In message snipped-for-privacy@4ax.com, Cursitor Doom snipped-for-privacy@notformail.com writes
I have an Evolution circular saw fitted with a blade suitable for metal cutting. TC or HSS inserts brazed to the disc with a shoulder behind each tooth to limit the depth of cut. Handy for floorboard work.
Have a look at the Evolution site.
I would have thought using a cut off or chop saw would be better for cutting MS tube and even solid bar rather than trying to use a mitre saw as an all purpose tool, horses for courses.
There are plenty of angle grinder stands that take standard angle grinders and make a basic chop saw and most seem to allow the clamping of metal at
45deg.Richard
Alternatively, I picked up a second-hand bandsaw, that can be used free-hand vertically or with the metal clamped straight or angled and the blade operating horizontally.
If the motor on the saw is a universal motor, you might be able to set the speed using a variac, as in this Youtube demo.
Universal motors are ones where you might find a bridge rectifier in the housing, that makes DC from the AC mains. I think my electric lawn mower has a bridge rectifier in it. There are other motor types, maybe capacitor start, where the variac may not be a good idea. In a physics labs, variacs are used for blowing up stuff. It allows starting from zero volts. The range on a variac surpasses mains voltage. So it if says "110%" on the knob, strictly speaking that is past the spec for mains voltage. Some TV repair shops used to run the old TV sets up to 110% of mains, just to verify there are no issues with appliance operation on high-side of proper rails (the colour sets used to have a spark gap to prevent Xray production by the CRT). Rather than just testing the set at 100% as normal. You can't just wildly wing the control all the way up to the stop, in case components in the load aren't designed for that.
There are various sizes of variacs. And I don't know what the supply of those is like, or who sells them. But they are quite popular in science labs, for ruining stuff. Like putting mains current through a piano wire, when the piano wire is suspended between the two poles of a magnet. You get a standing wave pattern on the piano wire. When you wing up the control to 100% on the variac, the piano wire promptly "parts" with a little spark for the folks.
Another way to cut metal, would be a band saw with a metal cutting blade on it. It would throw sparks of course, because those aren't typically abrasive or diamond based. But it should give you a square cut, if the band saw is one of the older more rugged ones, and not some plastic piece of crap. The band saws in school were taller than I am, with adjustable height table, schemes for feeding and so on.
Paul
Chop saw makes more sense.
Yeah, that sounds potentially dangerous. I don't fancy taking one hand away to fiddle with a variac when I need to focus on the cutting itself.
BTDT. In my earlier days, I just assumed a variac was like a thumping great reostat and treated it as such. Blew up a lot of stuff by wanging the knob right up to max.
Depends on the wattage of the motor. Most variacs are only good up to
3A, so you'll blow its in-built fuse if you try to power a typical buzz saw up with one.Decent variacs are hard to come by for sensible money these days, so one often has to rely on picking up vintage ones from boot sales. I did that a few years back and got myself a 2A pre-war one which I planned to upgrade to modern day code. First thing I did (seemed a sensible thing to do at the time) was spray a load of Servisol all over the turnings where the wiper contacts them to improve conductivity. Next time I turned it on - BANG! The 'varnish' they used on the coils back in those days is not the same as we've used since and the Servisol washed it all off, leaving all the turns shorted. Oh well, live and learn. <shrug>
I'm beginning to think this may all be a wind-up. How do you think hacksaws and metal-cutting bandsaws work?
... snipped
There is either a missing "not" between <would> and <throw> or you have never cut metal ...
I've been tempted by those but having to buy replacement blades put me off. I used to have an ancient Rapidor powered hacksaw which was great for just nodding through metal but OTT for my uses, I sold it when I got the Evolution saw.
100% NOT a wind up. I've never seen a metal cutting bandsaw in action but if they're anything like hacksaws, then they only have tiny, tiny teeth. The rotary blades for mitre saws I've seen have great big ugly teeth that only look suitable for wood. Are you telling me it's safe to cut steel with a rotary blade that's got great big ugly teeth? And how long do you suppose those teeth are going to stay straight and sharp if you're going to try cutting steel with them?
Have you ever thought about what an end mill or slitting saw has on it? Typically HSS or carbide teeth... They cut steel just fine.
Slitting saws have tiny teeth that aren't going to dig in and break off. End mills are held in an extremely strong chuck and the bed on which the work is held moves very slowly in a rigidly controlled manner. Constrast that with the subject under discussion. Would you seriously consider cutting two inch mild steel box section in half using a Skill saw? And what sort of shape do you think the teeth would be in afterwards if you were stupid enough to attempt it?
The bandsaw blades I've seen are cheaper than I've seen the metal-cutting circular saw blades for.
I was originally planning on a powered hacksaw (as I used to use in my schooldays), but the bandaw - similar, but not the same as:
It's certainly not the solid build quality of a professional worskshop one, but it's more than good enough for home use.
One store I checked, they varied from 4 TPI to 14 TPI. They're bimetal. And some of them say "low tension", which implies maybe the joint doesn't go round the wheel all that well or something ???
By the way, it helps if you're a foreigner, and are fond of cracking jokes. It cuts faster if you do that. In this example, you can see the blade velocity isn't all that high, and they're using proper cutting fluid on it. For cutting tubular steel, you would not bother with those details.
For a light duty bandsaw, the bandsaw is fixed and the work moved.
For that bandsaw, the work is fixed and the bandsaw moves.
There are also crazy gadgets like this. Power hacksaw. Apparently cuts straight and true. When the hacksaw blade is knackered, you can make a knife from it (that's what we did in shop class). Probably too slow for the impatient, but on the other hand, this thing is cutting solid stock, which is reasonably impressive. Even if it takes a while.
The fact remains that the blades have teeth and they cut metal using quite mundane chop and circular saws. Let it go.
Chop saw makes a lot more sense and is much faster.
Standard teaching is that there should be at least 3 or 4 teeth in contact with the work at the same time, to prevent snagging and tooth or material damage. Those metal cutting circular saw blades have such wide tooth spacing that only one will be in contact muchg of the time, being able to drop as that leaves the workpiece and before the next slams into contact. They must work, but they do seem a poor option.
The blades intended for metal cutting do not have the deep throat found behind the face on those used for wood. Instead, there is a support which prevents the tooth in work from taking more than a shallow cut.
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That's how I see it too. I'd *much* prefer the toothless kind of cutting disk that's typically seen on angle grinders, which cuts by abrasion. I don't see any obvious reason why I couldn't use one of those in the mitre saw I'm considering buying.
With the right type of saw and blade certainly. There are lots of "cool cut" (i.e. cutting rather than abrasive bladed) skill saw form factor metal cutting saws about.
You can get them in traditional "cut off" saw form factors as well (i.e a bit like a chop saw arrangement) but with a work clamp etc. Very good in fabrication workshops, and they don't throw abrasive dust into the air in the same way as abriasive disc saws.
On the occasions I have seen them used, the teeth remain exactly the same shape as they started.
A comparison of blades in cut off applications:
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