R the F
Luthier / Guitar Maker
Posts: 1,135 
My main instrument is: bandsaw
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Post by R the F on Jan 10, 2017 22:56:27 GMT
I’ve started to build a guitar which is based rather loosely on the carefully laid plans to be found under the heading, Ramblings/Plans. What’s changed? Well, the adjustable neck fittings have been modified – refined, I like to think. And now there’s going to be a space between the body and the heel just like a Howe-Orme so that eliminates the need for all the navels (or holes in the body and heel):
 
I’ve also decided to do the decent thing and join it up at the 14th fret but I am also going to compensate for this slightly (in terms of neck length) by shortening the scale to 630mm; that seems to be a nice finger-picking length anyway – though I’m happy to be contradicted if anyone has strong feelings. The sound-hole may therefore have shifted position very slightly and the new position of the bridge has necessitated a slight tweaking of the bracing plan, though it’s fundamentally the same as usual i.e. using the bridge as a “stressed member” (if you’ll excuse the expression) to avoid the need to have a cross-over of the main braces and allow a little flexibility in the middle of the soundboard.
Here then, for comparison, is the last plan (left) and the latest plan (right):
 
The first thing you need to make a guitar is something to help shape the soundboard correctly and, when you’ve got a big ridge down the middle, that’s a bit special. I carefully cut the ribs from lowest class of plywood thus:
I then made my first mistakes of the build – and notice I haven’t even started to make the guitar yet. I needed something thin, fairly hard but flexible to provide a skin over the ribs. My first thought was 1.5mm plywood but nobody sells it round here and it was going to cost quite a lot in delivery charges so I went to an excellent place in Cambridge where they sell any kind of plastic you can imagine. I picked up something which might do the job, I thought, and stuck it on the ribs with Evostik. It felt just a tad too soft and spongy:
So I swallowed my pride and bought the plywood. When it arrived I couldn’t really work out how to clamp it to the ribs since it was right at the limits of its flexibility following the curves down the middle. So I gave up on that too and got a piece of door (Douglas Fir) and ran it through my table saw cutting off 2mm strips. Then I spent an age removing the Evostik. Finally, I glued these strips across the ribs side by side using hot-hide glue because of its ability to grab and hold – its “tack” – without real need for cramping in place. I hope that will do the job when it's sanded a bit smoother:
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ocarolan
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Post by ocarolan on Jan 10, 2017 23:33:01 GMT
Good to see this one underway Rob! 630mm is indeed a very usable scale length.  May your member never be over-stressed. Keith |
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Post by nkforster on Jan 11, 2017 16:20:43 GMT
You've an uncanny ability to make life complicated Rob! I made my first HO top former with a parallel hump (like yours) but I did it on the tablesaw or the router (I forget which) from a sheet of thick mdf. It was very easy. Then I quickly sanded out any ridges from the machining. If this one doesn't work out, give that a try. All the best everyone! Nigel www.nkforsterguitars.com/steel-string-guitar/ |
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 11, 2017 18:17:00 GMT
I sort most things out in my head whilst running and, unfortunately, I've had a slipped disc and a heavy cold/flu over Christmas so only got back to running on Monday. That's why it didn't occur to me to use my table saw on a sheet of mdf. From now on I'll be efficiency incarnate, Nigel.
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 11, 2017 22:41:01 GMT
Well, perhaps just one more snag before the plain sailing... I ran out of my spray adhesive half way through attaching the sandpaper to my newly prepared and sanded soundboard-former:
Still, not to worry; after all I didn't have a soundboard to form yet. But I had a door and I set about taking it apart so that I could get at the meaty bits; very close to skilled butchery in fact. Here are the best cuts and joints:
  
As you may be able to see, I've used the bottom board (bottom left in the first two pictures) which I've sliced into three with a combination of table saw and hand saw. I'm using the outside slices for the soundboard and I've cut them quite thick to make sure I can get through any surface stains that might be lurking under the paint. I will come to regret the fact that they are quite so thick - about 8mm - when I come to plane them down to their final thickness. But first they needed gluing together:
I've come clean here; yes, that is a bottle of yellow glue aka aliphatic resin aka Titebond Original. I felt I had worked enough unreliables into the plans without needing to worry too much about glue as well and, I'm afraid, this stuff is pretty reliable as long as you don't want to reverse it (= unstick it). I believe I've described the contraption for attaching the boards elsewhere but nkforster has done it best here. It was only when the glue had gone off that it really dawned on me that I'd bitten off more wood that I could chew:
Getting 8mm down to 2mm takes a lot of planing and sanding. I was up to my knees in shavings by the time I had finished but here's the result:
 
You might even be able to make out the outline of a guitar body on the first picture. If you're wondering, then it is true that this is quite thin; it's at or just below 2mm but it has to be around that to be pliable enough to follow the corrugation without splitting - and that's what I am soon going to ask of it. Well, when the spray adhesive arrives....
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leoroberts
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My main instrument is: probably needing new strings
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Post by leoroberts on Jan 12, 2017 9:32:37 GMT
Just occasionally, Rob, your build threads read like a Donald Trump press conference LOL
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 12, 2017 10:30:34 GMT
That's fake and despicable as all good folk know and I won't be responding to any of your posts from now on, Leo.
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 12, 2017 10:36:59 GMT
Just occasionally, Rob, your build threads read like a Donald Trump press conference LOL |
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 15, 2017 11:26:24 GMT
Well, the glue turned up and I sprayed the sandpaper ( ) and stuck it down with a roller on to the contoured board:
though it will, of course, peel off so that it can be replaced. It's rather critical to get the braces exactly right since they dictate the shape of the corrugation so I clamped straight guides to the board in order to sand accurately:
 
It has occurred to me that the logical way to go about bracing a soundboard with a central ridge or corrugation is to go for ladder bracing; i.e. side-to-side bracing which follows the curve on to the flat areas of soundboard (as in the drawing in a previous post labelled "crossbrace"). However, I wanted to retain my normal bracing pattern and I have to adapt that to help retain the contours of the soundboard. The drawing below has, marked in orange, all the bits of bracing and blocks which help to form the corrugation and you will notice there is a rather big gap between the head-block and the braces coming up from the bridge area:
There is also a bloody-great hole in that part of the board and it's hard to corrugate a hole. With this in mind, I have decided to reinforce the hole. Now, you may say, surely it is standard practice to reinforce the hole. Well, so it is but this is normally done with an extra layer of soundboard material around the hole or some such and there is no reason for this to play ball and follow the desired shape. I have decided to reinforce the hole vertically, by which I mean I want to line the edges of the hole with a shaped ring which has a depth of, say, 10mm and will hold the rim of the hole at the correct contour to follow the corrugation. This will be tricky but I have calculated the shape it needs to be before being bent into a ring:
At the moment I'm wondering whether to laminate this or cut it from solid wood; the problem is that the solid wood might not want to bend that far at that thickness especially where the grain runs out at the edge of the wavy line. I'll have to play it by ear. However I end up doing it, it will be quite an interesting feature to have a raised rim around the hole which will also extend inside the box for a little distance. I like the idea.
All this talk of lining holes and I haven't got a hole to line yet, you cry. Well, you're wrong and here it is:
This board is very thin at <2mm and I was worried first about cutting out the guitar box shape on a bandsaw since the violence of the cut can cause thin wood to split along the grain at some points and, secondly, about cutting out the hole with a router without even using shellac to help hold together the grain around the hole; remember, I don't want traces of anything around here which may inhibit the gluing of the reinforcing ring. I solved both potential problems by cutting accurately round the lines with a scalpel; I cut right through the soundboard outline thus avoiding the bandsaw altogether and scored it deeply before offering it up to the router. Anyway, here's a final picture or two of the result of routing:
 
(These also provide a timely reminder that the sun does sometimes shine.) Anyone about to spend a fortune on a Stewmac precision hole-cutter (other precision hole-cutters are no doubt available) should note that the set-up consists of a nail knocked through a piece of shuttering ply (underneath the board) and a number of holes of a matching diameter drilled into the base of my router. (The trick is to find the right hole!) The lighting doesn't actually help but what you can see is a 12mm(?) ring-channel routed out leaving a disc of soundboard in the middle and the rest of the soundboard standing proud. And yes, they've a right to stand proud having endured the dangers they have endured....
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 17, 2017 22:25:28 GMT
Not much progress mainly because of people wanting their chairs mended and their tables polished but I did draw some lines on the inside of the soundboard:
Obviously these will help me to locate the correct positions for the braces but I can already foresee some problems; even with all the braces fitted, there is a line straight down the middle of the soundboard with nothing to guide it into shape until the rim (with head and tail blocks) is added and the soundhole is reinforced and the bridge is glued on the other side. Once they are added, there shouldn't be a problem but I'm a bit worried about leaving it flopping about with all the strain on that central glue-line - only 2mm thick - until that point. Maybe some kind of temporary bracing to hold it together until it's attached to the sides? Anyway, for the time being I decided to do a dry run in the go-bar deck; yes, I'm afraid it's not even glued yet, which is what I mean by "not much progress". Sorry. Anyway, here are some pictures to give you an idea of how alarming it looks when it's coaxed into its final shape. (Be aware that the cross-braces at either end are only there to help hold it in position; they will not be part of the final glue-up). First with only a few of the braces in position so that you can see a bit more:
And then with a forest of bamboo (and the rest of the braces):
If this works out, I don't see how I can avoid calling it "spider bracing" since it's looking more and more arachnic with each guitar I make. More specifically, I notice the braces are still rather wider than they need to be so I'll trim them down before I stick them.... maybe tomorrow (but there are other jobs I need to do...)
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 20, 2017 19:23:09 GMT
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Post by ashley on Jan 23, 2017 21:39:45 GMT
Rob, that is really quite incredible! Is the soundboard profile the same as a Howe Orme guitar?
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R the F
Luthier / Guitar Maker
Posts: 1,135
My main instrument is: bandsaw
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Post by R the F on Jan 23, 2017 22:13:48 GMT
I hope "incredible" is a good thing! God knows how much like the Howe-Orme profile it really is. It's the result of me drawing a line that looks more or less like the bottom end of a Howe-Orme type guitar and thinking to myself, "Yeah, that's about right". That then gets turned into an arc and regularised a bit and incorporated into a drawing of one of my previous guitars and, hey presto, I find myself turning it into a wooden thing. Thanks for your interest, ashley .
(It does also sometimes occur to me that one ought to be able to produce a guitar which, while it doesn't necessarily sound very good, looks so interesting that it would be worth the money just to hang it on the wall alongside other works of art - of the painted or sculpted kind. I'd also like to think people would pay the same sort of money for it, too!)
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Jo whoever he is.
