Ideas?: Executing the side stripe on this Martin & Coupa

[n~dl]

This one's got me stumped, I'm hopin' some of you could spitball some ideas and we can figure this out! http://www.vintagemartin.com/MartinCoupaSpanish.html



Join the sides before bending? They'll just come apart under heat and moisture. Join (or at least glue) them after? Gluing bent ribs to bent marquetry sounds like an impossible nightmare. You can see in this picture here that they're at least three separate pieces with some extra reinforcement in the way of hefty side braces:



Inlaying them like a back strip would probably leave the ribs too weakened for bending.

I putzed with the idea of doing it like this with a layered up sheet of veneers...



...but it would require some kind of elaborate jig or something to keep the ribs in line, and would result in lots of weird variation between end grain and quarter surfaces on the stripe, and just seems too elaborate and insane an idea to work and...i don't know!

Thoughts?

[P Bill]

I think the easiest way would be to groove the sides before bending and inlay after closing the box. A few tests wouldn't hurt.
Alignment at the tail block gets more precise.

[n~dl]

I think the easiest way would be to groove the sides before bending and inlay after closing the box. A few tests wouldn't hurt.
Alignment at the tail block gets more precise.

Yeah, the more I think about it this seems like the most viable option, given that the long with-the-grain channel routed out doesn't just split on you when you bend or glue it. And then still I worry about sanding the veneer thin enough to see through after you've leveled out the sides for the binding routes, and finally finish sanded all of it. I'm still impressed at this being pulled off the way it was in those photos; those old builders must have been born with chisels and planes in their hands.

All the building I'm doing now is for school and I unfortunately don't have much time in the course for trial and error, so this one will ultimately have to wait.

[P Bill]

It looks like one of those things a builder wouldn't want to repeat very often. All your stars in alignment.

[Bob Connor]

Send an email to Howard Klepper. He does this sort of stuff and more. You can find him with a Google search. He used to hang out on the OLF but I haven't seen him around there for a while.

Regards

[n~dl]

Ah yeah! I've seen his guitars with the crazy dovetailed tops before. I'll definitely sending him an e-mail since I don't think C.F. Martin is checking his these days.

[kiwigeo]

If the stripe is to be purely decorative then keep it simple and do it as an inlay. Id do the inlay the same way I'd do an inlay along a back join. The channel would be routed and inlay glued in while the side is flat and then bent with the side. If heat from bending was a potential problem I'd bend the side after cutting the channel and then glue in the inlay.....same process as doing a purfling glue in.

[Allen]

My first thought is to rout it out and inlay it with HHG as a flat. Then bend it.

I bend bindings with purflings glued on with HHG all the time. Never had a worry doing this.

[simso]

Looking at the picture, it definetly looks like two different pieces of rosewood, you could cheat by routing and inlaying the centre and then simply egg white the bottom rosewood and z-poxy the top this will give the appearance of two different pieces of rosewood being utilised, the egg white will give a very light natural colour and the z-poxy will give the darker almost indian rosewood colour

Or just bend up the sides and put a couple of veneers over the top, wouldnt surprise me if thats actually what they had done at manufacture


All tricks to the eye

[simonm]

Both the construction picture and the first shiny picture clearly show two sets of wood being used. Most likely the whole idea is a case of need being the mother of invention. The need for deep sides with narrow boards. The construction image shows a large number of particularly solid side reinforcements no doubt to ensure the whole thing holds together.

I imagine that if you use a full outside mould, and a fox type bender, it shouldn't be too difficult to build this up piece by piece.

[Nick]

With the advent of side forms and heating blankets, repeating the shape accurately is a lot easier these days, it wouldn't be altogether impossible to form the side. Doing a channel and inlaying is definitely a good safe way of doing it but if I was to attempt it I would have a go by making up a side by taping all the pieces up side by side 'dry' then wrapping them up and bending them with a form and blanket. I would imagine that they would come out close enough that once glued up, a quick scraping would flush everything up?

[kiwigeo]

With the advent of side forms and heating blankets, repeating the shape accurately is a lot easier these days, it wouldn't be altogether impossible to form the side. Doing a channel and inlaying is definitely a good safe way of doing it but if I was to attempt it I would have a go by making up a side by taping all the pieces up side by side 'dry' then wrapping them up and bending them with a form and blanket. I would imagine that they would come out close enough that once glued up, a quick scraping would flush everything up?

There is a similarity between what you describe above and what happens when you build up the body of a lute. In the case of a lute the ribs and intervening strips are individually bent and then glued up over an internal mold. Once out of the mold paper reinforcing strips are glued along the inside of the rib joins.

[Trevor Gore]

Check out the side inlays on the Torres FE08. (Just google it - lots of images). Quite a few replicas of this guitar have been made and at least one (the only one I know how it was done) was inlayed flat, then bent. That maker bent the sides by hand on a pipe and said it went quite easily. So, given the relative simplicity of this side inlay, I don't think that it would be too difficult to inlay first, then bend.

[n~dl]

Thanks everybody, some great ideas. Time permitting I ~might~ actually try this seeing as I have a billet I can cut out some more side wood if the first attempt fails. Now I just need something long as straight enough to act as a guide for the laminate trimmer...

[Crafty Fox]

This is all assuming that the sides have to be made from solid; would it not be simpler to make a male/female mould and build the ribs from (2 or 3) veneers, inlaying the stripe between the external veneers as you go? The 3 external pieces can be held in place with veneer tape.
I've built a few resonators by laminating the ribs. I suppose it depends on whether you are looking primarily for the appearance of the stripe or for the tone of the instrument?

[hutton99]

Sorry for my late response to the thread, I saw it for the first time yesterday.

I have actually seen this particular guitar and a number of other Martin & Coupa guitars with the two piece sides.

The sides are in TWO pieces, the purfling is not inlaid into the side. The sides are sometimes book matched so there can be little doubt that the sides are in two pieces. The joint is supported by a silk "gimp" strip glued over the joint. As well there are a number of elegant "wishbone" braces around the inside periphery of the guitar that tie into either the top or back (but not both) braces and keep the sides in place.

I have some interior photos if someone can explain how I can download them.

The two-piece side Martin & Coupa guitars seem to be from the 1842 to 1846 period. I have no idea how Martin assembled them. It would seem, however, that the back or top was used as a template to build up the sides (otherwise I can't see how Martin could have installed the "wishbone" braces).

[auscab]

We would Like to see your pictures ,thanks .
There is a thread in the tutorials section that describes the photo loading . It was started in 2008 and the last post was in 2012 down the bottom of the page. I'm pretty sure the early posts are out dated and the later ones down the bottom are right .

viewtopic.php?f=5&t=669

[hutton99]

Attached is a photo of the interior of a Renaissance-shaped Martin & Coupa period guitar sold by Gryphon Guitar in the last couple of years.

The shot of the interior (also by Gryphon) is the best I have encountered (mine are not nearly as good) so I thought I would use it as an example.

This guitar has a 5-strut fan brace that probably places it in the 1842-1843 period. It does not have a Martin & Coupa label (only those
Martin guitars sold in New York received the M & C label).

You may notice that the kerfing is made of individual blocks, not a strip of kerfing. I understand this is a typical feature of Spanish guitar construction from the period. Other Martin guitars have quite crude-looking kerfing blocks (widely spaced and of irregular size and shape).