mpedrummer

Hey -

So, when you sand wood, you start with a heavier grit, and move up to a finer grit.

Do you need to do the same with metal?

MPEDrummer

bishopwill

I can't tell you, but you might want to head over to www.hardforum.com and ask in their Cool Cases forum. You'd be amazed at the number of ways they've found to modify their cases and the hours of work they put into them

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HALDONIA

IT TOTALLY DEPENDS ON THE BASE METAL ITSELF,WHAT YOU ARE SANDING OFF,AND THE DESIRED FINISH.SMOOTH FINISH ,DEPENDING ON THE METAL,WILL PROBABLY REQUIRE A VERY FINE GRITT AND THEN AN EXTRA FINE GRIT BUFFING.

BEST WAY IS TO SODA BLAST REGARDLESS OF THE METAL

mazak

so. what does the finished product need to look like?what are we working on ? a car body requires a lot more effort than a lawn chair or a mail box. let us know!

josh_s08

In art, we started with a low to a high. But this wasent the best of metal, just for art and such.

mpedrummer

Well, first, thanks for the responses.

Second, not sure how much more info I can give.

My girlfriend is Glass major at RISD, and she's taking a welding class this semester. She is currently building a chair of some sort, I assume (this is really a guess) it will be steel?

Thanks

MPEDrummer

mazak

a buffing cup[a big wire wheel] on a grinder is about all she will need. clean the metal with that and the slag from the welding. then prime it andpaint it what ever her favorite color is. also for a smoother look she might want to take raised part of the bead down a little. good luck.

william

Steel is not the same as wood. For a finer finish, you will want to use a finer sander (paper) either way. Wood is not as strong as steel, so don't go as tough. Glass is even less durable, so go easy.

clavus

I agree with the above.

Keep in mind, some sandpaper works better when wet. Always sand in the same direction.

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TequilaJr

coarser to finer grit is the way to go, but keep in mind that if you go too coarse to start, you have a lot more work cut out for you when you're trying to get the surface finished. So, try to use the finest grit that will do the job.

mazak

it will be steel?

maybe i miss read?

homerhop

Start with a coarse and work down to a very fine.If its a small area and you have alot of time you can draw file which will give a very polished surface and remove any traces of the the file marks . It all depends on what the metal is and how high a quality of a finish you want

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frankyfish

for metal you want to end with a very fine sandpaper, and you want to wet sand it. wet sanding helps keep it from coming out all scuffed looking and gives it a smoother feel. i bought a sword (high carbon steel) in which the blade was acid etched after being ground (produces a nice sharp edge but not pretty) and then not really cleaned well or polished. it was sharp but there was alot of crud on the blade. this type of sword is more for practical use such as to go along with a course of martial arts study vs hanging it on your wall to look pretty. to clean it up i started with a 1000 grit sand paper and then moved to 2000 grit. all the sanding was done wet. the finish isnt amazing since i didn't want to spend all day on it, but it looked much much better afterwords. i cut the sandpaper into managable sized pieces and then would wet them before sanding. you want to run the sandpaper only one direction on the metal and for the full length of the piece you are working on to prevent swirl marks and little scuffs.

longjohns

i fabricate some metal furniture at my work. the think to keep in mind about sanding steel (as mentioned above) is that it's much harder than wood, so requires much more effort to sand. It is definitely smart to use the finest grit you can which will still yield results. Be very diligent about progressing sensibly through the grits - you can waste a lot of time if you skip too many grits and find yourself unable to remove scratches from the last step.

there is also a big difference in the finish you'll get depending on what methods of sanding/grinding you're using. for example, here's how i might go about polishing a piece of steel:

on a disc grinder:
grind any big welds down almost flush with a cutoff disc
grind welds flush to the surface with 120 grit fiber-backed disc
scratch removal with more discs - 65 micron, 45 micron (approx 220 grit, 280 grit, respectively)

then i switch to a dual-action sander with 150 grit sandpaper. i might then use 220 grit on the DA sander, but often i'll just go to the red 3M ScotchBrite pads. much of what we do gets nickel plated, and the nickel can cover some degree of scratching. for chrome plating, the metal must be extremely smooth, almost polished.

that's probably more technical than you're looking for - i guess the point i'm emphasizing is being very deliberate about removing scratches at each step. contrary to a comment above, it is often helpful to alternate sanding directions between steps. two reasons - it is easier to tell when you have successfully removed the last step's scratches, and your piece will stay flatter.

if flatness is a concern, keep in mind that your workpiece will usually be as flat as what you use to sand it. this is why people use thick plate glass or accurate grinding stones to lap precision metal surfaces. if you use nothing but soft-backed pads or sandpaper held in your hands, expect to lose flatness. where it's important, use sanding blocks, belt sanders, files - things with hard, flat reference surfaces.

the higher polish you put on metal, the more you will notice if it's not flat.

i'd better quit babbling!! ;-)

toxic515

longjohns has the best info. The dual action sander or random orbit (air powered is best) will yeild by far the finest most polished results. All of this depends greatly on what the metal is, and the desired end result, but the teacher in the class should (SHOULD) be well schooled in this as well, and be able to provide the best final answer overall.. Otherwise, if your friend is cute, have her put on a revealing top and head for a local body shop... They'll probably be glad to help!

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