Mounting Aluminum letters to Fir??

[scottbot]

Hi,
I've been asked to cut 14" tall letters out of 3/16" Aluminum and mount the letters to a 16' wide by 18" high and 8" deep slab of Fir.

The letters are to stand proud of the Fir by 1-1/2". I had planned to weld 3/8" Aluminum dowel to the back of the letters and epoxy them into 4" deep holes in the face of the Fir.

My concern, of course, is what the wood movement will do to the letters over time so I thought it might be better to drill oversized holes (say 3/4") and use silicone as the adhesive so it will absorb the movement. But... I have no idea if it will actually work.

Does anyone out there have any experience or ideas how to to tackle this??

Thanks in advance.

Scott

[dubliner]

Scott, there is a neat little process that welds aluminum threaded rod to letters, I havent seen the gun but its something like a spot welder. You might take some by a sign shop & see if they do that, & I bet you they ask you to cut some for them. You could then put a nut on each rod & silicone it in place. That would probably allow for movement.

[scottbot]

Thanks Neville,
I've got the welding part all worked out. I'm mostly concerned about the relative movement between the wood and the aluminum.
I spoke with a friend tonight and he suggested slotted mounting holes. I like that idea better than my oversize hole idea but we both are unsure if the silicone has enough 'give' for this application.

I think I'll have to do some testing.

Scott

[chodges]

Scott;

Silicone is our preferred way to mount signs of all types - it never hardens as rigid as wood, but it REALLY sticks once it has set.

I think you would be very safe using silicone in oversized holes.

[scottbot]

Thanks Charlie,
It's great for us new guys to get help from those who've been through it already.

I think I've got a got plan for this job now. I'll post pictures when it's up.

Scott