colins
Luthier / Guitar Maker
Posts: 2,397 
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Post by colins on Oct 18, 2018 13:22:26 GMT
Do you use side supports with these linings? Sometimes, sometimes not. I have never been a builder who believes that they do much good anyway, the old Martin tape system probably does something, but overall I think that side supports do virtually nothing in stopping side split propagation. Just a bit of a comfort blanket really, but a lot of customers expect them. Never use them on classicals, as classical players are used to no side supports, just some short brace blocks. |
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Post by Alan J on Oct 18, 2018 16:03:44 GMT
That’s the approach I took. I started with 19mm linings will reduce them as I radius the edges.
I opted to go for the continuous linings at the bottom but I take your point about the end pin. I like the idea of the continuum and will engineer an end block to take account of the potential weakness.
Saw your Brazilian rosewood guitar on another thread. “Wow” just “wow”
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francis
C.O.G. 
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My main instrument is: Whatever I'm building...
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Post by francis on Oct 18, 2018 19:33:57 GMT
Having bent my sides and fitted the neck and tail blocks I shape the front and back edges of the sides to the radius required for the front and back plates (on radius dishes), then add the laminated linings. I usually uuse three laminations of limewood or mahogany leaving the linings just proud of the edges so they can be sanded back to the correct profile.
I keep the neck and tail blocks full height but chamfer back the inner edge until I have the same contact width as the linings.
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colins
Luthier / Guitar Maker
Posts: 2,397
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Post by colins on Oct 18, 2018 19:52:51 GMT
Francis does basically the same as me, I don't chamfer the edges of the tail block, but see no reason not to if you want. I roughly shape the back edge profile before bending, mainly to remind me to bend the sides in opposite directions, the straight edge of the top is put along the edge of the bending form to keep everything squared up. Once bent I use my side profile template to mark the full back and side profile which I then plane to shape. Head and tail blocks are then glued in and the rim set sanded to profile with the radius dishes. The laminated linings are glued on just proud of the sides and then planed and sanded to profile in the radius dishes. So as I said basically the same as Francis. I've done this for something over 100 guitars so it is probably quicker to do it than to describe doing it. But to quote one of the great characters of string instrument making, the Padma, "whatever gets the pig clean", in other words whatever works for you.
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francis
C.O.G.
Posts: 2,483
My main instrument is: Whatever I'm building...
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Post by francis on Oct 19, 2018 6:07:11 GMT
I place the sides over the radius dish with each end supported on wedges to level/true things up and scribe around the top edge first, plane that down where required then turn everything over, re arrange the wedges to give me the correct heel / tail heights over the radius dish, then scribe round again to give me the back profile - image shows my high tech gauge block working off the back's radius dish.  |
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colins
Luthier / Guitar Maker
Posts: 2,397
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Post by colins on Oct 19, 2018 8:57:43 GMT
Back in 2006 I posted a tutorial on using the mould and radius dish for making side templates over on the Official Luthiers Forum. There had been a thread on there that went into great detail on how to calculate the profile, this involved a series of fairly high level calculations. I thought that as usual the simplest technique that'll get the job done was the way to go so I devised this method. www.luthiersforum.com/forum/viewtopic.php?f=10102&t=8117%22In all my years of academic work I have probably never had a piece referenced and reposted as much as this post. Colin Colin |
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Post by Alan J on Oct 23, 2018 14:31:53 GMT
So I went ahead and fitted continuous laminated linings onto some sides.
Pros: the frame is incredibly rigid. There is hardly any flex when the frame is squashed either top to bottom or across the lower bout. So much so that I could attach the top and the back with having to keep the frame in a mould.
Cons: glueing the laminated in situe was reasonably quick. Tidying up the glue over spill with tools and papers was incredibly time consuming. I wanted to make sure that the depth of the lining was constant around the rim. This meant routing the inside of the frames linings. Very messy.
Next step: I will build the continuous laminated linings outside of the frame about 22mm thick. Then use the profile from the 3m radius dish to preshape the upper and lower edge of the rim.
Thanks for the ideas.
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francis
C.O.G.
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My main instrument is: Whatever I'm building...
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Post by francis on Oct 23, 2018 21:38:35 GMT
Alan JLaminate your linings and clean them up before you glue them to the sides - run a router round the inside edge and finish them with a little radius...
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colins
Luthier / Guitar Maker
Posts: 2,397
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Post by colins on Oct 23, 2018 22:12:21 GMT
Yes as Francis says you need to laminate the linings prior to installing in the sides, you'll need to make a dedicated linings mould mine are cork lined to ensure tight glue joints. the non glue edge of the linings is then rounded off. Only then are they glued into the bent limbs, very little glue clean up is needed just any slight squeezout. Check this recent build thread and you'll see what I mean. acousticsoundboard.co.uk/thread/9234/hb9-prize-guitar-build-threadColin |
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Post by Alan J on Oct 24, 2018 9:46:56 GMT
I saw that walk through. Beautiful work.
Here’s my difficulty with laminate linings for the back plate.
My guitars have a 15mm taper on them from bottom to the neck. They also have a 3m curved radius. Any laminate I build has to be 15mm + 16mm = 31mm deep to glue to the sides square and flat. Obviously you can’t lay laminated linings on the diagonal to the sides as they won’t fit flush.
31mm is enough would to make two sets of linings of course. I am investigating the idea of putting 5mm steps into the laminates yo make allowance for the 15mm taper.
Or am I missing something?
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colins
Luthier / Guitar Maker
Posts: 2,397
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Post by colins on Oct 24, 2018 14:02:39 GMT
I feel that you are overthinking this, I use a 10mm-15mm taper and a 4.5m back dome. I just make my linings 18-20mm and glue them in, this one has a 12mm taper and 4.5m back radius.  Colin |
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Post by linn on Oct 26, 2018 8:46:40 GMT
Aha! Side struts.
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Post by Alan J on Oct 26, 2018 8:58:07 GMT
Hee hee. I needed side struts on mine too. Just boxed up the guitar with laminated sides and I have to say I am a convert. I can’t say that the guitars tap response is any better but the fitting of both the top and back felt so much more inflexible because of the rigid sides. Cutting out rebates for the bracing was quick and simple as there was no need to protect the kerfs which fall apart when cut at angles. Thanks colin |
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colins
Luthier / Guitar Maker
Posts: 2,397
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Post by colins on Oct 26, 2018 9:31:25 GMT
On this one yes, see my answer above. I personally believe they are just decorative, like frets above 7 for a lot of players, but some end users expect them.
Colin
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Post by Alan J on Oct 26, 2018 10:05:44 GMT
I used to think that. This last box I put together had incredibly warped sides with bulges and dips nearly 1mm deep. The struts made it sit up straight again.
Probably a bit too much steam during the bend!
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Jo whoever he is.
