I have the occasion to make about a dozen or so cuts in corrugated iron roofing (they build everything out of it here in New Zealand). A coworker suggested I put an old blade backwards in my circular saw. Says it doesn’t do the blade any favours but gets the job done.
The only crap blade I have is a cheap tungsten-tipped one. Am I in danger of the tips getting ripped off the blade and piercing my flesh?
Seems to me this would work, but I just want to make sure I’m not setting myself up for a Homer moment.
Is there a reason you can’t go to the store and get a metal cutting blade? You should be able to cut iron with a circular saw that has a ferrous metal cutting blade, or a reciprocating saw, again with a metal cutting blade, or a jigsaw with a metal cutting blade (slower).
Don’t ruin a perfectly good blade, and endanger yourself in the process, get a blade designed to cut the metal (both type and thickness) that you’re working on and be safe.
You can run a non-carbide blade backwards…it makes one hell of a racket and a better finished cut is made with a blade with more teeth…you can also run a carbide blade backwards, but you might loose a tooth or two…highly unlikely, but possible. In any event you want to wear safety goggles…preferrable with vent caps rather than the perforated sides and hearing protection. Like the last reply, however, you can buy a metal cutting blade for a few dollars which is made of metal and smooth rimmed or you can run a corrundum blade used in steel chop saws—also cheap. The carbide tipped blades for running in metal saws run at a different rpm than a wood (skill) saw and they are not cheap.
Of course! I’m cheap as hell. If it comes to either spending money, even thirty bucks (this is New Zealand, stuff’s a bit more expensive here), and wrestling with tinsnips, I’ll probably go with the snips!
Might borrow a recipro saw. Blades for those are cheap enough.
Both my parents grew up in Montclair, and my grandmother lived for years at 480 Valley Road and before that, 246, I think.
The teeth on wood cutting blades are usually larger/deeper cut than those on metal cutting blades, they are also cut at a shallow angle (metal cutting blades are often just a sort of a disc with little notches in them) - attempting to cut thin metal with a wood blade installed the usual way might well result in the teeth snagging the metal and tearing it to pieces or buckling it - any of which could result in dangerous flying metal or a stalled motor.
Running it backwards presumably means the teeth would slice rather than bite, but I still think it sounds a terrible idea; experimenting with unconventional uses of tools is interesting when the tool is a wrench or a clamp, but when it’s a powerful rotary cutting device, common sense ought to be screaming “THIS CANNOT BE A GOOD IDEA!”.
If you do go the manual route, a nibbling tool might be better than tin snips (although you’ll have forearms like Popeye either way when you’re done)
Backward blade (not carbide) OK, but lots of burning of paint. (it was “pro panel” not sure what they call it in NZ, but painted white rather than Zn finished)
Cutting torch. Quick, messy.
Abrasive (AlOx I think) blade in circular saw. This is the best way I’ve found. Very quick, very clean. Take care not to twist saw and bind blade.
I’m a machinist and sell cutting tools for a living.
If it were me I’d use a reciprocating saw. The biggest drawback is keeping a straight line. If the edge is going to be finished this isn’t a problem.
I’ve run a circular saws backwards. It was to rip a 12 foot length of aluminium. Leaves a great finish and screeches like banchee and is hell on the saw. However if it’s a wood blade with deep gullets don’t even try.
I’d have to see your tungsten tipped blade, but I’ve got a bad bad feeling with any tipped blade on steel running backwards. If they are brazed tips it could be a very bad thing.
Beg borrow or buy a proper small tooth metal cutting blade if you need to make long clean cuts. You can justify spending the money on it by saying you will use it again on cutting thin wood and getting a wonderful finish.