Two Knife making questions

[Jedadiah]

OK, here goes,

i want to put a flat grind on the knife i am making and wanted to know two things. Firstly, how close do you go to the cutting edge before heat treating? It is 3mm 01 tool steel and i'm putting a 6mm grind on. I intend to hand file it but i've heard that if you go all the way to a cutting edge, it would be too fine and there could be a possibility of damage, so, how close do i go?

Secondly, i'm not sure about the fella who says he can heat treat the blank and i do not have the equipment to do it myself, could anyone do a top job on both my blanks for a nominal fee? It would be very much appreciated as this is my first foray into blade making and i'm not made of money.

Your assisstance would be greatly appreciated.

Jedadiah

 

[Longstrider]

Hi Jed, Don't make the edge too thin prior to heat treat. You'll want to leave the cutting edge about 0.5mm thick so it does not ruin during the process. If it's too thin, that part of the steel heats up quicker and gets hotter than the rest of the blade and it burns (Actually it's called "decarburisation as the carbon burns out of the steel). This means that you have to put the final edge onto the knife once it's in it's hardened state. I find that this is best done with a diamond hone as a file will no longer cut the steel then.
By "flat grind" and the fact that you state that you want it to be 6mm, I guess you mean you are planning on whats called a Scandi grind ? (Like a "Woodlore" knife has?) This will be far easier to make with a file than a full (true) flat grind.

There are a few guys on here who can heat treat a blade well. I've had a couple done by one of the mods, but I can't say that he'd be able to do it for you, and he's away from home at the moment so you'd have to wait until perhaps the end of the month to find out if he could do it.
I have a heat treat oven (digitally controlled electric) arriving soon from the States, but I wouldn't be happy to take on someone elses blade for at least 3 or 4 months. I need to do plenty of experimenting before I would risk ruining a project for someone else

A couple of my knives to show the different grinds. Firstly, a Scandi Grind...


... and a Full Flat Grind...

 

[Ogri the trog]

Hey Jed,
Good info there from Longstrider re the thickness of the bevelled edge.
My comment is to counter your thinking that you don't have the means to heat treat the steel. I often say that if "Iron Age" man could do it, then we ought to be able to at least try. If you have a coal fire or a barbeque and a hair dryer, you have more than enough to treat your steel. A few more items such as a magnet and a pair of pliers would help. All you need to do is get the steel hot enough so that a magnet no longer sticks to the steel and its hot enough to quench. Then after a polish, heat it again till the blade turns a light straw colour and leave it to cool - job done. I've done a few in my kitchen Rayburn.
I have it on reasonable authority that there might be some audio/visual assistance in this field on its way to this forum, so patience is the key - in the mean time a visit to www.greenpete.co.uk and look for the knife making pages would help a lot.

ATB

Ogri the trog

 

[forginhill]

Excellent advice given. I generally take my edges pretty thin because I use hand tools to make my knives. As was mentioned it's easy to overheat that thin edge. When heat treating, bringing the blade up to temp very slowly is critical. That helps to avoid overheating the edge. I used to use a magnet, but I don't anymore because I was overheating my blades. I've experimented starting out on the low end of red heat and worked up from there to learn the right colors and look of the steel when it's ready to quench. I am having good success now. Get your quench oil nice and warm too. Right after the quench test the edge with a file. You'll know if it got full hard. If it didn't just do it again but a little hotter. At least that's what's working for me. Todd

 

[Singeblister]

Above is all good advice.The blade shape has a lot to do with it as well ,
the more curve you have in the blade the more likely it will be to warp the thinner you go, on a blade with curves i tend to leave them around 1mm , but i have a grinder so i can do this, working by hand means you want to go as thin as possible but its just going to be trial and error.

 

[JohnC]

Id agree with giving heat treating a go yourself. There are a lot of DIY threads about. I've had success with charcoal and a home made firebowl. The knives are still going strong and I learned a lot researching how to do it and had the fun of giving it a go... Good luck with it!!