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Dremel vs. Thin Aluminum

S

starhawk

[H]F Junkie
Joined
Oct 4, 2004
Messages
8,908
Hey, my father let me borrow his dremel...

...god I sound like I'm fourteen or something (I'm 26). Ack... oh well, someday I'll be able to afford my own power tools!

Anyhow, I'm cutting a really thin aluminum tray, like an office inbox tray. Got it from a prof in college, actually -- he was going to throw two of 'em out, because they're so thin they bend when you poke 'em. I saved 'em for the trash can and have been looking out for a use for them ever since. The tray is like maybe 1/32" thick :eek: this here is thin shit.

Anyhow, I'm trying to cut one with a dremel. I've made it about 1/4 of the way, over the past HOUR. I'm using a cutoff wheel, and the dremel is a Model 800 with a LiIon battery. That battery is now down to about 2/3 but I think it was at about 90% when I fired it up anyways.

I've got the little speed knob at about the number 2, maybe 2-1/4, a pity the damn thing doesn't have a built in tach or I'd be able to be more precise. At least it's not throwing too many sparks. One thing I know is: I do NOT want to shatter the cutoff wheel. That thing looks nasty, and I don't have work gloves. (I've got safety goggles, but that's it.)

What I want to know is, why the fuck is it taking so long?! Am I being too conservative with the speed? or would going much faster (3 or 3-1/2 on the dial) risk shattering the cutoff wheel?
 
There are bits made for cutting metal. If your using a general purpose one its going to take longer.
 
It might not be aluminum, sounds like you might be trying to cut through steel instead, which is of course much more durable.
 
Here's a pic (clickable thumbnail)...



...used one just like it awhile back on some steel and it went a lot faster. But steel is thinner, I think.

EDIT: @Goty -- magnets don't stick to this thing. I tried.

EDIT2: BTW, the dremel goes up to 10. I find it amusing that it cannot be "turned up to 11", although in my case that's almost certainly just fine ;)
 
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use some snips for something so thin. the problem you are having is aluminum is a terrible material to use a rotary tool on.
 
Thought about that. I don't want to spend the rest of my life bending it back into shape after the tin snips are done.
 
...not quite what I meant by "bent"... more like "useless arc of metal" rather than "it's got a couple dents". It would actually wind up almost C shaped overall.

...besides, it's almost impossible to get a straight line with snips. Particularly for me. I got all the way through college without taking a course in scissors somehow.
 
Increase the speed a good bit. Down around "2" is what you'd use for cutting into plastic or wood.
Try a higher setting to get through the work. Something like around 7 or so. And let the cutting wheel do most of the work, don't force it...

This should also help a little:
http://www.youtube.com/watch?v=9iMiH8wYTDY

Since the aluminum in downspouts is close to what you have thickness wise this may also help:
http://www.youtube.com/watch?v=sY0ytyle46Q
 
From the picture, it looks like you have a reinforced cutting wheel, so you shouldn't have to worry too much about shattering and getting hurt from it. I had a smaller, thinner cutting wheel break during normal usage and it didn't pose any threat as long as you wear proper eye protection. If you're not cutting through, you need to increase the speed. Since you have a 10 speed, 8 should be sufficient. At that speed you shouldn't have to apply much force either since more force will damage and wear down the disc a lot quicker. Plus it gives time to the disc for cutting down the material rather than brute force. In the future, stick with a corded dremel. Battery operated dremels lack power in my opinion. Good luck with the cut!
 
My father has two battery dremels (I'm using the more capable of the two) and one really old not-dremel-brand corded model. When I ask for a dremel, he brings me the two battery ones, which is fine with me. I don't use 'em that often (this is time #2) and they're strong enough for what I'm doing.

...I don't know if he could easily FIND the corded one anyways...
 
+1 for insufficient cutting speed. High speed slow feed; that's the aluminum way ;) It's hard for those battery operated dremels to keep pace with their corded counterparts. You've got the right wheel.

That said, I'd recommend multiple passes. DOn't try to break through and then cut across your line. Score it first. Then go back and cut a little deeper. Then more and more until you're all the way through.
 
How thick is the aluminium? Where did you get it, any idea what type of Aluminium?

In general, people are telling the truth when they say aluminium is soft and you can use the same cutting disks. However, there are many varieties of aluminium that are stronger than your average steel and significantly harder to cut. Those big planes flying through the air are mostly aluminium, and I can almost guarantee the aluminium in them is tougher/stronger than most of the steel used in your car.

I had some aluminium shafts I was using for arrows and foolishly thought a standard dremel cutting disk would work fine, it was less than 1mm wall thickness and about a 5/8ths inch diameter and we went through 2 or 3 dremel disks just to cut 2 shafts :p Ended up swapping to a small drop saw instead.
 
Thank you, cmadki4, that's extraordinarily helpful! What I'm doing at the moment is, instead of trying to make my wobbly hands and vibrating dremel cut across a ~11" line all at once, I'm doing ~1/4" sections at a time. I touch it to a section for a second, then lift it up and let the motor spin back up. Rinse and repeat a couple thousand times and I'll be done :eek:

Tudz, please re-read my original post, as your questions are answered within it.
 
Exactly what cmadki4 said. Dremels and rotary tools in general cut not through torque but through the sheer speed the wheel is moving at. You shouldn't press a rotary tool into the material you're cutting, you should apply mild pressure and let the pure speed of the tool cut through.

For what it's worth, I have a Black and Decker RTX (three speed) that you can likely get at Home Depot or Lowe's for $20. It works with Dremel accessories and I used it to cut the hell out of my Cosmos S, it carved aluminum like butter on the maximum speed. It takes quite a bit longer with steel, but aluminum is pretty easy to cut and it doesn't fire sparks everywhere like steel does, though it does make dust.
 
Thanks! I'll look into the RTX.

I wasn't putting any real pressure on it, just touching it to the metal and lifting back up.
 
I have an RTX as well and it's been great to me. I used it almost weekly for 3 years. It takes all the same toolings as the Dremel brand rotary tools.

For what it's worth, always use a reinforced wheel. It's safe and the cost difference is negligible considering the safety, reliability, and speed of the wheel. I usually start around medium speed if I'm working with metal and speed it up more if the cut is going slow or the wheel is wearing out too fast. Just make sure you cut at an angle away from your face so if the wheel were to shatter it won't fling pieces into your face.
 
"My eyes, the goggles, they do nothing"... at least, against cutoff-wheel shrapnel? Hmmm, not as funny as it sounds. Especially since my goggles are cheap plastic junk.

...Lowe's website only lists four brands of rotary tools, and Black&Decker ain't one. I'll give 'em a call probably tomorrow -- they're in the next town over and public transit totally sucks (as does my budget) but I'll see what I can find out.
 
For eye protection, go to Academy or a similar sporting/outdoors store. Get a pair of decent glasses for eye protection while shooting. That's what I use while cutting since if they are rated for use with firearms, they're likely plenty good enough for use with power tools. I also use them when I edge my yard, I've had little rocks hit me in the face too many times.

The side benefit is the next time you go shooting, you already have eye protection!
 
Hmmm... the problem with that is that I'm a Democrat. I'm allergic to the types that frequent those stores, and they're good at picking arguments with me (this does not go well).

The other problem being, I have little money. I'll be OK. I made serious progress today -- nearly doubled the distance I'd cut in 15min! I've got that little bugger on 6 now and it's a lot easier. I'm a bit of a nervous fellow, so it's not going any faster.
 
Ballistic glasses are cheap, I think I got mine for $8 or something like that. Don't take risks with your eyesight!
 
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