Any awesome secret (enclosure) sanding tips?

pricklyrobot

pricklyrobot

Well-known member
I etch my enclosures. And I’ve discovered, through trial and error, that getting the enclosure sanded to a mirror-like smoothness makes for a much more consistent (iron-on) toner transfer.

I’ve got one of these:
IMG_0349.jpeg
I start with a fairly coarse grit to make sure the surface is leveled out, and then work my way up to 2000-grit wet sand.

It works, but it can be pretty time consuming.

Anyone got any brilliant sanding hacks to speed up the process? Or maybe enclosures from a particular manufacturer/vendor that arrive in a shinier state and require less work? 🤷‍♀️

Hit me with your mystical sanding wisdom, my metal gurus! ;)
 
If you can put a non-cushioned pad under the paper in your sander, it will sand the high points first, getting you a flatter surface. Most sanders have rubbery pads that you attach the paper to, and that sponginess will also press down on lower spots, so that you have to sand through more material (and if you were doing something more critical than a pedal enclosure, you wouldn’t be as able to get a truly flat surface. In my shop we’d use a granite surface plate for this, typically after machining a surface flat with a mill, to get rid of the machining marks.

For flat surfaces (like most of an enclosure), I put the paper down on a flat surface and wet sand by moving the box over the sandpaper. For cast aluminum, unless it’s really coarse, I don’t think I’d start below 220 or so.

It’s been years since I bought them, but the Delton enclosures that I used to get from Mouser were noticeably cleaner castings. Their sizes are similar, but slightly different from the Hammond standard sizes.
 
I have used about the same process you are discribing. I used a sander with 150 then 400, then hand sand with 1000 and 2000. I've also used buffing wheels in my drill press with polish compound to get a mirror finish.

I think for etching just a quick hand sand with 400->1000>2000 would be enough?? I don't see the point of getting a mirror finish if you are going to spray paint.

Tayda used to sell polished enclosures for $7.99 but the've been out of stock for at least 5 years, lol. Not sure why they still list it.
 
I've seen this question come up before, and I'm always tempted to spout off with what I think would work, but instead of filling the internet with more speculation, I'm going to try one later and report back whether I knew what I was talking about...

How long would you say your current process takes?
 
i've got a cheap orbital sander. i hit it with 60 grit first, then 220. if i'm painting, i'll just clean it up with some steel wool and then alcohol. if i'm keeping it metal, i'll wet sand with 400, 800, and polish with steel wool. i can't get the perfect mirror finish, but i'm also working out of a one bedroom apartment, so i'm content with the results.
 
@Alan W
Good tip re: using a non-rubbery sanding block component. I’ll see if I can rig something up.

Bio77 said:
I think for etching just a quick hand sand with 400->1000>2000 would be enough?? I don't see the point of getting a mirror finish if you are going to spray paint.
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No spray paint involved. Maybe you’re thinking of laser etching? I’m doing acid etching. If you look at the last post in this thread: https://forum.pedalpcb.com/threads/demo-tape-fuzz-w-white-tailed-kite.24105/ I give a little rundown of the process.
The mirror finish is just for toner adhesion (if you don’t get them smooth enough toner tends to flake off), not for aesthetics or paint prep.
Bio77 said:
Tayda used to sell polished enclosures…
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This would be ideal. Too bad they are no more 😢

Erik S said:
How long would you say your current process takes?
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Maybe 15-20 minutes per enclosure 🤷‍♀️
Never actually timed it. Maybe it just seems longer because it’s tedious;)
 
I'm still "figuring it out" but this is my method currently.
Orbital sander wet sand with Diablo discs(they're awesome) with 220 then wet sand on the flat bench top with finer grits, often just 400 or 500 and 99% alcohol to avoid oxide formation. 0000 steel wool pads slapped on the orbital can work for mirror finish.
I have noticed that leaving the sanded enclosure for a couple of days leads to poor adhesion of the resist. I think the oxide layer that forms over time contributes so if I have to let them sit, I sand with alcohol and fine grit again to make sure the oxide layer is depleted.
 
That's harder than I gave it credit for!

I thought I was going to skip a bunch of steps, and I went right for a fine scotchbrite disc on a disc polisher/ grinder. What I hadn't accounted for was that there was (at least on this enclosure) some bumpy texture there I wasn't expecting. That's where your early steps with coarse grits would have helped. There really are no shortcuts in life.

I finished it off on a buffing wheel and got it shiny, but probably not as flat as what you're going for.
 
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Gotta be honest, I was always just much more of the “start with a low grit of sandpaper and go in one direction, then choose a higher grit and go in the perpendicular direction, and then choose a higher grit and go back in the other direction… “ kind of guy. Works for me.

Mike
 
Belt sander sounds like the right tool for first steps. Leveling and such.

Those palm sanders are meant for finish work more than material removal. Very useful, but taking off the high points will be faster with a belt sander.
 
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