to build up a 8x20 bellows

[fujinonA]

I have already built up three bellows by myself on the past .
one for a 11x14 camera (the rear standards size has the same square size 35x35 cm) ,and one for a 7x17 camera .
The problem I have met with the 7x17 camera is that the size of the rear standard is not the same.One size, of course, has to be more big than the vertical one so the bellows corners don't fold perfectly like the 8x10 square size .
The corners infact are not perfectly on line and this make the bellow more thick ....
Looking at the drawing of this we-site (formula to determine the widht of the web):

http://www.cyberbeach.net/~dbardell/bellows.html

it says" With a plastic 45' triangle draw line down from the 45mm line, draw a second line from the 90mm line up at 45'.

This little triangle provides several bits of information. As illistrated above, measure from the point of the triangle to the 45mm and 90mm lines, this is the width of the 2 webs (24mm and 21mm). From the point of the triangle to the line which represents the length of the panel is the space required between the panels....."

Question:Which of the two panels for a 8x20 " camera I have to consider?
I tried to conatct the guy time ago but it doesn't reply but it's still useful his info.
If someone already experienced this problem any useful word will be appreciated.My wish is to make a bellow as good as possible.
I reapeat, for the 810 or 4x5 format with a square size standart not problem but with a 7x17 (45 x 25 cm standart size ) or a 8 x20 ( 57x 35cm standart size) this is very more difficult , but not impossible...
Thanks

 

[phfitz]

Happy New Year,

This post is a bit confusing because I have not read the other web site. The side of importance for this would be the vertical sides, the 8 inch for 8X20, these would have the tapers at the ends.

It is easy to figure out if you draw it out full size. You need to find the Max. & min. sizes for the rear body and front standard. Also the Max. length and min. compressed/ closed length. You need all the specs. to figure the growth rate per pair of folds and how many folds will close into your camera body.

On 8X10 and larger the folds are usually 1 inch but you may need to make them smaller at the very rear so it does not vignette the film.

For building bellows you will need normal tools PLUS 2 special tools:
a 1/8 inch punch
a 3 bladed knife
You will need to make the knife yourself.

Good Luck With it.

 

[fujinonA]

Thanks for the info but I don't use
a 1/8 inch punch.
I was talking about how to get the lines of the firts pattern aligned with the lines of the second patterrn IF the bellow is not a square one (for example a 4x5 bellow with the equal sizes edges).
The bellow of the 8x20 has 2 DIFFERENT PATERNS so the one pattern has more "triangle shape" of the other one...
It's very difficult to expaling with words....
BTW Happy New 2005

 

[phfitz]

Hi there,

This does take longer to explain than to do. You need:

the inside measurements of the rear body -1/8 in. for space
the outside measurements of the front board
the total length extended + 2 in. for stretch

draw out the rear, full size outside and parallel lines 1 in. inboard of these out to the outer lines. draw diagonal lines at the corner boxes, the points go on the 8 in. sides. trim the 20 in. sides 1/8 in. for space. these will give you the actual size of the rear for both sizes you need.

do the same for the front board full size, points on the 8 in. side, trim back the top 1/8 in. this gives the sizes for the front of the panels.

now draw a base line and perpendicular center line full length. center the measurements you just made and mark them keeping everything square. connect the end points from front to back. mark a parallel line 1 in. inboard from these lines. mark off a series of parallel lines from the base every 2 in. on all panels.

you are almost there! each pleat is 2 folds, these need to be different sizes to make the bellow expand from the front size to the rear size. you need to know the number of pleats, the front size and the rear size. the largest growth for this will be on the 8 in. side. without the measurements this cannot be figured out.

Good Luck

 

[fujinonA]

phfitz ,
you can go to the technical gallery and see a very simple example .
( already I have built three bellows so the problems is only for the panoramic format).

On the drawing there are 2 patterns for the square standards.
The size of the rear standard is 40 cm and the front one is 20 cm.
As you can see on the pic (a little bit small ) there are two red arrows to show the line of the FOLD "A" .In this case since the two patterns have the same size for a squared bellow the lines of the FOLD "A" can be joined together with no problem.
However FOLD "B" lines not of course.....

Now consider that the second pattern on the left has another size (for example 80 cm on the rear standard).The shape of it is different from the pattern "A".This is the case for the building up a panoramic 8x20 bellow.

THE PROBLEM is :
Do the smaller pattern's folds have the same size of the bigger pattern's folds?
I suppose not ...But before to waste time, energy, money it's better make a search.
.The leather has a cost so just to get a good shape for the bellow I need the measuruments well made.
BTW Thanks for the message

 

[phfitz]

Hello,

The problem is that the two sides must grow at different rates with the same number of pleats so that the folds MUST be different sizes.

It is much easier to do it twice, the first time glue it up on heavy paper completely and make sure the design works correctly. This will be a very difficult bellows to build because of the difference is sizes.

Once the paper one works, cut it down one corner to see the size and shape you need the leather to be.

Good luck.

 

[fujinonA]

Thanks so much.
I will try it ASAP.
Cheers