Forged razor out of 1084 not performing as well as I hoped trying to figure out why

So I make knives via stock removal and have had good success over the last few years. I'd done a bit of blacksmithing in the past, and recently picked up an anvil and a gas forge and thought it'd be fun to forge a straight razor from some inexpensive 1084 I had sitting around.

I'm worried that it's more of a razor shaped object than an actual razor at this point though, and I'm trying to figure out where I went wrong, hopefully someone here can help.

Potential issues:
1. Heat treat - I've got a digitally controlled Paragon kiln that I've used for heat treating for years now with great results, but the razor came in at around 57 Rockwell using hardness test chisels, which was softer than I'd hoped for, was aiming for 60+. Maybe I should have just quenched it and skipped the tempering?

2. Edge geometry - I'm worried that the blade is too narrow near the edge, because initially, the edge was crumpling like foil. I'm not sure how narrow of a blade 1084 will actually work with. With AEB-L, for example, I know that a blade this narrow wouldn't have the foil crumpling effect with an edge this narrow. I ground it back a bit and resharpened it, but the profile looks like crud now.

3. Overall geometry - I did my best to hollow grind it properly, but doing it by hand and this being the first one I've made, it's entirely possible I made a mistake somewhere and I'm wondering if the general geometry is good enough to get it to shave like an actual straight razor.

It will take the hair off of my forearm with some effort, but it doesn't do a thing to the stubble on my face. I've sharpened it with the same Japanese water stones and strops I use for my commercially made straight razor (1k, 6k, 8k, green chromium stopping compound on a hardwood backed leather strop, red compound on another strop, 1 micron diamond strop paste on a third, 0.5 micron diamond strop paste on a 4th), but the edge isn't working nearly as well following the exact same sharpening process I've used to good effect with my commercially made straight razor.

As this thread is useless without pics, I'll add some and provide some measurements:

Measurements:
0.007" thick at the edge
0.214" wide at the spine
1.05" to 1.14" tall
3.304" blade length

Pics:
Attachment 304884

Attachment 304885

Attachment 304886

Any thoughts on where this razor went wrong and what to change on the next one would be greatly appreciated.

Well I am not a builder. I have done a fair amount of honing. At this point my first guess is that you angle is too low, due to the ratio of spine to width. Try building up your spine with three layers of electricians tape. You might make it with two. Also when honing a brand new razor that has never had a bevel established, the 1K can take a significant amount of time, and if you do not have a perfect apex from heel to toe it will never shave well, or sometimes at all.

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Originally Posted by RezDog

Well I am not a builder. I have done a fair amount of honing. At this point my first guess is that you angle is too low, due to the ratio of spine to width. Try building up your spine with three layers of electricians tape. You might make it with two. Also when honing a brand new razor that has never had a bevel established, the 1K can take a significant amount of time, and if you do not have a perfect apex from heel to toe it will never shave well, or sometimes at all.

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Interesting! Never knew that it could be too low!

Are there any guides as to what the ideal spine to width ratios are?

!/4 of the width of the blade is pretty standard for big razors.
8/8 should have a 1/4 wide spine.

Well first off, let me say, I could have messed up on the math.
http://www.coticule.be/wedges.html?f...alculation.xls
Is a good resource.

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Originally Posted by RezDog

Well first off, let me say, I could have messed up on the math.
http://www.coticule.be/wedges.html?f...alculation.xls
Is a good resource.

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That is very handy, thank you!

It looks like my blade is waaaay too wide. I'll have to see if I can grind it down into something workable or just make another one - practice makes perfect!

If i remember correctly you want to be around 3.8-1 from the edge to where the spine contacts the hone for a given spine thickness. 16*-18* included angle. This is a generalization btw. I made one and it was at 3.4-1 after a piece of tape and it shaves well.

What temp did you temper it at? Maybe too soft, at 57rc I suppose your edge could be too flexible to stay on the hone. I’d do what rez said and try a bunch of tape to see if it will hold an edge. First thing to do is to get the edge to follow the shape of the spine, set a bevel then grind to it to clean up your hollows and get the geometry close.

I’m sure one of the resident makers will be along and should be able to sort you out.

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Originally Posted by jfk742

If i remember correctly you want to be around 3.5-1 for the edge to where the spine contacts the hone for a given spine thickness. 16*-18* included angle.

What temp did you temper it at?

I’m sure one of the resident makers will be along and should be able to sort you out.

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I tempered it at 425 F, which should have resulted in 60 Rockwell, but the oven I used to temper it was not my digitally controlled kiln, as it was still cooling down from 1,500 F at the time, just an inexpensive small toaster type oven that would go up to 500 degrees F or so. I used an oven thermometer, but had a hard time getting the toaster oven to stay exactly at 425 F - dial didn't have exact markings, rheostat style rather than 'punch in a number', small, cheap, etc.

I think for the next one, I'll just wait the two or three hours it takes the kiln to cool down and use it instead, as it's a lot more reliable and easy to use.

Looking at http://www.cashenblades.com/steel/1084.html, it looks like I could have tempered it as 300 F and gotten it to 65 Rockwell. Time to make another then! Thank goodness 1084 is cheap and plentiful. If I'd blown through a chunk of CPM S35VN, I'd be a lot less happy right now :D

Maybe try putting it in the oven or a couple of fire bricks before it gets to room temp to give your kiln a chance to cool without the blade sitting at room temp too long. Also try tempering it at 400, you can always temper it again if the edge is chippy to bring the hardness down.

I just want to say I’m a complete novice at this and just regurgitating what I learned recently at a meet. I’m very interested in how it all goes though.

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Originally Posted by jfk742

Maybe try putting it in the oven or a couple of fire bricks before it gets to room temp to give your kiln a chance to cool without the blade sitting at room temp too long. Also try tempering it at 400, you can always temper it again if the edge is chippy to bring the hardness down.

I just want to say I’m a complete novice at this and just regurgitating what I learned recently at a meet. I’m very interested in how it all goes though.

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Yeah, I need to figure out how long I can wait between annealing at 1,500 F and tempering at 300 F. At this point, I'm uncertain as to whether 1084 needs to be tempered the moment it cools to room temp, or if it can stay at room temp for several hours before being tempered.

So austenizing at 1500 should get you about 65rc as quenched, tempering at 400f should be in the 60-61rc area (I’m referencing Kevin Cashen’s website). Maybe your low rc is due to making the edge too thin before ht? ie., losing heat on the way from kiln to quenchant?

60-61 should work just fine at the angles we hone razors at, as I understand it.

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Originally Posted by jfk742

Maybe your low rc is due to making the edge too thin before ht? ie., losing heat on the way from kiln to quenchant?

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Entirely possible. I did grind it fairly thin before heat treat, definitely thinner than the usual 'thickness of a dime' recommendation. It did hit the oil quench within 5-10s of getting out of the kiln though. A good possibility is that the tempering temp was too high, I believe the small toaster oven hit as high as 450 at points, and with the ah, lack of stability in terms of the tempering temp, that could be another cause.

Is there any issue that you know of with letting a blade sit at room temp for say, 2 hours or so before tempering it? I'm thinking if I can wait for my digitally controlled kiln to cool down from the 1,500 F annealing temp, I'd have a lot more luck with getting an even tempering temp.

I would say go to the thickness of a dime or a little more, it will also help with warping, and then get it to the quench as fast as possible. You’ve got to beat the nose, from 1500f to 1000f in less than 2 seconds if I’m reading the graph correctly. At 400f you can take it out and let it air cool from there to room temp, should give you enough time to cool the kiln if you leave the door open.

You may want to send a pm to bruno, bluesman7, or spazola. The 3 of them have a ton of knowledge. If you do, report back to your thread, as we all like to learn.

Attachment 304899

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Originally Posted by GuyMontag

That is very handy, thank you!

It looks like my blade is waaaay too wide. I'll have to see if I can grind it down into something workable or just make another one - practice makes perfect!

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Also the width of the razor should be even along the length. Your razor seems much wider at the heel than at the toe.

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Originally Posted by GuyMontag

Entirely possible. I did grind it fairly thin before heat treat, definitely thinner than the usual 'thickness of a dime' recommendation. It did hit the oil quench within 5-10s of getting out of the kiln though.

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I'm sorry, 5 to 10 seconds? Did you have coffee first? ;) I know knives let you get away with that sort of thing because they have a lot of thermal mass.
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that is much too long. I try to keep this time as short as I possibly can: out of the kiln and into the quench in 1 fluid motion that takes a second or so.
A razor has a very low thermal mass. Especially if it is already much thinner than is good, I can pretty much guarantee that this right here is your problem.
A razor's edge works like a thin cooling fin. By the time you hit your quench it was already far too cold.

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Originally Posted by GuyMontag

Is there any issue that you know of with letting a blade sit at room temp for say, 2 hours or so before tempering it? I'm thinking if I can wait for my digitally controlled kiln to cool down from the 1,500 F annealing temp, I'd have a lot more luck with getting an even tempering temp.

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None whatsoever in terms of end result. The only risk you run is with san mai blades that have a lot of stress in them after quenching.
If you leave those sitting for 2 hours, there is a good chance your razor will become 2 pieces :)

Subscribed....this is really interesting stuff....im sorry i have nothing to add but im here to learn!

You have received some pretty good info here.
The general rule is that 4:1 ratio of blade width to spine thickness. Greater than that and the edge crumbles while honing because it has lost carbon while heat treating and it is to thin while honing.

Use a meat thermometer inside the toaster oven to set the desired temp.

You have about 1 second to go from the forge/kiln to the quench. Practice/adjust your setup/layout before you start

The edge of the blade should be about the thickness of a dime or more before heat treating. It means more work while finish grinding but you get better steel as an end result.
and you avoid the "potato chip" edge.

Just my 2¢ :)

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Originally Posted by Bruno

Also the width of the razor should be even along the length. Your razor seems much wider at the heel than at the toe.

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It was before I realized the edge was too thin and was crumpling like foil :( I ground it back to the point where it was an even thickness the length of the blade, even if the aesthetics were shot by that point. It could be salvaged with more hollow grinding, but between the handle being too heavy and the tempering leaving it softer than I wanted at ~58 Rockwell, I'm just going to make another. I've got enough 1084 for at least several more, doesn't hurt to practice. Going back to forging after years of stock removal is a complete head trip in some ways, definitely will take some getting used to.

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Originally Posted by Bruno

I'm sorry, 5 to 10 seconds? Did you have coffee first? I know knives let you get away with that sort of thing because they have a lot of thermal mass.

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Might have been less, I had the bucket of oil in front of the kiln, aside from a brief fumble gripping it with the tongs and not touching the kiln with my soft, delicate human flesh, it was fairly quick. Given the 1 second ideal mentioned earlier, it won't hurt to practice a bit with the kiln cold. Some box jaw tongs vs the flat tipped ones I have now would probably also help with getting a good, accurate grip quickly.

I received an email reply from Kevin Cashen about how long you can wait between quenching and tempering, it sounds like the ideal wait between quenching and tempering is "as soon as the blade is comfortable to hold", but if your only (reliable) heat source won't be at the right temp for a few hours, doing a snap temper by quickly bringing the blade up to 275 F, then letting it cool can keep the stress levels down until the conditions allow for a longer tempering cycle.

Make sure you come to Charlie Lewis Texas razor meet next February. About 10 miles north of Wichita Falls.

You will have fun. :)

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Originally Posted by randydance062449

Make sure you come to Charlie Lewis Texas razor meet next February. About 10 miles north of Wichita Falls.

You will have fun. :)

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Randy speaks the truth here. Guys will stumble over themselves to help someone along. As you have learned already, knives are much easire than razors.

Question? Do you shave with straights?

I use wolf jaw tongs for forging, and a simple flat tongs for HT handling.
If the jaws are close enough, you only need to grip hard to get a solid grip.

I just use unlined leather gloves...yes, I am that tough!

once again, I'm late to the party. I just skimmed through the above stuff. Here are some things that might be helpful:

1. Design the razor for a 16 degree included angle, at a minimum. Up to 18 degrees is fine.

2. Leave the edge at least 0.030 thick before heat treatment.

3. Put blade in preheated kiln. For 1084, soak the blade for 5 minutes at temperature.

4. Quench - one smooth motion from kiln to quench. If using oil, rapidly agitate the blade from edge to spine. You only have 0.5 seconds to get below 1000F, once the blade hits the oil. Interrupt quench at about 400F. Cool to room temperature in air.

5. Temper immediately at 330F. Don't wait for your kiln. Get a deep fat fryer at Walmart. Don't trust the control knob, get a good thermometer.

6. Hardness chisels are not very reliable. They also include abrasion resistance and operator bias in the readings.

7. You will have 0.005" - 0.010" decarb when using an open air kiln. Plan for that.

I hope this helps.

Late to the party as well.

A couple of points that may or may not have been covered in the preceding post.

What is your quench oil? 1084 requires a fairly fast quench, you can get by with Canola or peanut oil, but something like Park's 50 would be better.
A way to get a toaster oven fairly even is to put a 1/4" thick or so plate in the bottom, nothing special, just a large chunk that will fit. It will help even out the oven cycling temps for a more even temper. I also let the toaster oven run for a while before use, about a half hour or so to let the temp stabilize and to be sure I'm at the rite temp.

As an aside, I've only made a couple of razors, but the one I did out of damascus, 1084 and 15&20, while it works well, doesn't have the edge retention of the ones I've done from higher alloy steels like 52100. Just means I have to touch the edge up a bit more often than others.