Cast Threaded Brass Tangents
Cast threaded brass tangents are now offered in two lengths, 28mm and 32mm. These tangents are slightly softer than the strings they will be hitting. They are ‘as cast’ and therefore as supplied are in their softest state. The tops are polished smooth, and cut at a very slight angle (highest away from the player, naturally); this should help keep the string in place.
Tangents should be screwed in using a tool of steel with a tapered slot sawn and filed into the end (an old screwdriver is ideal). If the keys are made of a really hard bit of lime it can help if a couple of longitudinal grooves are filed at the start of the thread, like a tap. The only lubrication permitted is tallow, since all other things, (for instance soap) eventually behave like glue; but I don’t recommend using anything. Most of your adjusting for height will be done within a week or so of the instrument becoming stable. Now I know these are not like ‘original’ tangents, but I have never been comfortable with setting or adjusting those either in old instruments or when making new ones; I believe these to be an improvement worth your consideration.
The tangents can if necessary be bent using a steel rod with a hole drilled in the end, but remember that every bend you make work-hardens the brass so that if you do this too much the tangent will eventually snap. Old tangents are more prone to this since for some reason brass becomes brittle with age alone….many English spinets have strap hinges broken where the right-angle bend occurs….. You will have enough spare tangents to try these things out to destruction.
The drill size should be chosen with care, and will to some degree depend upon the hardness of the wood used for the keyboard. Try it out first. The larger bass tangents will require a larger hole. The threads on the masters were 4BA (and M4 for the bass ones), but such is the nature of casting that the size of the cast items will not correspond in any useful way to this information, nor is there sufficient guarantee of repeatability for me to suggest drill sizes.
Ideally the instrument should be strung and the strings tightened somewhat and laced before the positions of the tangents are marked. (The lacing will have to be repeated after proper tuning so that the correct amount of resistance is applied the string band; no-one gets it right straight away.) Marking is done using a long thin sharply pointed scriber passed down between the pairs of strings, held at whatever small forward angle allows the scriber to retain this angle when the key is depressed. The hole for the tangent is drilled at this angle, so measure it; it may vary from bass to treble. This angle helps to keep the strings on the tangent as the string is sounded, under the most extreme amounts of ‘bebung’.
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