hard steel

I would, at first, change the RPM from 60 to 45 or, alternatively,

1. This may help if this RPM causes resonance effect. 6x6 is not that big.

"Hot-rolled" and "cold-rolled" are actually finishes, not steel grades. 1018, 1060 and 1090 are typical steel grade designations and can be had in both hot-rolled and cold-rolled finishes. What you really wanted was mild steel, like 1018, in a hot-rolled finish. When you're shopping the drop boxes, it's hard to say what you'll get. Probably what you got was somebody's pre-hardened plate remnants. If it's a straight carbon steel, you'll be able to anneal it the way you describe. If it's something fancy, like an air-hardening alloy, that won't do it. Sometimes mystery metal isn't a bargain.

Stan

I do this sort of thing often. I have a large side grinder and grind away the heat affected zone (HAZ). Doesn't take long with a good grinder. The rest of the material machines fairly easy.

Karl

What did the material do to your bandsaw blade? Depending on the bandsaw/blade combination, 1/2 hour may not be too bad. It takes me about 12 minutes to cut through a 4" round of mild steel on my Taiwan

Try a good file on the edge that you are trying to cut. Compare the "fileability" to some known mild steel (something that does machine well on your equipment). If it files well, then it's not that hard. If the file "skates" across the cut edge then it IS hard and definitely is NOT mild steel. If there is one edge that was not Plasma-cut, try filing there as well. If the plasma cut edge files about the same as the other edge, then the heat didn't do it. If the edges file about the same and file easily, then its your equipment; tooling or machine rigidity. You didn't say how heavy your tools are. 30 thou on a micro mill may be too much. Are you taking a full depth (1") cut? Try taking only a quarter inch at a time. Are your tools sharp?

In any event, if the metal did harden up, the hard zone won't be deep. Get some carbide cutters to get through it.

One way to get a feel for the material would be to bandsaw a 1/4 inch wide slice off about 3 or 4 inches long. Heat the piece to red hot (so a magnet is not attracked to it, plus a little) and quench it in water. If it gets so hard that the file won't cut it at all, forget that piece and go get something that is truly mild steel. You don't want to deal with it at this time anyway. Consider it a lesson learned.

Pete Stanaitis

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Kelly J> Hi all.

It's possible. Should be visible sign of that on the cut edge though. Shouldn't be thick enough to prevent machining.

Don't bother with lathe or mill for trimming the corners. The bandsaw will do the job with less effort. If it is too big for the vice, clamp it vertically and feed very gently until the blade has cut a flat for itself.

If the piece really has got a deep heat-hardened edge, compromise slightly on flywheel size and trim the HAZ off with the bandsaw.

Mark Rand RTFM

Indeed. I grabbed some 3/8' x 3" by 12" rems

Took em home to make some brackets. Stripped the teeth off a new bandsaw. WTF?

Put it on the grinder..bright white sparks...wtf

Used the hardness tester...RC 55 aprox

Freaking 20 lbs of D2.....sign....

Too thinck to make knives out of without milling em thinner..did made some splatter scrappers for MIG welding though.

I got my moneys worth...on stuff I couldnt use for much. Still got some kicking around..might make some custome shaper tooling out of it

Gunner

"Confiscating wealth from those who have earned it, inherited it, or got lucky is never going to help 'the poor.' Poverty isn't caused by some people having more money than others, just as obesity isn't caused by McDonald's serving super-sized orders of French fries Poverty, like obesity, is caused by the life choices that dictate results." - John Tucci,

D2 is used a lot for punch dies. I have some D2 also, it is unbelievably strong stuff. Cuts steel like butter. I have some pictures of it here:

Plasma hardens a thin layer, a cutting torch is worse. I anneal those pieces in the wood stove overnight. If they are back in a ways away from the oxygen-rich draft they won't develop much scale. The metal starts to soften when it turns blue but it's better to heat it to glowing red, until a magnet doesn't stick, then let it cool slowly at least until the glow is completely gone. Then you can dip it in water or let it cool by itself. The old-timers say that quenching when the red is gone, called water annealing, makes steel the most machineable. At best I've seen only a slight difference.

You might be able to use it without annealing if you drill a hole near the hard edge and grind through into the hole. Then the bandsaw can saw through the rest. Saw the square octagonal by cutting in from a previous cut, stop before the blade hits the skin, then break the piece free with a chisel. The lathe bit may work better if you begin each pass in solid metal and cut outward rather than going across the edge.

I learned not to buy flame-cut scrap pieces too big to fit the stove. A couple of them are tractor counterweights.

A plain open fire won't do you much good. If the fire dept. allows it, try a vertical box of firebricks or fluepipe big enough to hold the plate upright in the middle so the fire burns on both sides. Support the plate a few inches above the bottom of the fire. A chimney at least three or four feet tall should have enough natural draft to heat the steel red in an hour or so. It will emit showers of sparks but probably little smoke. I built a blast furnace like this when I was a kid. The grate was the two halves of a broken garden rake, kept cool enough to support the metal in the column above it by the incoming air.

You can grind the thin layer off or try to machine it with carbide. The tool seems to last longer if the cutting direction allows the hard skin to chip off. I use a brazed bits because they can be resharpened.

Good luck with it, Jim Wilkins

That worked great. I have also determined that it isn't hard throughout, just about 0.050 deep all along the cut surface. I also checked the mill for looseness. All I found was some unexpected backlash inthe spindle. I suspect that as someone else said it was near it's resonante frequency and the cutter was bouncing back and forth in the backlash as it cut. I bumped up the speed to around 850 RPM and reduced the cut to less than half the cutter diameer and no more than 0.100 deep (0.030 deep near the HAZ) and all seems to be working out.

Thanks for the suggestions.

I am curious now about the backlash in the spindle. This is a "new" machine, one owner, and low hours. (It's a Grizzly vertical-horizontal mill.) I haven't seen any wat to adjust this backlash. IT appears to be in the spline between the spindle and the drive shaft. Any thoughts would be appreciated.

thanks

I have a new RF45 clone , it also has backlash in the spindle . Is yours gear drive ? I'm sure most all of mine is in the drivetrain ... doesn't seem to make any difference , except a lotta noise on interrupted cuts .

no, belt drive. I never noticed it before now.