Old French Bass full Restoration

[matthew]

For me the Chladni patterns are merely a way of measuring in a pictorial way the flexibility of a plate. The plates all exhibit these "modes" of resonance to one degree or another. The lower the frequency at which the modes appear, the more flexible the plate and vice versa. Each mode means something slightly different, for example the first mode is a twisting mode where at this frequency the top and bottom bouts are oscillating in opposite directions. In the second mode they are moving in the same direction, and the centre of the plate is "pumping" the other way. Third and fourth modes are complex interactions between the first, second and fifth modes. The fifth mode shows the nodes of resonance where the plate is flexing longitudinally.
Obviously the wood is stiffer this way so the frequency is higher.

On their own the patterns mean little. However when you have a number of different plates measured this way you can start to analyse and make some educated guesses as to what and why. For me, luthiery isn't a science; it is a series of educated hunches, and the better your hunches the better you are as a luthier.

What I glean from the fact that the lowest modes are at a higher frequency that the modes on the other basses I have measured, is that this plate is still quite stiff. I already knew this from feeling the plate, but how much i might try to lighten or un-stiffen the plates is a matter of following a hunch, and the more information I have the better the hunch will be..

[matthew]

A bit of progress with cleating the top. There are many ways of doing this, but I prefer long diamond cleats because they make most sense to me; maximum glue contact and flexibility and offset grain. They are a bit tricky to trim without nicking the top, but I've done enough now to be able to do it fairly quickly.



Very sharp blade essential!



Some more trimming will be done before I'm happy. Although this is work that only the angels will get to see I like to make sure it's done neatly.



I might add a few more cleats later or some linen strips depending on how I feel.



Here for comparison:



And here's a video of how i do it:


youtu.be/
Link

[Nick]

You are right Matthew- I can see a sharp chisel is essential! Are the cleats just trimmed to a "what looks right" or to a specific sizing in order not to upset the vibrating board's frequency (or would they create 'false' or 'dead' nodes if too large) ?
By the way, is it just me or is the sound of a sharp cutting tool carving through wood almost 'erotic'?

This is the final re-constructed message of this topic posted by the ANZLF recovery team.

[Kim]

Great save reconstructors

Cheers

Kim

[matthew]

you bet. Wonderful effort.

Chapeau!!




[edit: in response to Nicks last question before the lights went out - the top is so big these cleats are just like flyshit in comparison. Their weight is negligible i think. I just trim them so they are feathered to virtually nothing at the edges and trim the height back to about 2-3mm.]

[matthew]

OK resuming where we left off ...

Back to purfling repairs. Here are the main tools I use:



The job is exceedingly tedious and performed under a powerful magnifier; the original purfling is very brittle and has to be cut back to a suitable point, then the new beesting is cut following the original purfling lines ... and guessing a bit too.



This is the first one I did, and I changed the way I do the scarf joints after this one. But it's OK.





This is more like dentistry than luthiery!

It is difficult to match the edges of the purfling invisibly, even using a scarf joint. In this next corner I decided to make the joint in the purfling coincide with the grain lines; one is almost a butt, the other is a longish scarf.



I think, under varnish, all these repairs will be virtually invisible.

Ah the varnish. How the hell am I going to save the varnish? That's another problem.

[Kim]

I am certain that you are correct Matthew. Once the varnish goes on it will draw the instrument together so that anyone breathing it all in will be hard pushed to notice anything but the awesomeness visual impact of the instrument as a whole. Great work mate

Cheers

Kim

[Nick]

I think on the scale of a double bass, these repairs would be like looking for a hair on a whale Matthew It looks pretty good even close up. If it does become noticeable however, you could always paint the bass purple and dip the edges in sequins

[matthew]

Well, this hunk of timber needs to be replaced. It's going to be a time consuming and messy job pulling it out without damaging anything. I'm going to try to steam it all apart but if this gets too tricky I'll probably end up cutting it out.

[/url]

I found a bit more of the original varnish under a lot of dirt; it gives me the original colour, but there's no chance of recovering any of it on the ribs.



found some more metalwork holding the ribs on. Glad I found these before my blades did.



And yet MORE Metalwork ...



This is the wonderful screw I'm going to keep as a trophy! Pretty amazing that another hole was drilled right through the shank for the bolt that I originally extracted from the back of the button!



Loosening the neck block at the back seam. Look at all that stickiness:



Previous button repair came away. Some of it has been repaired with spruce, and there's a fair whack of putty in there too. I'm going to have to restore the whole button from scratch.



I got the old neck heel out sans trop de dégâts. The tear you can see on the right is the old spruce block that will be replaced entirely. Look at that lovely crack, subject to so much metalwork and dowelling in its lifetime!

[Allen]

You'd be hard pressed to drill a hole that neat in a screw if you tried. Did they do that blind and just got lucky?

[matthew]

Yes, amazing. and I'd say it was accidental. I think it was two separate repairs.

[Nick]

Good job the screw wasn't too tight to remove! Not much metal under the head to drive it out, could of had more work on your hands there Matthew.

[Alan Stassforth]

Mattew, thank you for documenting this fix.
You are amazing.
Looks like it ain't yer first rodeo cowboy.

[Dominic]

Yes Matthew, this is amazing watching you put this thing back together. I am learning a whole bunch of things but mostly what a frigging genius you are.
Keep them coming.
Dom

[charangohabsburg]

This is the most amazing and interesting instrument restoration - fotoreportage I have ever seen!
Thanks a lot for your additional effort sharing those pictures and explaining the restoration steps to all of us!

I have a question on one of your earlier posts:

Back to purfling repairs. Here are the main tools I use:

Maybe I'm just a poor ignorant... I couldn't figure it out: what is that piece of bone for?

[matthew]

You're not ignorant, just observant! I was wondering when someone would ask ...

I found that the edges of the bone have a variety of different curves in them. So I use it a bit like a "french curve" to help me lay out and scribe the line of the purfling. I did tidy the edges of the bone a bit with a file in places. And first, of course, I had to cook and eat the osso bucco.

I'm surprised no-one asked about photo #3 in my last post ...

[charangohabsburg]

Thanks Matthew. Cool idea to use a bone as a small "french curve". This is a really good reason to cook (and eat) osso buco.

[...] I'm surprised no-one asked about photo #3 in my last post ...

The 3rd picture is the one after this comment:

I found a bit more of the original varnish under a lot of dirt; it gives me the original colour, but there's no chance of recovering any of it on the ribs.

I thought the plastic thing in the lower third of the picture was some of those high tech cleaning devices, maybe lent from a dentist's laboratory?

Or are you talking of another picture?

[matthew]

That's the one. Steamer from ALDI. They don't all come with eyes, though.



Do you have wombles where you are?

(And next time i buy osso bucco I'll get the butcher to cut the bones twice as thick so i can use the bone for a nut or something useful)

[DarwinStrings]

I did wonder about that one Matthew but with the way it was looking at me I thought it best not to ask.


Jim

[charangohabsburg]

That's the one. Steamer from ALDI. They don't all come with eyes, though.

Mine is yellow, without eyes, and I use it to glue things together when gelling time is an issue - I know, you are more skilled than me and don't need high tech solutions for ordinary hide glue jobs, as far as I remember you simply use an electric iron...

Do you have wombles where you are?

Maybe, but I didn't know they exist. Which were first, the steamers or the wombles?

[Nick]

That bloody Womble's got a 4001 Ricky! Bet he didn't find that in a rubbish tin on Wimbledon Common! (As the words to their theme tune go "Making good use of the things left behind")

[matthew]

OK guys (and Lillian) I'm just going to insert a catchy lil tune in your brains. See how long it stays there ...

http://www.classickidstv.co.uk/wiki/ima ... e_Tune.mp3

MOOOOHAHAHAHAHAHA!

[Allen]

Dammit Matthew. I'm going to be hearing that in my sleep. I should have know better.

[Lillian]

Sorry to disappoint Matthew, this is the first time I've heard this, so there is no sticking. And it's 4:25 in the AM. Nothing is sticking. But thank you for sharing. And because I like you, I won't post the Barne song.

[charangohabsburg]

I'm just going to insert a catchy lil tune in your brains. See how long it stays there ...

Thanks for that nice melody. It really seems that the wombles never made it to "the continent".
Strange... every time I want to recall now this tune, my head is playing Strawberry Fields, Penny Lane or also a tune of the Cats musical. Very strange.