I need a quick tip

[NotSoYoungRascal]

Hi! I'm trying to screw a piece of aluminum to a section of plywood, and I want to make it perfectly flat against the plywood. However, no matter how careful I am to smooth the aluminum, by the time I get to the final screws there are several portions of the aluminum that are annoyingly separated from the wood. When I did this on the second piece of plywood, I was even more meticulous in affixing the aluminum but I got the same result. Tomorrow I have to do three more pieces. Any tips on how I can do it so that the aluminum is perfectly flat against the plywood in all places?

 

[oldognewtrick]

What size screws are you using and how thick is the aluminum? Have you considered glueing it to the ply with construction adhesives or contact cement?

 

[NotSoYoungRascal]

Thank you for replying, olddognewtrick! I don't know the size of the screws but I drilled holes in the aluminum that were just large enough to accommodate the screws. The aluminum is of the thickness that is normally used for flashing. I checked the flashing package and it only has the length and width, not the thickness. I haven't considered using glue or construction adhesives for this project because a) I don't really have anything but Crazy Glue and Gorilla Glue b) I've had very disappointing experiences using both of them, as well as things like epoxy, and c) I want to be absolutely sure that this will hold up when stressed, and I can only be sure of that using screws.

 

[bud16415]

When you use a screw in thin material when you tighten it down it indents into the material ever so slightly and that dimple will cause the material to pucker. You need a screw with a flat head and then a washer to spread out the surface area.

Even then it may not remain flat as with temp the wood and alum. will expand at different rates and can ripple.

 

[joecaption]

The hole in the metal should have been slightly bigger then the screw, and the wood would needed a pilot hole the root size of the screw.
If you used a flat head screw, you would need to use what's called a finish washer under it.
I'd use a Pan head screw and flat washer.

 

[billshack]

I would suggest contact glue. Just cover both sides with glue wait 10-20 minutes until both sides are dry then bring together. A word to the wise make sure that the come together as you want them , because once they touch nothing can take them apart. if fact i doubt you will need screws .

 

[vinny186]

Perhaps you could use a somewhat large metal washer against the aluminum and a rubber washer on top of the metal one to disperse the pressure a bit.

 

[Johnboy555]

Liquid Nails has a new product called Fuze*It. It goes well beyond normal construction adhesive. I used it for something, (don't remember exactly what it was), and tossed the partially used tube back in the truck. I small glob leaked out. A few days later I noticed it and could not believe the bond strength between the tube and cabinet that it was stuck to. It's interior/external rated and may be a great choice for your project. Gorilla Glue has it's place, but can be messy and hard to work with. I think I have found a new "Super Adhesive" for my "arsenal of "good stuff to know!"

 

[soparklion11]

Something like a roofing nail with a wide head would have a low finished profile if you need more than the adhesive....

 

[Jeff Handy]

Gorilla Glue will foam up and push that piece of aluminum out of place.

 

[Jeff Handy]

Liquid Nails has a new product called Fuze*It. It goes well beyond normal construction adhesive. I used it for something, (don't remember exactly what it was), and tossed the partially used tube back in the truck. I small glob leaked out. A few days later I noticed it and could not believe the bond strength between the tube and cabinet that it was stuck to. It's interior/external rated and may be a great choice for your project. Gorilla Glue has it's place, but can be messy and hard to work with. I think I have found a new "Super Adhesive" for my "arsenal of "good stuff to know!"

Sounds interesting, I will check that stuff out!