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[Neural]

I... don't want to waste time with a long explanation unless it's requested, so...

I have four (4) pieces of flat aluminum.  Dimensions are 3/4" wide, 3" long, and 1/16th" thick.

I need to firmly attach them to a piece of 1/2" thick plywood, and I need whatever is fixing them to the plywood (i.e. wood screws) to be completely flush with (if not a tiny bit sunken into) the aluminum.

My initial thought is small, long wood screws, but doing a countersink on 1/16th thick aluminum is tricky without a drill press.

Any other ideas?

[Rockoteer]

Not really.  They make a countersink bit that you can use in your hand held.  Go slow so it cuts smoothly.  I just got finished countersinking 1/8" steel on the fence support for my table saw.  Aluminum will cut easier.

Make sure you clap the piece of aluminum down.  clamp clamp not clap

[Slabbercabber]

Countersinking thin aluminum without a fixture is study in frustration.  It will flex and need flattening several times.  If it is appropriate, Gorilla glue will hold very well.

[lithicbeads]

If you glue it rough up the back a bit to give the adhesive some tooth to hold on to. It needs to be clean as well and the appropiate epoxy properly mixed. Normally the epoxy is stronger than the wood.

[Neural]

It looks like glue will be the best option.  I was hoping to avoid a permanent solution, but it seems to be the only one that is going to work.

Basically I'm making brackets to hold a work piece in place, and they need to be 1/16th" thick.  I have a couple pieces of plywood though, so making more than one for different sizes won't be an issue.

*edit* Ug.. except I can't glue them.  The sheet aluminum I'm going to be using isn't *exactly* the same size every time, as the shops cut them with a tolerance of like 1/32"  If I glue the brackets down for one piece, they may not fit the next.

[Rockoteer]

Countersinking thin aluminum without a fixture is study in frustration.  It will flex and need flattening several times.  If it is appropriate, Gorilla glue will hold very well.

Well I just did it.  No fixture (whatever that is).  Never flexed.  Held it down with a clamp and a stop.

[vitzitziltecpatl]

Put a countersink in your plywood, then sharpen a wooden dowel to match the countersink profile and use the dowel to form the aluminum to the countersink in the plywood. If you clamp wood blocks (or whatever) close to the edges of where you'll be tapping the aluminum down into the countersink you should be able to get a nice neat edges.

Knowing you, I'm sure you've already allowed for the thickness of the aluminum when figuring the size of the countersink in the plywood.

[vitzitziltecpatl]

Countersinking thin aluminum without a fixture is study in frustration.  It will flex and need flattening several times.  If it is appropriate, Gorilla glue will hold very well.

Well I just did it.  No fixture (whatever that is).  Never flexed.  Held it down with a clamp and a stop.

Yep, Rockoteer - you know the lingo better than I. Your post went up while I was trying to figure out how to explain what I knew would work from my years of forming sheet metal on steel buildings.

[Neural]

I found a solution.  It's called "neighbor who has a drill press".  :)  I have my brackets now, and it appears to work

Thanks for all the info.  I've learned stuff I can use in the future moving forward. :)