Postholes tapered, not pins!

Irish Flute
1

Some time back I commented, in response to someone attempting to pull apart a post-mounted flute, that to be careful, as some have tapered pins which have to come out one particular way.

Jem responded that he hadn’t come across that, which put doubts in my mind. Today I’m working on such a flute, so I investigated further.

Seems the short answer is that we were both right (if this flute is typical). The pins are not (originally) tapered - they appear to be just under 2mm diameter, presumably to be a smooth but free fit in a 2mm tube. That makes sense; you wouldn’t want the whole pin to be tapered.

It’s the holes in the posts that turn out to be tapered, well, at least different. Each post in a pair has differently sized holes. The pin is a loose fit in one and a tight fit in the other. In the loose fit hole, the pin will pass through easily. In the tight fit hole, it will only just enter the hole and stop. Both ends of any pin will enter the tight hole about the same distance, and enter about the same distance from either side, which suggests that the tight hole is cylindrical, and that the tip of the pin has been tapered or chamfered just enough to allow it to start in the hole. Hard to be sure of course, because both hole and pin tip will have been modified by the pin having been pressed firmly in.

So, at least on this flute and others I have dealt with, there is a definite direction for the pin to enter, and thus leave by, and not much to tell you what it is. Fortunately, it seems it’s mostly intuitive - ask yourself if you were pushing these pins in, which direction would you want to approach it from and go the other way. Otherwise, look for an end to a pin that looks minutely smaller, and tap from that end to remove.

So that now gives us a further rivettingly-fascinating thing to look for as we dissect our flutes. You guys are sure lucky to have someone like me allerting you to the big questions facing human kind!

(Hope someone is keeping an eye on Global Warming and the US Elections. I’ve kinda got enough on my plate down here at the moment!)

Terry

2

Back in the years when I was a student, long ago, I spent much of my leisure time working with antique clocks, in a clock shop as then run by an elderly gent, and I have had literally hundreds upon hundreds of clocks apart, in my hands. Moreover, many such antique clocks are held together with tapered steel pins, in a number of ways.

That’s not to say that I know anything about the making of flutes, but I indeed can appreciate how such tapered pins could be employed.

:slight_smile:

3

Ahhhh, more typological variants!!! Deep joy!

It does kinda make sense, though, doesn’t it? I haven’t your vast experience - so far all the pillar-mounted flutes I can remember handling have either had screw-ended pins with appropriate pillars, or have had simple push pins that fit quite tightly in the pillars but will push in or out in either direction unless (as is not uncommon) one of the pin ends is burred - they often seem not to be tidied up much from being cut off a wire, or only one end was filed clean enough to go through the pillars freely - and that is not usually a consistent feature on a particular flute, just happenstance. Some are even rather loose at both ends and really only don’t fall out because of the pressure of the spring.

From a practical engineering point of view, it would seem much simpler to drill a slightly tapered hole in a receiving pillar (just need appropriately profiled drill bit) than to create pins with a tapered end (filed off by hand), or indeed pins which are in effect conoid segments (would have to be specially rolled???) - and which would probably cause the pivot tube to rock at one end (not that most of them are that finely engineered anyway - they usually have a fair bit of play even when everything is cylindrical!) unless it was made with a matching taper… In general the engineering tolerances on antique flutes just aren’t to that kind of level - because they don’t need to be! Simple cylindrical push pins through not-too-tight fitting pivot tubes into fairly tight fitting pillar holes (and remember the steel pins are much harder than the cupro-nickel or sterling silver pillars, so a little pressure will stretch a slightly undersized hole to fit tightly around the pin) provide a perfectly satisfactory degree of precision, even quite crudely done, for single action keys.

It is only with the advent of more complex and interactive Boehm type mechanisms that the engineering needs to get significantly better - and even then it was mostly done by hand and eye well into the C20th and still doesn’t absolutely need to be done to clock-making or similar high-level engineering tolerances, though of course in higher end instruments you pay for that kind of attention to detail.