Metal cutting circular saw

[bluedog225]

I’ve got the Milwaukee 8 inch metal cutting circular saw. I was using it to cut my 11 gauge 4 in. square steel tubing. I bought this thing used, but in like new condition. I think it still has the original blade on it. I can’t make out much on the blade since it’s worn off.

Anyway, I went through about 12 cuts halfway through the 4 inch tubing and it cut like butter. Then all of a sudden it would barely cut it all. I checked out the blade and it looks like about a third of the carbide tips (?) are gone.

I’ve ordered a new Diablo blade since they’re not in stock at Lowe’s or Home Depot. The job is on hold till that shows up.

My question is, did I push this thing too hard? Do I need to cool that blade off between cuts by running it through some water? Given the thicknesses of steel this thing is supposed to be able to cut, I thought 11 gauge would’ve been a light duty.

Thanks

 

[whateg01]

Yes probably took the last successful cut a little too fast. If it's like other blades, once you start knocking off teeth, it just snowballs. Thinner material can be harder on them because there's more "time" between the teeth to advance so you end up taking too big of a bite. Same thing can happen with a bandsaw blade if you have too coarse of a blade for the material.

 

[bluedog225]

Yes probably took the last successful cut a little too fast. If it's like other blades, once you start knocking off teeth, it just snowballs. Thinner material can be harder on them because there's more "time" between the teeth to advance so you end up taking too big of a bite. Same thing can happen with a bandsaw blade if you have too coarse of a blade for the material.

Thanks. Lesson learned. I’ll go slow. I was pushing it pretty thoughtlessly through the steel.

And hopefully the Diablo blade will be a little better quality.

 

[Mike65]

I buy metal cutting blades & put them on my angle grinder & it cuts through metal pretty good.

https://www.lowes.com/pd/DEWALT-Aluminum-Oxide-4-5-in-24-Grit-Cutting-Grinding-Wheel/1062419

 

[PCustoms]

I buy metal cutting blades & put them on my angle grinder & it cuts through metal pretty good.

https://www.lowes.com/pd/DEWALT-Aluminum-Oxide-4-5-in-24-Grit-Cutting-Grinding-Wheel/1062419

I'm assuming OP has this:



Which takes blades like this:



I've run these in a beater skill saw, @whateg01 nailed it, as soon as you overheat it or throw a tooth it's done, especially on thicker material.


Not sure what an abrasive blade in a grinder has to do with it...

 

[Crazyjake8493]

I use a Diablo Steel Demon blade in a regular circular saw even though it isn't really designed for it. Still working on the same blade that cut up a sheet of 3/8" plate, some square tubing, and a couple pieces of 1/2" plate for some bucket cutting edges. I imagine they would work even better in a proper saw.

 

[jack stand]

I've noticed that not being directly "in" the cut is hard on the carbides. In other words twisting or side loading them will take them out along with too aggressive push in the cut.
Using a fence of some sort (in long enough materials) will be very beneficial to the life and quality of the results.
Smaller cuts, I'll get the cutting wheel or portaband out.

 

[PCustoms]

I've noticed that not being directly "in" the cut is hard on the carbides. In other words twisting or side loading them will take them out along with too aggressive push in the cut.

Makes sense.

I had cut a lot of 1/4 and 3/8 stick with my blade (definitely got my money's worth!) but what killed it was a stack of metal roofing. Pretty sure it shifted and took a tooth off, then that was it.

 

[bluedog225]

I've noticed that not being directly "in" the cut is hard on the carbides. In other words twisting or side loading them will take them out along with too aggressive push in the cut.
Using a fence of some sort (in long enough materials) will be very beneficial to the life and quality of the results.
Smaller cuts, I'll get the cutting wheel or portaband out.

Guilty. The last good cut bound up.

 

[tarbellb]

I would consider any carbide tooth metal blade a short lifecycle consumable in my experience

They make clean, fast, accurate cuts- until they dont


Ive found having spares is always a good idea, buy blades when on sale, and consider getting a bandsaw

 

[MoonRise]

IME (limited, not running them daily or in a production type environment), the metal cutting carbide-tipped circular saw blades work great until they don't.

At which point you replace the blade.

If carbide tips are gone, then the blade is no longer a blade. It is breakfast food. AKA toast.

If you use or might use the blade even semi-regularly, have a spare blade on hand.

So update your order to qty=2 or place another order so that you have one blade on the saw and at least one spare on hand.

I have used a Freud Diablo steel cutting blade in a 5000 rpm circular saw to cut some steel plate. Worked great, but LOUD and threw HOT sharp chips of steel around. PPE is Essential! The cut edges on the steel plate were almost milling machine square and sharp, needed to knock the edges/corners off for safety!

 

[strength_and_power]

Thanks. Lesson learned. I’ll go slow. I was pushing it pretty thoughtlessly through the steel.

And hopefully the Diablo blade will be a little better quality.

Better technique will yield longer blade life. You can usually hear when the blade is twisting in the cut,

 

[bluedog225]

I’ve got a dozen or so 5’ sections of square tubing I can use to support the 37’ pieces now. Should be a more stable platform. I’m working out in a field.

 

[tarbellb]

I found what did the most damage was material movement, second was overheating the blade

Clamp as much as possible

 

[bluedog225]

Dunno. Dragging the genny out to the field to cut the stuff did some damage.

 

[dnschmidt]

Carbide blades are wonderful but sensitive. I've got that exact saw but have never used it (it's still in its original packaging) as I have a 14" Porter-Cable 1410 dry cut saw and these of course have vises and hold the material firmly. Let the blade feed itself and preventing material movement are the keys to longevity with these carbide blades. I also have two of the M18 small steel cutting saws and they work fairly well but the same preconditions apply.

 

[whateg01]

Carbide blades are wonderful but sensitive. I've got that exact saw but have never used it (it's still in its original packaging) as I have a 14" Porter-Cable 1410 dry cut saw and these of course have vises and hold the material firmly. Let the blade feed itself and preventing material movement are the keys to longevity with these carbide blades. I also have two of the M18 small steel cutting saws and they work fairly well but the same preconditions apply.

if this is the same person, OP was using the saw to cut off metal posts that are already in the ground. if not that person, then, oops! I have a 14" evolution but am looking at getting a small circular saw for cutting sheets. I can use the plasma cutter, but I don't always want to drag it out.

 

[bluedog225]

if this is the same person, OP was using the saw to cut off metal posts that are already in the ground. if not that person, then, oops! I have a 14" evolution but am looking at getting a small circular saw for cutting sheets. I can use the plasma cutter, but I don't always want to drag it out.

They’re on the ground, not in the ground. Cutting a bunch of posts for a solar array.

 

[whateg01]

They’re on the ground, not in the ground. Cutting a bunch of posts for a solar array.

gotcha! I would definitely be using my evolution 14" dry cut, but that's because I have one. lol

 

[Dig Doug]

I have a metal cutting skill saw, I bought it to cut a bunch of M deck material for a building we built

I find the blades to be expansive and once one toof is gone it’s toast! Cut slow and don’t use much pressure let the saw do the work

not sure how many cuts you need to make

You can make the same cut w/ a bunch of thin blades in a 4.5 in grinder you’ll just have to cut all 4 sides

they have a bunch of different 4.5 & 5 inch thin blades
&
diamond cutting blades for metal

also a portable band saw but it’s also cutting all 4 sides to keep cuts straight

 

[KnurledNut]

I have experience with this saw and quickly learned freehanding is a no-no. Metal is not forgiving like wood. Sideloading or binding the blade will eventually damage it. Use a cut guide and set your blade depth to the thickness being cut. Let the saw do the cutting and don’t force the feed. Think of this as a machine shop tool instead of a carpenters saw and set up accordingly.

Edit to add: The factory Milwaukee cermet blade that comes new on the saw is extremely resilient and long lasting when used properly.

 

[lilscorpion]

A couple of tips from experience -

first: heat control is king. Use a guide whenever possible (even on square or rectangular tubing). The key is to let the blade cut the material , remove the chips as it wants to, and not force it thru. The guide allows you to get linear pressure and helps prevent you from getting slightly off square with the cut as you go. Let the saw run max rpm. If it bigs it can’t remove chips like it needs to. Smooth and steady pressure.

Second: use the right blade for your material thickness. You want about 3 teeth hitting the material at once. Too many and you get heat buildup, too few and you’ll get tooth shock.
Tooth shock will damage the teeth and game over. Thin stuff (14/16ga) use a heigher tooth count. This wil help prevent tooth chipping. Thicker like 1/8-1/4 use fewer teeth (the 66 tooth that most saws come with is good). Checkout BenchmarkAbrasives for blades. They have a variety of sizes and tooth counts.

Third: tubing…if you try to cut tubing, as you get to the last 1/2” or so the cut will pinch the blade and your fears of #1 and #2 will all happen at once. For square and rectangular set the depth to just deeper than the wall thickness and cut all 4 sides independently. It’ll slow you down a bit but blade life will increase significantly.

Fourth: make sure you’re not recutting your chips. If you put a piece of wood under the metal your cutting, like a sacrificial table top, the blade can push chips into the wood and pull them back into the latter part of the cut. This increases chip load on the teeth, heat, and the rest of the bad stuff. Cut into a cavity but make sure your work piece is clamped well so you’re safe.