Hi Thalatta, and welcome. Like many of your recent queries, there are plenty of old threads (pun taken advantage of!
) on this topic. Do check out the forum search facility. I know I’ve described my methodology here before somewhere. Here it is again:-
Thread Joint Lapping – a quick guide
Traditionally joint lapping is done with a loosely spun linen (flax) or hemp thread, waxed before or during application. If you can get it, use it. Bagpipe makers seem to use it and have no trouble getting supplies, but I have never been able to find a reliable source of such thread – the linen threads one can usually find at haberdashers are usually highly twisted, quite thick and hard “button threads” which are not suitable for this use. Apparently (though not unexpectedly) it is not immune to swelling with moisture, according to a bagpipe website I perused recently. Therefore, for many years and with good success (and no ill effects to any flute) I have used embroidery “silk” thread – actually pure cotton. This is readily available in an infinite variety of colours from any haberdasher. The only drawback I have ever found with it compared to linen is that it is less durable – a frequently used joint will need the lapping renewed every 3-4 years as eventually the thread wears out. I have never had problems with it swelling. It comes in small 8 metre skeins. The thread consists of 6 lightly twisted strands (themselves being medium twisted 2-ply threads). If you care about the finished colour, choose a colour several shades lighter than you’d like as the grease will darken it considerably
I proceed thus:
First, unravel the skein of embroidery thread and make sure it is tangle-free. Separate the six sub-threads into two groups of three at one end and split the entire length (being careful to run the twist out and not to tangle). An assistant to hold the ends you start from, or a door handle or nail on a wall or some such is necessary. Coil up the two triple threads around your hand (or wind onto a bobbin of some kind). Now you are ready for the flute.
Make sure all traces of old lapping have been removed from the tenon and clean it. Apply some cork grease (from any woodwind supplier/music shop) to the trough/combings on the tenon and spread it. Start to wind on the thread by laying the starting end diagonally across the tenon and, starting from the inward end, winding over it to secure it (the grease will help, but the first few turns are tricky). No tying or glue is necessary. Always hold the joint of the flute in your left hand and wind over the top of it away from you (i.e. clockwise around the tenon when viewed end on). Use moderate tension, but not excessive – you need the thread to seat firmly but not to constrict the tenon. If the tenon is “combed” (has turned grooves), start by laying a turn of thread in each groove systematically. If it isn’t combed, just lay the thread neatly side by side until you have completed one layer to the outer end of the trough/combings. Now apply a generous layer of cork grease and spread it around. Lay the turns of thread at the extremities of the lapping a little tighter than the rest as they have to resist the drag of assembly/disassembly more. Work your way back down the tenon with another layer, filling in the gaps if covering combing grooves. Now grease again and check how you are doing by test assembling the joint. Always hold the section in your left hand still and introduce the tenon to the mortise, twisting the section in your right hand over and away from you (in the same direction as the lay of the lapping thread) as you push the parts together.
It is unlikely on most flutes that you will yet have a snug joint, so apply more grease and add another layer, continuing to grease, test for fit and so on until you have built up a sufficient lapping. Be careful to keep the profile of the binding flat/cylindrical (unless the mortise tapers inwards, in which case you will have to work out the correct lapping profile by eye and test-fit) and test frequently. You want a snug, even, but not over-tight fit, that does not rock laterally. If you lay too much thread, just unwind it back beyond where you will need to finish and re-apply it spread more widely – the last layer/turns need not be laid completely systematically side by side but adapted to achieve a good fit in the mortise socket. You can add thread to just a little beyond the point where the joint assembles easily as it will compress a little over the first few days of use, but don’t make it excessively tight or you risk cracking the socket. Never force a joint together with more than moderate firmness! If it won’t twist on with only moderate resistance, take some thread off. Check the surface is even and not convex or concave by observing the grease on the surface – if it doesn’t soak into the thread evenly, or if the joint rocks when assembled, you need to unwind some thread and re-lay it. Be liberal with the grease, and continue to be so for the first couple of weeks as the thread will continue to absorb it.
To finish the lapping, you need do no more than grease the end of the thread down when you are satisfied with the fit. Try to have the final turns of thread towards the middle of the lapping. Should you need to remove or add some thread as the joint settles, you can just scrape up the end with a fingernail. It is unlikely to start to unravel, especially if you assemble the joint correctly as described above (never twist against the wind of the thread). If you need to add more thread after cutting an end, the best thing to do is to unwind about 50cm of thread, cut it off and start laying on a new, longer piece, binding over the ends of the old and new pieces as you did at the start.
When you have a completed lapping you are happy with and that has settled in for a week or two, you can do a more permanent finish if desired by unwinding about 50cm and rewind it laying the last 6-10 turns over a looped spare piece of thread with the loop pointing towards where the lapping will finish, then put the end of the last 5-6cm of your working thread through the loop you have bound over and carefully pull on the other ends (held together!) to draw the working thread-end under the last few turns of the lapping – pull it clear and tug it tight, then cut it off flush. That won’t unravel, but isn’t easy to adjust! (I don’t usually bother to do this any more.) A mid-way alternative – more secure than a free end but less so than a whipped-over one - is to lay in two half hitches in the last couple of turns of thread, making sure they lie in the same direction as you were winding.
Good luck!
(P.S. I didn’t write this anew for this thread - it’s a text I had saved on my computer.
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