Bottlehead Forum
General Category => Tech Tools => Topic started by: adamct on June 13, 2013, 06:51:16 PM
-
I really like the matte, brushed, slightly grooved finish on my stock Crack chassis plate. On another amp, I'm working on creating a custom chassis plate. My aluminum plate arrived today. It looks OK, but the surface is a bit scratched (nothing major). The rest has a very dull shine to it. Any advice on resurfacing the plate to look like the stock plates? Should I sand it? Or make a few passes over it with a wire brush using my drill? Any advice?
Also, do I need to coat the plate with anything, or is it OK to leave it "natural" / untreated? I'm using 6061 aluminum with a T6 temper.
Thanks!
Adam
-
You should convince Doc B. to post a video of himself running the brush.
If you have a beefy corded drill and a wire brush, it's not too tough, and you can always go over the plate again if you don't like what you get (I know this from experience).
-PB
-
I have tried different techniques as well, but usually, I like to sand in just one direction. Wire brushing is something I just don't trust myself with. You can do a couple of experiments on the underside first. I won't tell anyone.
-
Fortunately, I bought 3 plates, to give myself plenty of chances to screw up first... ;D
OK, now I'll add a wire brush to the list of things I need to buy... :-\
-
Hard to demonstrate the technique on video because a lot of it has to do with how much pressure you apply. I'll give it a shot, maybe when I'm back from our vacay.
I'll start with the disclaimer - you can f**k yourself up if you are not very careful! I work outside, wear safety glasses, hearing protection, and a dust mask. Some aluminum does actually get airborne. There is a reason that is not good for you to inhale it, but my short term memory loss seems to be prohibiting me from remembering why...
It's not a bad idea to wear leather gloves too. Make sure they fit snug like mechanic's gloves so they wont catch if the spinning brush hits your hand.
Basically I hold the drill with the spinning brush (fine bristles about 3-4" diameter) with two hands at a 45 degree angle to the sides of the plate, and get an even finish over the whole plate except the two opposing corners that I clamp to the work surface. Don't need a ton of pressure and it is hugely beneficial to make sure the plate is grease free before you start. Contrary to what PB says I do find that going over a spot several times starts to eat into the finish and make a spot that looks more worked than the rest of the surface. Once I have the even finish I turn the wheel to 135 degrees (the "other" 45 degrees relative to the edge of the plate). Then I just sort of randomly wiggle the drill and let it sort of bounce lightly off the surface to generate contrasting marks 90 at right angles to the base pattern. Then release one corner clamp and carefully brush it to match. Release the last corner, hold the drill in one hand and hold the panel with the other and very carefully brush the final corner.
Be VERY careful, particularly along the edges where the brush wants to catch on the edge of the panel. In fact I will say just don't do it if you have any doubts. The ability to safely control hand held spinning motor tools is something a person needs to make their own decision about attempting.
-
Thanks, Doc. That's very helpful advice indeed. And I have a newfound appreciation for the stock chassis now that I know what goes on behind the scenes!
Best regards,
Adam
-
One more question...do you use a brush "cup" like this (http://www.amazon.com/Vermont-American-16784-3-Inch-4-Inch/dp/B000GTQNEC/ref=sr_1_3?ie=UTF8&qid=1371232525&sr=8-3&keywords=wire+brush+cup+fine), or a brush "wheel" like this (http://www.amazon.com/Vermont-American-16794-4-Inch-Brass/dp/B000PS9TIG/ref=sr_1_1?s=hi&ie=UTF8&qid=1371232815&sr=1-1&keywords=fine+wire+wheel+brush)?
I was assuming you use a brush cup, but re-reading your last post, it sounded more like a wheel...
-
Wheel.
-
Got it. Thanks again.
-
And BTW you want a fine steel brush, not brass.
-
OK, thanks again. Out of curiosity, why is that? (The ones I linked to were brass-coated steel.) Is there some sort of chemical reaction between the brass and the aluminum, or is it just that brass is too strong/aggressive for the relatively soft aluminum?
-
I just saw the pic and assumed it was pure brass. Steel is harder, and if you want to reproduce the pattern I make, steel is what I use. Can't speak to brass plated steel. That seems weird for a wire brush.
-
I would wonder if the brass plating is to avoid sparks (and possible ignition) when brushing steel?
-
I predict that the brass plating on the tip of the wire would last perhaps one revolution.
-
I went to the local hardware store and they only had brass-plated (no steel only), so we will find out tomorrow! (I'm not betting against Doc...)
-
Real brass-wire wheels are often used for cleaning steel things (like threads, tool parts, and such) while not taking off the base metal. They cost way more than steel wire wheels, and tend not to last as long. They would probably not work as well to grain aluminum plate as steel wire. A lot of wheels sold as brass are actually brass-plated steel wire, which would work fine - no harm for the brass to be there and might keep the wheel from rusting (as if that's a concern).
Ditto Doc's cautions about doing that outside, not only because of inhalation issues, but aluminum dust can be an explosion hazard. Though it seems unlikely for a small-scale job, it is still possible...as if you needed another reason to take it outside, I suppose.
-
My take would be that brass, being much softer than steel, would be less aggressive than steel wires, ie for cleaning and not marring the base metal ( much). Since you are trying to mar the metal you want steel. As for brass plated... must be for anti corrosion, as stated before.