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 Post subject: Bending machine caul
PostPosted: Sun Nov 05, 2017 7:12 pm 
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Walnut
Walnut

Joined: Wed Jul 29, 2015 12:40 pm
Posts: 30
First name: Richard
Last Name: Bello
City: Weymouth
State: Ma
Zip/Postal Code: 02189
Country: Usa
Focus: Build
Status: Amateur
I made a "universal caul" out of thin wood strips which works OK but I've seen others that use a metal loop which seems like a great idea and might conform better to a variety of waist/cutaway shapes - can anyone who has gone this route volunteer what kind of metal they used? I was thinking spring steel but I don't know what gauge would be appropriate so it was rigid enough or even if this is the right choice. Thanks.


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 Post subject: Re: Bending machine caul
PostPosted: Sun Nov 05, 2017 7:42 pm 
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Koa
Koa
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Joined: Mon Jul 27, 2015 8:21 am
Posts: 806
First name: Brad
Last Name: Combs
Focus: Build
Status: Amateur
What I did was use a 2x2 piece of oak stock and marked the radius on each end of the board. Then used the belt sander to sand the contour onto one side of the board. On the other side (the flat side) I put threaded inserts. Then I drilled two holes on the top plate that was originally holding together the thin wood strips for the “universal caul”. That makes it easier to swap out for other shapes. I’ve noticed the waist bends turn out much better because the caul fits the waist of the body mold exactly.

Don’t forget to glue a couple small wings to the sides to keep the caul aligned in the registration channel.

I saw someone here that did this, which is where I stole it from.

Hope that helps.

Brad


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 Post subject: Re: Bending machine caul
PostPosted: Sun Nov 05, 2017 8:12 pm 
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Koa
Koa

Joined: Thu Nov 04, 2010 1:46 pm
Posts: 868
First name: Freeman
Last Name: Keller
Focus: Build
Status: Amateur
I do something entirely different. Instead of making a "universal" caul I make a different one for each size and shaped guitar that I build. Since I am going to make an external mold for it anyway, when I cut out MDF or plywood for the mold, I keep the "innies" to be my bending form. For example, here is a Weissenborn in its mold

Image

and the bending caul

Image

I also use the caul to bend all my wood bindings

Image

As far as the metal slats, they are just two pieces of spring stainless steel.


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 Post subject: Re: Bending machine caul
PostPosted: Sun Nov 05, 2017 8:24 pm 
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Koa
Koa

Joined: Thu Nov 04, 2010 1:46 pm
Posts: 868
First name: Freeman
Last Name: Keller
Focus: Build
Status: Amateur
Here is the same idea, completely different guitar (ES-175 style). Bolt four pieces of MDF together with flathead bolts and cut them out on the band saw. Sand the thickness of the sides off of one or the other

Image

Make a body mold with a little gizmo for the Florentine cutaway

Image

Make a caul for the bender

Image

When I put them away I just put the caul back inside the mold so they'll be together for the next time


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 Post subject: Re: Bending machine caul
PostPosted: Sun Nov 05, 2017 8:41 pm 
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Walnut
Walnut

Joined: Wed Jul 29, 2015 12:40 pm
Posts: 30
First name: Richard
Last Name: Bello
City: Weymouth
State: Ma
Zip/Postal Code: 02189
Country: Usa
Focus: Build
Status: Amateur
Freeman wrote:
Here is the same idea, completely different guitar (ES-175 style). Bolt four pieces of MDF together with flathead bolts and cut them out on the band saw. Sand the thickness of the sides off of one or the other

Image

Make a body mold with a little gizmo for the Florentine cutaway

Image

Make a caul for the bender

Image

When I put them away I just put the caul back inside the mold so they'll be together for the next time



I was actually talking about the caul/ram at the end of the press screw, not the form itself but it turns out that your bender has exactly what I was referring to. Is there something solid inside the metal loop that you change out for different forms or is it stiff enough to conform without collapsing? I'm trying to figure out what the correct material/gauge would be.


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 Post subject: Re: Bending machine caul
PostPosted: Sun Nov 05, 2017 9:56 pm 
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Koa
Koa

Joined: Thu Nov 04, 2010 1:46 pm
Posts: 868
First name: Freeman
Last Name: Keller
Focus: Build
Status: Amateur
Rbello wrote:

I was actually talking about the caul/ram at the end of the press screw, not the form itself but it turns out that your bender has exactly what I was referring to. Is there something solid inside the metal loop that you change out for different forms or is it stiff enough to conform without collapsing? I'm trying to figure out what the correct material/gauge would be.


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My bender is a commercial Fox style, the waist caul was on it when I bought it. Frankly I've never paid much attention to it - it is wood with the sheet metal covering. I have never changed it and I bend everything from parlors to fairly large guitars - it seems that once I have set the two holders for the upper and lower bout that simply screwing it down brings the side totally into the waist. It most definitely does not conform to the curve of the waist. I also haven't paid that much attention to the little metal covering - it was on when I bought it and its worked fine ever since. I would assume that it is not spring steel, probably just some 22 gauge stainless.

Remember that thing is pushing down on a fairly thick sandwich - the side has kraft paper on both sides, then the stainless slats top and bottom, then on top the heating blanket.

I'll add that I do not have the Venetian cutaway bending option for my Fox bender - I simply don't do cuts on acoustics (the 175 was a special case and the cut was done on a hot pipe).

I would be happy to take a closer look at the waist caul and take some pictures of it, but as I've said, it just works fine so I've never given it much thought.


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 Post subject: Re: Bending machine caul
PostPosted: Sun Nov 05, 2017 11:11 pm 
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Contributing Member
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Joined: Sat Jan 31, 2009 8:50 pm
Posts: 1240
Location: Seattle WA
Focus: Build
Status: Semi-pro
I have a Blues creek bender and it has .022 ss. It used to have a 1.5" wooden dowel inside but I took it out. Seems to conform to the waist a little better. Still plenty rigid.


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 Post subject: Re: Bending machine caul
PostPosted: Mon Nov 06, 2017 3:34 am 
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Mahogany
Mahogany

Joined: Mon Oct 31, 2011 8:50 pm
Posts: 40
First name: Bob
Last Name: Howell
City: Atlanta
State: Ga
Focus: Build
Status: Amateur
I made a Fox bender and tried a wooden caul shaped by eye. It caused problems so I made one with out of galvanized roofing flashing, loop, as shown somewhere. Same material I used for metal slats. Works much better.


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