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Bellows Prototype!


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#1 guckey13

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Posted 12 September 2003 - 06:20 PM

Hey Everyone! :D

I thought I would let everyone tell me what they think of my second attempt at the art of making bellows. I really am just getting practice with making them! The picture below of the bellows I made are made out of cardstock and, dare I say it, masking tape!!! They are very felxiable and agile. They have good "spring" I guess you could say, in other words they do not push your hand like strait back but they do "assist". But like I said, I'm just doing these to test my abilities of making the design! Not making functual bellows (all though they are air-tight!)

Constructive Criticism Anyone???

P.S.
I am practicing the art of skiving with leather, but a 16 year old can't afford making practice bellows!

-Sean

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Edited by guckey13, 12 September 2003 - 06:24 PM.


#2 JimLucas

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Posted 13 September 2003 - 12:09 AM

Constructive Criticism Anyone???


As in "criticize the construction"? ;)

Impressive. I wonder if it will last longer than cheap Stagi bellows under heavy use.

The little diamonds between the sections appear also to be made of masking tape, and it looks like it may be sticking to itself. I suggest that in the next go you do those with some kind of plastic or impregnated cloth, i.e., something still airtight and flexible but not itself sticky. Maybe a plastic or impregnated cloth tape (but I think not the thin film stuff they use on packages these days) instead of the masking tape, too. IME, masking tape gets stiff after a few months.

As for skiving: There are skiving tools available. I have a hand skiver, purchased at a leather supply store, which is a slightly curved tool that holds a single-edge razor blade in a way that holds the handle away from the leather. I think that with most standard knives the handle tends to get in the way of the skiving process. (Of course, it could be that I'm just not adequately skilled.)

There are also skiving machines, but they have a different purpose. Tapered edge skiving is what has been talked about so far in this thread, but their is leath known as "skiver", which is split or shaved to be almost paper thin. These machines can be used to "skive" and entire piece of leather to such a thickness (or should I say "thinness"?).

I look forward to hearing your next report.

#3 Mr. Bellows

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Posted 13 September 2003 - 01:44 AM

Go! Go! Go!
You are on the right track!

#4 Richard Morse

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Posted 13 September 2003 - 07:57 AM

There are also skiving machines, but they have a different purpose.  Tapered edge skiving is what has been talked about so far in this thread, but their is leath known as "skiver", which is split or shaved to be almost paper thin.  These machines can be used to "skive" and entire piece of leather to such a thickness

There are many leather "thinning" machines. I think what Jim was referring to is called a "splitter", which comes in small types (like for making belts thinner, to bed-sized ones for making an entire skin thinner. Skiving machines are different in that they perform a tapered thickness rather than a uniform thickness.

Here's a photo of our skiving machine. Its "business" end is a rotating cylinder (about 3" diameter) with a curved, highly sharpened leading edge. You pass lengths of leather from left to right, and much like a sewing machine, you can control the width and thickness of the skive and rate of material feed.

Wrapped around the arm of the machine you can see a single length of a bellows "top run" which had been skived on both edges. Each side takes several seconds with this machine. Smaller pieces we work as efficiently as we can - bellows gussets are a single long strip, skived both sides, then sheared into diamonds and hand skived the other two sides.

Also interesting in this photo is one of our bellows moulds....

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Edited by Richard Morse, 13 September 2003 - 07:59 AM.


#5 JimLucas

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Posted 13 September 2003 - 08:37 AM

Rich Morse:

There are many leather "thinning" machines. I think what Jim was referring to is called a "splitter",...


That sounds right. As for whether it's wrong to refer to it as a "skiving machine" or "skiver"...? It may be that -- as with "what's a concertina" -- there are differences in terminology, since it was professionals in the leather business who first described the machine to me and described what it did as "skiving".

---BRIEF PAUSE---

"So," I thought, "why not check my old Shorter Oxford English Dictionary?" And I did.

to skive (vt): "To split or cut (leather, rubber, etc.) into slices or strips; to pare or shave (hides)

skive (n): "The surface part of a sheet of leather cut off by a skiving machine; a skiver

skiver (n): "1. A thin kind of dressed leaether split from the grain side of a sheep-skin and tanned in sumach, used for bookbinding, lining hats, etc. 2. One who pares or splits leather."

skiving (n): "The parings of hides; the piece or sheet of split leather from the inner, or flesh, side.

skiving(gerund): "The action of splitting leather, etc."

All about splitting; nothing about tapering. And so it goes.

#6 guckey13

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Posted 13 September 2003 - 05:21 PM

Richard!

I have a question for you!!! The metal thing holding you cardstock, what is it? And can you explain how it works??

-Sean

P.S.
Thanks ya'll for all the info posted so far! Keep it coming!!

#7 Richard Morse

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Posted 14 September 2003 - 07:06 AM

The metal thing holding you cardstock, what is it? And can you explain how it works??

Our bellows mould is of a typical design though the others we've seen are made of wood and ours is aluminum. There are 6 sections (lengths, not rounds) of one side of bellows folds with the two ends being solid and serve to hold those 6 pieces in place. Attached to the center of the ends is a round delrin "handle" which also serves as the axle for which the entire affair can be easily rotated in (for making the bellows) or removed from (for jig dismantlement) the wood stand (you can just see in the lower part of the photo).

Note that the 6 sections don't quite meet each other at the tips of the bellows folds, and that that gap gets appreciably wider as you go down into the gusset area. This gap serves two purposes: to allow the gusset material to fold into the area to make uniform and nicely shaped gussets, and to allow the jig to be disassembled.

To remove the jig, we remove it from the stand and take off the ends. The 6 fold parts are then free to rotate into the hollow center and be retracted.

Other bellows moulds I've seen are also hollow in the middle though usually have a single fold section that is dismantleable (different from the rest which are solid). sometimes these special dismantleable sections are made of 3 pieces with a center which can slide out leaving both triangular sides to be removed. More often I've seen it made of two pieces with one of the pieces being a parallelogram (following the slope of the adjacent piece) which can be slid into the center enabling the rest to collapse and to be removed.




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