disappointing results with aluminum

Joe:

A Dremel motor tool is the wrong tool.

You should get either a metal cutting bandsaw, a table saw, or mitre saw. For the table saw or mitre saw you need a carbide blade. It cuts through aluminum like butter. Note that hot metal aluminum flakes can potentially ignite the saw dust that tends to collect around a table saw that is used for cutting both wood and aluminum.

You should see if you can find a Harbor Freight retail store in your general area. They sell the same Chinese import stuff that Home Depot does, but at significantly reduced prices. The reason for buying retail is so that you can return stuff if it is a "lemon". The fit and finish of the Chinese import stuff varies all over the map -- some is total junk and other stuff is quite functional. Buy it, try it out, and if it works, keep it; otherwise return it for the cost of gas required to drive it back to the store.

I usually cut aluminum on my bandsaw (an old Sears Craftsman with speed reducer that predates Harbor Freight by a decade or so.) I prefer the bandsaw because it is harder to cut off a portion of your body with a bandsaw. (Also, with the right blade, my bandsaw will cut steel, which a table saw will not do.) I don't own a miter saw, but I suspect that they are pretty safe, too. I think the bandsaw is a more flexible tool than the mitre saw; more expensive too. It is a real bummer that good tools cost real money. Sigh.

-Wayne

Wish you had asked before about this (or I overlooked it) The Dremel is a great tool to have in your box, but it's a pain as you have found out when you need to do a lot of cutting. No - it's not you. It really is just a pain. See below for more info on better ways ...

Hey Joe. I just use a $99 Ryobi saw from Home Depot (like model # TS1341 ) . I paid almost that much again for a special non-ferrous metal cutting blade, but I do a LOT of cutting aluminum with it. You *might* not need a special blade - just get one with as many teeth as possible and be SURE to wear your safety goggles! Here's a link to the one like I use:

Here's what I've learned from a couple of close calls:

1) Make SURE the aluminum is seriously clamped down. 2) After the cut is complete, continue to hold the saw down when you release the power trigger and let the blade spin down. Only then do you let the saw raise back up! Otherwise - you risk launching any free pieces like a missile in an unpredictable direction.

Some other tips for cutting aluminum with what you have on hand are:

1) Mark the cut line with a sharpie or even pencil 2) Drill several holes down one side of the line 3) Use a hack saw to cut through the holes. This way you don't have so much to cut with the hack saw. 4) To get a good finish (and SAFER, too) use a file to clean up the raggedy cut line.

Also, the people on the metalworking newsgroup have been invaluable to me. Sometimes there's a lot of Off Topic stuff posted on there, but just ignore it ( or even read it if you just want to feel better about yourself ! Ha! ) The guys that answer your posts will be more than willing to listen to your "dumb questions" ... just like they did - and still do - with me.

Here's the newsgroup: rec.crafts.metalworking

A couple of guys from this robot newsgroup show up on there now and then, too. I would post on that group - telling them exactly what you want do - and let them guide you in your tool selection. Then you can come back to the robotics group for info regarding building the bot itself.

Good luck ! JCD

You should be able to cut common aluminum alloys with a hacksaw with very little trouble. Are you using a metal cutting blade? Also, when cutting aluminum, use liquid soap as coolant. Get a bottle of liquid soap with a pump and apply to the cutting area.

Did you possibly pick up some alloy like duralumin? Most hardware store stock won't be a hard alloy, but surplus might be. If so, just get a carbide hacksaw blade.

You're using a real hacksaw, right? Not a hand jigsaw.

The way you get a clean edge is by cutting, then cleaning up with a grinding wheel or file. You can put a grinding wheel in the Dremel tool, although a small bench grinder is more effective. Wear goggles.

This should be a three minute job with hand tools.

John Nagle

A Dremel isn't good for applications like this, for exactly the reasons you cited.

For cutting, I have had a great deal of success with hacksaws (I can't imagine what the problem could have been with yours -- hacksaws cut mild steel quite nicely, and barely notice aluminum) and jigsaws. Drilling is also easy with a high speed steel bit.

A Dremel is totally unsuitable for this type of work, and something is seriously amiss if the hacksaw did not even scratch the aluminum. You could try a simple miter box - get a good blade for your hacksaw and it should easily cut the aluminum. A large clamp might also come in handy to hold the miter box and the aluminum angle to your workbench while you do the cut; that way it will be steadier and you can use both hands on the hacksaw which will give you better control.

Buy a decent woodworking mitre box - they use saw blades which are about an inch wide, give you a better cut than a traditional hacksaw.

This will give you perfect cuts in ali and mild steel - use a little oil when cutting.

Make sure that there are at least two teeth in contact with material when you are cutting - this will usually mean going for 24 tpi blade or finer. It is ok to use a fine blade on thick material, but it will seem slow, the teeth will tend to clog with the swarf.

OK, your blades will have a comparatively short life when cutting steel, but they are cheap to replace and everything is safe and controllable ! I have cut slices off a 3 inch steel bar in about 5 minutes.

Another gadget worth knowing about is a 'sheet metal saw'. This can do infinite length cuts, unlike a normal hacksaw where the frame gets in the way.

Dave

Hi Joe,

1/6" is a funny number. Is that a typo from 1/16" ? If it is 1/16", that is pretty thin stuff and sheetmetal shears or tinsnips are the best answer. 1/16" is too thin and floppy to saw very well.

If it really is 1/6" (0.1667"), then the saws that others have mentioned will work well. For power tools, a saber saw will work. A small horizontal bandsaw will be better for angle stock and tubing. A vertical bandsaw works pretty well for small sheet parts, but large parts get into trouble on the back side of the vertical bandsaw. To use hand saws, you really need to clamp the work to something. If you are cutting angles, a simple miter box with the work clamped to one face works as well as any hand saw arrangement.

Working with the mechanical bits is as much a skill as the electronics or software. If you could find someone local who has the skills and tools to help you through the first project or two, it would be a good thing. It is the path that many people have taken.

Good Luck, Bob

and also some

Thanks to all for the advice. It sounds like the Dremel is, in fact, simply the wrong tool for the job, but the hacksaw should have worked.

What I have really is a hacksaw, not a jigsaw; the standard kind with a frame (but the frame is plenty big enough for this 1-inch angle stock). I don't know what kind of blade it is, though; it's just whatever came with the saw when I bought it. I'll look into getting a carbide blade for it; it sounds like that's the best for cutting metal. I also wasn't using any lubricant or sealant; I'll try some liquid soap or cutting oil.

As it happens, there is a Harbor Freight right here in Fort Collins, and I've been there a couple of times -- for some reason I often forget about them when I run out for tools (probably because Home Depot and Ace are both significantly closer). I'll check them out today.

I did some searching for power miter saws yesterday; I'm glad to hear that Pogo has had good luck with the Ryobi TS1341, since that's the same one I was thinking about trying. At $99, it's not bad for what will probably be an extremely useful addition to my toolset. I'm going to have to wait a while before getting it, though, so it's still worth seeing what I can do with hand tools.

Finally, thanks for the pointer to rec.crafts.metalworking; I've subscribed and I'll probably follow up with additional metal-working questions there.

Best,

- Joe

Based on what he seems to be cutting, a small bench top bandsaw may work well.

If it were my fingers, I would prefer a bandsaw over any rotating blade saw if an accident occurs.

A small bench top bandsaw would be useful in future robotic building so it would be a good investment.

The small benchtop saws do work well with wood and aluminum...no steel though without slowing the blade speed up alot and a different blade.

Also remember that when using a saw blade, one wants three teeth to always contact the item being cut to prevent damage to the blade.

TMT

I would suggest you put a better blade on your hacksaw to be honest, angle is a bit unpleasant to cut at the best of times, but I can use my junior hacksaw to cut inch by inch by 1/8th stainless steel angle in 5 mins, alu should be no problems at all!

As others mentioned, a [good] hacksaw blade [chuck the one you have if it won't cut soft aluminum!] and miter box will work fairly well. If you're going to build an entire large robot this way, you might invest in a cut-off saw. On sale now.

They should have them at Harbor Freight in Ft. Collins. [BTW, Ed.Rupp in FRRC has one].

Forget the following one, it's a total piece of crap. Use for plastic only, not metal as advertised ... get the real one above.

Thanks -- I was there yesterday, and bought a similar item, also by Chicago Electric, but that uses 6" wheels. For the 1-inch stock I want to cut, the size certainly shouldn't be a problem, and if it doesn't work, I can return it. (It was on sale for $18 -- a mistake, apparently, but they manager let me have it anyway; the regular price is $40.)

I'll try it soon, after carefully reading the manual and finding something to put over my ears (I suspect that these abrasion wheels scream like a banshee when cutting metal). Will report back.

Best,

- Joe

Yes, good catch; I meant 1/16".

Hmm, that's an interesting thought. It doesn't seem at all floppy to me, but that's probably because it's angle stock; I did notice that flat stock of the same thickness was pretty floppy.

I just bought a cut-off saw, but if that doesn't work out, mayble I'll give the tin snips a try.

No doubt. I asked on my local club mailing list, and didn't get any takers, so I guess I'm on my own -- with the help of kind folks here and in rec.crafts.metalworking.

Thanks,

- Joe

grinding aluminum is usually not much fun. it is softer than iron and has a tendency to gum up grinding wheels really fast. circular saws will generally produce much cleaner cuts than band/hack saws since the blade is stiffer. i've found the best way to make aluminum look pretty is to cut it a little large then finish it on a mill, but doing that is seldom worth the effort.

also, you may want hearing protection in addition to goggles. i suppose this depends on the saw/blade/clamps/material/etc, but i've generally found that when sawing aluminum the noise is much more irritating than the swarf.

if you don't have the right tools and are not overly price or accuracy sensitive, onlinemetals.com will, for a fee, do custom lengths in small quantities.

-chris.

Worry more about the swarf and wearing goggles, after spending 4 hours in the hospital I found its much harder for them to pick a non- magnetic shard from the centre of your pupil than it is to get a chunk of steel out :-)

Dremel tools are great for doing itty-bitty detail work. Other than that, forget it.

A hacksaw with a good metal cutting blade should work. I use a sawzall with a metal cutting blade and clean up the cut with a file and/or hand grinder. 3 inch steel angle is a cinch this way.

Everyone has already responsed about the Dremel.

As I've said before, I built EVERY robot in the original Robot Builder's Bonanza using only rudimentary hand tools, including a hacksaw I bought at Builder's Emporium for $1.99. The drill I used was an old Black & Decker that didn't even have a reverse or speed control on it. I discuss using these tools in RBB, which you can get at most any library. I have more indepth coverage on basic metalworking and tools in Constructing Robot Bases, which is out of print so you can probably find it in the remainder bins.

Obviously, you need new and sharp blades made for non-ferrous metal. Blades are different, with different teeth spacings and set. You probably wouldn't get good results using a fork to comb your hair, so likewise, there's always the right tool for the job.

-- Gordon

--A hacksaw will cut aluminum without any problems. I suspect you've either got the wrong blade or a dull blade; probably both! If you're starting out from scratch with nothing but hobby tools the very first thing you've got to do is get a good vise and bolt it to your workbench which is hopefully not the kitchen table! Once you can hold the stuff you're trying to cut in a good vise you can have at it with a new hacksaw blade. The next thing you should get are some decent files that you can use to refine the edges that the hacksaw leaves ragged. After that you'll need a hand drill or, better yet, a small drillpress and a good collection of drill bits. Next thing to get would be a tap handle and some taps, then you'll be able to make stuff and connect the dots. --For more on what you need to know you should go over to rec.crafts.metalworking and find the FAQ (posted weekly) and give it a read: it's a real education.. :-)