Exception (was wood vs metal bandsaw)

Usual rule of thumb for cutting steel is at least 3 teeth per metal
thickness and speed of 150 to 300 SFPM -- but I've discovered a
notable exception with very thin steel. .
Had some .020" steel siding to cut. Usual practice is to use snips
for the fitted parts like angles that meet roof gables. Neighbor
wanted to try the bandsaw. He discovered that the 18 TPI blade (way
less than 1 tooth per metal thickness) running at wood speed (3000
SFPM) cut that .020 steel cleanly as fast as he could push it thru the
saw. No heat problems, no broken teeth, smooth cuts. Ear protection
strongly recommended!
Yes, I'm sure it's steel. A magnet proved it.
Now that he's discovered that, I'd better bolt my saw to the floor!
(He's a contractor, does siding every now and then.)
Reply to
Don Foreman
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Zero TPI works for this, too, BTW, with blade speeds ranging from 3000 to at least as high as 15,000 SFM. Starting with a fine-toothed carbon steel blade, it will be effectively zero TPI after a couple uses, anyway. In this case the cut is achieved by friction, though, so your remark about no heat problems might not apply. I seem to recall hearing (no personal experience) that up to 1/4" thick steel can be cut by this method on a woodworking bandsaw. Of course, the blade is destroyed for other purposes.
Reply to
Jim Wilson
You discovered friction sawing. The purpose made friction blades are almost all 10 TPI. The teeth soon become rounded nubs in use, but continue to cut til the weld breaks from fatigue.
The speed of the saw will limit the thickness of material to be cut. Real friction saws run at several times the speed of wood saws, up to 15,000FPM or more. 1/8" stainless is about the limit on my old DoAll, which tops out at 1500FPM, but I used to regularly cut 1/2" SS on a 36" saw running at around 6000FPM.
Be careful of sparks, particularly on a saw that's also used to cut wood or other flammable materials.
More deatils here:
Ned Simmons
Reply to
Ned Simmons
here's a crazy idea... use the blade at a recommended sfpm for tool steel in low carbon steel, (60) and you will get a reasonable blade life.
Reply to
Jon Grimm
Ran across a DoAll saw book at work a number of years ago. As I remember, the saws were first called Dual (?) meaning regular and high speed friction sawing.
The book had lots of illustrations and examples. Even directions for the women who were running the saws in WWII in the aircraft shops.
We had some high speed roller guides (big diameter, ball bearings) and I tried to set the saw up for high speed cutting (it had 3 speed ranges), but the boss heard the whine from the high speed and had that range locked out. We did try friction sawing a couple times, but I claim that they never got the speed high enough. Wonderful to play with, though. Would cut high speed steel tool bits!
Ned Simm> >
Reply to
Karl Pearson

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