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Welding a sandwich panel

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Welding a sandwich panel

Postby homeboy » Mon Aug 14, 2017 10:53 pm

I am going to build the legs for a heavy live edge oak slab table which consist of a contoured 2in. thick vertical panel at each end varying between aprox. 10in to 20in wide. I am using 1/8 flat stock for the outer skins with 13/4 x1/8 angle interior spacers tack welded between between the outer skins and 2in X 1/8 flat shaped to fit welded both sides to cap them in. The top and bottom will be capped with 2in. wide tubing to fit for slab attachment and wheels. Question is, would it help to prevent heat distortion to immediately quench each weld with a wet rag ? I plan on going slow and using small aprox 3/8in tacks spaced out along the interior spacers.It will be securely clamped to a steel workbench. I watched a bodyman do this when brazing patches and it seemed to work ok. Any ideas would be appreciated. :?: :?
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Re: Welding a sandwich panel

Postby cj737 » Tue Aug 29, 2017 8:15 am

I don't like to quench steel when welding. A body panel on an auto, sure, because you haven't put so much heat into it and its not "structural" in the same sense. Best to clamp your project while welding, move around the area to distribute the heat, and use PATIENCE when welding large, thin, structures to minimize distortion.

You can even tack on some "stiffeners" temporarily to alleviate any pulling/distortion. An X brace works well for legs or rectangular structures.
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Re: Welding a sandwich panel

Postby MinnesotaDave » Tue Aug 29, 2017 12:59 pm

Every weld will shrink, quenching it just makes it shrink faster.
Depending on the type of metal, it can also cause strength issues.
(stainless can often be quenched or speed cooled though)

It's more beneficial to plan for the shrinkage so it pulls the direction you want.

Or you can weld support in a place that prevents a piece from pulling.

It must be something you want to stay in place though, once the support is cut off the stress with be free to relieve itself.

Many people will clamp something to a flat table, weld it, let it cool, take off the clamps only to watch the piece move in a direction they did not want.
Dave J.

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Re: Welding a sandwich panel

Postby homeboy » Tue Aug 29, 2017 8:09 pm

Thanks for the info. Sometimes I may tend to overthink about trying different approaches to try to improve a project. The quenching idea was just a thought and is now a definite non starter. The local fab shop has 1 3/4inX1/8 wall rst. which I am considering using for the inner frame and drilling the 1/8in outer skins to match, clamping and plug welding to the frame slowly. I am in the process now of planeing the slab with a router sled to get the finish thickness before I can start the legs to get the proper finish height. Problem is the guy that cut the slab did it freehand with a chainsaw apparently in an advanced inebriated state and I have no accurate idea of the finish thickness. :x :geek:
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