I left you on a half-finished bridge-blank. We now have a wholly finished bridge blank, though a "blank" is I suppose, by definition, unfinished. This is as far as I got before I lost interest in it:
I like to keep a few plates spinning at the same time and I'm trying to appear youthful by shortening my attention span so.... I stopped work on the bridge and moved on to the back. As you may know, I've never fully decided what I think about backs so they seem to change every time I build a guitar; another sign of a young mind. Well, this time is no exception. It's boring old 1.5mm sapele constructional veneer on the outside (again), but on the inside I thought I'd shake things up by having a sheet of 0.6mm oak! I bet that's got you excited. Well, hold on because I haven't finished yet: the grain is orientated side to side!! I have a vague idea that this combination will keep it thin (at about 2mm total) but strong. I may even be right about that. Anyway, here are some pictures to accompany my words.
I began by planing the edges of the two book-matched pieces of veneer:
It's actually less critical here than it would normally be to get an absolutely light-tight join all the way along because they are going to be firmly held by the inside veneer but I nevertheless made an absolutely light-tight join. I then roped it up in my contraption with a little glue along the edges:
All of the planing and cramping has to be done rather delicately since it's only 1.5mm thick and can barely wait for a chance to split; I was delicacy incarnate.
I can't think of any way to avoid the next photo but it is a go-bar deck. I used francis's mini-paint-roller technique for applying Cascamite to both surfaces of veneer - not that you would have been using Cascamite, Francis - and then sandwiched them together between my back-contoured trough and a piece of pliable hardboard:
"That should do the trick," I muttered... And it did; here is the trick, done:
And here are the two sides: inside and outside:
(Can someone explain to me why two photos that went through exactly the same process should come out as different sizes? It's beyond me all this technology stuff.)
And that's where I've got to... except that somewhere along the line whilst preparing the bridge blank I decided I needed to prepare the bridge gluing caul so that I could make sure my blank fitted tight with the caul in place. After all, I've no idea how close to the original plan the curve of the corrugation on the soundboard is by this time so I need the bridge-base to fit the caul rather than fitting the soundboard as it happens to stand. If you follow. So I made a caul:
and here it is:
It's rather organic looking, isn't it? What you might call a "caul of nature". Anyway... I finished the sanding of the bridge-base (foreground) against this rather than against the soundboard itself to make sure everything would fit. And I don't think I've done anything else apart from painting a landscape for my evening class and sanding down the garage-door ready to re-paint it - if we can decide on a colour. Maybe you can help: we're getting new aluminium windows which will be RAL 7033 "cement grey" (what an enticing name). Now we're trying to decide whether you paint your front-door and garage-door the same colour as the window frames or some other whackier colour... You don't have to come up with an answer.
p.s. I should say (to anyone looking for mistakes I might have made) that this was a relatively error-free passage of building... except that the bracing is not absolutely symmetrical and I glued the caul up backwards the first time and had to remake it and also you may also notice that I had begun to round off the back of the caul instead of the front of it but stopped before it was beyond redemption... Nothing has changed. R
There's something else that needs doing before I can stick the back on: I have to install the so called flying buttresses. These will support any attempted movement of the heel - well, the whole neck really - against the strongest part of the sides of the guitar, the waist area. davewhite makes extra sure with his doubled-up carbon-fibre buttresses but so far I've gone for a single pair of wooden ones. Still, the principle's the same. One end is glued into a hole in the neck block and the other end is held by a small block against the waist. Here is one under crampage:
As you can see, the other side is already installed:
I also need to get the bridge glued in place while the back is still open - it's easier to glue with access to both sides and I can pretend to fine-tune the bracing at the same time - so that means a blank will have to be turned into a finely sculpted thing. So far I've shaped the bottom but it's too thick and it's rectangular. However, it's as well to cut all your holes and grooves while it's still a regular shape so that you have some reference points to work from. Here it is marked out:
The string numbers aren't strictly necessary (unless you have a history of accidentally making mirror-image bridges...). Next it's drilled using a 4mm drill-bit whose point has been ground flat so that the grooves have flat bottoms:
To give credit where credit is due, I should say that I used the calculator on the liuttaiomottola website to work out the precise angle of the slots; it's not a piece of knowledge I was born with. Anyway, having drilled, I did a rough trimming job - rough in the knowledge that I was about to slice the top off the whole thing to get it down to somewhere near its final dimensions. But first here is a picture of the rough trim - done with a chisel, not a piece of blunt flint despite appearances:
I now have slots which are the right sort of depth - they come within about 1.5mm of the other side of the bridge in the middle - and in the right sort of place. So at this juncture I sliced a few millimetres off the top and sanded it flat and then cut the shape around the while line; (all done with a bandsaw):
The top will have to be shaped to match the radius of the fingerboard but, apart from that, we're almost there. Unfortunately I do have to polish the soundboard and then scrape some polish off before attaching the bridge but we are getting there. Here's another picture which shows some minor imperfections:
You can't see them? Well, that's very kind of you. You can see them? Well, don't be so critical!
Concentrate! I may have succeeded in not making a mirror image version of the saddle slots but a quick glance will reveal that I have produced a mirror image of the groove and holes into which the ball-ends of the strings disappear. Luckily I noticed before I started drilling any holes but this is what it should look like:
cf the pictures in the previous post in which the paper cut-out appears.
That was a close shave. If you're going to read this, you've got to keep your wits about you and save me from myself!
Pitfall avoided, I next radiused the top of the bridge to match the 16" radius of the fingerboard. You can't really see it but here is the result:
I then started work on the holes down which the ball-ends disappear. These are a bit complicated because they are sloped forward at about 20 degrees so that the ends can't slide up and out when they are under tension and because they also have to have a place under the bridge to accommodate the ball-ends themselves. I started by drilling 1mm holes through as a guide to relate the top face to the bottom. Then I used a flat-ground 5mm drill-bit to finish off shallow holes in the base (where the ball-ends will sit). Finally, I turned it the right way up again and drilled the angled holes right through. Of course, all this drilling has to be done on a piece of wood which is rounded convexly on the top and concavely on the bottom and, consequently, needs to be seated on the bridge-gluing caul on one side and on the radiusing block on the other. If you followed that, you won't need to look at the pictures below:
I then put in some slots along which the ends of the strings run from saddle to anchor-holes:
Then a spot of sculpting to make it look nicer and to remove a little weight:
and here's the other side:
I must admit I've quite impressed myself with this. It's an extremely complicated little component with curves on both sides and angled holes, grooves and slots in just the right places - I hope - and it arrived at the workshop inside a log. colins would be pleased to know that it weighs no more than 24 gms and there's still a little excess to trim off so I should be able to get it down to 22/23. We'll see. I'd better get polishing tomorrow.
I only started it about 6 months ago and you can't rush something like this, Ged. It probably won't actually work when it's finished so you just have to enjoy the process. (They reckon Stone Henge might have been like that; it may not work but boy did they have a great time building it.)
There's not much to say about French polishing so I've taken a few pictures of various points in the process to show you that it's not really that clever. First I sanded the box down to about 240 grit - i.e. pretty fine. I should really have been a bit heavier with the coarser grades because, by the time I'd finished, I realised I'd left quite a lot of dints and dents and little gaps. Ah well, at least it'll look hand-made. So there it was all smooth and dry and along I came with a fad full of polish. (A fad is a folded/screwed up piece of skin-wadding, which is rather like a sheet of cotton wool with a thin almost papery skin on both sides.) Here it is ready to pounce:
And here it is wiping the polish on to the soundboard, coating it in along the grain:
I probably did that a couple of times to make sure I'd washed it thoroughly with a coat of polish. You then go a do something else for a while - though it's touch-dry almost immediately - and then come back and de-nib it. i.e. if you run your had over it you can feel tiny little specks sticking up from the surface and you want to lightly removed these with used 320 grit paper:
Sanding with the grain of course, though it doesn't really matter at this stage. Next you polish it. This means you have a number of sessions forcing polish into the surface - definitely not with the grain but in circles - until you feel soft polish starting to catch your rubber, at which time you leave it for a few hours. In this weather the solvents disperse pretty quickly but ideally you want to leave it so that the thin layer of polish sinks into the grain as the solvent leaves before you do anything else. When the polish has sunk or when you can't be bothered to wait any longer, you sand it flat with 320 or maybe 240 grit paper if you want to be a bit more severe. The idea is to flatten the whole thing off, leaving polish in the grain but probably sanding through to the wood itself on the "ridges". Then you go through the whole process again putting on more polish, leaving it to sink and then flattening it off or "cutting it back". And then you do it again. And again. And as many times as you can be bothered or until you are happy with the finish. Here's a rubber:
It's a piece of old cotton pillow-case wrapped around the skin wadding that you saw before and it's not very damp; just enough to slide over the wood/polish under pressure so that you feel it's gripping and you are forcing an instantly dry layer of polish on to your finish - but not hard enough so that it start ripping off what you've already put on. A bit of a balancing act. If the surface starts grabbing the rubber, stop for a few minutes and try it again. Or just stop and leave it over night so that it's ready to cut back again. Anyway, here's a picture of it at an early stage:
Notice that I'm working on the top and on half the side; you need to leave enough to rest it on and enough to hold it firmly whilst you polish with the other hand. I usually wear thin rubber glove on my left (holding) hand so that I don't leave finger-prints in soft polish if I stray on to a polished area. That's the end of today's little lesson - patronising bastard that I am - and here's where we are:
(I didn't actually notice that white horned creature with the shirt collar when I took the photo. I'd better keep my eyes open next time I venture into the workshop...)
p.s. Don't expect the next French polisher you meet to agree with my way of doing things; there are many ways to skin a wooden thing.
robmc: Oh yes, I imagine her needlework is faultless
Apr 30, 2020 21:55:27 GMT
walkingdecay: I saw her at the Beeb when she was promoting an album called Living In The USA. Can't say I remember much of the music, only that she was an utterly gorgeous pocket-sized Venus. My tongue fell so far it's a wonder it didn't pick up fluff from the carpet.
May 13, 2020 13:28:38 GMT
Akquarius: that was... when exactly? not recently I suppose?
May 15, 2020 13:01:44 GMT
josemarques: hello, about my fast sale it will be only for more a few days, after this I will pack to send it back to Portugal , if you have some question or offer to do please contact me ... chears
May 19, 2020 7:31:45 GMT
walkingdecay: Dolby Atmos is snake oil even if you don't bash your leg up on the stepladder.
May 19, 2020 7:44:47 GMT
walkingdecay: Surround AI is surprisingly good though, so it turns out.
May 23, 2020 7:23:28 GMT
walkingdecay: No rain, fever and fire in the trees.
May 28, 2020 7:20:18 GMT
walkingdecay: Explanation for last. Two fires over the local common, probably resulting from arson, have ensured that self-isolating neighbours have had to keep their windows closed in hot weather. Would also be a good song title, if anyone wants it.
May 28, 2020 14:03:08 GMT