Good results cutting aluminum

I finally got a chance to try my 6" abrasive cut-off wheel from Harbor Freight (regularly $40, on sale for $18). It worked like a charm!
Sliced right through my 1/16" aluminum angle stock, and left a reasonably neat edge too.
So I think I'm in good shape to start building an armature for my humanoid figure. Thanks to everyone for your guidance!
Best, - Joe
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Joe:
To the best of my knowledge, an abrasive cut-off wheel is *not* the correct cutting tool for aluminum. The aluminum will clog the cut-off wheel and you will have to redress the wheel or replace it. Instead, you want a carbide blade with as many teeth as you can swing. The more teeth the better. The abrasive cut-off wheel is exactly the correct tool for cutting *steel*.
Hmmm $18. I may have to make a trip over to Harbor Freight myself. ;-)
-Wayne
Joe Strout wrote:

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When I work with aluminum, I make a rough cut with a fine tooth bandsaw, leaving about 0.05" of slack. Then I finish it with an endmill, using a climbing cut on the first pass, and a higher speed desending cut on the final pass. This gives a very accurate cut (+/- 0.001") and a mirror smooth finish.
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Wayne C. Gramlich wrote:

I have heard of abrasive wheels made specifically for aluminum cutting that will not gum up like the steel cutting wheels. I have not seen one personally though. If the wheel gums up, it's worth looking for.
Good Luck, Bob
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Joe Strout wrote:

I am not sure anyone else has mentioned it but...
If your hacksaw will not cut aluminium, something is badly wrong. You do have the blade the right way round don't you? It should cut on the forward stroke. Sorry if that is insultingly obvious.
Pete
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It's not obvious -- in fact it's not clear to me why it should matter. If I had it the other way, it would simply cut on the back stroke, right? But in my hands, it didn't seem to be cutting on either one. (Or perhaps it was, but well below my patience threshold.)
However, I'm inclined not to worry about it, since the cutoff wheel is working beautifully. (I will keep in mind Gordon's warnings, however.)
Best, - Joe
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Oops -- I meant Wayne's warnings. Sorry about that, Wayne!
Best, - Joe
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Joe Strout wrote:

No sweat.
If any documentation came with your abrasive cut off wheel, look to see what materials it is approved for.
Back when I was taking metal shop in the early 70's in high school, the metal shop teacher would really hassle anybody that put aluminum on the grinding wheel. It was easy to tell when the grinding wheel was gummed up with aluminum.
It is possible that there have been technological improvements that have made aluminum abrasive cut off wheel feasible. Carbide blades work great tho'.
Enjoy,
-Wayne
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Nothing that came with the wheel or the cut-off saw lists any materials. I'm calling Harbor Freight's "for technical questions" line, so we'll see if they have a clue. (So far they don't, but I'm being transferred to "the technical department" as we speak.)

I'm hoping I'll be able to tell when it starts to get to that state. So far, after making 5-10 cuts, I can't see any change in the wheel. If it does get gummed up eventually, I'd be inclined to just replace it -- they're less than a buck each, so I'd have to go through a LOT of them to bring me up to the cost of a power miter saw.

No doubt -- but that'd be a different tool, I think (i.e. not just a disc change). One I will probably spring for eventually, but I'll take my $18 chop saw as far as I safely can first.
Best, - Joe
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Well, frick. I did finally get somebody at Harbor Freight who sounded like he knew what he was talking about, and he said that using it (or any grinding wheel) on aluminum was a very bad idea -- the aluminum might expand during cutting, grab the wheel, and cause it to fraction into lots of pieces. He recommends this tool only for cutting steel.
And yes, this is what you all have been telling me all along. :)
He said that for aluminum a hacksaw or bandsaw is the right tool; I presume from what I've read elsewhere that a power miter saw, with the right sort of blade and some lubricant, would also be safe. But I haven't got one of those, so maybe I'll turn my hacksaw blade around the right way and give it another try.
Fortunately, I'm still well within my 90-day return period... so now I just have to decide whether to take it back, or keep it and figure I got a great deal on a steel cutter. Can't imagine why I'd be cutting steel though -- it's too heavy for most bots, and I can't drill it (not with my current tools, anyway). So this would probably just end up sitting on a shelf.
Rats! But, at least my education is ongoing, and I didn't sustain any injury in the process, so I guess in that sense I'm doing well. :)
Thanks, - Joe
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Joe Strout wrote:

But you ask so politely, and you actually listen to the answers. Everybody benefits from the dialog.

If you can find a 6" carbide blade that fits your chop saw, it should cut aluminum just fine. Doing a Google search for 6" circular saw blade carbide returns multiple hits. You want as many teeth as possible. The only issue is what size hole is in the middle of the blade.
While I'm talking about it. Cutting aluminum with circular blade is *noisy*. You definitely want some ear protection -- either ear plugs or ear muffs.
Of course, eye protection is an absolute must. Don't even consider turning the saw on without adequate eye protection.
Lastly, the resulting aluminum flakes are messy. Don't run the saw in the middle of your living room. ;-)
I'd recommend keeping the chop saw if you can find the carbide blade.

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Personally, I've benefited greatly from this discussion. I hadn't realized that my knowledge of hacksaws (and grinders) was so lacking. This explains some of my frustrations in the past dealing with these tools.
Thank you to both the original poster, and those who followed up on it.
Joe Dunfee
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I'll mention here that rec.crafts.metalworking is also a group filled with many knowledgeable people, who are very quick to help as well (on the downside, it tends to have too much off-topic politics, and of late it's been hit as hard by the sporge and mi5victim floods as this one).
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I may give it a try. I'd be surprised to find another blade fitting on the mount in my cutoff saw; that'd be a miracle of standardization that I have come not to expect. But maybe tooling is better than other areas of industry.

Yes, I'm all about safety equipment. Safety earmuffs and goggles are on before I even approach a tool that loud. (For less noisy tools, I do omit the earmuffs, but I don't even use a drill without the goggles. I not only want to protect my own eyes, but I want to be sure I'm demonstrating good habits to my boys when they start working with tools.)

No kidding. I run it in the basement guest room, but I sweep up afterwards. While we're on the topic, I was surprised to find that aluminum has an odor when it's cut. Should I be wearing a breath mask too? My intuition tells me that it's not a problem; the dust doesn't seem to hang in the air, but instead spews itself neatly over the table and floor. But I've been wrong before.

I do still have plenty of time to return it, so maybe I'll make an effort to find such a blade first. I guess fundamentally, a blade and a grinding wheel are both just discs with a hole in the middle (and this saw accepts wheels with two different arbor sizes -- 5/8" and 7/8").
So, would you guess that any 6" blade with a 5/8" or 7/8" arbor diameter, and rated at 9000 RPM or higher, should be safe to use?
A brief search suggests that this may be hard to find; 6.5" seems more common in circular blades, and most of them have a 1/2" arbor. I did find this diamond segmented blade: <http://www.toolbarn.com/product/makita/A-94708/
It's the right diameter and arbor size, but they suggest it for cutting concrete, block, and brick. What would it do with aluminum?
Best, - Joe
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Joe Strout wrote:

Harbor Freight sells a basic handheld bandsaw that has worked very well for me in cutting off steel and aluminum. If you watch carefully, it comes up for sale at about $60 once or twice a year. The blade that came with mine is still going even though I bought a package of Milwaukee brand blades (they're the same size for the ~$300 Milwaukee handheld bandsaw and the HF unit).
Pete
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Joe Strout wrote:

Depends on the cutoff disc, but some are made to work with non-ferrous metals as long as the metal isn't too thick. The advantage is that they're cheap. If you want the absolute proper cutoff saw for a power saw you'll want to get a blade for non-ferrous metals, but these things are often more expensive than the tool you're putting them in.
Unless you're doing production work, or have a ton of material to cut, you really don't need it just to cut aluminum extrusion. A hack saw with a good miter box does the trick. Just buy a pack of good blades and let the tool do most of the work.
-- Gordon
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Any power drill with high speed steel (or better) bits is perfectly capable of drilling steel.
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Joe Strout wrote:

The natural action when cutting is to put downward pressure on the forward stroke and lift up on the reverse stroke.
You may like to have a look at this:
http://www.tpub.com/content/aviation/14001/css/14001_25.htm
Pete
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Thanks, that's a very helpful reference. Based on this, I'd guess that the problem might have been the wrong blade; this aluminum is only 1/16" thick, and I don't think two teeth of this blade would fit on it at once -- I haven't counted, but I'd guess it's closer to the 14 teeth/inch than the 24/inch recommended for angle iron (or, presumably, angle aluminum).
Best, - Joe
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Joe Strout wrote:

Good hacksaw blades will have an arrow the shows which end goes at the front of the tool. There is more cutting pressure, and therefore results, when you push a saw rather than pull it. That means you want the teeth pointing away from you, or the front of the tool.
The biggest problem with using any power tool for cutting channel stock is that you MUST use a clamp to hold down the free ends. Otherwise, do it often enough, and eventually you'll have a piece of aluminum hurling toward you, your car, a pet, or a loved one. I had this happen once, and I calculated the metal flung out at around 50 mph. It hurt like hell and seriously bruised my hand.
-- Gordon
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