-finished-splits or http://www.tandyleather.eu/en/product/white-finished-split or http://www.tandyleather.eu/en/product/economy-cowhide-sueded-split-assorted-colors-2-to-4-oz ... risky for size, though.

Neil