Resolved Oversize backing board

[Melinda Tennis]

I have a 56 x 66 oil to stretch. I checked Coroplast and they show only 48 x 96. Is there larger material available to use for backing. I can cut it on the diagonal and fill in the corners but was hoping somebody makes a big enough sheet? Yeah, then it has to be shipped by freight. Here's hoping.

 

[Ylva]

Could you do it in two pieces with a seam in the middle and tape that part? Or not solid enough?
You could check Home Depot and the likes to see if they have fluted plastic in larger size, or check with sign companies.

 

[Melinda Tennis]

That was my next step and yeah, I can piece it. It will be plenty solid, I just want to finish it with as few steps as possible. Thanks

 

[Jim Miller]

Taping works well for a no-load application such as a canvas backing board, but as an alternative to taping, you can stitch the Coroplast pieces together for greater strength. Of course, this does not make as flat a seam as taping.

First, prepare the edges of both boards: Slit the end-flute lengthwise on one board. On the other board, cut away the end-flute and push that board over the other one.

I've stitched the seam three different ways using dental floss:
1. Loop-stitch along the length of the seam.
2. Zigzag stitches using a curved needle all along the seam on the front and the back of the board.
2. Loops of thread every few inches over the length of the seam.

I hope these drawings are clear enough.

 

[Jim Miller]

Another alternative would be to stack two layers of 4 mm board together with the flutes crossed.

 

[Melinda Tennis]

Thank you, Jim. I get the first one, not the second. But I'll do the first one.

 

[RoboFramer]

The second one is easier and you wouldn’t have to buy the huge sheets either. You just bond sheets together so that the flutes on each layer run perpendicular to each other.

Obviously the bigger the sheets you use, the less individual panels will be needed to achieve the overall size.

 

[Bruce Papier]

Do you only need the front side to be flat? If so, couldn't you cut the whole sheet diagonally forming two long triangles then slide the triangles along the cut edge until the combined width is 56" and reinforce along the seam with something stiff like another piece of Coroplast or foamboard and then cut off the smaller triangular scrap pieces? Or is that what you were thinking to do in the first place?

 

[Melinda Tennis]

Thanks Bruce. Yes that was what I was trying to avoid doing, but it appears I'll be piecing it. Probably using Jim's coroplast method. Thank you all very much.