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Thread: Two questions from a newbie

  1. #11
    Home of the Mysterious Symbol CrescentCityRazors's Avatar
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    Kind of a noob at bladesmithing, just bought my first HT oven a few months ago and haven't done any major bragging rights projects since then cause I want to build a twin grinder before I get serious about anything. But I have never had a problem grinding down to .05" prior to HT and I have USUALLY been okay down to .04" but under .04" thick, I lose too many in the quench. Two batches in a row, I lost 3 for 3, pushing the limit to see what I could get away with. If you are a metric kinda guy stay at about 1.25mm or thicker pre-HT is my rec.

    My first razors were major Gold Dollar regrinds and stock removal razors I made out of vintage through-hardened files. (modern imported files seem to be all case hardened, no good for grinding out a razor.) Didn't take long to realize that the more grinding I could do on annealed steel and the less I had left to do on hardened steel, the less time wasted and the fewer belts or wheels worn out. My first "barbecue grill" razors were from a couple of those old files and the process went a lot quicker. Now I got a bunch of O1 and 1095 pieces waiting to be turned into razors and stock removal, sure. That's how I roll. But everything gets almost down to final grind before HT and edges will be in the .04" to .05" range.

    I have heard of guys going even thinner but I know my limitations. I don't have the expertise for that.

    After quench, you can thin the blade as much as you want before honing, as long as it doesn't get too flexy. The thinner the better, up to a point. It is good to leave a "backbone" in the blade just above where the bevel will start, for a little more rigidity, but if it is too close to the edge it gets incorporated into the bevel and you have a wide contact area which will in extreme cases make honing more difficult and time consuming. A super narrow bevel is a joy to hone if you know to use a very light touch. A backbone allows you to go just a teensy bit thinner and still have a razor that will still stand up to normal use and pressure.

    The razor can be a LOT thinner than any knife you have ever made. And so, you need to be very careful when finishing with power tools. Talking about the body of the blade, not just the edge. Thin steel overheats really quick, really suddenly, and the Blue Stain of Death will shock you with how suddenly it can appear on steel this thin. Once you are at final thickness you can forget about annealing and requenching. Color change = dead razor. R.I.P.

    No fancy thermostatically controlled HT oven? No proper forge, either? Plenty of razors have been made in fire pits or barbecue grills, with a piece of pipe taped to a hair dryer for draft, and a magnet and eyeball for judging temp. Failure rate will not be so bad once you have done a few razors. Anneal, grind, normalize, maybe grind some more, HT and quench, temper in a toaster oven and bobs yer uncle.

    I hate wedges, but they are probably a lot easier for a beginner. You might try a quarter hollow. I wouldn't try a full hollow. In fact I have never tried one yet.

    Good luck, and have fun!

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    Thanks to everyone for all the help. I got two rough ground and heat treated today. I’ll try to get some pics up later on.

    Everything went well in the quench. I was pretty nervous but no cracks and no warps.

    I figured since I was trying something new I might as well try my hand at bringing out a hamon. I haven’t etched them yet but the edge skates a file and the spine is still soft so hopefully I get something.

  3. #13
    Heat it and beat it Bruno's Avatar
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    Quote Originally Posted by Permarcustomknives View Post
    I have been making knives for a few years now and recently got the itch to try my hand at straight razors. It seems like they are a completely different animal, but after some reading and research I think I’m ready for the challenge.

    Two questions that I can’t figure out-

    How thin do you want the edge to get during finish grinding before moving to the hone? For most knives I’ve done it’s been around 5-10 thousandths before sharpening. Is that too think for a razor?

    I only do stock removal right now, and typically do all grinding after heat treat to avoid warps during quench. Is that normally how it’s done for razors or should I be hogging off some material before hardening?
    I grind literally to foil before going to the hone. Joe Calton checked my work with calipers though I don't remember how thin it was. All I remember is that it was consistent thickness along the entire edge.
    There is this video of me on youtube, from a couple years ago at the TX meet.

    Til shade is gone, til water is gone, Into the shadow with teeth bared, screaming defiance with the last breath.
    To spit in Sightblinder’s eye on the Last Day

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    Well I had some uh-oh moments on the two I started on. The first one I burned the edge slightly and ruined. On the second one I though everything was going well but I got the area behind the edge too thin and got a small crack. I must have taken my hollow too deep on that one. I learned a few things that I can apply on the next ones so not a total loss.
    rolodave, RezDog and jfk742 like this.

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    Home of the Mysterious Symbol CrescentCityRazors's Avatar
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    Quote Originally Posted by Permarcustomknives View Post
    Well I had some uh-oh moments on the two I started on. The first one I burned the edge slightly and ruined. On the second one I though everything was going well but I got the area behind the edge too thin and got a small crack. I must have taken my hollow too deep on that one. I learned a few things that I can apply on the next ones so not a total loss.
    That is a very common thing getting started! You really have to burn or crack a couple to know what you can and can't get away with.

    You may be able to salvage a 4/8 out of one or both, with a careful regrind. It is a chance at redemption.

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    Senior Member jfk742's Avatar
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    Quote Originally Posted by Permarcustomknives View Post
    Well I had some uh-oh moments on the two I started on. The first one I burned the edge slightly and ruined. On the second one I though everything was going well but I got the area behind the edge too thin and got a small crack. I must have taken my hollow too deep on that one. I learned a few things that I can apply on the next ones so not a total loss.
    You can get about 13/16” out of a 6” wheel, edge to spine without going too thin above the edge. I use a 6” for rough grinding, and a 4” and sometimes down to a 2” to hog off material before heat treat. I’ll run the 6” up to about 3/4” above the edge to a parallel scribed line that follows the spine. After heat treat I’ll run the 6” down to finish thickness at the edge. As I get close I run up the grits as well as push the spine/hollow junction up .0625-.125” as I’m finish grinding. That just gets me prepared to step down to a 4” wheel. I do the same process until the grind at the edge side of the hollow begins to blend with where I left off with the 6”. I then run through the grits making sure everything blends well. If you want to go past a 1/2 hollow then do the same thing with a 3” wheel, 2”- 1 3/4” for full hollow. Most the blades I’ve made have been 7/8- 8/8.

    Make sure you’re using sharp belts for post ht grinding, then use new belts when finishing. I trashed a few blades I put too much heat into because I using used belts that still “felt” sharp, I should have been using new belts. The added pressure to get a used belt to cut causes undulations in the finish, not to mention the grit is usually unevenly worn, then there’s the heat generated. Any cost savings from using belts too long is quickly lost in the extra time hand sanding or fixing bad grinds from uneven belts.

    Definitely try Bruno’s technique of foiling the edge. He showed it to me in person but he covers everything he showed me, in the video. The technique I laid out was shown to me by Victor of Bluesman Blades.

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    I tried again, this time using my 10” wheel instead of the 4” is was using before. Was way more forgiving. I guess that would be considered a near wedge. I got it done to about 3 thou and I got a bit scared to go any further. So I guess I’ll spend some time on the stones to get a feel for the geometry. Name:  87E1521A-8A88-4972-A3B7-7328BD9D3C69.jpg
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    Also my first try at a hamon, not a ton of activity and I over etched it a little but I’m happy with it for my first time.

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    Senior Member Tim Zowada's Avatar
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    As always, I'm a little late to the party. In response to the original question, I grind my edges to 0.030" thick before heat treatment. After heat treatment, I start with 60 grit and grind to about 0.001" or slightly less, and 220 grit. Then, I set my honing bevel. After the honing bevel is set, I even things up with 400 and 800 grit as some of the guys stated above. After heat treatment, all grinding is done wet.

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