Monday, 19 March 2012

In spring a young man's fancy lightly turns to.....

.....problems with drains, for the most part, is what has been occupying what I laughingly call my free time. As I speak there's a mini digger and a large hole in my front lawn, and neither seem like going away very soon. Then given that weather has been dry ( Ok, what I really mean is less rain) I've also been occupied with garden chores, which aren't really chores as long as you don't have to do them in the rain.
So today, I finally got around to replacing my very old strawberry plants which produced good quantities of large but entirely tasteless berries, with a new variety, which will hopefully be better on that front.
Then on the flute front, which is why I presume most people read this stuff...... ( thank you seven followers!)
I took the models for the new keys up to the casters in Dublin ( see entries for 20th and 21st Feb). I always like to try and establish a personal relationship with people who do work for me, and in the past I've traveled as far as Arizona to do so. This was a useful visit, as one of the problems with castings can be the way in which the rubber mold is cut open to remove the model, in order that the empty space left can be filled with molten wax. If the seam of the mould passes over the surfaces which on the finished key will be those that bear against the sides of the block, this can sometimes cause problems.
 When the original model is being made, one must take into account the fact that there is a degree of shrinkage...about 4%...between the model and the casting. Also, the amount of material removed when cleaning up and polishing the castings must be taken into account, and one learns just how much bigger to make the model by trial and error...experience, I suppose. But what can affect this hugely, is if the rubber mould is closed slightly "off" then the two sides of what is cast in the this case the wax...will not match exactly. This is normally a very small deviation, but it can add considerably to the amount of material that has to be removed to get a clean surface, and the result is a key which is too loose a fit in the block.
So...this time I was able to explain to the casters which surfaces are dimensionally important on the finished key, and which are not, so these moulds can be cut in a way which won't effect the former.
Meanwhile the dies for the cups are nearly complete, and I expect to have the first castings back in about two weeks.
 I'll post photos of the new keys....won't promise when, mind you.
On a different topic, I have nearly finished the restoration of the Rudall Carte flute which inspired me to post about the issue of pitch some time ago. I'll post a few pics of that when the time comes.

No comments:

Post a Comment