1/4" thick brushed aluminum

[bluehammer]

Does anyone know a source for 1/4" thick brushed aluminum sheets?

 

[signheremd]

Brushed Silver Composite comes in 1/4" (aka 6mm)

 

[Gino]

Ya better look locally if you want 1/4" sheets, cause that'll cost quite a pretty penny to ship.

 

[GaSouthpaw]

If your regular aluminum supplier can't handle it, they should be able to refer you to a shop that can do it for you. I know Phoenix Metals (local to us, not sure about who might be in your area) sells brushed sheets. Be forewarned, though- in my experience, the sheets will often be bowed (I guess due to the heat generated during the process).
Our process is: cut out what's need (almost always copy) with the router. We use bridges on each piece, leaving them in the material, then cut off only the section of the sheet needed. Our lead in the paint department then uses a large, handheld belt sander to do the brushed surface. (Practice, practice, practice) He's quite good at it.

As mentioned above, ACM is available with a brushed surface, or you could laminate a piece of prefinished aluminum to a piece of .188" acrylic- or even another piece of aluminum.

 

[JBurton]

I've used a velcro sanding attachment with an 80 grit paper mounted in the CNC spindle to brush a sheet. It worked well, but you have to make sure you have no oil on the sheet, even finger prints would cause the grit to slip past areas and not properly brush.
When we buy sheets brushed, I usually need over 1k in product before they'll do it, but Eastern Metal Supply has a company they ship work with for brushing full sheets. No extra cost to ship, just the minimum to brush and skid.
Oh, and if you plan to route these, use stainless steel appliance cleaner to get the lubricants off and keep an semi uniform appearance.

 

[GaSouthpaw]

I've used a velcro sanding attachment with an 80 grit paper mounted in the CNC spindle to brush a sheet. It worked well, but you have to make sure you have no oil on the sheet, even finger prints would cause the grit to slip past areas and not properly brush.
When we buy sheets brushed, I usually need over 1k in product before they'll do it, but Eastern Metal Supply has a company they ship work with for brushing full sheets. No extra cost to ship, just the minimum to brush and skid.
Oh, and if you plan to route these, use stainless steel appliance cleaner to get the lubricants off and keep an semi uniform appearance.

Interesting idea for using your CNC. How do you mount it? With a sanding disc off an orbital? And how do you do it without the spindle spinning?

 

[JBurton]

Interesting idea for using your CNC. How do you mount it? With a sanding disc off an orbital? And how do you do it without the spindle spinning?

We have these sanding pad add ons from 3m on our sanders, I just unscrewed it and gingerly clamped the collet on the threads. Aside from leveling the table, the hardest part was deciding how 'deep' to drag. I probably ran it 5 times at .02" different depths until I liked the amount of brush I saw showing up.
Then I turned around, flipped the spindle on to around 2k rpm, and ran it like a sander and it worked brilliantly! I'd never want to use it for production, but it was entertaining enough to watch it run.
One thing to consider, it's not going to look perfect from end to end. I started with the pad fully on the sheet, and went just past the end of the sheet. Where it started would have swirls as the pad found the path of least resistance, at the end it would spin just a bit as it left the sheet. So if you plan on doing anything other than letters like a background, you'd need a sheet wider than the sign face.

 

[GaSouthpaw]

We have these sanding pad add ons from 3m on our sanders, I just unscrewed it and gingerly clamped the collet on the threads. Aside from leveling the table, the hardest part was deciding how 'deep' to drag. I probably ran it 5 times at .02" different depths until I liked the amount of brush I saw showing up.
Then I turned around, flipped the spindle on to around 2k rpm, and ran it like a sander and it worked brilliantly! I'd never want to use it for production, but it was entertaining enough to watch it run.
One thing to consider, it's not going to look perfect from end to end. I started with the pad fully on the sheet, and went just past the end of the sheet. Where it started would have swirls as the pad found the path of least resistance, at the end it would spin just a bit as it left the sheet. So if you plan on doing anything other than letters like a background, you'd need a sheet wider than the sign face.

Interesting idea. I'll have to play around and see what I can come up with.
Thanks!

 

[JBurton]

I should mention, I kindly borrowed the idea from folks in the WSA trick of the trade contest. Their concept was a steel wire brush bolted to the cnc gantry, which worked well, but it was hard for me to mount anything to my shiny new cnc at the time, so this was my compromise.
Also be sure to vary the density of strokes, you'll find that one side grinds more than the other, and it can produce a repeated pattern in larger pieces that is not really desirable.

 

[GaSouthpaw]

I should mention, I kindly borrowed the idea from folks in the WSA trick of the trade contest. Their concept was a steel wire brush bolted to the cnc gantry, which worked well, but it was hard for me to mount anything to my shiny new cnc at the time, so this was my compromise.
Also be sure to vary the density of strokes, you'll find that one side grinds more than the other, and it can produce a repeated pattern in larger pieces that is not really desirable.

I actually use a wire brush at low speed to "rough" the surface for some applications. That doesn't work for the brushed look, though- obviously. I can set it to "No Spin" on the machine, but the spindle will still rotate when movement starts, so I'm still looking for an "easy" automation.

 

[JBurton]

Here's a picture of the other shop's bracket solution, I'd also seen a wire brush version that they through bolted onto this plate, but I can't find that picture now. I found that even with the pad mounted in the spindle, it would find a path of least resistance and stop spinning after a few inches. The wire brush would fix that I imagine.

And when I say wire brush, I guess I mean like steel bristled hand brush, wire brush makes one thing wire wheel: