The edge, how thin before heat treat?

[Jacktheknife]

Gentlemen,


How much can one bevel a blade before heat treat?

I have a 6" Skinner of 3/32 1095. The blade is beveled down to 3/64ths on the edge,
or 3/4 of 1/16th. The blade steel is so thin that the edge is 2/3rd of the thickness of the spine so ... its thin but then so is the blade.
But before I heat treat this blade what is the proper thickness of the edge and the angle of the bevel to have on this thickness of steel before heat treat?

I am about to figure this out and I would call my new friend Master Blade Smith 'Stan' but he is asleep. I intend to quench this blade in peanut oil and to 'edge quench' as recommended by Stan. Got to be better than the used motor oil with 20% transmission fluid in it. The peanut oil will let me get right up there and see whats going on with the blade. The used motor oil 'likened' to have choked me to death.


Thank you...


Jack the Knife

[jmccustomknives]

I personally run mine down to 80% then heat treat. I'd practice the motion before firing up the forge. The edge quench can be tricky on a thin blade, it will warp on you if everything isn't perfect. Good luck.

[NorCal Nate]

The thickness of a dime is the general rule of thumb..
~Nate

[NorCal Nate]

But some ht before any bevels are ground too. Less stress on the steel and less time wasted if something twists or whatever ..

[Crex]

Peanut oil is not "fast" enough to let you see what is really going on with 1095.
Also and edge quench with that thin a blade just might produce cracking along the edge (as mentioned above.

[Jacktheknife]

Gentlemen,


The edge is thicker than a dime alright, and I may sand off a little more of the bevel if 80% stock removal before heat treating is acceptable. I got all the scratches out too.
I'll remember those guides and call 'old Stan' this morning as well.
The last steel I bought was 1/16th, even thinner than the 3/32nd but more expensive as it is hard to cut at the factory. I figured thinner steel would make a sharper knife everything else being equal but even though the 1/16th is said to be hard to work I never cracked any. I did bend a few so I went to 3/32nd.

Old Stan the Master Blade Smith who lives three miles away told me:
When non-magnetic, to quench the edge about half way to the spine and when the blade is black in color drop it in the quench, take out, clean and put in the tempering oven for an hour, then cool to room temperature and put back in the oven for another hour, cool and do it again.

Also I found a stainless steel container to quench in. I just hope it is big enough. It holds a gallon of water and is elongated so a skinner will fit in there just right. Is a gallon enough quenching oil? Stan also said to heat a piece of rebar or something and put it in the quench to warm it before use.

I don't know but I may be on the verge of making a salable knife!
Thank y'all for your help.


Jack the Knife

[jmccustomknives]

I use a version of Goddard's Goop in a baking pan for my edge quench needs. The stuff is solid a room temp, for small blades no preheat is necessary but for larger ones I'll heat up a scrap piece and melt a channel in it. I will be easier if you use a pan for the edge quench, just have something that can cover it when it flames up!

[Gary Mulkey]

Jack,

Shallow hardening steels like 1095 are difficult steels to get the H/T correct and nearly impossible without a fast commercial H/T oil. If you can't afford commercial quenching oils then I would suggest something like 5160 or 1084 which can be quenched effectively in the peanut oil that you suggest.

You are starting with some very thin stock as well which is going to present some problems as well. There is a lot of info on H/T'ing steels on line and I would do A LOT of research there as it will determine the quality of your blades more than any other factor.

Gary

[Tai Google]

On a thin blade like that peanut oil, canola or any common vegetable oil should be fine... just about any oil should work when it's that thin or at least get the edge fully hard. The vegetable oils are considerably faster than the un-accelerated commercial quenching oils or motor oil, because there is no vapor phase. Vegetable oils should be fine at up to about 1/8-3/16 inch thick max. Remember that thin section cool faster than thicker sections.

Warping can be a problem with thin blades though. If the edge warps, but spine stays straight, it can be difficult to straighten. How thin you can go without warping really depends on the overall geometry of the blade and quench speed.

[Jacktheknife]

Thank you...?


J. Knife

[Tai Google]

You should get it 50 to 100 degrees above non-magnetic for the quench and don't waste anytime getting it into the oil.

The main concern with edge quenching thin blades like that is they take a set or bend real easy. This does make them easier to straighten after HT, but not sure you want a blade that's so easy to bend in the long run. I'd consider a full quench on a thin blade like that. It will be more springy.

[Jacktheknife]

Tai sir,


"50-100 degrees more than non-magnetic" I'll remember that.
And I was told by another knife maker too:
"Get those thin blades under the oil in less than a second"!

And a full quench sounds good to me as I have done that before and I was gonna ask:
Is a gallon of peanut oil enough to quench a 6" skinner?


Thank you...


J. Knife

[Tai Google]

Getting it in the oil is a matter of temperature, but time is a factor. You need to get it in the oil before it gets below about 1350. On thin blades you don't have much time, but it's doable.

A gallon will probably be enough for a thin little 6" skinner, but two would be for sure. The only real advantage of the peanut oil is that it has a higher flash point than the other vegetable oils. I think it's more expensive than canola though, which I get on sale for about $8 a gallon. They all have a relatively high flash point compared to the commercial petroleum quenchants and are safer in every respect.

... on second thought, a gallon should be plenty for that blade.

If it warps a little with the full quench, you should be able to deal with it in the tempering cycles.