Is it imperative that one ALWAYS apply veneer to both sides of a substrate?

[Glen Blanchard]

I am familiar with the rule to always veneer both sides of the material being veneered, but I have a question. I am building a miter saw station and am making the fence out of 3/4" MDF (2 1/4" tall x 6' long). I have cemented plastic laminate to the face of the MDF. The fence will then be screwed to a smallish torsion box platform that is also 2 1/4" tall x 6' long. As the MDF will be fastened to the torsion box with screws (and will be supported by it for its entire length) does it matter that the back side of the MDF has no p-lam? If the spacing of the screws are sufficielnty close, I don't see how this would allow for any movement of the MDF.

Thanks in advance.

[Jeff Monson]

Glen, I wouldnt see it necessary if you are using laminate. I think the rule applies more to wood veneer, I always veneer both sides of my substrate. When it comes to laminate only 1 side.

[hank dekeyser]

ALWAYS - no - however if it were mine I would absolutely laminate bothe sides. be certain to use the same type and thickness material as well. Now if it were say a shop benchtop, I wouldn't take the time and material to do it, just fasten it well. Back in my commercial laminate days I had seen many table-tops,etc that did not have "backer" on them and they twist and curl all over the place. It depends on the substrate and the environment it will live in. You don't want to have to build it twice, and want it to last along time - so bite the bullet and do it.

[Tony Bilello]

[QUOTE=Glen Blanchard;1627324....I have cemented plastic laminate to the face of the MDF. The fence will then be screwed to a smallish torsion box platform that is also 2 1/4" tall x 6' long. As the MDF will be fastened to the torsion box with screws (and will be supported by it for its entire length) does it matter that the back side of the MDF has no p-lam? ....
Thanks in advance.[/QUOTE]

I wouldnt think that p-lam would be needed on the rear of the fence because it is afixed to another surface. That surface will provide enough protection so that the MDF wont suck in or lose any moisture. However; The top, bottom and ends that have been cut on ths table saw now have their raw edges exposed and this is where the problem would be. When the raw edges suck in moisture, they will bloat like oatmeal. For what little effort it takes to lam all surfaces, I would just go ahead and do it since one side is already done.
On the other hand, if you havent applied and p-lam yet, dont. Just plan on cutting a new piece of MDF every 2 years or so. Wait until you see how well your experimental fence works before you spend too much time on it.
I'm in the hot and humid, cold and wet area of Houston-Galveston. As long as I dont spill a lot of water on the MDF, it lasts long enough for me to redesign my jigs 2 years or more later.

[Ron Bontz]

Just a note. I have laminated MDF on several types of projects. They make a "balance backer" for just this purpose. It cost a lot less as well. If you are using a torsion box assembly I would still use the balance backer. Just my opinion. I have had things pull and eventually warp a little. Why take the chance by adding stresses to the assembly? Good luck on what ever you do.