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I Forge Iron

Cutting S7?


JHCC

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I just got a good deal on a fair quantity of S7 steel, which I plan to use for tooling and possibly as tailgating/trading stock. However, it's coming to me in 1/2" x 2-1/2" x 36" flat bar, so I'll need to cut it up to make it usable. My options are:

  1. Big cutoff saw. This is not running great right now; I think I need to get a new blade.
  2. Cutoff wheel in angle grinder. Probably not as precise as the big saw, but leaving an acceptable cut finish. Probably kind of slow.
  3. Horizontal bandsaw. Not sure if the steel is coming to me hardened, in which case this would not be a good option. Acceptable finish, much less flying grit.
  4. Cut hot with hardy and/or appropriate top tool. Fine for my own stuff, but probably not for metal for sale.
  5. Oxypropane torch. Probably the fastest option, but rough cuts will require some cleanup. I don't know if I'd be creating a decarb layer or other metallurgical issues. Discoloration in HAZ might lower selling appeal.

Any thoughts, recommendations, cautions?

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Buy a blade for the cut off saw. While it's probably annealed you never know a bi metal bandsaw blade aught to work though I'm not sure about S-7 it may eat band saw blades.

The HAZ from a cutting torch would diminish it's value for resale if for no other reason than marketing ugly.

Frosty The Lucky.

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I have never cut S7 but I have made several cuts of forklift tine - while softer, much larger cross section. I would recommend using 24 TPI bandsaw blade running as slow as the saw will go. Make sure the oil is steady so that high TPI blade does not gum up with shavings. If you turn where you are cutting with the half inch side up, it should cut.  My opinion- I am sure someone here knows the secret. 

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Stand it on edge so it has the minimum thickness to cut. 3 tpi on the material rule says a 12 tpi blade is ideal but don't use any finer than you can get. A variable pitch does a good job of clearing cuttings. Slow speed is good but what you really want is a low feed pressure / speed. Just let it ease into it very slowly.

The flush fluid is primarily to clear cuttings not cooling. If cuttings start balling up between the teeth they begin to slide and eventually gall and break the blade. You can use a spritzer bottle on squirt and use water if you want something. The "coolant" flush prevents chips from sticking in the teeth and helps float cuttings out of the kerf. 

I run my blades dry, have been for 25 years on my current Jet horizontal vertical bandsaw but have never used coolant on a band saw. EXCEPT in another person's shop and they want it used. 

The above is assuming you CAN cut S-7 with a bandsaw, that I don't know. I DO know cutting metal with a bandsaw. 

Frosty The Lucky.

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We have a couple of those in the tool room at work. Using one to cut a straight line in bar stock would be like bringing a tank to a water gun fight.. It would work quite well though...

I would use use an angle grinder because that's what I have available. It might not be the cleanest cut, but it could be cleaned up.

 

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Starting you have to know if the material has been hardened any.  If it's annealed you have a lot more choices than if it a bit or really hard.

If It's soft I would go with a saw.   Cutting with a cut off wheel may harden the face due to heating and contact quenching.

Got any friends with an old school mechanical hacksaw?

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That's a very interesting thought. Tthat might explain why I had such trouble a few months ago on the cutoff saw with a piece of mystery tool steel, especially if it was air-hardening.

We had one of those mechanical hacksaws in my junior high school shop class, but I don't know if anyone around here has one. I'm picking up the steel on Saturday, so I'll be able to check it for hardness then.

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I'd use your band saw and hand water for cooling as needed

I  would think its a pretty safe bet to assume lengths like that are annealed other than, perhaps the ends. Try a cut with a hand hacksaw and see what happens. I just saw Thomas said this as well.

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There's a place much nearer that seems to do EDM and waterjet, and I just sent them a message asking what it would cost to cut each bar into six 1/2" x 1-1/4" x 12" (approximately) pieces, and indeed if they'd even do the job. We shall see what they say.

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I have cut hundreds of blanks of this size on annealed S7 on my portaband. If hardened, an abrasive cutoff wheel works fine. Waterjet sounds like major overkill and *very* expensive. Losing a single blade testing on the portaband will likely be a small fraction of the setup charge on a water jet. 

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Oh come on John, ONE stroke with a new hacksaw blade will tell you if a bandsaw will cut it. Hiring it out is expensive cutting into your potential profit margin. Figuring out contingencies is sound reasoning but let's not get too carried away shall we? 

Frosty The Lucky.

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Not including ALL options only reduces your chance for success, or being able to think outside the box.

Put all the options on the table and then choose the one that best works for the job at hand.  

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