polishing enclosures

[Mgt280y]

Im looking to do a polished enclosure with a water slide decal for my little angel build,
Started wet sanding the box tonight but don't seem to be getting very far still have quite a few casting marks and deeper scratches, need to get some compound to polish it up will that just bring up a shine or will it remove any pitting?
and to check is it then clear coat, cure with heat, decal then clear coat.

As always any advise greatly appreciated 

[smallbearelec]

Hi--

I have gotten a pretty good "gun-metal" finish like this:

http://diy.smallbearelec.com/Projects/BareAssBoost/BareAssBoost.htm

by sanding progressively starting from 220 grit, working through five or six stages through 2000 grit. You can find super-fine carborundum papers and mag/aluminum wheel polish at a shop that sells auto-body finishing materials.

[vigilante397]

I also tend to do a finish similar to smallbearelec, it's just a lot less time and effort than going all the way to polished. The only time I got an actual polished finish was multiple sanding stages to WAAAYYY fine grit, and then taking it to a buffing wheel with buffing compound.

[Pettol]

I use a randon orbital sander (speeds up the process a lot!)  and like smallbear I go from 220 (ish) to 2000. Then I finish off with some polishing compound.

[PRR]

> casting marks and deeper scratches, need to get some compound to polish it up will that just bring up a shine or will it remove any pitting?

Polishing compound will just shine-up the edges of the pits.

On some castings, you really have to start with heavy cutting. #200 paper in a power sander. Get it down to uniformly scratched. Spray a thin coat, then start your next finer grit. If you still have pits, they will show clearly where this sanding doesn't take the paint off like the rest of the surface. Go back to a heavy cut.

[Mgt280y]

I think that's where I was going wrong don't think I started corse enough need to get some more paper to try I only have 800 upwards

[Gus]

Sometimes I will use a mill files to flatten the surfaces, after the surfaces are flat I will use sandpaper.

[Ben Lyman]

what about a belt sander? Is that overkill? I've noticed that some of the enclosures I buy have such uneven surfaces that they can't be sanded/polished with a sanding block. I sometimes think it would be nice to quickly grind all the sides down perfectly flat before shining or painting them

[Mgt280y]

Funny you should say that I am considering trying that on a box as the flat thing is a issue I have been fixing the paper down on a sheet of glass so ultra flat and rubbing the box against but the tops are not flat for a fair bit of sanding.

Rather than start a new post
If I want to have a power coated box then sand off and polish just the top to apply water slide
With the water slide I'm using it needs acrylic clear to make backing transparent
A will clear coat adhere to powder coat and the polished bare
B use powder clear coat but will water slide survive the powder bake and will powder clear make the backing go clear still

[PRR]

> what about a belt sander? Is that overkill?

Effective but potentially VERY dangerous to work a small object with a belt sander. When it grabs it will throw the box a mile a minute.

And die-tapered boxes don't clamp well.

An orbital sander won't throw so violently.

[DK1]

I've found that many castings just aren't that great of a starting point. Many have uneven spots that are hard to get flat, beyond just pitting in the surface.

I've got a piece of plate glass that is use as a base. Start with 220 wet/dry. I might actually drop to a lower grit for getting everything flattened, because even 220 takes forever.

Also, the aluminum quality isn't outstanding. I've had slivers tear out of the aluminum and scratch the finish up. Don't think it was aluminum... Just something embedded in the casting process.

Mind, this has been my experience with Tayda enclosures. Name brand Hammonds might be better.

[Mgt280y]

My conclusion, tayda boxes have too many casting marks they appear within to walls so they keep appearing as you sand, mirror abandoned ! Might just spray in and aluminium metallic paint I can get gloss silver from that

[deadastronaut]

imo you just cant beat a bit of elbow grease and coarse paper and a sanding block...(safer than belt)

if you want a polished enclosure your gonna have to go with

rubbing compound...and preferably a polishing mop.  (very messy..wear overalls.)

however your box will go dull after a while..

clear coat is ok, but it does chip/digs etc ...

[mcknib]

Although it won't get rid of the pits etc I use this cheapo kit to get a nice polished finish

http://m.ebay.co.uk/itm/Aluminium-Brass-Steel-Metal-Polishing-Kit-3-x-1-2-Fits-Drill-/291465775070?nav=SEARCH

Then I use cheap clear vinyl adhesive sheets on my laserjet printer and Roberts yer uncle ^ as deadastronaut says it can get messy I ended up with black compound dots flying all over the shop and best to clamp your enclosure it can zoom across the room like a Frisbee

[duck_arse]

has no-one thought to etch the front flat? spray to fill the dings, sand thru the face, and etch. maybe?

[Groovenut]

On the ones I used to do, I used a rotary sander starting with 100 and working to 440. Then wet sand with 600 and buff with a wheel. The small pits that are left are wholly unnoticceable to the naked eye. I used the 1590As and Bs that Tayda sells.

[Joe]

[PRR]

> many castings just aren't that great
> Many have uneven spots that are hard to get flat
> the aluminum quality isn't outstanding.
> I've had slivers tear out of the aluminum
> Don't think it was aluminum...

What do they say the boxes are made of? (Never assume.)

Even if it says "Aluminum", you can be sure it isn't Pure Aluminum. There are many "better" alloys and mixes. Copper, Zinc, Mang/Magn, and Silicon add strength and hardness, or cut cost.

I'm sure it is in the range of what we used to call "pot metal". You could make pots with it. The main use was car door handles, taillight trim, carburetor bodies, wiper gearboxes, all the many little bits of a car which need detailed shape with no great strength and LOWEST cost.

There's various grades of "pot metal". A carburetor needs fairly good stuff. A headlight switch body only has to last 31 days. Since this is all casting, molten metal, I'm sure each operation buys various grades of various metals (refined, sorted scrap, mixed scrap) and blends to the quality/cost needed for their application.

These little boxes are sold as UTILITY boxes. I have several power and signal junction boxes down cellar. As long as it doesn't cut my hands or fall apart in drilling, I and 99% of users really don't care about Surface Finish. To make utility boxes into Things Of Beauty, you may have to select your raw material (brand, lot, and batch variations) and put more time/effort into re-finishing than was ever used in manufacturing.

Of course the alternative is to pay a fortune for some pre-beautified box (jewelry? Pedal specialty?) or to make your own with careful blending, stirring, and casting. Home casting is a DIY thing, but costly and dangerous and a real time-sink for pedal making musicians.

[Gus]

As I posted before try a wide mill file.  Go to the home depot, lowes etc. and pick a flat mill file.
This flattens the surfaces faster than sand paper.
If you use it correctly the surface can be very flat and smooth.

[DK1]

What do they say the boxes are made of? (Never assume.)

Even if it says "Aluminum", you can be sure it isn't Pure Aluminum. There are many "better" alloys and mixes. Copper, Zinc, Mang/Magn, and Silicon add strength and hardness, or cut cost.

Who's assuming? They are aluminum die cast boxes, per Tayda. I understand alloying additives, but those should be fairly homogeneous close to a molecular level. Most likely, what I'm encountering is just particulate debris that made its way into the mold. It happens in cheap castings.

I'm not criticizing their product. It's a cheap box that isn't intended to be made mirror perfect. I'm simply relaying some of the issues that arise occasionally should you try. I'd hate to see someone working on a great 800 grit finish and then be devastated when a grain of debris pulls loose from the surface and gouges it. Just be aware that stuff like that is possible.