http://au.youtube.com/watch?v=OKKhx89MCqs :eek:

Nice work... what praytell might you be doing in the bass?

That's some chunk left on the tailblock! :crying:

ok, what about this:
http://au.youtube.com/watch?v=r5oJk3Q-lr8

is this a common repair technic?

Geez Matthew, now you've wrecked it! :D

That's some chunk left on the tailblock! :crying:

yeeearrr it is isn't it? I was going OK until I got there. Well it's a nice clean chunk, will glue OK, and there's plenty of wood left on the plate ...

What am I doing to it? Well, the bass is just too bright, so I'm regraduating the top.

And this tells me something:

http://farm4.static.flickr.com/3206/3050079714_ab23d3b9f1.jpg

ran it backwards so it had a happy ending :D +1 on the aklop music

Were you in a hurry because of the camera running? Or maybe that restless music??

That's some chunk left on the tailblock! :crying:

Wow. I didn't see that earlier... :eek:

When I was looking at the video my wife said 'That sounds like your working music!'

I listen to the local French FM station 'Radio L'Espace' and they play a lot of of French/African jazz. Nylon guitar, accordion, double bass and percussion, all with killer groove - now you're working......:)

yeeearrr it is isn't it? I was going OK until I got there. Well it's a nice clean chunk, will glue OK, and there's plenty of wood left on the plate ...

What am I doing to it? Well, the bass is just too bright, so I'm regraduating the top.

And this tells me something:

http://farm4.static.flickr.com/3206/3050079714_ab23d3b9f1.jpg

I am curious, what am I looking at here? It almost looks like a sand pattern from testing for the vibrational anti-nodes.

http://au.youtube.com/watch?v=OKKhx89MCqs :eek:


Excuse my ignorance, but is that the "right" way to remove a double bass top??

I would like to know how to do it some day, and I have heard of using moist heat, white vinegar, etc to help loosen the seams first.

That just looks a little rough.

I am curious, what am I looking at here? It almost looks like a sand pattern from testing for the vibrational anti-nodes.

yes almost. Except it's tea leaves. What does the pattern tell you about the lower bout?

I'm not sure whether there's a "right" way to remove a top. I wasn't rushing; in my other life I was a film editor, so i know how to compress time. I only filmed certain bits, and edited them together so it looks like one quick jobbie. The different music tracks will give you an indication of the amount of time I spent on it. And I knew this one was glued on thinly, so knives and wedges were adequate can-openers. It sounds rough, yes, but I was only using gentle finger pressure on the knives. Hide glue makes a frighteningly loud crack when it pops!

Perhaps I could have spend some more time on the lower block with a hot palette knife, but I didn't, and the chunk is clean and (I hope) will easily glue back!

Matthew knows what he's doing - that chunk will glue back in there just fine.

Watch Rene Morel pop the top off a beautiful 1853 Vuillaume cello exactly how Matthew did it, here: http://ca.youtube.com/watch?v=zDGphZaQoSw&fmt=18

yes almost. Except it's tea leaves. What does the pattern tell you about the lower bout?

That is an interesting quiz question. I can only speculate. It seems that the upper portion of the plate is divided into one wide area, and the lower bouts into two independent areas. Their relatively small area suggests to me that they are not doing much sonically.

So, do you want that lower pattern to look more like a horizontal line than a vee?

What's the next step? How do you come up with a strategy for correcting something like that?

I know but I am not telling ...yet...and so does Matthew.

Matthew did get some fft's on that one before and after and a weight for the record?

Yes I got a weight but no FFT plot. That's YOUR thing! I find it less telling than the Chladni patterns.

The Strategy comes from a whole lot of things; the weight, the stiffness, the bass bar, the shape, the arching, the current graduation pattern, the chladni patterns, the frequencies of the first five modes, the coriolis effect ... and whether to use darjeeling or lapsang souchong.

Some luthiers consult the warts on a FU QUA (http://www.talkbass.com/forum/showthread.php?t=490182) and take their lead from that.

But I'm leaning towards lapsang souchong for now ... ;)

Yes I got a weight but no FFT plot. That's YOUR thing! I find it less telling than the Chladni patterns.

The Strategy comes from a whole lot of things; the weight, the stiffness, the bass bar, the shape, the arching, the current graduation pattern, the chladni patterns, the frequencies of the first five modes, the coriolis effect ... and whether to use darjeeling or lapsang souchong.

Some luthiers consult the warts on a FU QUA (http://www.talkbass.com/forum/showthread.php?t=490182) and take their lead from that.

But I'm leaning towards lapsang souchong for now ... ;)


...you are giving it all away, what if the Chinese get this information.

...you are giving it all away, what if the Chinese get this information.

It won't help. China is in the northern hemisphere, so the Coriolis effect is of the opposite polarity. :D

...and who has the most tea? Huh?

Keep us posted on your progress. Looks like a worthy project.

Matthew knows what he's doing - that chunk will glue back in there just fine.

Of course one would rather not pull large chunks out of the soft top plate. You never feel good damaging your own (or somebody else's) craftsmanship. I find it helpful to work from the inside to the outside around the blocks, and also to use a solvent to loosen up the glue bond. I routinely spend an hour or more getting the top loose at the end blocks, and there can still be damage. I say these things not to be a told-you-so, but to try and help others with this gut-wrenching task.:)

i have a question. is it better to remove the chuck and glue it to the top or leave it as it is untill you glue the top back.

I watched that Morel video with chagrin. He's removing the perfectly quartered top of a valuable cello which will most certainly have had weak hide glue used to fasten it, whereas I get to take the top off a CCB with questionable wood or an old Kay that's had loose seams fixed with Gorilla Glue! Ah well...:(

Oh man... Matthew,
I was grinding my teeth watching that.

Subscribed so that hopefully I can get the caveman version of what's up with the tea leaves. :)

No wonder it's expensive to get the top taken off. It's just cuz it's agonizing for the luthier! :eek:

ok, what about this:
http://au.youtube.com/watch?v=r5oJk3Q-lr8

is this a common repair technic?

Who's gonna explain this one? I'm totally baffled.

I think what he is doing is cleaning up the crack so he can glue in a small strip of wood to close the gap. I'm not a luthier so I can't say for sure, but that makes the most sense to me.

Who's gonna explain this one? I'm totally baffled.

Matthew's opening up a separated crack so as to be able to put a splint in the slot. Its not really feasible to make a 20 thou filler strip - its easier to widen the crack to a point where a thin slice of wood can be fitted.

Its still not easy.......

Matthew's opening up a separated crack so as to be able to put a splint in the slot.

hey, that's not ME!!

But it could be ... :D

hey, that's not ME!!

Sorry Matthew, the video style was so similar I made an unwarranted assumption. :(

And yup, it could any one of a number of us bass witch doctors! :D

cameo? had you pegged as a lefty;)

So what does the Chladni patterns tell you, Matthew?

Would the node still reach the lower block, once the piece that stayed on the block has become part of the top plate again?

I wonder - would you be able to obtain these Chladni patterns, while the bass is still in one piece? Or are they specific for just the plate by itself?

And finally, why could you not drop a matrix-dremel-ultrasonic-graduating tool into the bass while it is still glued together, and get your graduating done that way?

Keep us no longer in suspense - it is killing me!

Well actually, like Ken, I'm keeping my interpretation of the Chladni patterns to myself for a while. Soz!

They are just one more way of measuring the properties of the top. They mean little by themselves.

An explanation is that this is the lowest vibration pattern that shows how stiff the plate is along the grain. If you look at the photo, you can see the frequency written down next to the plate.

It takes some talent to be able to make the tea leaves dance so things become that clear with a bass top.

The first time I saw Chladni patterns, the edge of the plate was excited with a violin bow. You know what that means...

French or German? Black hair or white? Soft or hard rosin? Pernambuco or carbon? Etc. Etc.

I asked about removing a top because odds are I will need to do that myself one day and would like to know how.

I play ply basses so I suppose it might not be quite as nerve-wracking. :confused:

I am not in the right tax-bracket to be able to pay a luthier to do most of my repairs, so I am studying bass luthier techniques out of necessity and personal fascination.

I will tackle most repairs and upgrades myself, except for fingerboard planing which I leave to the pros.

I am not in the right tax-bracket to be able to pay a luthier to do most of my repairs, so I am studying bass luthier techniques out of necessity and personal fascination.

I will tackle most repairs and upgrades myself, except for fingerboard planing which I leave to the pros.

I'm right there with you. Got two projects going. One well, the other less so, but both are a chance to learn. Thankfully folks are kind enough to offer advice.