Double Bass Grofiller Bass project

[ctregan]

You'll want to get that upturned iron mounted in a nice stable wooden box before too long![/QUOTE

I got the idea from a famous Australian luthier's web site.

 

[ctregan]

Making sure mould is square (flattest table i could find).
Mould portrait.

 

[ctregan]

1st discovery; the longer the ribs soak in water, the less likely they will burn on my bender.
30 minutes soaking, then I try bending. Still have to work on my methodology.

 

[ctregan]

Glued rib stock to MDF board with week hide glue.
Sent both through my planer to get 2.5 thick ribs.
Rib stock comes free of MDF with heated iron, after milling is complete.

 

[Matthew Tucker]

Gosh that looks like a heavy mold.

I'm building a three piece mold for my next bass and I'm trying to work out an economical way of makiing it stronger and lighter. At the moment the design is like yours; a big cheese! But I haven't cut the middle out yet.

 

[ctregan]

I switched from the Grofiller to the V. Panormo plans. We decided a D neck Bass would work out better for Orchestra playing- the Grofiller was Eb. The mold in the pictures is for a Panormo Bass.
It is still early in the building process, the change did not effect much at this point but we cant change things around now.
Three months into this project and have not made any parts of the bass yet. This week I may try to build the blocks.....

 

[ctregan]

Gosh that looks like a heavy mold.

I'm building a three piece mold for my next bass and I'm trying to work out an economical way of makiing it stronger and lighter. At the moment the design is like yours; a big cheese! But I haven't cut the middle out yet.

Its a double decker for support in the middle; Overbuilt, I hope it does not become clumsy wile making the Bass.

 

[Matthew Tucker]

Have you seen this pattern from Josf Krattenmacher?

Link Removed

Its a bit the inverse of your design, which is hollow in the middle.

I'm trying a similar approach - design my clamping points opposite extremities and inflections, then work out where to attach the sides of the mold to each other, then trim away as much of the surplus as I dare.

Actually, Chandlers original design isn't half bad. Certainly quite light.

 

[Jeff Bonny]

Not having done it myself there may be a perfectly obvious reason that would present itself if I did but wouldn't it be as effective and save a lot of space and even effort to build three separate outside patterns for the sides?

 

[Matthew Tucker]

I can't see how it would save space, time OR effort!!

 

[Jeff Bonny]

Three templates that when not in use would nest together used to bend six ribs wouldn't take less room to store and to work with?
Clamping....say a bout onto an independent smaller template just for that seems like it might be less trouble. You generally don't bend all six ribs at once do you?
Intuitively I want to bend something to an outside curve rather than force it to an inside curve which is why I ask about an outside template.
But then if I knew I would be telling you, not asking wouldn't I? Explanations of where my thinking is faulty very much appreciated.

 

[Matthew Tucker]

The mold exists to hold the blocks in place and to check the curve of the ribs and to stabilise them while the whole thing is being built up and glued together. Until the linings are glued the ribs are very fragile.

The mold is not just for bending, in fact in most cases bending is done separately on a bending iron. On my first bass, I used a heat-blanket and bent the ribs directly onto the mold.

You could build an outside mold, but it seems to me it would be bigger, waste more plywood (if you use plywood), the amount of cutting would be the same and it would take about the same time to set up. And both can be collapsed flat when not in use.

Apparently outside molds are more suited to production line use, but as I haven't tried one yet I have to go on what I'm told. KCStrings use outside molds for assembling the basses, but bend the ribs using heat blankets onto separate rib forms. But that's a production line.

Attached is a pic of my new mold in progress, three layers of ply shaped and with clamping positions sketched in. Tomorrow I'll remove the centre sections, then setup the layers with strategically placed spacers.

Try to work out where my corner blocks will be attached. Careful ... trick question.

Also attached is pic of my matured glueing station for you!

 

[Jeff Bonny]

Apparently outside molds are more suited to production line use, but as I haven't tried one yet I have to go on what I'm told. KCStrings use outside molds for assembling the basses, but bend the ribs using heat blankets onto separate rib forms. But that's a production line.

Ok, so I'm not completely out of my mind. The inside template once explained though does seem MUCH more practical for one at a time production. Hmmm, I should probably buy the Peter Chandler book and quit asking so many dumb questions.

Attached is a pic of my new mold in progress, three layers of ply shaped and with clamping positions sketched in. Tomorrow I'll remove the centre sections, then setup the layers with strategically placed spacers.

Try to work out where my corner blocks will be attached. Careful ... trick question.

I've been staring and thinking for about 20 minutes (I even put my new bifocals on) and I see a couple of ways but I doubt I see the most elegant and functional solution.....
I'm eagerly awaiting the progress to some explanatory pics!

 

[Damon Rondeau]

The Chandler book is good for visualizing. A good photo essay is better, I think. There's Matthew DownUnder's work, with which we're all so luckily familiar, but there's also that British guy. Hoskins? Hitchens? Higgins? Something "H". Anyone got the link? The link used to be at Bob G's page, and probably still is...

 

[Bob Branstetter]

The Chandler book is good for visualizing. A good photo essay is better, I think. There's Matthew DownUnder's work, with which we're all so luckily familiar, but there's also that British guy. Hoskins? Hitchens? Higgins? Something "H". Anyone got the link? The link used to be at Bob G's page, and probably still is...

It is Hitchings.Link Removed his website.

 

[ctregan]

Skilled luthiers seem to use minimal moulds that are uncomplicated.

 

[Bob Branstetter]

Skilled luthiers seem to use minimal moulds that are uncomplicated.

Skilled luthiers use what ever works best for them. Some are very simple, and some are very complicated. Even though there are only two basic styles (inside and outside) in general use, many variations of each are being used daily in shops around the world.

 

[arnoldschnitzer]

Skilled luthiers use what ever works best for them. Some are very simple, and some are very complicated.

Exactly right. Many bass makers, among them Daniel Hachez and the Krahmer Brothers (Pollmann) don't use molds. I don't use one when I make my "Ergonomic" style bass.

 

[Matthew Tucker]

So what/how do you/they use to keep the corner blocks in position fot glueing? A base plate with the blocks fixed to it?

 

[Don Harris]

Does not using molds create less built-in stress? Interesting...