Krenov Plane Irons

[eric mah]

I've taken the plunge and decided to make some Krenov style planes. I have already made one from the Hock kit. In my habit of going hard core diy, I have bought some A2 steel to grind the blades and then I will send them out to be heat treated. My question is what Rc hardness do I request? Having made some hunting knives in the past, the norm is an Rc 58/59. I noticed on the Hock site that he goes for Rc62 for A2. What is the real world advantage of either or am I just over thinking this.

BTW If I go full treatment including the steel, it will cost me around 30 bucks a blade plus my time, which is going to be around an hour a blade. If pay myself min wage, I'll beat the catalog prices.

Eric

[Mark Baldwin III]

I tested a Hock iron, and it was was RC61ish (my tester isn't the greatest, plus or minus about a point). The irons that I have recently made from O1 came out to RC60. You're right in sending the A2 out, I learned the hard way that it can't be home treated easily. If you have a torch and accurate oven, you might be able to treat your own irons if you were to use O1...which makes it really cheap!

[Casey Gooding]

Ron is the man and knows what he's doing. If you follow his lead it can only lead in the right direction.

[eric mah]

I actually have a small forge for treating knives and a toaster oven for tempering. However the forge is closed until it warms up outside.

Eric

[john brenton]

Why don't you do the heat treatment yourself and post pics for everyone? In other words, why don't you risk the money you spent on the steel for our benefit?

Seriously, though, I have yet to need to temper any home made tools, but it seems like such a valuable skill I don't know why you'd pass it up. This would be a good project to do it on seeing as though Krenov irons are so small.

I've taken the plunge and decided to make some Krenov style planes. I have already made one from the Hock kit. In my habit of going hard core diy, I have bought some A2 steel to grind the blades and then I will send them out to be heat treated. My question is what Rc hardness do I request? Having made some hunting knives in the past, the norm is an Rc 58/59. I noticed on the Hock site that he goes for Rc62 for A2. What is the real world advantage of either or am I just over thinking this.

BTW If I go full treatment including the steel, it will cost me around 30 bucks a blade plus my time, which is going to be around an hour a blade. If pay myself min wage, I'll beat the catalog prices.

Eric

[Trevor Walsh]

Id shoot for 60, that seems to be the norm for irons out there. I think knives are that much lower because they get a lot of prying forces and have longer moments of inertia, thus need to flex more.

[Mark Baldwin III]

Even with the forge, the A2 needs special attention. Mr. Wilson may be able to add his 2 cents on this. O1 is much easier for the DIYer.

[David Weaver]

I could repeat george's response i've seen it so many times.

I think the 62 is part utility (harder = hold edge longer as long as it's not so hard it chips out), and part keeping up with everyone else due to a lot of folks being magazine spec shoppers.

I'll bet if someone sold a replacement iron at 60, and someone else sold one at 62, most people would think "well, i'm getting more with the one that says 62, it's a bigger number".

At any rate, A2 that I've had hardness tested holds up well at 62. I think if I was going to have a hardness tester do it, I'd probably tell them 61-62 if I knew they nailed it every time.

[David Weaver]

Can someone answer a question I have? I've never made a krenov plane, but when I make planes, I always search for an iron long enough that I can fit the iron to the plane and likely not ever worry again about replacing it (especially if it's a really hard iron).

I see a lot of krenov planes where the irons are expensive, and they still barely come out of the mortise, giving you a tiny little thing to hammer. Why aren't they longer? Is it because they'll get in the way of your hands? What do you do when you've consumed a half inch of them?

[Mark Baldwin III]

I see a lot of krenov planes where the irons are expensive, and they still barely come out of the mortise, giving you a tiny little thing to hammer. Why aren't they longer? Is it because they'll get in the way of your hands? What do you do when you've consumed a half inch of them?

That's pretty much why I decided to make the irons in my last two planes. I made them more than an inch longer than a Hock, and w/out chipbreakers. I felt that I would get greater utility and life. As long as I maintain the mouth of the plane, the chipbreaker will never be an issue. I will probably continue to make my own irons, as it seems the best approach for me.

[Jon van der Linden]

Ron Hock does sell longer blades for the Krenov style planes. The "old" ones were 3 1/2" the "long" ones are 4 1/2" The length is critical as is how you shape the rear area for hand support. You really don't want your hand against the blade. You can see the hand support is much higher than the area supporting the blade on Krenov's planes.

Using a chipbreaker is good for a number of reasons. It adds mass and functions as a vibration dampener, and the "improved" style breakers, whether from Hock, or Lie-Nielsen, or whatever, relate to studies on how a chip is deformed by the chipbreaker for improved performance in difficult grain. Whether they actually function that way depends entirely on setup.

[eric mah]

Thanks guys, I just sent them (12) off the Texas Knifemaking in Houston. Going for Rc 62 and cryo treatment. I modeled it after the hock blade although I shortened the slot as I doubt that I will take more than 3/4" off the blade in my lifetime.

Went with A2 3/16" thick steel. If I make more I will probably go with O1 so I can treat them at home. I don't like to play with fire in the house, so heat treatment takes place in the other 3 seasons outside.

My next task is to make the chipbreakers. I'll post some pictures when they get back.

Eric

[eric mah]

Anyway guys, here are a couple pictures of my efforts. First is the hock kit with a small adjustment hammer made of brass and ash. The second are the blades getting ready for shipment to the heat treater.

Thanks
Eric

plane1.jpgplane2.jpg

[Dale Osowski]

I use mine as a pull plane so the 3.5" blades are plenty long for me:

[George Beck]

Outstanding! I like the simplicity. I made one as a pull plane as well. I even shaped the bottom as a Japanese plane.