LastRonin Posted March 5, 2014 Share Posted March 5, 2014 http://www.iforgeiron.com/gallery/image/38054-skinner-wrench-knife/ Ok... here it is. My very first attempt at a knife. It started as a rusty, broken combination wrench. It is 6 7/8" overall. 3 7/8" handle. 3" blade. Blade is as deep as the wrench size (7/8") and tapers from 1/8" down to about 1/16". It is only ground down to 80 grit because I only just got my belt grinder built and that was the only grit I have. I had read that wrench steel wasn't that great for knives, so I decided to try to get it as hard as I could. I forged the small broken off portion of the wrench down to about 1/2" x 1/8" and then heated to nonmagnetic and quenched in water and transferred into a slurry of dry ice and acetone. File seemed to skate off it. My diamond stone would cut into it like when I sharpen my store-bought knives, so all seemed good so far. Stuck it in the vice, put on safety glasses, face shield, welding jacket and gloves and then bent it til it broke. It went almost 45 degrees before snapping. I tried to take a pic of the end, but my camera stinks and wouldn't show enough detail to matter. Anyway, the test seemed to come out well... so I went ahead and forged, ground and then heat treated the blade the same way as the test piece. Tempered to 350 degrees for an hour. It seems to be holding an edge pretty well. Underlined portion added to correct the omission of a step. Thank you Steve for bringing it up. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted March 5, 2014 Share Posted March 5, 2014 Did you quench in the sub zero mix, or use that to super cool after a normal quenching? if you did actually quench into the explosive acetone then you are a very lucky man. Quote Link to comment Share on other sites More sharing options...
LastRonin Posted March 5, 2014 Author Share Posted March 5, 2014 Sorry. I forgot to include that step in the explanation. I quenched in water, THEN went into the mix. I work with fire detection and suppression equipment for a living, so know how lucky I would be to survive unharmed dropping something that hot into an explosively combustible liquid. Thank you for bringing that to my attention, I'd hate it if someone made the mistake of following what I originally posted instead of what I did. I based it off of reading extensively through the HT threads on here and elsewhere on the web. I know it isn't the best material, but I unfortunately fit your signature Steve. I do honestly enjoy, err, I mean suffer from both ADD and minor OCD. When I get an idea in my head, often the only way to settle it out is try it. I had the idea for this come up and HAD to try. I got the dry ice by emptying a CO2 extinguisher that was condemned and unable to be recertified into a sock. Quote Link to comment Share on other sites More sharing options...
Frosty Posted March 5, 2014 Share Posted March 5, 2014 A good synthetic hydraulic fluid like DN-600 will stay fluid below -80f, the temp of dry ice and is far less flammable than acetone. I don't know if you can still get DN-600 but there are better extreme low temp fluids available. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
LastRonin Posted March 5, 2014 Author Share Posted March 5, 2014 Thanks Frosty. I didn't know about that. I had already quenched the knife in water and then into the slurry, since everything I read said that the wrench steel wasn't really hard enough for a good knife, I wanted to get the best I could. Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted March 5, 2014 Share Posted March 5, 2014 A sub zero quenching isnt going to do much with the low alloy steels. it is needed for many stainless steels to force conversion of the retained austinite. For that we need the -170F that the acetone and dry ice mixture gets. Nitrogen is much safer for this operation as far as flamability is conserned, but also has additional risks of burns from being so much colder. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted March 5, 2014 Share Posted March 5, 2014 Guess it is not a big surprise that Frosty would be current on oils that work well in sub zero temps........ Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted March 5, 2014 Share Posted March 5, 2014 I'm with Steve; if you are not using an alloy that is noted for retained austenite the sub zero quench after a "normal" quench is a waste of time and money. Now if your "normal" quench doesn't get it hard enough look into using Robb Gunter's Superquench as your first and only quench. Quote Link to comment Share on other sites More sharing options...
LastRonin Posted March 5, 2014 Author Share Posted March 5, 2014 Thanks again Mr. Sells. I had hoped it might help. Thank you for the info. Thank you Mr. Powers. Luckily it couldn't have been cheaper, I got the acetone free from the discard bin at a work site I was at. The dry ice I got from a discard CO2 fire extinguisher from my work. Discharge it into a sock and it catches the frozen CO2, even seemed to increase the amount of solid... I've discharged numerous CO2 bottles in my work. Quote Link to comment Share on other sites More sharing options...
LastRonin Posted March 6, 2014 Author Share Posted March 6, 2014 I appreciate the advice on heat treating. Can I ask opinions on the design, shape and such? I didn't attempt to copy anybody else's work on this. I just went with it and let it just take shape. Quote Link to comment Share on other sites More sharing options...
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