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View Full Version : Mill finish on Aluminium sheet.



ynneb
07-03-2004, 05:26 AM
I wish to get a consistant mill finish on sheets of aluminium.

I have tried randon orbital sanding but it shows each pass of the sander. Its shows the track that the sander took.

I have thought about sand blasting the sheets but havnt yet tried that.

Does any one have an idea of how to get a consistand mill finish accross the whole sheet, without it showing tracks.

kong
07-03-2004, 07:08 AM
Excuse my ignorance, but what is "mill finnished"?:confused:

ger21
07-03-2004, 07:38 AM
Do you mean you don't want to see any marks at all? Try using very fine paper on a random orbit sander, like 400.

HuFlungDung
07-03-2004, 11:09 AM
If the surface is in excellent condition, likely all you would need is a Scotch-brite product. I would imagine that if you want a "parallel finish" that you're going to have to use the edge of a "wheel" and take lengthwise passes with it. A fine, soft wire bristle wheel may also accomplish this surface conditioning.

If you have sanding gouges to remove already, you could wrap a sheet of emery cloth around a short length of a padded 2 by 4, and take parallel strokes with it.

NIGEL
07-03-2004, 12:01 PM
Do you mean "brushed" fininsh. How big are the sheets and how many do you need to do? I'm thinking big belt sander 1400 wide, any help?

metlmunchr
07-03-2004, 01:32 PM
For a non-directional matte finish, get a hook and loop backing pad for your random orbital sander and cut yourself some circles from maroon scotchbrite. They'll stick well enough to the hook and loop for use like this so long as you've got the sander in the random mode and not the spinning mode. Keep the surface wet, as this prevents bits of aluminum from clinging to the pad and scratching the surface. Pay attention to keeping the pad flat on the surface, and don't let it rock up on edge, and the resultant finish will be very uniform.

For a brushed finish, a pneumatic sander which resembles a dough rolling pin can be purchased. It has handles at each end and the drum rotates. Does an excellent job, but the sander itself is very expensive, on the order of $600+ US last time I noticed.

IJ.
07-03-2004, 08:04 PM
Benny: A nice "finish" on sheet is the "engine turned" you use a round wire brush in a low speed spindle then just touch the sheet move forward 3/4 of the brush and repeat so you end up with overlapping circles.

ynneb
07-03-2004, 08:21 PM
Thanks guys for your responses. I will give them all a go.

Kong the only way I can describe a mill finish is like sandblasted glass, but in this case on aluminium.
It is a uniform finish across the whole sheet and there are no discernible paths. I guess like white noise on a TV, only much finer.

I will post some pictures of the results, after I have tried each method.

EDIT: I noticed at out hardware store they are selling sandblasting attachments that fit onto a standard compressor. They only cost 20 bucks. I think I will give this a try first.

Ken_Shea
07-03-2004, 10:27 PM
Benny, sand blasting and glass blasting while two distinct types of blasting are often grouped under the term sandblasting. In your case you would want a fine or very fine glass media (depending on what finish you desire) if you decide to blast and definitely not silica sand. Glass would leave a smooth and very attractive matte finish

Ken

Patrick2by4
07-06-2004, 01:04 PM
I tried the maroon scotchbrite pad and it works beautifully. Thanks for the tip metlmunchr.

BT1
07-08-2004, 06:21 AM
Scotchbrite is good! yep...

Jim Stein
07-25-2004, 01:05 AM
Mill finish is when the chrome wears off of the rollers at the mill.Before the chrome wears off the metal is called bright metal.It would be very hard to reproduce a mill finish.

apache405
06-22-2008, 06:52 AM
Benny: if you go with sand blasting make sure you use an aluminum oxide based media, so that you do not have to deal with all of nonsense surrounding silicon based products (if you breathe the dust you put yourself at risk of contracting some lung disease, silicosis or something like that.)