Darryl Keil Last Activity 2025-02-12 2:48 PM
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DavidG

Posts: 2

Joined: 2010-05-20
Location: Portland, OR

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Subject : Compound Curves
Posted : 2010-05-20 10:17 AM
Post #36030
I'm wondering about a project I've got coming up. I am re-veneering the accent pieces on the dashboard of a vintage Mercedes. I've done a bit of veneering over the years. Flat or simple curves. The part of this project that I'm thinking about is the horizontal accent strip that goes across the full width of the dash. For most of that run, it's simply a 2" wide band, slightly ovalized. The troublesome bit is at either end, where that ovalized band also curves around the ends of the dash, and toward the front of the car. This creates a compound curve.

I'll be veneering in a burl.

I can imagine creating - by trial and error - a taped piece of veneer which will then lay down and fill most of the space, then infilling as necessary with slivers of the burled veneer.

I do not have a vacuum setup, but am sorta, halfway looking for an excuse to buy one. OTOH, it seems that I could also use the existing substrate, along with a fabricated female mold-half (probably made with bondo or filled epoxy, with the shape pulled off the existing trim pieces) along with mechanical clamping pressure to squeeze the mold-halves together

So - two issues:

First, can anyone advise me about a nifty way to create the veneer skin to lay down on this compound curved piece, leaving a minimum of voids or overlaps? Remember... it's a burl, so I have a little fudge-room when it comes to not having to line up a linear grain pattern.

Second, is this my excuse to buy a vacuum system, or can I readily accomplish the job with clamps?

Anyone who's done such a project, or who has more veneering experience than I & has thought it all the way through... I'd welcome your thoughts.

Perhaps this topic has been covered here before. IF so, perhaps someone could direct me to the thread?

Thanks!


 
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Don Stephan

Posts: 825

Joined: 2003-07-18
Location: Cincinnati, Ohio

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Subject : RE: Compound Curves
Posted : 2010-05-20 6:45 PM
Post #36033 - In reply to #36030
I'm confused a bit about the curve (but I'm over 55 so it's understandable). Is the curve like a compound bow, where the piece is perfectly vertical along its length, or is there more to it.
Regardless, I'm not sure where you'd need infill, unless the dash is like the surface of a sphere.
If you used the existing dash as half of a mold, wouldn't you be changing radii between the existing and new pieces? If so, not sure if the new one would fit.
You might be able to make a negative mold of the existing dash, and then use that negative by itself to make a new dash. In theory you could do this with lots of clamps if you add a number of extra plies on top of the glueup to spread out the clamping pressure. Sounds like a job for several octopi.
Just some knee jerk thoughts.
Don Stephan


 
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Darryl Keil

Posts: 1454

Joined: 2003-05-22
Location: Maine

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Subject : RE: Compound Curves
Posted : 2010-05-21 9:05 AM
Post #36036 - In reply to #36030
David,

Like Don, I don't know the exact shape you are trying to conform to but there are very successful techniques you can perform with a vacuum press for this type of work.

First, you apply a veneer softener to help with flexibility. Then you massage the veneer right through the bag as it is being pulled down. You do this in stages, draw some vacuum until the bag starts to bend the veneer, stop the pump and massage the veneer with a small wallpaper roller. Repeat this process three or four times in stages, pump on, off, and massage, until the veneer has fully conformed.

If you are using walnut burl, which is the common choice for cars, you are in luck. Walnut burl is probably the veneer that conforms to compound shapes better than any other. Make sure the veneer is not too saturated with the flattening solution or you will have adhesion problems.

You can also soak the veneer, bend it around the part like I described above but sopping wet with no glue and use repeated applications of newspaper to dry the veneer out. Once fairly dry the veneer should be permanently shaped to the part. Then glue it down in a second operation.

Darryl Keil


 
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DavidG

Posts: 2

Joined: 2010-05-20
Location: Portland, OR

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Subject : RE: Compound Curves
Posted : 2010-05-22 12:13 AM
Post #36038 - In reply to #36036
Don & Daryll,

Thanks for the responses.

As to the shape -- imagine a flat rectangle. Then roll both long edges slightly - like one was starting to roll a cigarette. That's most of the run. Then... at each end of the dashboard... bend one end slightly, perpendicular to the first bend. Compound curve.

Daryll, either of your processes sound perfectly manageable. I just have to decide about the vacuum technique, or not.

Oh, the burl is Amboyna. And - veneer softener? I've heard of such a thing, but never used it. Where might I look to purchase it, or is it a home-brewed concoction? Recipe? PEG? Glycerin?


 
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Darryl Keil

Posts: 1454

Joined: 2003-05-22
Location: Maine

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Subject : RE: Compound Curves
Posted : 2010-05-26 6:08 PM
Post #36048 - In reply to #36038
David,

Sorry, I didn't notice you asked a question about the flattening solution. If you do a search on this forum for "flattening formula" or some version of it you will come up with a solution you can make. If you want one you can buy, we have it, plus just about every other vacuum press supplier carries it too. There's pretty much only one solution commercially available, its a product called GF20 and we all put our own pet names on it. The home made one or the commercial one both work fine.

Darryl Keil
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