Author: Gordon (NZ)
Date: 2005-12-01 11:04
As Ron indicates, technicians have used a range of glues, mostly of the superglue type or of the solvent-for-abs-plastic type.
Be aware that there are many types of superglues (cyanoacrylate) and while some may work well, others will be useless. Some technicians claim that the result can be stronger than the original material.
I have some reservations, having seen SO many glue failures in all sorts of applications, especially other superglue. Many glue joints wait for a while to mature before they fail. Superglue eventually sets very brittle. I think it is likely to succeed only if it has a solvent action on the plastic and actually welds it together.
So to be certain, I developed my own method of inserting 6 or 7 hidden stainless steel rods, about 1.2 mm diameter and 40 mm long, surrounded with epoxy cement, in 1.4 mm diameter lengthwise holes in the body wall.
An advantage of this is that the glue around the pins is stresses in SHEAR, where adhesives are typically much stronger. I have been able to guarantee the result, and after perhaps over 60 of these, I have never known of a failure. Indeed, many of the joints I have done in this way were tenons, and I have had a few instruments come back with broken tenon sockets, next time those instruments were sat on, testifying to the reliability of this method.
Of course it takes somewhat longer - perhaps 60-80 minutes for me, and is therefore more expensive. It is the detail that makes this a complicated job to do with a reliable result, especially in the middle of a body, so it is really outside the scope of the home handyman.
Perhaps some day I will trust butt-joint glue on its own. :-)
It is interesting that this instrument is a Vito. It is reasonably common for a Vito to break, and this is one of the advantages I have found in Yamaha.
It is also interesting that the break is at the thumb ring. I once encountered a run of several instruments of the same make that all broke here. They were either Armstrong or Artley. They must have been a faulty batch from the factory. My theory is that the thumb tone hole insert was jammed into too small a hole, such that the plastic was highly stressed in the vicinity. Then in cold weather, when the plastic shrinks more than the metal, the stress would be even greater. Then just a little extra force, say during assembly, and the body broke.
Sometimes technicians may get a replacement half body, but often it can be a major job re-fitting the keys to a replacement body, when the model does not have sufficiently standardised spacing between posts. Some keys need shortening and some need lengthening. Repadding may well be necessary too, so it can grow to quite an expensive job.
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