Thread: Two questions from a newbie

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?

Should have it ready to finish grind, why do all that hogging out on a hardened blade? And a razors edge is much thinner than a knife so it doesn’t translate. You only want to leave enough edge to keep it from warp at heat treat

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Is this you?


https://www.instagram.com/p/5pELL7ia1i/?hl=en
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Nice looking knife
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https://www.razorsharpunlimited.com/...ions/benchmade

OK, a few guidelines ....

Use unalloyed high carbon steel. 1075 - 1095.
It gives a finer grain size resulting in a smoother shaving edge.
No to 440C except as a practice razor.

Ratios .... blade width to spine thickness 4:1 or less
Ignore this and the bevel gets very wide, difficult to hone, and the edge is prone to chipping.
Leave a small amount of extra width to compensate for a decarburized edge that will need to be ground off after heat treatment.
Then you will know you have good steel on the edge.

Rough hollow grind to an edge thickness of about a dime.
Bring the decorative spine work, spine and tang to a high finish before heat treating/tempering. Make for less work afterwards.

Finish grind slowly. The enemy is heat and losing the temper.
Take the edge as thin as you can then hone. The honing will show you where the bevel is uneven and wide in spots. This will tell you where to grind some more. Repeat this last process as necessary..


Just my 2¢

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...jfk742 has made some very nice razors, listen to him ......

Grinding to a foil edge relies a lot on the sound of the belt. I don't even try.

You can get very close to a foil when you send out the blade. This I can do.

Originally Posted by randydance062449

OK, a few guidelines ....Just my 2¢

Gee Randy you've learned a lot more than i have about razors since I first met you. LOL. That's worth way more than 2p.

One knifemaker to another...listen to these guys and this gets a lot easier.

As to my advice, learn to thermal cycle that bar of 1084 and eliminate the warping tendencies before you begin. You can do that with a very simple heat treatment setup even if you don't forge any blades.

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!

Originally Posted by randydance062449

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Is this you?


https://www.instagram.com/p/5pELL7ia1i/?hl=en
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Nice looking knife
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https://www.razorsharpunlimited.com/...ions/benchmade

No that’s not one of mine. But I guess I need to look him up to see if we are related.

Thanks to everyone for the tips. I’ve got a bar of .250 1084 on hand right now so I’ll get busy practicing on that. I’m sure I’ll have a few more questions once I get going.

What you are asking is beyond me so i cant comment. But we do have some great razor makers on this forum that have been doing it for many years. Just be sure to do it right and come out with the proper geometry and grind.