While researching more and more for my bellows project, this relationship question formed. For the sake of my musing, let’s assume that the whole set is sound without superfluous air losses (no leaks in any component, and reeds that seal well). Also, I understand that a practice set will use less air when playing than a full set with someone leaning on the regulators often. Finally, I understand that the terms ‘small’ and ‘large’ are relative.
Is there an ‘optimum’ balance/ratio/whatever set up between the volume of air a bellows moves, and the capacity of the pipe bag? How does the pipe configuration (practice vs. half vs. some amount of regulators) affect this?
Naturally, a smaller capacity bellows will move less air per stroke than a larger capacity bellows, and a smaller capacity bag will hold less air than a larger one. It stands to reason then that if you pair a small capacity bellows with a large capacity bag, you’ll need to pump more often to keep it topped up. The reverse would also reasonably seem true: a large capacity bellows and a small capacity bag means less pumps to fill the bag.
But here’s where I’m curious. What is the optimum bag/bellows pairing? Is it ‘better’ (I use that term very lightly) to have the most efficient, large capacity bellows possible, or does the size of the bag affect this need? Would the effect of a large bag + large bellows be essentially the same as a small bag + small bellows? I’ve always been under the impression that a full set of pipes will benefit from a larger bag, but is this truly the case, and does the volume of air a bellows can move play a big role as well?
If the volume displaced by the bellows equalled the volume of the bag, your left arm would have to work as hard as your right (or vice versa) - this could start off a new dance craze. What could we call it?
We’ve already had the funky chicken so how about the pumping chicken.
The thing to keep in mind is that , for a bellows to work efficiently it must be opened fully on the outward stroke . If a set of pipes are set up properly all you are using the bellows for,is to top up the air to keep the bag at playing pressure. If the volume of the bellows is to large and you are using it properly ,this means you have to let the bag deflate to much before topping it up. Of course the habit would be not to let the bag deflate to much and you would start the pump the bellows before enough air has gone out of the bag to need a full bellow amount of air. What then happens is that you only open the bellows part of its full stroke and because of this you get a very jerky inefficient bellows stroke. As a ballpark figure I think four full strokes to fill a bag would be good.
It is not correct to say that if the bag is larger and the bellows is smaller that one would have to pump more often to keep the bag full… the amount of bellows pumps needed, whilst playing, is a result of how much air is going out of the bag .
Rory’s approximate 4 full pumps to fill the bag is a reasonable figure. The size of the bellows , or its shape, should be such that the effort (force) needed for each elbow is similar… in other words the normal arm pressure on the Bag to blow the set should be reflected in the amount of pressure needed to actuate the bellows… thus the piper feels balanced.
The amount of pressure you need to apply to the bag should not differ much whether you are playing a practice set or a full set… it is just the amount of air flow which will be different.
The size and shape of the bag will affect the leverage available (comfort of arm movement) and the position of playing. A too fat bag will inhibit the use of all the regulators by not allowing the ‘bag arm’ to position the chanter so that the lower hand is in a good place for regulating the regulators in a regular fashion .A too skinny bag will cause the bag arm to need to squeeze in an inefficient position… like trying to run to the toilet with your legs crossed.
Likewise the shape and size of the bellows needs similar consideration ; the length to width ratio is important for leverage… too wide and/or too short = hard work on the elbow.
Generally too large a bellows also equates to heavy effort of actuation.
A length to width ratio of the Bellows paddles that is somewhere close to 2:1 will be found to be comfortable to use.
Thank you very much for the comments everyone! And a special thank you to Geoff, I appreciate the insight of such a skilled pipemaker.
One question for clarification however. You mentioned airflow, and how this is different when comparing playing just a chanter versus playing the chanter with the drones running and regulator work. In a case like this, where there is more airflow (more reeds requiring more air) is a larger capacity bellows a better idea, or doesn’t it matter as much as I think it might? I don’t have regulators yet, but I surely feel the difference in pumping when I am playing just the chanter versus when I flip the drones on as well, and to me it would seem that having a larger capacity bellows may be an advantage. Again, this may be just in my head, so I defer to the knowledge of the experienced (and appreciate the time you’ve taken to wade through my questions!!)
More ‘airflow’ is more air exiting the bag and there is a great difference between that for a practice set and a full or half set. A larger Bellows will only increase to effort needed to re-fill the bag and, as Rory says, the bag will need to be further emptied before a full sweep of the bellows will bring it up to the ‘almost full’ position.. which by the way should never be exceeded on the Uilleann pipes…( some types of pipes use the stretch in the bag material to create the pressure for operating the reeds but those are bagpipes that use one pressure to blow all the notes… very unlike the UP)…
One basic problem that needs to be dicussed is that when a person starts to play the UP they usually , these days, begin with a practice set… NOW!,… because the good chanter reed uses very little air there is virtually no ‘practice’ for the new piper in the pumping and squeezing department… what then happens is that the reedmaker can allow the use of a much heavier (Wind consuming Reed) to be fitted to the practice set… this is not a critticism of the reed maker/pipemaker but it can happen because that reedmaker is a player who is used to blowing a full or half set… so what appears to them to be normal airflow is often too much for just one reed… the beginer is going to push and shove at that reed so perhaps a tougher one is a sensible idea… sensible but should be used with caution because…:
When the new piper has gotten used to the heavy blowing reed… and has got plenty of exercise on the elbow muscles… he/she now wants the other bits (drones and regs)… the heavy airflow chanter reed needs to be balanced with heavy and loud drone reeds… and eventually the Regulator Reeds… this all can become too much effort… very quickly… I do it myself Every Time… new set new chanter reed now going nicely… lets see how the chanter plays with the new drones… Opps still too strong…
So, coming back to your question… you must seperate ‘airflow’ and ‘pressure’ and simply do this by thinking of the speed that your elbow moves at a constant-ish pressure… the velocity of your elbow… very slow with just the chanter… faster with the drones going… pressure similar.
A wider Bellows paddle will be harder to press to obtain the pressure required to overcome the pressure in the bag and thus allow the blowpipe valve to open.
A longer Bellows paddle will have greater leverage and make it easier to obtain the pressure you need… however if it is too long then it will start to get in the way of things… like the back of your chair and the drones (or stock)
SO, a compromise has to be found; my Bellows paddles are 10 1/2 inches long and 5 3/8" wide. Rebated 1/4", total hinging distance 10 inches… opening 9 1/2".
In the end, I think, that paddle width more quickly effects the effort required to achieve a certain pressure than does any changes in length… I’ve not measured this but…
One other point to keep an eye on, that would help to makes pumping a little easier is the position of your arm on the side of the bellows. Your arm should be back as far as it can go ,away from the hinge. It understandable to think of the bellows sides as a lever and that longer sides make pumping easier but the principles of leverage don’t apply , because the force (your arm) is directly over the resistance (The air in the bellows) . For example if you think of a bellows like a nut cracker, for the nut cracker to work the nut(the resistance) is placed as near to the pivot point (the hinge) as possible and your hands(the force) is placed at the end of the handles .The amount of leverage is the distance from the nut to your hands. If you imagine moving the nut right under your hands you would find it very difficult to crack the nut as the leverage advantage is lost.
To explain why its important to have your arm back as far as it will go on the bellows, if you again think of the nut cracker ,this time the nut is placed under the arms at the wrong end, as far away from the hinge as possible and you place your hands about half way along the arms, near the hinge ,now try and crack the nut.It would be very difficult if not impossible. I’m sure there’s a word for it but its like negative leverage. The same principle applies to the bellows. If the restraint around your arm is not designed well ,your arm will move nearer the hinge as you apply force and this makes pumping harder and if the bellows sides are too long and you have your arm the end of the bellows where it should be, its going to stick out to far .
Great info guys, thank you! I appreciate the measurements you’ve provided as well Geoff, very insightful. And Rory, it’s a great point you bring up, one that makes perfect sense (almost like a ‘duh’ to me) but that somehow I’ve never really thought about before in regards to bellows.
I’ve been working on a large capacity bellows in my free time, as my current set don’t move as much air as I’d like. I’ve played around with making sure my joints are air tight, valves are sealing, no leaks in the bellows itself, the connector hose and joints are solid, etc. but it still feels like it’s under-performing (takes a lot to fill the bag, and I feel like I’m flapping away like crazy while playing even just the chanter).
My paddles are stepped, and the inside step (where the gusset will be attached) is 11" by 6 7/8. I’m going to try a ‘musette-style’ spine with inlet and outlet which, for my body type at least, positions the bellows against my body such that my arm naturally falls over the back of the paddles, which should help make pumping easier with maximum leverage.
A master I ain’t, and I’ve been going with my gut on this, combined with past research and personal experience. But I’m enjoying this project and the insight that I’ve been gathering into the instrument, the bellows component thereof, and the very helpful comments and input from those who know what they’re talking about
By the sound of your comments in the previous post I would say that unless your current bellows is very small then you ARE leaking or your reeds are gluttons for air.
Test; take your Bag and remove chanter and drones and block up the outlet holes with Corks or something air tight… inflate to FULL (by bellows or mouth) .. then sit on the Bag.. your full weight…
The bag should remain Full !!
Leo Rowsome talks (in his Tutor book) of being able to play a complete tune with the Bellows disconnected… OK that might be a bit extreme but “flapping about” is really not neccessary and nor should an over large Bellows be either.
