Cheap steel? Chips?(Pics)

[bigjim]

I have a Tops neck knife. The blade profile is so thick and blunt edged that no matter how sharp you got it, it would give very poor cutting performance.

I thnned the edge WAY back and worked the edge with several levels of fine stones then used a strop. Then did a micro bevel.

This thing is VERY sharp now and cuts much better but..... Look closely at the pictures you will see chippingat the edge. Is this crappy steel? Bad heat treat? What!!!

 

[ecos]

sounds like youre experienced at sharpening so i doubt its a burr on the edge breaking off in spots...

have you heard of the brass rod test? hmm lemme see if i can find a link to it instead of trying to explain....ok found this from bob warners site (a very helpfull accomplished maker)

"How do you do the Brass Rod test

The brass rod test is performed to test the knife. The blade edge is held at an angle and placed on a brass rod. The blade is then pressed down on the rod until the blade bends around the rod. The blade is then moved forwards and backwards, rolling the brass rod against the table top. The cutting edge should flex over the brass rod for the entire length of the blade. After the test, the edge is inspected. If the edge is deformed, it means the blade is too soft and bent when moved over the rod. The knife needs to be redone starting with the heat treatment. If the blade has hairline cracks in it, your blade edge is too hard and broke as it passed over the rod. The knife has to be remade. Ideally the knife has no change at all. Here is a picture I took of the brass rod test. The brass rod is not brass in this case, I wanted contrast so I used a ceramic rod (not recommended). You can see the blade flexed in this picture:"

the link is http://www.warnerknives.com/knifemaker_faq.htm the brass info and pic is about 3/4 the way down

its a good test to find out if heat treating was done right and is pretty standard test for custom makers to use

 

[Valkman]

I wonder if it's not too hard. Could be it wasn't tempered enough.

 

[SeanSw]

If the edge is chipping then the steel is too hard. The reason that blade cut so poorly is because it was made thicker to provide for durability. When you remove metal to make better edge geometry and there is less material to support the edge, then it will get weak.

Those are very small chips though. Reminiscent of the edge chipping I see when I grind old files into knives (full hardness, no annealing)

The brass rod test works but I'm guessing the blade in question is too thick to provide for any kind of flexibilty in the edge.

 

[mete]

I am not familiar with the knife so I don't know the steel. However there is steel choice, heat treatment and grinding. Any of these may cause a problem. Grinding creates heat and if done improperly the edge will be damaged.This can be fixed by stoning away the damaged layer.

 

[redneck]

Tops generally uses 1095 if I remember right. Its a shallow hardening steel that does well with differential tempers, and can be made fairly tough. Looks like in this case they left it a little bit hard for the edge you want on it.
Everybody expects something different. You want good slicing performance, other folks expect that knife to chop wood. With the thick edge, they probably get away with a little higher hardness and can have a knife that holds a thick edge really well.
Looks like its not quite right for that razor thin edge you want on it though.
Those chips are awfully small though. You might try and sharpen it with a double bevel. Sharpen it as you have, then finish on a really fine stone at an angle thats maybe 5 degrees higher. It will have a little bit more support for the cutting edge, without that splitting wedge profile.

 

[bigjim]

Thanks Redneck....

That is what I have tried. But the chips got worse as I worked with it.
Not sure why TOPS put a AXE type edge on a 2 inch neck knife.... not much of a chopper. I had the stupid thing hair popping sharp and it still CRUSHED its way through thingsd like apples.

So I thined it back some. Its still not super thin. Heck still can't use a sharpmaker cuz the angle is to blunt. Do you know if all TOPS knives are like this? I think any thing you call a knife should be able to slice something.

This is not just a TOPS issue.....Most knives now days are coming with very thick edges.... I just recently Bought a BM Aeres 730 and it was sharp as heck and still would not slice nicely.

I have even bought customs that wont cut.... I know it takes time and effort beyond the grinder to make a realy good cutting edge but geez... you would think with a knife greater than 300 dollars in price the maker could spend some time hand honeing a edge useful to the knifes intended purpose.

 

[ecos]

a thicker edge is less likely to get damaged.
in todays knife market advertising knives as near indestructible is a big selling point. knives that are driven through steel plates, chopping througn bricks, heavy prying, etc. many people find this very appealing so knife companies cater to them. a knife made for such activities is designed different than a knife made to cut.
personally i prefer to make knives geared more towards cutting than crowbar/hammer activities, explain the difference to my customers and hope they use the knife for its intended purpose....to cut.

 

[redneck]

Couldn't tell you if all TOPS knives are ground that way. I will say that both benchmade knives I own, and the handful that I've sharpened for other people all came with that same type of edge. The difference is they can be resharpened to a very fine edge and don't seem to have any problems chipping. Maybe that TOPS isn't representative of all of them, but I can see where your not real happy about it.
It is getting hard to find good cutting knives anymore it seems. At least without doing a little bit of work on them. Fewer and fewer people carry them anymore, and it seems like a lot of them either haven't experienced or don't appreciate a really efficient cutter.
Another problem is the overall grind of the knife. A very narrow (spine to edge) blade, thats made out of thick stock will have a lot of drag to it regardless of how the edge itself is sharpened. You can zero grind a maul, and it will still be a maul.....but people love their sharpened pry bars Sometimes its better to leave the edge thicker, and grind the whole blade behind it differently so that there is less drag. Thats an issue thats hard to fix though if your not the one who made the knife :banghead:

 

[bigjim]

Ecos,

Music to my ears...... you mean you make knives that cut?
Got a web site..... Pics and price lists?....Hooorah! Now were talkin.

Jim

 

[ecos]

no website yet. ive been making knives parttime/sparetime for 14years and am just now in the process of going fulltime. im setting up a website right now and it will be up within 1-2months. ive started a new knife "company"(feels odd saying company because right now its just me and some of my family helping out) that will offer standard models to help keep prices and waiting time low. all knives will still be made by hand, no cnc or jigs. prices will start at about $40 and i plan on building up inventory to be able to ship all items within 1 week...as opposed to a several month waiting list most custom knives have. and yes all knives must be able to shave before they are shipped
here are a few examples... please bear in mine half these are only 90% done and need the finishing touches, touchup in the finish,epoxy cleaned up etc. i just threw these in an album for friends that wanted to see some of what ive been playing with lately

http://pg.photos.yahoo.com/ph/jason...pg.photos.yahoo.com/ph/jasons_blade/my_photos

 

[bigjim]

Ecos we should talk...
I see 7 or 8 of those knives I would buy right now.

Lets take this to E-mail
[email protected]

 

[Valkman]

Great knives, ecos. I really like the etched recurve! I've been etching all my blades lately and then buffing them to different levels of brightness. Neat stuff! I think Big Jim would be happier with a well made custom.

 

[ecos]

thank you valkman, same applies to you etching hamon lines is something relatively new to me. most the time ive been making ive used high alloy steels and am just now tinkering with differential hardening...as you said neat stuff

for the record wanted to say there are many makers that make very good cutting knives. with what i said before i meant i dont suscribe to the prybar knife designs, not that my work is superior to others...just made differently than the afore mentioned styles.

 

[nomadboi]

When you ground the blade thinner, did you take precautions to keep the blade froim getting too hot? If not, you could have actually taken the temper out of the steel in the grinding process.

 

[bigjim]

The work I did was by hand with oiled stones.... No heat at all.

 

[redneck]

If the blade had been overheated, it would be more likely to have the edge roll than chip. This definitely seems to be an issue of either too hard, or too coarse a grain structure to hold that fine edge.

I hope I didn't make it out like I don't think anybody can make a cutting knife anymore. Lots of people do, its just that the sharpened pry bar craze has really gotten strong. Cutting knives aren't that hard to do really....even I turn one out on occasion

I find a lot more uses for a knife that will cut than a knife I can use as a pry bar. Its fun for braggin too. You'll find yourself in a situation pretty often where you can do some paper slicing tricks, or lop off a dangling peice of twine or rope. You'd just get funny looks if you ran around yelling "watch how far I can bend this!"