Advice Needed Determining Prioritites

[Way-Barney]

Hi I would appeciate comments on aspects of my process.

I am returning to knifemaking after a few attempts some 20 years ago where I built a few knifes from steel stock and handled a few bought in blades. Returning, I am feeling myself drawn into the steel side of the blade making and fit and finish is coming secondary, due to the fact that I am only making knives for myself. I want to make good users from correctly prepared and treated steel before considering hand sanding down to 800 grit etc. I am finding that I have enough problems already trying to get the heat treat right for designs I want to make. I have a particular problem with 80Crv2 which I hardened to 60 ( I think) but it will not support an 11 (each side) degree edge. Why do I want that edge angle I keep asking myself? I dont know, I have somehow convinced myself that it will cut keener and the angle will cut longer.

My grinding is not the best and I do need more practice, but this is bogging me down, should i just change the edge angle and crack on with getting better overall?

I really want to understand the steel and heat treatment aspects, The knife is ok going into wood but took a fair few minor rolls chopping into dried antler.

I seem to have turned this into a specific problem rather than the more general aspects I started out to obtain.

Priority > Steel or fit and finish?

 

[Joshua Fisher]

If the edge is rolling it means it could be harder, if it’s chipping it needs to be softer for the given geometry or task. 11 degrees per side is very low and likely will give you trouble for tough tasks. A easy way to dial in the ht is leave it harder than you may want test it and see if the edge chips and if it does retemper 25 degrees hotter for 30 minutes or so, keep testing and adjusting the temper up till the edge rolls then make a new sample and temper at the degree that didn’t chip/roll badly and see if you get the same results with the same geometry. Once you settle on a good ht schedule for a given style of knife you can make adjustments with geometry or angle without changing the ht. A steeper angle on the edge will be a bit tougher as well as thicker behind the edge, the behind the edge thickness will have a bigger role in edge retention than the edge angle itself, thinner behind the edge means the cutting edge doesn’t have to work as hard and doesn’t bind up, this is all task specific, I wouldn’t want an axe with a kitchen knife geometry and vice versa. Fit and finish is great to work on but geometry and ht are more important in creating a well functioning tool, I’ve seen pieces that look phenomenal but have poor geometry and would never make a good useable knife.

 

[DevinT]

Do you heat treat in a furnace or a forge?

Hoss

 

[Way-Barney]

Thanks for the temper advice, thats just the kind of practical soloution I was hoping for and also that I am not needlessly trying to get things right. I have a lab grade Snol oven (Max1100c), austenitised the knife straight from stock at 840 and tempered 220(is metric ok?). I found the recipe from this site somewhere, since heat treatment more research has identified a couple of areas that indicate I may not have achieved the best possible results from that recipe. I think that I will easily get the sanding right eventually but need this steel sorted to my satisfaction first.

Joshua, I also see some, what i consider, basic errors in knife design. and these issues I feel the need to address in my own projects.

Thanks for replies

 

[Sando]

W Way-Barney you are going about this the right way! I made too many knives before I started destruction testing.

For example, 26c3 can make a mean slicer. But it can break/chip pretty easily at lower tempering temps. I finally tried a temper at 450, then another destruction test. That made a completely different knife! The hardness only dropped to 61, but it was so much tougher my eyes popped out.

So no advice from me other than to follow what Joshua said. Rest assured you're going about this in the right way.

PS I don't know about 80CrV2, but you can get 26C3 to support an 11 degree edge with high enough hardness. I put one in my kitchen (63-64 Hrc). No one is allowed to use it but me. It's so much fun I won't share.

 

[Alex Topfer]

(is metric ok?)

Metric is superior

What quenchant did you use?
Looking at Larin's work on this you could try a slightly higher austenitising temperature to get a little bit of extra hardness?
IMO an 11 degree secondary bevel is too fine for what you are doing. A typical wood chisel has a ~30 degree total angle

 

[Way-Barney]

Thanks for the reasuring advices, I will try to heat treat a bit harder, this time from pearlite not shperoidized, and if I cant make that work lower the angle slightly. I use Rye 32 quenching oil. I must also comment on the quality of knives you guys are making, truly outstanding and I am humbled that you have taken the time to try and help a noddy messing about in his shed. I have been assembling equipment for a couple of years. when suitable stuff pops up, in preparation for my retirement when hopefully I will dedicate more time to this amazing hobby.

ThankYou

Wayne

 

[Stacy E. Apelt - Bladesmith]

Welcome Way-Barney,
Fill out your profile so we know where you live and a bit about you. It helps us give better advice.

...."a noddy messing about in his shed.".......
That describes the vast majority of people who make knives. I think pretty much every one of us started that way. The shop I made my knives in until three years ago measured 7X8 feet (2.15X2.5meters).

As suggested, start with an angle that seems as acute as you would want. If it does not hold up well, resharpen at a slightly higher angle. Usually about 3° higher will make quite a difference. 11° per side (22° inclusive) is good for knives in the kitchen, and 20° per side (40° inclusive) is good for hunting and utility knives.