I had finally worked out in my head how I was going to make the custom copper bathtub while finishing up installing the tub base in the last installment of this project.
When I first started the bathroom remodeling project I had decided that the best way to move forward was to make a model of the bathroom complete with a model of the copper tub. The tub model was also made out of copper and included the same tabs and joinery methods that I would use on the full sized version. This gave me the opportunity to get my head around the basic methods of construction however, some details I figured I would have to come later. I had time to think about it then but not anymore.
I rolled out the 3′x10′ sheets of the thick copper and after careful calculations accounting for the multiple compound tapers, I began to mark out where my first bends would be. With each line scratched into place with an awl and a marker I had to visualize the bends, tabs and joinery so that it all fit together properly.
It was a rather time consuming process and one that would have been quick work for a true coppersmith.
My goal was to use one sheet of copper that ran from the head of the tub at the wet wall to the foot of the tub. This would have to include the measurements for the deck of the shower and the flashing that would be needed at either end. By using this method I would limit the number of seams that would need to be made. Along the entire length I would not have to account for one seam on each side that would use a double hemmed folded seam. Once hammered flat and soldered the seam ‘should’ be water tight. This is similar to the type of seam used in copper roofing.
The seam would involve each edge tab to be bent properly so as to make a lap that could be in turn hooked together. — This would have to be on the outside of the tub as I didn’t want the seam to be visible from the inside. this however, complicated things as I would have to account for the additional thickness on each side as once finished it had to be flat enough that it would fit properly when set down inside the box without any room for ‘play’. If there was ‘play’ then I feared that there could be enough shift that could cause hairline cracks in the solder and therefore enough room for a leak to develop.
From one end to the other I had to make sure that my bends were precise. The sides would be two separate pieces, each a trapezoid, for the facing copper along with the proper material remaining to fashion the tabs for the seams.
Another complication is that running along the length of the top side would have to be enough material so as to bend up and over the ply and tuck down along the outside to create the edge of the tub. Toward the side of the walls I would need enough tab material in order to create proper flashing that would bend up over the top of the tub and then angle upwards to provide flashing behind the tile that would be installed.
It was a lot to think about but I believed that I had it worked out in my head.
A friend of mind dropped off a 12′ break for me to use which would prove to be an incredibly valuable tool for making my bends accurate.
With my marking in place I began to bend the copper. Balancing a ten foot 2×4 on my head I crawled under the length of the copper inserted into the break and while bending the copper upwards supported the length on the 2×4. This prevented the heavy copper from buckling under its own weight.
With each bend I would transfer the the copper back to the work area to confirm measurements and prepare for the next bend.
Once I had all of the bends, tabs and double lap seams made I could move on to the next step of soldering the seams and shaping the custom copper bathtub.
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