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interesting views inside steel


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I am building a KMG clone and hade these pieces of scrap cut on a band saw at the local metal supply place. A couple of days later I was looking at the cut edges to see if they had rusted any when I noticed a strange thing had been revealed by the cutting.

 

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The cut was made with the steel lying on its larger side and when the blade broke free from that it was only cutting the vertical portins of the narrow sides. I guess the inner core of the steel is softer and the blades teel have some set to the so they didn't cut the harder outer skin as easily as they did the inner softer core. This left visible bumps.

 

Not earth shattering but just a neat thing that was revealed by accident. A neat way to show something visibly that we don't always get to see inside the metals we work with.

 

Ben

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Yeah, I've seen the the same thing over the years. The pattern seems to match the profile of the part. On solids, tubes, angles, heck just about everything! I assumed all kinds of things, but now I "believe" it's a vibration the blade picks up as each tooth hits the edge of the piece. Sound good until something better comes along.

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Yeah, I've seen the the same thing over the years. The pattern seems to match the profile of the part. On solids, tubes, angles, heck just about everything! I assumed all kinds of things, but now I "believe" it's a vibration the blade picks up as each tooth hits the edge of the piece. Sound good until something better comes along.

 

 

sounds correct to me :)

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Yeah I have seen this also and I arrived at the same conclusion ......harmonic vibes? I like the "sound " of that also ,till some one comes up with a proven senerio.... I hope someone can chime in who has studied this and has more than a "intuition " like the rest of us have....

Dick

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One way to find out if it's vibration (which I think it is) would be to change the tension

on the blade and see if the cutting pattern changes. :ph34r: If it does, then it's vibration

of the blade.

 

Bill

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Actually, I think the pattern is related more to the tooth spacing than the blade tension.

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Actually, I think the pattern is related more to the tooth spacing than the blade tension.

See,

I was thinking it was more to do with varying hardness within the steel. HMM.

If the outer layers of steel are harder than the interior the tooth will cut it differently when it runs perpendicular to the face. As it moves from hard to soft steel it will cut away more of the softer steel.

That is my theory anyway since the pars of the piece that were parallel tothe blade didn't show the same effect.

 

Do the teeth of a metal cutting band saw have any set? If so then what we are seeing could be due to the alternating teeth's set as they enter the cut.

 

Could it be both?

 

FWIW I just looked at both sides of the cut and they both have the same pattern. The blade cut deeper at the center of the steel than it did close to the edge.

 

Mybe it does have to do with tooth spacing. If the tooth spacing put 3 teeth in the steel at once and the teeth have some set, the 2 teeth going to one side would tend to push the tooth facing the other side into the steel harder that it could push back. This would always push the center tooth into the cut face harder than at the edge. Sound plausible?

 

Ben

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Looking at the corner, it's reproducing the inside contour, not a certain depth in the wall.

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