Boring thoughts

[Steampacket]

Found a couple of articles in FOMRHI Quarterly : Quarterly No. 55 April 1989 regarding the measuring of flute bores - prehaps of interest:

http://www.fomrhi.org/uploads/bulletins/Fomrhi-055.pdf
“BORE MEASURING: I told you a while back about a bore-measuring machine which Tom Lerch brought here from Berlin, which had a wider range to its bull.55 , p. 6 probe than Rod Cameron's, was more stable, and had an electronic digital read-out, rather than a chart recorder. Herewith as a Comm. is a note by Its inventor, describing this machine In passing but concentrating on his newer model, which puts the information into a computer. To my mind, this Involves one of the major disadvantages of Rod's machine: more clobber to carry about, more space to set It up, more things to go wrong. What attracted me to the simpler version was that it all went into a box about the size of a renaissance basset recorder case; long enough to take a base about a metre and a half long and less than 10cm wide and deep. There is also a very considerable price difference between the two versions! The simpler version costs about 2100 DM, and the computerised one about 11,000 DM (plus the cost of a PC-compatible computer of course); neither price is definitive since the former is subject to inflation, etc., and the latter machine is not yet completed. One reason that I asked Mr.Evald for more Information about the device is that, like Rod's machine, It makes very light contact with the bore of the instrument. The ideal is no contact at all, but while this Is theoretically possible (for example with ultrasonics), the equipment necessary is wildly expensive unless you happen to work in a hospital which has already got it, and I don't know how portable It is. In this Imperfect world, Rod's and Evald's machines are by far the best and safest ways of measuring bores that I have yet met. I Just wish I could afford to have one of them here. “

S. 28
High Tech in Instrument Making
by Stephan Blezinger et Jesper Evald
A major problem in investigating and building woodwind instruments is the examination and control of the bores. Be it the unharmful, however precise measurement of a historical instrument, be it the production control of a new instrument in comparing with a master - until now, no measurement equipment was available, which could fulfill all reasonable requirements as to accuracy, reliability, innocuousness and ease of use. A promising method of measurement, using a thin spring as a mechanical sensor, converting its deformation electronically and plotting the measurements on a paper recorder, until now had serious problems in use, as those early equipments suffers from electronic and mechanic wavering as well as severe unstability of the adjustment. The technique has, however, now been improved by the undersigned manufacturer, eliminating the problems mentioned. A series of these new equipments has already shown their value in praxis, giving stable and reliable measurements results. They comprise a measurement sensor rod connected by a cable to a handy electronic unit, giving a direct digital readout in millimeters.
Together with some instrument makers, this equipment is now being further developed in order to have an augmented version, connecting the electronic measurements results into a computer and providing automatic traction of the sensor rod. The advanced equipment retains the good stability and measurements reliability of the handheld version and in addition offers further comfort of use, such as automated measurements and organized storage, together with a series of facilities for drawings on paper and comparing different measurements with each other.
The standard maximum mearuring depth is 95 cm, however it may be made to other requirements also. With the standard sensor rod, the smallest measurable bore diameter is approximately 6 mm. A miniature sensor allowing measurements down to a narrow 4 mm is under development. Upwards, practically no limit exists, as any measurement range (each with a span of 20 mm) may be selected by mounting a correspondingly sized auxiliary feet on the sensor rod.
The electronics for control, sensor signals conversion etc. are all build into one box, which is connected via a standard interface available on any computer.
Personal computers have in the last few years found widespread use, also among instrument makers. As no modifications to the computer are required, lowering the costs by reusing an existing computer is quite feasible without impacts on its normal use. The personal computers which have found the most extensive use, are the IBM PC compatibles. This is not the least due to attractive pricing and a large selection of quality software. Furthermore portable computers of this type are available today at reasonable prices. Using such one, it would be practicable to carry the whole equipment around. Thus it has been decided to write the measurements program for PC's and compatibles, running under MS-DOS. However, if interest exists, the program could be rewritten for other types. The program to be installed on the PC is very easy to use. It takes care of all low level functions such as detailed calibration, control of the mechanics and storage of the measurements, and provides the user with error-proof high level command options. Some of the more advanced functions of the program are - Manual input of existing measurement data. - Simple calibration by known-size test rings. - Organized storage of measurements on floppy disk or hard disk. - Printout on the screen or on paper as tables in different formats or as drawings. - Comparison to any reference measurement. - Transfer of the data into standard PC programs, e.g. spread sheets, for further advanced analysis. - Intelligent guidance of the user. In order to keep the cost of the new equipment on an affordable level, also for smaller instrument makers, it would be advantageous to spread the development costs (most of which concern the computer program) over a number of units. For this purpose, the manufacturer and the instrument makers involved so far have agreed to invite further interested parties to join the group, thus gaining lower price with increasing number of units. This subscription club will be closed for further members at a later date. For orders hereafter the manufacturer will set the price. For further information, please contact:
Jesper Evald Kasernenstr. 9 D 5300 Bonn 1 FRG. 00 -n 0 E o e J 5 Telph. international: + 49 228 639856

[Feadoggie]

That is sssooooooooo 1980's!

Here's what's happening these days - micro-computed tomography. http://today.uconn.edu/blog/2014/11/the ... struments/

Interesting how things have proceeded in such a short time. But basically greater computing power and better scanning methodology. 3D reproduction is the new bit.

Cheers.

[Steampacket]

"Here's what's happening these days - micro-computed tomography. http://today.uconn.edu/blog/2014/11/the ... struments/
Interesting how things have proceeded in such a short time. But basically greater computing power and better scanning methodology. 3D reproduction is the new bit. "

Yes, this blog was discussed three weeks ago on FB's Flute History Channel. As Jem pointed out there the bores being measured are not in their newly made original condition. Years of use, wood movement, shrinkage, etc. means there will still be limitations and guesswork needed as to the what the bore original specifications were even using this new 3D technology.