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Discussion Starter #1
I have 3 high speed steel knives from a wood planer that I need to shorten by several inches.
What is the best way to shorten the knives without damaging them?
 

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A dedicated cutoff tool uses a much thinner disc. Doesn't produce anywhere near the heat as a grinder cutoff disc.
 

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Discussion Starter #6
Getting too hot without quenching will actually take the temper out and soften them. Quenching from the wrong temp could result in excess hardness.

An abrasive cutting wheel is your best bet though. Flood cooling it would be ideal. Got a tile saw handy?
Thanks everyone for the replies. Learned something new. I do have 2 tile saws, one with an angle grinder as the head, the other has a 10" blade. I never though of using those for cutting steel. Thank you again.
 

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Because stone and metal have different characteristics. You're welcome to try it but I'd be prepared to buy another diamond blade, and an abrasive disc. ;)
Won't hurt a thing. I was a machinist in a prior life.
 

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Discussion Starter #13
Because stone and metal have different characteristics. You're welcome to try it but I'd be prepared to buy another diamond blade, and an abrasive disc. ;)

I will change the blade on the saw I use to make the cuts. I have abrasive blades in both sizes.
 

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That's the smart thing to do. :thumbup1gif:

There's a reason abrasive disks wear down so fast; it's due to exposing new cutting edges as the oxide matrix gets loaded up and dull causing the crystals to fracture and make new sharp edges.

Diamond wheels for cutting stone and tile aren't designed to handle the heat generated by cutting steel, and they're also not impregnated at the same density as a wheel or cup used for sharpening tools (there are diamond wheels made for steel, they're not found on tile saws by design). Then they're impregnated with larger diamonds with less edge, because they're not actually cutting stone, but chipping away at it.

Will the stone diamond wheels cut steel? Sure, but for how long?

Is it worth trashing a wheel to find out? Not in my opinion.

It's also going to be extremely slow cutting - you'll find numerous accounts of this via a quick google search. :)
 

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I cut some high speed steel for shaper knives using a 10 inch abrasive blade on my table saw. Worked great. But I should have cleaned out the sawdust below the saw first. It was a dramatic and long lasting learning moment.
I use a 10" sanding disk on my table saw for grinding; but I always vacuum out the sawdust to avoid 'dramatic learning moments.' :laugh:
 

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I've used a special metal cutting blade in a wood table saw in the past. It's basically a friction cutting process that erodes the steel. Left a mean burr!

There's lots of ways to get things done, some work better than others.
 

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I'm just glad I cut 13 years of metal long before the internet was invented and explained to me how to do it. Not sure where some of the electronics on the Trident submarines, MIAI tanks, optics in satellites and numerous other projects would be without that prototype machining.
 

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Guys, please? It's ok to disagree. I go through this everyday with my wife. I call her a liar, she disagrees and says she's not, therefore proving my point. :lol: Seriously, we're all friends here, even if we don't agree on everything. :drinks:
 

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Bottom line is what I've encouraged the OP to do is improvise the functional equivalent of a surface grinder on the cheap. Trying to help him get the job done with minimal cost and maximum results.
 
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