Yikes, sanding enclosures is expensive

[Beo]

I just picked up an orbital sander at Harbor Freight, and built up a jig for some 1590BB's and 1590DD's I plan to etch. I planned to use 100, 150 and 220 Grit with the orbital, and then switch to a block for 400, 800 and 1000. I just finished up four enclosures using 100 Grit... and I used all four 100Grit aluminum oxide sheets I had. I didn't see the need to buy bulk packs of 50 sheet of each grit. A pack of four was close to four bucks... that's a buck per sheet.

I'm starting to think that the polished enclosures at SB and PPP are a deal. To bad they aren't offering bigger enclosures already polished.

Am I doing this wrong, or is this just an expensive process?

Travis

[deadastronaut]

wow.. i use 180 ...then 400-600...by hand..that does me...but im not going for a polished mirror finish..

[Philippe]

Am I doing this wrong, or is this just an expensive process?

Are you wetting the abrasives? The sanding process will clog up the paper quickly.

If you think sanding enclosures can be costly, try re-finishing a guitar in nitrocellulose lacquer...the various stages (i.e. removing the poly finish + leveling/sanding the primer & color coats) can easily run $40+.

BTW, you might consider procuring some abrasive wet-dry cloth sheets from an autobody shop. The Eagle brand comes to mind & it holds up pretty well when wet. I've used it from 400 upwards to 1200-1500 for finishing.

[derevaun]

I try to avoid the whole progressive-grit sanding thing, but when it's gotta be done, I try to use this stuff: http://www.woodcraft.com/Family/2005416/NORTON-Wet-Sand-Sheets.aspx. With a RO sander I'd be tempted to start finer than I would by hand--like around 200 and see what problem spots remain.

[darron]

by hand is the best way that i can sand to polish, making sure every step has no faults. haven't had much luck with orbital and bench/belt

for sure, small bear's price to effort ratio is tiny!!!!! i got one with the zvex logo stamped in it once! hehe

[tiges_ tendres]

I just picked up an orbital sander at Harbor Freight, and built up a jig for some 1590BB's and 1590DD's I plan to etch. I planned to use 100, 150 and 220 Grit with the orbital, and then switch to a block for 400, 800 and 1000. I just finished up four enclosures using 100 Grit... and I used all four 100Grit aluminum oxide sheets I had. I didn't see the need to buy bulk packs of 50 sheet of each grit. A pack of four was close to four bucks... that's a buck per sheet.

I'm starting to think that the polished enclosures at SB and PPP are a deal. To bad they aren't offering bigger enclosures already polished.

Am I doing this wrong, or is this just an expensive process?

Travis

I'm sure there are a couple of issues at play here.  Start at a higher grit.  I think 100 is probably doing more harm than good.  Also, as previously mentioned, wet sanding will get you a better finish, and stop aluminum dust getting in your lungs. 

But!  Dont be wet sanding with an electric orbital sander!  If you have the orbital sander that attaches to a compressor, that will work much safer.

[defaced]

If you do not clean the part between sanding steps, you are doomed for failure.  This is something you learn very quickly standing at a metallographic polishing wheel where the end result has to be dead smooth at 1000x magnification.  Also, for sanding metal, silicon carbide paper is preferred because as the pieces of SiC grit fractures, it stays sharp. 

[Earthscum]

All I got to say is you're using the expensive stuff!!!

If your sander uses the sticky disks, go spend like $20 at your local auto parts store and buy a roll of cheapies for body work.

If you want to go even cheaper, just go get the regular sanding disks from your local hardware store. They should come on a roll as well. Aluminum is soft enough that you can use many wood tools on it, you just have to go slower, i.e. saw blades (also, they make a wax lubricant for using wood cutting utensils with Aluminum... last time I bought a stick, it was $10 for a caulking tube sized... well, tube of it.)

I could burn down a nice dull paintable surface on a 4ft x 10ft sheet of aluminum with a single 180 grit disk. Mind you I was using a DA sander (air orbital), but your orbital should be fine. The one disk would be good enough to smooth out the grained side of a full sheet of 6061-T6 or 5052-H32 aluminum. Just take your time and don't expect the disk to have the same bite after 5 minutes of sanding. The wood disks clear themselves out fairly decently, and end up about the same as a 380 grit when it's finally spent. You can jump to a 600 grit afterwards and get a surface that only needs a wet sanding with 2000 grit to get near polished. There's a benefit to running your paper down farther than you think is working good.   

[yeeshkul]

I've been sanding aluminium enclosures for some time now. I use sand paper 200 and then 600 with really good results. The thing is that after polishing it with 600 i can't get better results with polishing again with something >600 - it turns the polished aluminum into ugly grey hue and gets pretty awfull.

[Earthscum]

... i can't get better results with polishing again with something >600 - it turns the polished aluminum into ugly grey hue and gets pretty awfull.

Wet sand it. Just like they do on cars. Get yourself a spritzer bottle for water, spray the WET/DRY (important) sandpaper and the enclosure with water and start workin away by hand. After you get all the smallest scratches out, then you polish it on a wheel.

Once you get above about 800 grit, you have to start slowing down your speed substantially.

[yeeshkul]

Thanks David, i'll check it out.

[Beo]

Thanks for all the advice guys. Heading to the auto store today to see what other sheets I can find.

Can I take a used hook and loop sheet that worn down bare, and use it as backing for adhesive sheets?

[cloudscapes]

I stopped sanding them. it was too much hassle.

I use this primer that's like glue and so far it's been working. I just wash the enclosures first.

[Hides-His-Eyes]

You use clear epoxy don't you?

[davent]

I stopped sanding them. it was too much hassle.

I use this primer that's like glue and so far it's been working. I just wash the enclosures first.

Etienne what kind of primer are you using and where do you purchase it?

Thanks
dave

[Earthscum]

Etienne what kind of primer are you using and where do you purchase it?

Thanks
dave

I know, I'm not Etienne... but:

Here's the (cheap) primer I use: http://www.rustoleum.com/CBGProduct.asp?pid=397
I used it and Rustoleum Acrylic Lacquer on my GF's Little Angel.

To get a really nice paint prep, use a Self Etching primer. Basically, if you are sanding to paint, just grab a red scotch-brite pad and smooth out the aluminum surface so you don't have any rough shards. Then you use some Acetone (IMPORTANT! acetone is some volatile stuff!!! It will evaporate out of an opened container and settle on the floor, and WILL ignite if ya make a spark! VENTILATION!). Acetone lifts the oils baked into the aluminum during the casting process (release agent residue). Lacquer thinner won't lift as many oils out, but can be used instead.

Now ya shoot the primer. I prefer to do 3 coats of primer. Basically, primer does 2 things... it fills imperfections in the metal, and makes the bond between metal and paint. Use it as filler material. Shoot one coat, let it dry and scuff it smooth with the scotch pad, then wipe the dust with a tack rag. Shoot another coat, do the same, then the same with the 3rd coat. The trick is to knock down each coat to smooth it out and fill imperfections. I ALWAYS scuff my primer coat before shooting my paint.

Proper process calls for an acid soap treatment, self etching primer, filler primer, then your base coat, etc. For stompboxes, well... some LOOK like they can travel at parsecs per second, but I really don't think they have to endure regular 60+mph rock blasts and such. For most of us, chips are battle scars. I would be more prone to buy a vintage guitar that looks like it's been loved than one that looks like it sat in the corner for decoration next to the soda machine and jukebox.

Oh yeah, if ya want something to elevate your boxes, rip the tap off a couple soda cans and fill them with dirt or sand and tape the top closed... or fill them with plaster and re-use them. You can clean the paint off the outside if it gets too much build-up, and it won't blow out from underneath with the air pressure. If you are ding smaller boxes, cut a can down and punch the aluminum into a rectangle to fit in the box, then fill the can. If you use sand or dirt, tape it closed so you don't blow any of it out onto your paint job.

[cloudscapes]

I'm currently using sico goprime all-in-one. it's not oil-based, so it works well with my acrylic paints. I can't guarantee it'll work with enamel. also, I use thick epoxy as a final cover of protection, so while this whole combination works well for me, I can't guarantee it'll work for others with different finishes. it may just be the epoxy holding everything together and the primer does little difference.

[davent]

Thanks for the info Dave!

Rustoleum Automotive products don't show up on the Canadian website,  I've yet to find a spray can of self-etching primer of any brand for sale in this country and i've been looking/watching for a long time. The closest i've come was at a Marine supplier and what they had was a highly toxic, expensive quart can. Anybody in Canada know?

The other problem is the weather window for spraying the toxic soups outside is too limited so i need products i can use indoors 12 months a year. I've had good success so far using an airbrush layering- AutoAir Bare Metal Primer/BIN Primer Sealer (heavy bodied, sandable)/various brands waterbased acrylics/StewMac waterbased sanding sealer and lacquer. Seems to hold up well  but i'm always on the lookout for better products/ways to try. Tried zinc chromate primers, automotive primers, Tremclad Metal primers but what i outlined above is the best i've worked out so far.

Thanks Etienne, i'll keep an eye open for the Sico product.

Take care!
dave

dave

[aquaboy1993]

Been lurking for a long time here but this topic really caught my interest.

Been sanding enclosures for a little while now.  Wet is definitely the way to go.  I saw a Youtube video of a guy sanding under the running water of his bath tub.  Made it really quick. 
I let my paper soak between 5 and 15 minutes.  Using a block is definitely easier and better than fingers.  They get tired.  I got a rubber block from my local hardware store.  They only use a quarter sheet of paper.  I can usually do a B sized box and still have some grit left on each quarter sheet.  BB size takes a little more.  80 seems to knock down the funky milling marks around the edges of the dies.  100, 200, 400, 800, then 1500 and you end up with an amazingly smooth surface that is almost mirror.  I have a BB that you can tell it was poured twice because of 2 different shades of aluminum.  Takes about 30 -  40 mins if you don't get distracted.  I also use lukewarm water.  Seems to help a little.

When I can figure out how to post a photo or two, I will.

Thanks for the great site and forums folks...

Mark

[amptramp]

Rustoleum Automotive products don't show up on the Canadian website,  I've yet to find a spray can of self-etching primer of any brand for sale in this country and i've been looking/watching for a long time. The closest i've come was at a Marine supplier and what they had was a highly toxic, expensive quart can. Anybody in Canada know?

dave

I believe Performance Improvements and possibly some other automotive stores carry etching primer in a spray can and they are also the best bet for black and red wrinkle finish paint.  Canadian Tire carries some stuff but even they still don't know what they have put into space.  (There is some Canadian Tire paint in synchronous orbit.  I know.  From back when I worked at Spar Aerospace.  We put it there.)