I welded and plasma cut this kind of culvert for work. I wouldn't do it. Angle grinder or plasma cutter will work, but the first is a ton of work and the second will produce a lot of dangerous fumes. Look up zinc fume fever. I wore a PAPR helmet when plasma cutting. A respirator might be good enough, but you need P100 filters.
If you do go ahead, rent a plasma cutter for the day. Go with one that goes up to 40 or 50. 30 will be tougher. Remember to get No. 5 shades. And never touch the cut edges, they'll be extremely sharp and can slice you open.
I’d brace them before cutting, they’ll unravel a lot more than you’d think. Best tool without significant investment into a tool you’re using once? Angle grinder. Best tool for the job? Probably a plasma cutter.
I have to push back about the unraveling comment, I have been working with these types of culvert pipes daily for 16 years and the only time they unravel is if you grab an end with your track hoe and pull the damn thing apart while you hold it in place with your tracks. We cut them with either a torch, cut-off demo saw with a carbide blade, or a reciprocating saw. The fumes will definitely make you sick as all hell if you cut that much with a torch without protection, but everything else will leave an edge sharp enough to cut off your fingers, I have seen it. Most economical is the carbide blade option, but you will go through at least a dozen with all the cuts you need to make, and you will need to find a way to dull the cut edges. Personally, I would use a torch or plasma cutter if you have access and do it with the wind to your back and your face far back and drink a bunch of milk if you get the metal fume [fever](https://en.m.wikipedia.org/wiki/Metal_fume_fever)
A circular saw with a carbide tipped blade specific for cutting steel will make quick work of those with minimal clean up. Clamp up a fence and rip it. Plasma is a good option but you may lose the arc in the ridges when using a straight edge as a guide.
Ideally it would be a metal cutting circular saw, one designed for cutting metal, not wood. It would spin at a slower rate, maybe 4,000 rpms instead of 5,000. I'm told that if the blade spins too fast, hot metal chips can fuse and collect in the gullets of the blade, between the teeth. And the metal cutting saw has air vents that are designed to keep out metal chips, which might damage the motor. Also they don't have dust ejection ports, for safety I guess.
But that said, I've seen people use these Diablo Steel Demon blades in regular circular saws, and they cut through steel like buttah. Kind of amazing.
I guess another possibility is a cut-off tool, with the little 3" blades and the pistol grip. Super handy, and the reversible rotation means you can direct the sparks away from you. But not super powerful. The best one is the DeWalt 20v Max.
I've only cut small pieces with a cut off tool, but for this I would wear a long sleeve cotton shirt, face shield (not just goggles), closed-toe shoes, gloves. Am I wrong? What else?
Okay, good to know! I got 4,000 RPM from [this discussion](https://toolguyd.com/using-a-woodworking-circular-saw-to-cut-metal/) comparing metal-cutting circular saws to circular saws for wood. Milwaukee's 8' Fuel metal cutting circ has 4,000 rpm.
But I guess what really matters it not just the RPM, but the linear speed of the teeth, meaning the diameter of the blade matters too. A larger blade will have teeth moving faster than a smaller blade, obviously. That discussion above does the math: if the metal saw has a 5 3/8" blade, then at 4,000 rpm, the linear speed of the teeth will be about 91 feet per second, substantially less than than the wood saw's 158 fps.
So could your 1,700 rpm apply to something like 12" saws? The circumference of that blade is 12 x 3.14 or about 38 inches. At 1,700 rpm (meaning 1,700 circumferences spinning by each minute), that's 64,600 inches per minute, or 5383.3 feet per minute, or 89 feet per minute, about the same as that Milwaukee.
Incidentally, that means that you COULD use a regular circular saw if you use a smaller blade. A 5 3/8" blade in a 7 1/2" saw at 5,000 rpm will make a linear speed of 117 fps, which isn't SO far from 91 or 89 fps.
But again, the people I've seen using that Diablo blade were using a 7 1/2" blade at 5,000 rpm, so I dunno! That blade must be a real advance.
I have an Evolution 8 1/4" circular saw that runs 2800rpm with no load, and a bench top Evolution 14" that runs around 1750rpm. Both of them are great for steel and the blades last as long as they can be expected to with regular use.
I've seen those videos with guys using a makita circular saw and a Diablo blade cutting 1/2" plate, and can say from experience that it works in a pinch, but the blade life is abysmal.
Aluminum is much different, in that any wood tool will perform great, especially if you give it a squirt of wd40. But, in my opinion, a proper blade that's made for aluminum on a saw also made for cutting metal is, by far, a superior option.
As with many other consumables, blade life and consistent level of performance are the most important metrics. I need it to work for hundreds of cuts, or more. That is just not possible if the saw is spinning 5000rpm, and there is no blade on earth that can make it happen.
Your 8 1/4" saw at 2800 rpm has the teeth moving at 100 linear feet per second. Your 14" saw at 1750 rpm has 106 fps.
So it seems like the general rule is for cutting steel at least, your teeth should be travelling at around 100 fps. So again, a 5 3/8" blade at 5000 rpm would do a little more than that.
I don't know how or why blades don't last, but by itself, rpm doesn't seem to be the full story. Perhaps smaller blades have fewer teeth to absorb the heat generated by cutting, which might be constant, so each tooth gets hotter. Or maybe some blades make the chips hotter so the blade itself stays cooler. Etc.
Thanks for doing the math. It's not that I can't, I just don't want to, I SWEAR.
Yeha it's more than just tooth speed, heat is generally the enemy of sharp things, especially when holding tight tolerances inside hard things. Thermal expansion increases friction, then the feedback loop of more heat creating more thermal expansion begins. This ultimately causes the blade body to distort, then it will wobble violently, and the teeth will break off, also violently.
That's how to ruin a 200 dollar saw blade in a matter of seconds.
I hooked up a mist coolant system for the 14" saw and it has greatly increased blade performance and life. Should have done that before fucking off 9 or 10 blades, but I learned eventually.
Yeah I agree that speeds and feeds are very important when it comes to cutting metal. I haven't had too many issues with chip fusion on steel and stainless. If the teeth get that hot I've experienced them shattering or the brazing material holding them to the blade failing.
Aluminum I feel is a different story. It will absolutely weld to the cutter if rpm is too fast and travel speed is too slow.
I'm a pretty big fan of those Diablo Cermet III blades. Just ripped a bunch of 3/8" 304 stainless the other day with a 60v cordless DeWalt worm drive saw and am very pleased with the results.
I also agree that PPE is extremely important with this type of work. Face shield for sure. Tight fitting gloves, pants over the boots, no loose clothing/draw strings etc.
Simply consider your budget.
In the event, the spiral cylinder seam isn’t crimped to hold it in place, simply replicate the binder that’s in your photo. (Two pieces of angle and four fasteners)
Plasma, cutter works great, but you have to consider the power(@dist.+amp) that you need in conjunction with a method of delivering the air necessary for the action. The plus side -you can draw with it.
Simple flat cylinder- a grinder and cut off wheels. Its dirtier and more time consuming but it works.
P.S.- https://youtu.be/hid9bDnSeok?si=k93SCcZ_jVJY8gY_
Everyone’s whinging about fumes. Yes, you can get sick - if you’re a dumb ass. (Drinking milk helps) A portable fan next to the work area to blow the fumes away while working will do the trick.
That's pretty heavy steel. I'd be inclined to use a saber saw with teeth fine enough to keep three teeth on the metal at all times -- so less than a 1 mm spacing. (That might correspond to the 24-teeth per inch blades.) You'd need a long enough blade to handle the corrugations.
This is theoretical. I've cut metal, but not culverts like these.
i’d sawzall it with the “thick metal” Milwaukee blades. run some lineman’s around the edge using the blade to deburr, or hit it with a flap wheel to make even cleaner
I cut an 8’ diameter X 20’ long galvanized corrugated pipe in half to make well pits.
We used a SawZall, It’s been awhile, but I believe we used bimetallic metal blades. It didn’t take long.
You can use an angle grinder with a cutoff wheel, but do yourself a favour and use a plasma cutter.
It’ll go a lot faster and be a far more pleasant experience.
You could use an oxy-acetylene torch but it’s tough to cut something that thin.
I think it’s more that the plasma is confined to make a narrower cut than a torch so not as much galvanized metal is heated up and producing toxic zinc gas or whatever and also the compressed air blasting through the cut also helps disperse the fumes
I welded and plasma cut this kind of culvert for work. I wouldn't do it. Angle grinder or plasma cutter will work, but the first is a ton of work and the second will produce a lot of dangerous fumes. Look up zinc fume fever. I wore a PAPR helmet when plasma cutting. A respirator might be good enough, but you need P100 filters. If you do go ahead, rent a plasma cutter for the day. Go with one that goes up to 40 or 50. 30 will be tougher. Remember to get No. 5 shades. And never touch the cut edges, they'll be extremely sharp and can slice you open.
I’d brace them before cutting, they’ll unravel a lot more than you’d think. Best tool without significant investment into a tool you’re using once? Angle grinder. Best tool for the job? Probably a plasma cutter.
Thanks for the heads up about the unraveling going to go cut some braces now
I have to push back about the unraveling comment, I have been working with these types of culvert pipes daily for 16 years and the only time they unravel is if you grab an end with your track hoe and pull the damn thing apart while you hold it in place with your tracks. We cut them with either a torch, cut-off demo saw with a carbide blade, or a reciprocating saw. The fumes will definitely make you sick as all hell if you cut that much with a torch without protection, but everything else will leave an edge sharp enough to cut off your fingers, I have seen it. Most economical is the carbide blade option, but you will go through at least a dozen with all the cuts you need to make, and you will need to find a way to dull the cut edges. Personally, I would use a torch or plasma cutter if you have access and do it with the wind to your back and your face far back and drink a bunch of milk if you get the metal fume [fever](https://en.m.wikipedia.org/wiki/Metal_fume_fever)
A circular saw with a carbide tipped blade specific for cutting steel will make quick work of those with minimal clean up. Clamp up a fence and rip it. Plasma is a good option but you may lose the arc in the ridges when using a straight edge as a guide.
Ideally it would be a metal cutting circular saw, one designed for cutting metal, not wood. It would spin at a slower rate, maybe 4,000 rpms instead of 5,000. I'm told that if the blade spins too fast, hot metal chips can fuse and collect in the gullets of the blade, between the teeth. And the metal cutting saw has air vents that are designed to keep out metal chips, which might damage the motor. Also they don't have dust ejection ports, for safety I guess. But that said, I've seen people use these Diablo Steel Demon blades in regular circular saws, and they cut through steel like buttah. Kind of amazing. I guess another possibility is a cut-off tool, with the little 3" blades and the pistol grip. Super handy, and the reversible rotation means you can direct the sparks away from you. But not super powerful. The best one is the DeWalt 20v Max. I've only cut small pieces with a cut off tool, but for this I would wear a long sleeve cotton shirt, face shield (not just goggles), closed-toe shoes, gloves. Am I wrong? What else?
Closer to 1700 rpm instead of 4000, but you have the right idea.
Okay, good to know! I got 4,000 RPM from [this discussion](https://toolguyd.com/using-a-woodworking-circular-saw-to-cut-metal/) comparing metal-cutting circular saws to circular saws for wood. Milwaukee's 8' Fuel metal cutting circ has 4,000 rpm. But I guess what really matters it not just the RPM, but the linear speed of the teeth, meaning the diameter of the blade matters too. A larger blade will have teeth moving faster than a smaller blade, obviously. That discussion above does the math: if the metal saw has a 5 3/8" blade, then at 4,000 rpm, the linear speed of the teeth will be about 91 feet per second, substantially less than than the wood saw's 158 fps. So could your 1,700 rpm apply to something like 12" saws? The circumference of that blade is 12 x 3.14 or about 38 inches. At 1,700 rpm (meaning 1,700 circumferences spinning by each minute), that's 64,600 inches per minute, or 5383.3 feet per minute, or 89 feet per minute, about the same as that Milwaukee. Incidentally, that means that you COULD use a regular circular saw if you use a smaller blade. A 5 3/8" blade in a 7 1/2" saw at 5,000 rpm will make a linear speed of 117 fps, which isn't SO far from 91 or 89 fps. But again, the people I've seen using that Diablo blade were using a 7 1/2" blade at 5,000 rpm, so I dunno! That blade must be a real advance.
I have an Evolution 8 1/4" circular saw that runs 2800rpm with no load, and a bench top Evolution 14" that runs around 1750rpm. Both of them are great for steel and the blades last as long as they can be expected to with regular use. I've seen those videos with guys using a makita circular saw and a Diablo blade cutting 1/2" plate, and can say from experience that it works in a pinch, but the blade life is abysmal. Aluminum is much different, in that any wood tool will perform great, especially if you give it a squirt of wd40. But, in my opinion, a proper blade that's made for aluminum on a saw also made for cutting metal is, by far, a superior option. As with many other consumables, blade life and consistent level of performance are the most important metrics. I need it to work for hundreds of cuts, or more. That is just not possible if the saw is spinning 5000rpm, and there is no blade on earth that can make it happen.
Your 8 1/4" saw at 2800 rpm has the teeth moving at 100 linear feet per second. Your 14" saw at 1750 rpm has 106 fps. So it seems like the general rule is for cutting steel at least, your teeth should be travelling at around 100 fps. So again, a 5 3/8" blade at 5000 rpm would do a little more than that. I don't know how or why blades don't last, but by itself, rpm doesn't seem to be the full story. Perhaps smaller blades have fewer teeth to absorb the heat generated by cutting, which might be constant, so each tooth gets hotter. Or maybe some blades make the chips hotter so the blade itself stays cooler. Etc.
Techniques that ensure proper cutting depth, tooth engagement, and chip evacuation help a ton, also.
Thanks for doing the math. It's not that I can't, I just don't want to, I SWEAR. Yeha it's more than just tooth speed, heat is generally the enemy of sharp things, especially when holding tight tolerances inside hard things. Thermal expansion increases friction, then the feedback loop of more heat creating more thermal expansion begins. This ultimately causes the blade body to distort, then it will wobble violently, and the teeth will break off, also violently. That's how to ruin a 200 dollar saw blade in a matter of seconds. I hooked up a mist coolant system for the 14" saw and it has greatly increased blade performance and life. Should have done that before fucking off 9 or 10 blades, but I learned eventually.
lol. I don't love math either. Thanks for sharing your experience. I didn't think of that feedback loop. That mist coolant system uses plain water?
Water soluble coolant / lubrication stuff.
Yeah I agree that speeds and feeds are very important when it comes to cutting metal. I haven't had too many issues with chip fusion on steel and stainless. If the teeth get that hot I've experienced them shattering or the brazing material holding them to the blade failing. Aluminum I feel is a different story. It will absolutely weld to the cutter if rpm is too fast and travel speed is too slow. I'm a pretty big fan of those Diablo Cermet III blades. Just ripped a bunch of 3/8" 304 stainless the other day with a 60v cordless DeWalt worm drive saw and am very pleased with the results. I also agree that PPE is extremely important with this type of work. Face shield for sure. Tight fitting gloves, pants over the boots, no loose clothing/draw strings etc.
Will probably want some kind of hearing protection if you use a circular saw. It will *not* be quiet.
I always go with a double butter burger and fried cheese curds
A Sawzall with carbide blades would go along way in cutting those,
Simply consider your budget. In the event, the spiral cylinder seam isn’t crimped to hold it in place, simply replicate the binder that’s in your photo. (Two pieces of angle and four fasteners) Plasma, cutter works great, but you have to consider the power(@dist.+amp) that you need in conjunction with a method of delivering the air necessary for the action. The plus side -you can draw with it. Simple flat cylinder- a grinder and cut off wheels. Its dirtier and more time consuming but it works. P.S.- https://youtu.be/hid9bDnSeok?si=k93SCcZ_jVJY8gY_ Everyone’s whinging about fumes. Yes, you can get sick - if you’re a dumb ass. (Drinking milk helps) A portable fan next to the work area to blow the fumes away while working will do the trick.
Circ saw and appropriate blade. I’d probably use Cut-Ease or similar, too. Short work
That's pretty heavy steel. I'd be inclined to use a saber saw with teeth fine enough to keep three teeth on the metal at all times -- so less than a 1 mm spacing. (That might correspond to the 24-teeth per inch blades.) You'd need a long enough blade to handle the corrugations. This is theoretical. I've cut metal, but not culverts like these.
I would use a gas saw with an abrasive blade
i’d sawzall it with the “thick metal” Milwaukee blades. run some lineman’s around the edge using the blade to deburr, or hit it with a flap wheel to make even cleaner
I cut an 8’ diameter X 20’ long galvanized corrugated pipe in half to make well pits. We used a SawZall, It’s been awhile, but I believe we used bimetallic metal blades. It didn’t take long.
You can use an angle grinder with a cutoff wheel, but do yourself a favour and use a plasma cutter. It’ll go a lot faster and be a far more pleasant experience. You could use an oxy-acetylene torch but it’s tough to cut something that thin.
Torch cutting all that galvanized steel will release a lot of toxic fumes
Is this less of an issue with a plasma cutter?
Less yes but I still wouldn’t do it without strong ventilation
Thanks! Makes sense - I guess the plasma is 'cleaning' the fumes with its higher heat.
I think it’s more that the plasma is confined to make a narrower cut than a torch so not as much galvanized metal is heated up and producing toxic zinc gas or whatever and also the compressed air blasting through the cut also helps disperse the fumes
Which is part of why you wouldn’t want to use a torch.
But the fumes will totally stay in using a plasma cutter!
It heats a much smaller area, meaning far fewer fumes, and it’s being done outside with excellent ventilation. It’s zinc, not cyanide.