Valve Shapes & Materials
Posted: Sun Dec 06, 2020 2:54 am
Over the past few days I've spent a lot of time experimenting with valve materials and shapes. Mostly in relation to my multi-valve Gasket-Valves for chromatic harps, but the principles apply to single valves also.
Most harmonica and accordion valves are made of two parts: the flexible valve itself resting on the reedplate, and a stiffer spring above it, which returns the valve to a flat position after being activated. Generally the valve has some under layer which is slightly textured and preferably soft, to reduce capillary attraction and noise.
Diatonic harps only require 'sitting valves': that is, ones which sit down naturally with gravity, on the upper surfaces of the reedplates. They're either on the inside of the draw reedplate, or the outside of the blow reedplate. In these positions, soft flexible valves work fine without a spring, because they always return to the flat position under their own weight.
In chromatics, half the windsavers are βhanging valvesβ, mounted on the underside of the two reedplates, fighting gravity to return to the flat resting position. Valve materials which are fine in diatonics won't necessarily work well in chromatics.
For example, PT Gazell's thick Ultrasuede valves work well in diatonics, but are too floppy and heavy to function as hanging valves in a chromatic harmonica. For chromatics you either need two-piece valves with a spring, or a light material with enough inherent springiness to combat gravity and return even the longest lower valves to rest on the underside of the reedplates, over decades of hard playing!
Whilst two-piece valves work well enough, I'm always searching for the perfect one-piece valve solution. It's not easy to find!
Some contenders are laminated valves: two materials with useful qualities, springiness and softness, bonded together. Wally Peterson came up with a good combination many years ago: thin Mylar sheet stuck to Micropore medical tape. Mylar (a trade name for Polyester sheet) is thin, springy, and wants to return to its flat original profile. Micropore is soft, flexible, and conveniently adhesive, so you just stick it on the Mylar and cut valves out of it. He's been selling single valves in this laminate material for many years.
For my Gasket-Valves I also prefer to choose a one-piece option. Whilst they can be designed to be made with separate valve and spring layers, keeping cutting simple as well as maintaining the smallest overall thickness are both important criteria. Laminates can work, but they add complexity, time and hassle to the manufacturing prices. So I prefer to stick with one-piece valves made of a single material.
Finding the ultimate single valve material is a fascinating, never ending quest! It has to combine several desirable qualities together - mainly the right amount of springiness, plus a textured surface to avoid capillary attraction. Few materials fit the bill.
One interesting option was found by the late great Doug Tate, co-designer with Bobbie Giordano of the highly innovative Renaissance chromatic harmonica. He cut his valves out of bakeware liners! They're composed of non-stick Teflon covering a thin fibreglass weave, so you get both of the main desirable qualities of good valves in one.
(To be continued...)
Most harmonica and accordion valves are made of two parts: the flexible valve itself resting on the reedplate, and a stiffer spring above it, which returns the valve to a flat position after being activated. Generally the valve has some under layer which is slightly textured and preferably soft, to reduce capillary attraction and noise.
Diatonic harps only require 'sitting valves': that is, ones which sit down naturally with gravity, on the upper surfaces of the reedplates. They're either on the inside of the draw reedplate, or the outside of the blow reedplate. In these positions, soft flexible valves work fine without a spring, because they always return to the flat position under their own weight.
In chromatics, half the windsavers are βhanging valvesβ, mounted on the underside of the two reedplates, fighting gravity to return to the flat resting position. Valve materials which are fine in diatonics won't necessarily work well in chromatics.
For example, PT Gazell's thick Ultrasuede valves work well in diatonics, but are too floppy and heavy to function as hanging valves in a chromatic harmonica. For chromatics you either need two-piece valves with a spring, or a light material with enough inherent springiness to combat gravity and return even the longest lower valves to rest on the underside of the reedplates, over decades of hard playing!
Whilst two-piece valves work well enough, I'm always searching for the perfect one-piece valve solution. It's not easy to find!
Some contenders are laminated valves: two materials with useful qualities, springiness and softness, bonded together. Wally Peterson came up with a good combination many years ago: thin Mylar sheet stuck to Micropore medical tape. Mylar (a trade name for Polyester sheet) is thin, springy, and wants to return to its flat original profile. Micropore is soft, flexible, and conveniently adhesive, so you just stick it on the Mylar and cut valves out of it. He's been selling single valves in this laminate material for many years.
For my Gasket-Valves I also prefer to choose a one-piece option. Whilst they can be designed to be made with separate valve and spring layers, keeping cutting simple as well as maintaining the smallest overall thickness are both important criteria. Laminates can work, but they add complexity, time and hassle to the manufacturing prices. So I prefer to stick with one-piece valves made of a single material.
Finding the ultimate single valve material is a fascinating, never ending quest! It has to combine several desirable qualities together - mainly the right amount of springiness, plus a textured surface to avoid capillary attraction. Few materials fit the bill.
One interesting option was found by the late great Doug Tate, co-designer with Bobbie Giordano of the highly innovative Renaissance chromatic harmonica. He cut his valves out of bakeware liners! They're composed of non-stick Teflon covering a thin fibreglass weave, so you get both of the main desirable qualities of good valves in one.
(To be continued...)