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PostPosted: Tue Jan 14, 2014 3:15 pm 
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I'm considering making a bellows for my SSPs, and I'd be interested in any thoughts about incorporating some of the features of musette-style bellows. My current bellows is small and suffers from a fair amount of ballooning during compression (delivering air to the bag), and collapse of the leather during extension of the arm (drawing outside air into the bellows). Because of the collapsing (sucking-in) of the leather during arm extension, air doesn't really enter the bellows until it is maximally open, which pulls the leather taut, so half-pumps move hardly any air. Because of the ballooning problem, a lot of the air remains in the folds of the leather and doesn't get pushed into the bag. This, on top of the small size of this bellows, results in very inefficient air delivery.

The musette-style bellows are accordion-like, with ribs. It seems to me that this style of bellows should give the player more air control because the air volume in the bellows as a function of clapper distance should be close to linear. No collapsing or ballooning. Am I overlooking any shortcomings to this design? Also, I like the curved saddle on the inner clapper of musette bellows.


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PostPosted: Tue Jan 14, 2014 6:02 pm 
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The accordion ones suck.
Just trust me on this.

Good French bellows typically have triple clappers, which aids stability immensely.
The rib-side 'saddle' (good word for it btw) is really comfy.
The inlet 'shield' is of superior design and I have yet to catch a sleeve in one. :D
There are French bellows that have inlets on the 'saddle' side, these also are very difficult to block with clothing.

Suggest the cause of 'ballooning' to be a too- narrow inner diameter of the blowpipe. hmm?

One last thing to bear in mind is that this French-type bellows are (usually) squeezed by the forearm...as opposed to the elbow, as in uilleann, etc... worn a bit closer to the sternum than the pelvis.

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PostPosted: Wed Jan 15, 2014 12:17 am 
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CHasR, thanks for that information. As usual, your expertise is much appreciated.

I think you're right that part of the problem with my current bellows is a small outlet pipe. The brass fitting that joins the bellows to the pipe is small, and I'm sure that drag in that bottleneck contributes to the ballooning of the bellows.

Out of curiosity, what makes the three-clapper design superior to the wire-rib accordion-like design, in your experience? When I say accordion-like, I mean that the design I imagined has the wire ribs and folds (baffles?) but it still has a hinge. I could see it being a bit frustrating and inefficient if it resembled actual accordion bellows in that it had no hinge, like a concertina.


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PostPosted: Wed Jan 15, 2014 2:44 am 
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You want a mostly full draw on your bellows. Half-pumps aren't very efficient and could lead to bad technique. Bellows extended should be your default position. After you complete a pump, extend the bellows back out to be ready for your next pump. With a full draw you have more reserve to feed air to the bag more slowly and smoothly, resulting in steadier tone.

You also don't want full expulsion of air from the bellows. It's hard to control that last bit and it can get pushed out harder, resulting in a surge which can lead to chanter squeals.

Ballooning is not good though. A common cause for that is thin leather. It's not unusual for makers to double the leather. Other than being air tight, efficient bellows have hefty gussets and a solid hinge. With efficient bellows you're less apt to strain and jab the clapper into your ribs and arm (not to say I don't like the padding on my bellows).

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PostPosted: Wed Jan 15, 2014 8:42 am 
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well, everything Aaron said, for a start.

Image

Image

Its so much work for so little return. More parts to fail. Its like, asthmatic or something.. never inhales fully, wheezes upon exhale.

The old original Bechonnets have the accordion folds, and iirc, the bellows images in DeScellery, Hotteterre & Praetorius are likewise. (An interesting digression would be the evolution of the bellows in general...from blacksmith & organ designs, to the double back Asian one, to the Eastern Euro "hinged clapper" idea, extremely uncomfy...)

3 clappers in my estimation gives best of both worlds, lg capacity, stability, efficiency, minimal parts, many common design flaws have been addressed.

Image

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PostPosted: Wed Jan 15, 2014 12:54 pm 
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I'm familiar with the basics of good bellows technique. I mentioned half-pumps just to describe the behavior of my current bellows. What I meant is that from fully closed to half open, my current bellows draws in almost no air. That phase of the pumping cycle just pulls the gusset from the ballooned position to the sucked-in position, without much change in the volume of air in the bellows.

I imagine my bellows, a better SSP bellows, and an accordion-style musette bellows (all of equal clapper area) performing like this:

Image

Because the gusset on my bellows billows in and out, there is a plateau just after fully open and fully closed. During that phase, the movement of my arm is not moving any air (or not much). This is problematic for air control. For a better SSP bellows, I would imagine this effect to be reduced. For an accordion-like bellows, I would imagine the maximum volume to be lower than the others, but I would expect the function to be linear because there should be almost no billowing of the gusset. An accordion-style bellows should approximate a piston, except that the volume can't go to zero. There will be some residual volume because the stack of wire ribs would prevent complete clapper closure. I would expect this to prevent too much of a poorly controlled "huff" at the volume minimum, when the elbow is all the way down. From an air control standpoint, this seems ideal. Slightly larger clappers could compensate for the smaller volume. A three-clapper bellows would fall somewhere between the blue and green lines, I would imagine.

Is this reasoning consistent with your experience, CHasR? I think, since you mentioned that the accordion-like bellows suck, that one or more of my guesses must be off. Maybe that little bit of curvature in the blue line helps to stabilize bag pressure?


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PostPosted: Wed Jan 15, 2014 3:37 pm 
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well what can i say, you got a graph & all. go & build one, or more than one. & see what way you prefer, its the only way to find out for sure. Till then its all guesswork. My guess is youll be flappin like mad with them accordion bellows, no matter how linear if functions or how large area the clappers are. If you can come up with a better way of doing it, go for it! Good luck :thumbsup:

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PostPosted: Thu Jan 16, 2014 2:11 pm 
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What make of bellows do you have? Is it a Garvie?
I make my bellows to have a definitive fold in the gusset so it has an easy pumping action. The outlet plug bores are 3/8". Thats plenty wide for smallpipes. One of the most important things is getting the right leather. Not too thick, and not too thin. Too thick and it becomes restrictive and hard to close. If its too thin the gusset will always balloon.
This is one of my bellows:
Image

from the side:
Image

*edit to fix pic link


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PostPosted: Fri Jan 17, 2014 12:43 am 
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The bellows I have are from an old Naill border set. They're surprisingly small (about 5" x 9"). Quietpiper, what thickness of leather do you use for your bellows?


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PostPosted: Fri Jan 17, 2014 2:06 am 
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Why I included the bellows technique is that I think the value of how much volume the bellows hold at half-extension (or half-compression) is purely academic. Where the rubber hits the road is what happens when compressing from full extension.

I think it's the stability of the hinge and the gusset that are key to good bellows.

The only time I've been frustrated with a pair of bellows is because the hinge was inefficient. The hinge is where the fulcrum is. A sturdy hinge will allow the top clapper to move easily in an up-and-down lever motion and will restrict any lateral motion of the lever and other motion at the fulcrum. Any non-essential motion at the fulcrum impedes extension and compression.

When the gusset balloons, there is a delay in air delivery because too much air is pushing against the sides of gusset instead of pushing through the outlet. A sturdy leather gusset won't balloon.

I think good bellows are going to have more air volume when closed just because the sturdy leather can't compress down as far and that's good. You don't necessarily need full compression. There is a sort of golden ratio of air volume that a bellows delivers. It just needs to reach that ratio when extended then deliver it to the bag in a steady, controlled fashion,.


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