7 1/4" Metal Cutting Blade

[dkroth]

I'm going to buy a ferrous metal cutting blade for a spare circular saw. I'll be using it for general metal cutting: angle iron, small box and tube sections of 1/16 and 1/8 wall thickness. Low volume homeowner project stuff.

Should I get 40 tooth or 60 tooth blade?

 

[Tenex]

You should be using an abrasive blade

 

[dkroth]

You should be using an abrasive blade

Meh, I've got that already. Sparks and messy. I'm hoping the toothed blade will be "cleaner".

No?

 

[johndeereman]

Buy both they are both useful in their own way. I have the 8'' milwaukee saw. The heavier tooth count seem's to work well for sheet/flat material and the lesser teeth work better for solid/round.

 

[Bobcat753]

Look into the new blades Lenox came out with. They are a Diamond coated blade for metal cutting. They still make some sparks but last for a long time. I bought a 4.5" one for my grinder and it works awesome. Lowes has the blades currently.

 

[jeff000]

Using a metal cutting blade in a saw that spins twice as fast as the blade is designed is asking to get hurt.
But good luck.

 

[dkroth]

Using a metal cutting blade in a saw that spins twice as fast as the blade is designed is asking to get hurt.
But good luck.

Jeff,

RPM is something I didn't think about. Thanks for bringing that up.

The blades I'm looking at are rated at max rpm of 7430. My saw says 4900 rpm. The blades don't seem to have a recommended speed.

 

[PT Doc]

Metal cutting circ saws run around 1200 rpm if memory is correct. It will probably work. But the carbide might not like it.

 

[tarbellb]

You can run those blades, some are made specifically for that application. Just expect short blade life and sketchy cutting sessions.

Rule of thumb is thicker the material, the less teeth you want. I bet the 60 tooth will be a good compromise for sheet and thin wall tubing.

Anything thicker then 1/8 wall angle or tube I would use a 4.5" angle grinder w/ .045" blade.

Wear all your ppe, especially face protections from hot chips.

 

[jeff000]

Jeff,

RPM is something I didn't think about. Thanks for bringing that up.

The blades I'm looking at are rated at max rpm of 7430. My saw says 4900 rpm. The blades don't seem to have a recommended speed.

That is really fast for not abrasive blade. I've only ever used carbide metal cutting blades that are rated to a max of 1600 rpm. I hardly like using the 1200 rpm specially made metal cutting skill saws.

I will cut aluminium with a 5000 rpm aluminium cutting blade without issue though.

 

[Hornman]

Buy a cheap steel framing blade and mount it backwards. It will cut sheet metal very well and I have cut up to 1/4" with it. It will be very noisy and throw lots of hot and sharp chips.

 

[strutaeng]

I bought one of these once:
https://www.amazon.com/dp/B00008WQ3B/?tag=atomicindus08-20

I made about 20 cuts in 1x2 tube (13 gage thickness or something) and about 5 cuts in 2x2x1/8 angle. It cut smoothly, burr-free with metal ships flying everywhere, so I was happy. However, the next time I tried to use it would not cut anything! nada! I had to trash the blade.

They certainly have wall thickness limitations, so look closely. I never figured out what I did wrong with mine.

I now use a portable band saw or angle grinder with cut off wheel.

The Lennox blades look interesting:

Heck, they are cutting steel at the speed as if it were wood!

 

[EdT]

RPM is important, but the velocity of the teeth is what really matters. Many "dry cut " metal saws use 14" blades and turn them fairly slowly compared to an ordinary wood cutting saw or an abrasive cut of saw which often has a 14" blade as well. The cold cut I have is 1400 RPM IIR and I've seen lower on some other brands. If you drop down to a 7" blade, the same surface FPM will be at twice the PRM of the 14" blade. I have used a DIABLO metal cutting blade on an old $99 table saw and it works, but it's not a comfortable job. Keeps your attention. I am not sure if I would ever attempt a cut with the same blade in a hand held "skil saw", but I have read of folks doing it. I think Jack Olsen cut up some cabinets with one. Anyhow, RPM alone is not the key.

 

[MoonRise]

Folks, the OP is asking/talking about a 'special' ferrous metal cutting blade made to work in a standard circular saw.

He's not asking/talking about a 'cold cut' ferrous blade. That's a different beast, blade and saw.

Freud Diablo, Lenox (note spelling, as Lennox is the HVAC folks), and MK Morse all make ferrous metal cutting blades to go in a 'standard' ~5000 rpm 7-1/4" circular saw. Sidewinder or worm-drive.

http://www.lenoxtools.com/pages/metal-cutting-circular-saw-blades.aspx

http://www.diablotools.com//products?c=Saw_Blade&material=Metal_Cutting

http://www.mkmorse.com/products/index.aspx?product=75

They work. Waaay better than an abrasive blade in the same circular saw. Faster, much cleaner cut, much 'cleaner' work space without clouds of abrasive dust and smoke, but hot sharp chips.

Still loud. Still have to really pay attention to what you are doing.

They make sharp swarf, and a sharp 'milled' edge on the sheet/plate you are cutting (because the blade cuts so 'cleanly' through the sheet/plate).

I have not yet had a chance to use the new Lenox diamond coated ferrous cutting blades. They look 'interesting'. But I now have a plasma.

http://www.lenoxtools.com/pages/lenox-metalmax.aspx

Yes, read and pay attention to what rpm the specific blade you have or are looking at is rated for versus the rpm of the saw you are planning on using it in.

 

[McLean]

OP- I have tried one of those (dont remember the tooth count) and it worked okay. It's slow, still makes a mess, expensive, and doesnt last long. I tried to use it on some thick material and it died real quick. Although, I bet if you babied it on thinner gauge material, it might survive for a reasonable amount of time.

After this FAIL, I purchased a Milwaukee metal cutting circular saw. It is an amazing machine and I would highly recommend. Still on the first blade and it's ripped many feet of plate from 1/8"-1/2". They're not cheap, but after you burn up a couple $40 blades, it will start looking like a good investment!