Cutting Steel…Dos and Don’ts per my experience

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Cutting Steel…Dos and Don’ts per my experience

Postby cracker39 » Sun Jan 29, 2006 12:35 pm

First, there is some discussion on cutting steel on this thread. In case some haven’t seen it, I’m starting this thread just for the subject…cutting steel.

I was advised for and against using a metal blade in my carpentry miter saw. I chose to try it and this is my experience. You can read it and use it any way you want.

1. It does work. I had some problems with slower cutting on either the top or bottom surface of the tubular steel. It was suggested that A) steel has grain and I may be cutting against it. B) One side may be the weld side and is harder. Anyway, starting the cut through a flat surface is much harder to do than cutting from the edge.. Once I got through the flat side, cutting on down to the bottom went quickly and then slow through the flat bottom. I tried, with success, using a 3” air cutter to start the cut through the corners and scoring along the cut line, then using the miter saw to finish the cut. That worked better and the miter cut went through the top quicker. Using a cutoff blade in a grinder would probably work much better. I had one cut that was off from top to bottom, but I solved that problem by clamping the piece to the saw, both to the bottom of the surface and another co the fence, making sure the piece was flat on both bottom and to the fence, and couldn’t move. That got me a perfect cut. A little clean up with the grinder, and then beveling the edges for the weld bead, and I was done...And, I still have all of my fingers.

2. Did it hurt the miter saw? No. I removed the dust bag, and the plastic insert and made deflectors from pieces of flashing and put them behind the cutting area to protect the plastic angle guide for compound miter cuts. I held the blade guard up out of the way when cutting.

3. Were there any other problems? Yes. The grit got into the circular track where the blade assembly rotates to cut angles. After making eight 45 degree cuts, I tried to move the blade assembly back to 0 degrees, and it wouldn’t budge. I sprayed WD-40 in the cracks on top and bottom and finally got it to move. So, I removed the cutting assembly, then the pivot track and cleaned everything with WD-40 and mineral spirits. I didn’t put any lubricant on the track when I was done, as I thought it would mix with sawdust and clog up again. After cleaning and reassembling, it rotated smoothly again. If I use the miter saw again for metal, I'll put duct tape over all of the cracks to prevent grit from getting in.

4. Did I save time using the miter saw? Under the circumstances, I don’t think so. I used it because I thought I couldn’t cut an accurate miter with the grinder and cutoff blade. After using my little 3” cutoff tool, I now think I could cut miter cuts with the grinder. And, I now think using the grinder would have been faster, considering the hour I spent taking my miter saw apart and putting it back together. It would take careful marking and following the lines closely. From my experience, I won't even attempt using the miter saw to cut flat plate. That's a job for the grinder with a cutoff blade. I may even use my old circular saw (it's all metal) that has a metal blade in it. I suppose I could use my table saw, but I don't think I'll try it.

Today, I will buy a cutoff blade for my 4 ½” grinder and see how that cuts both straight and miter cuts. I’ll add an update on that, probably on Monday, after I’ve tried it.

A final note. I DID wear long sleeves, a cap, and hearing and eye protection. I forgot the cap once or twice, but after a spark or two landed on my buzz cut, I put it on.
Dale

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Postby sedanman67 » Sun Jan 29, 2006 12:47 pm

Tubing has no "grain" in the same sense than wood does. When cutting flat areas you are dealing with a lot more surface area for the wheel to cut than if you are cutting on edge. It has a lot to do with 'chip clearance", if you look at a wood cutting blade you see voids after the cutting tooth, these carrry the severed wood out of the kerf. The voids in an abrasive wheel are tiny and fill up fast. If the void is full of slag, the piece of agregate in front of the void cannot cut another fragment of steel until the void is empty again. When making edge guts, the little chips of slag don't have to be carried a long distance to get out of the kerf. I do a fair amout of metal fabrication and a dedicated metal cut-off saw is a tool I would not be without. Next I will upgrade to a cold saw and remp up both speed and accurracy. Even my Milwuakee metal miter saw is not accurate enough to make "perfect" corners. I get the cuts close then fudge the weld to make true 90 degree corners.
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Postby cracker39 » Sun Jan 29, 2006 12:56 pm

sedanman67,

I agree about trying to cut through a flat surface as opposed to an edge, and I mentioned that in my post. What I may not have made clear was that when cutting a particular piece of tubular steel, one flat side was harder to start cutting through than another side. On a piece, it may have been harder to cut through the top than through the bottom. Then, when that piece was turned over, it was harder to cut throug the bottom than through the top. It appeared that one side was harder than the other.
Dale

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Postby alaska teardrop » Sun Jan 29, 2006 5:34 pm

Dale- I use a horizontal band saw. While I realize that one would be a large tool expense to build just one trailer, It's a pretty good investment as a project shop tool. Some horizontal saws flip up to also become a vertical saw. The advantages are: cuts aluminum or steel (for that matter, probably all metals). Precise straight cuts up to 45* on any shape (tubing, angles, flats ect.) Safety. Cleanliness. Variaty of blades available. Adjustable speed (and on some, lubrication). Easy repitition. No grinding before welding. :thumbsup: Fred :snow
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Postby mikeschn » Sun Jan 29, 2006 7:33 pm

Frank,

You got a photo of your portable bandsaw handy? Oh hold on, I found one...

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This band saw rocks...

Mike...
The quality is remembered long after the price is forgotten, so build your teardrop with the best materials...
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Postby cracker39 » Mon Jan 30, 2006 8:44 am

The band saw looks like a great metal cutting tool. But, after this project, I don't think I'll be doing any more cutting of heavy metal, so I'll stick with what I have. I returned one of the two 10" blades I bought, and got a few 4 1/2" blades for my grinder. I'm gonna try one in a little while as I have some straight cuts to make for the inside cross members and the bumper. I may not cut them as straight as the miter saw did, but I can clean up any irregularites with the grinder. I have a piece of cut angle iron somewhere, and if I can find it, I'll clamp it to the piece I am cutting and use it as a guide for the grinder's cutoff blade.
Dale

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Postby Steve_Cox » Mon Jan 30, 2006 9:13 am

That porta-band is a cool tool. Used them before when I did fab work in the factory, years ago. Shoulda appropriated one back then. The tool budget just won't stand it now. I liked the way my Sears miter saw cut steel, and I'll continue to use it for the occasional cuts I do in box, angle and flat bar. Maybe I just got lucky and found a cutting disk that does the job pretty good, I don't know, but I like it. The investment for the job was only $7 or $8. I know I liked that part. Most of my hand power tools are 20-25 years old, and with brushes or bearing replacements here and there, they will probably last me until I don't need them anymore. One exception is my new DeWalt cordless drill, the battery life is incredible.

Steve 8)
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Postby cracker39 » Mon Jan 30, 2006 12:07 pm

Steve, my Dewalt cordless drill came with two batteries. One of them still works great, but the other seems to run down quickly, and on the charger, gets charged up just as fast. It's probably bad. I bought a HF cordless drill, and then, got their combo pak with the detail sander as one of the accessories. I figure you can't have too many drills. One for drilling, one for countersinking, and one for putting in the screws. Their batteries hold up pretty good too. You just have to make sure you watch the time on the charger. They say in the instructions that over 2 hrs can damage the battery, as the charger doesn't have an auto shutoff like the Dewalt does. I got a timer to make sure.

Steve, did you have any problem with the grit getting into the circular track for moving the blade assembly for mitering like I did? Mine is a Craftsman too.

Now, for steel cutting. I used a cutoff blade in my 4 1/2" grinder, and it works GREAT!!! It was fast, and fairly accurate as I used a piece of angle that was cut square, clamped to the piece of tube, as a guide to make the first two side cuts, then moved it to the opposite corner and cut the other two sides. The final cut was very square, and will need only a slight dressing with the grinder. All I had to do with the grinder was move the shield about 60 degrees to get the right cutting angle. The remainder of my cuts, I'll be using the grinder.
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Postby Steve_Cox » Mon Jan 30, 2006 6:16 pm

sedanman67 wrote:Tubing has no "grain" in the same sense than wood does.


Most metals are manufactured by casting molten liquid. As the liquid begins to solidify, a small number of solid nuclei appear. A single crystal grows around each nucleus. These individual crystals are called grains. As molten steel flows the crystals align themselves in the direction of flow. Hot rolled structural steel is coarser in grain than fine grain steel that us to be used for tooling, etc. Foreign steel with recycled metals combined can often have areas that are inconsistant in grain causing difficulty in cutting and welding. This problem did not exist before the introduction of foreign steel into this country. Nobody could make steel like the USA. At least that's what I think about it after 40 years off and on making stuff outta steel.....

Steve :D
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Postby angib » Mon Jan 30, 2006 7:15 pm

Steve_Cox wrote:This problem did not exist before the introduction of foreign steel into this country. Nobody could make steel like the USA. At least that's what I think about it after 40 years off and on making stuff outta steel.....

I used to travel around a lot in shipbuilding and I've heard people in nearly every country say just the same, Steve. In fact, nearly every industrial country can and does make good steel - but many also import rubbish from other countries because it's much cheaper than decent home-made steel. So they think their steel is really good and others' steels are poor.

In fact, even India and China, two of the biggest producers of rubbish steel, also make perfectly good structural steels. However the good steels are not that cheap (though I can only speak for India here) and so they don't get exported much.

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Postby Nitetimes » Mon Jan 30, 2006 7:52 pm

sedanman67 wrote: When cutting flat areas you are dealing with a lot more surface area for the wheel to cut than if you are cutting on edge.


That is exactly where the problem is, what I have found is if the steel starts turning orange along the cut you need to let up fast, then take a piece of thin angle and tap it against the running blade, this usually cleans it out enough to get it cutting again. Then sort of bump your blade on your cut until it is throwing sparks instead of making the steel glow. If you get it glowing too many times you will get it work hardened to the point it will be almost impossible to cut.
Rich


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