Edge Thickness

[Phantom23]

Greetings, like another Newbie I was waiting for someone to ask the right question I wanted answered, but no one has, so I will have to ask it myself.

Over the past too many years I have been going to make a knife, started making a knife, or looked at the mess I have created and binned it and said another time.

This is another time, but it will be the time.

Minor problem is:

I am stock removing from a piece of 440c, overall knife 220mm blade will be 105mm X 30mm. I am flat grinding the blade, and already removed most of the metal. The spine is 3mm thick The question is how thin should I grind the blade edge. It is currently 1mm thick. I realize I will have to put an edge on it , but prior to putting the edge on it how thick should the metal be.

Thanks

[Don Robinson]

Grind the flats until the edge is about 0.5mm thick, heat treat, cleanup, then grind the cutting edge and sharpen. Your 3mm thick blade is evidently a general use knife, so this is a good rule of thumb. For a very thick survival blade or something like that, you might want to leave the edge thicker before sharpening, so it'll stand more abuse.

[Jason Cutter]

Whereabouts is Burpengary ?

0.5mm thick as Don suggested is a great way to start. It'll slice really nicely if the bevel is taken all the way to the spine. Commercial HT firms usually use vacuum ovens so there is no scale and the blade comes back pretty much the way you sent it, but with the tempering colour which could be just buffed off. So completely finish the knife before sending it off, even fit the handles with dummy pins and get the handle finish right, pop it off and just slap it back together when it comes back.

If you do a hand rubbed finish, you can manually sand the edge down less than 0.5mm so there is a bit of a convex to the edge which I like. When sharpening, the final edge bevel will be smaller and the blade will "slide" better when slicing.

Good luck. Jason.

[Phantom23]

Thanks for the answers. The info will help.


Burpengary is about 35 km north of Brisbane. It is on the main highway. It is about half way between the Sunshine Coast and Brisbane.

Importantly it is only about 1 hours drive from the Gabba the home of the Brisbane Lions.

Jason I saw on your website that you use Hills for heatreating. Do you post blades there? What is it worth (approx)? They seem to do a bit of work in Australia - AKC recommend them.

[Jason Cutter]

Hills HT is very near my workplace so I drop in there at 7am before work and collect them when done. They do very good work and they now do the full cryogenic (sub-zero tempering) and 3 tempering cycles if you ask them. They Rockwell test every blade. I think their prices range between $5 and $10 for a knife blade, depending on size and add $5-7 for the subzero quenching. I don't know how much postage would cost. The majority of the other makers who use high-alloy steels like 440C and ATS post their blades to Hills. I know 'cos I see them on their bench when I go there !!

Please don't take my prices as quotes, you need to call them directly and figure out the best way to go about it. They are very knowledgable about HT for knife steels, as opposed to some other HT companies (there are quite a number of them) but they may not know some steel names like RWL-34 (call it ATS-34).

I am not much of a footy fan, but you must be a proud Brisbanite at the moment !!:evil :evil Jason.

[Phantom23]

Thanks, bit of grinding, bit of sanding, bit of handle fitting and a phone call to Hills, a visit to the mates for some digital photgraphy and I may post a photo here one day.

Thanks again.