how to achieve factory like edge?

roosterscrow · Feb 18, 2016

I just picked up a new Stretch and I'm curious how they get that toothy edge and have a bur free finished apex? I debur on a paper wheel or a 1x30 leather belt and inevitably end up with a polished edge (perhaps just a lighter touch is needed?). My polish edges cut paper and shave better that these factory edges, but these factory edges (like on my stretch) feel so sharp when giving them a three finger touch and I'd like to know how they achieve such an edge.

REK Knives · Feb 18, 2016

Not sure how they do it in the spyderco factory, maybe someone else can come along here and comment =) But you are correct in that paper wheels/leather belts will remove any 'bite' or micro-teeth (I have found this as well, regardless of a heavy or light touch). So what I would recommend is cleaning up the edge on the power system, then finishing up w/ a microbevel on a fresh stone and no stropping (or light hand stropping depending on the substrate, Heavyhanded and Jason B can comment more on this and will probably be by shortly

Obsessed with Edges · Feb 18, 2016

I think Spyderco's edges are applied with something in the 120-180 grit range (don't remember if it's belts or grinding wheels), then buffed with a felt wheel to de-burr. This is only based on what (I think?) I remember seeing posted here sometime ago; I might be off-base on that. I think Jason B. has talked with them before about it; he might chime in here.

David

Jason B. · Feb 18, 2016

At one time I know Spyderco used a Norton Blaze 120 followed by a power strop, looked like some sort of sewn cotton wheel heavy loaded with years of polish and metal. They are automated now.

Overall I've seen factor machine edges from about 60 grit to 220 grit with varying levels of polish.

Seki made blades tend to be a little finer, at times I would even bet they are sharpened on water wheels.

bgentry · Feb 18, 2016

Just for an experiment I just tried a variation on this.

Using the WorkSharp Ken Onion, I started with a Norax stiff x100 belt and raised a burr on each side of a Spyderco Tenacious. Then I switched to a sort of worn "6000" purple belt. I removed the burr in maybe 1 to 2 passes. I did an additional pass on each side for good measure.

The edge looks pretty coarse and is sort of sticky. But not as sticky as I had expected. I *think* the edge straight off of the DMT Coarse stone (deburred on the same DMT C) is more sticky.

This edge from the X100/purple combo shaves decently, mostly push cuts phonebook paper, and (as I said) feels sort of sticky. I'll use this for a short while and see how I like it. It certainly was easy to apply. Just a couple of passes on each side, plus the few on the purple and *done*. The really nice thing is that the purple belt didn't even begin to raise a new burr. Just removed the large 100 micron burr.

Brian.

roosterscrow · Feb 18, 2016

Thanks! that has given me a few things to think about and try. It seems kind of dumb to try and get a duller but more sticky edge, but when sharpening for someone else ( usually guys I work with at the Fire Dept.), I've had a couple of experiences of handing them the knife and I can see in their eyes that they are less than blown away when they test it with their finger gently on the edge. I even had one guy that I thought was about to run his finger down the blade after failing to feel the typical bite and had to warn him not to as it would likely cut him to the bone before he knew/felt it.

Jason B. · Feb 18, 2016

Duller?

Sharpness is not measured by how polished the edge is, edge angle and cleanliness of the apex are what count.

After setting the edge on the belt it's important to follow with a high quality compound. I like a good chromium oxide bar compound and prefer a slower wheel speed, high wheel speeds tend to excessively polish the edge.

roosterscrow · Feb 18, 2016

Jason B. said:
Duller?

Sharpness is not measured by how polished the edge is, edge angle and cleanliness of the apex are what count.

After setting the edge on the belt it's important to follow with a high quality compound. I like a good chromium oxide bar compound and prefer a slower wheel speed, high wheel speeds tend to excessively polish the edge.

I guess I'm associating those micro teeth with the cleanliness of the apex and find it duller compared to a polished edge for tasks like shaving hair or cutting paper.

I'm going to give slowing the wheel down a try.

Rhinoknives1 · Feb 18, 2016

roosterscrow said:
I guess I'm associating those micro teeth with the cleanliness of the apex and find it duller compared to a polished edge for tasks like shaving hair or cutting paper.

I'm going to give slowing the wheel down a try.

Toothy, Micro Teeth are from of Appox 120 grit or less, Belt wheel

kwackster · Feb 19, 2016

This is an example of how i try to make "factory like" edges:

http://www.bladeforums.com/forums/s...n-a-Sebenza-25?highlight=sebenza+factory+edge

What helps is to find a deburring compound that only just abrades the burr away yet leaves the scratch pattern intact as much as possible.
For edges done on my Rubber Wheel coated with 230 grit mono diamond powder i still use 1 micron mono diamond compound on a Paper Wheel, but i plan to get some 0,5 mono diamond as i think that would leave even more of the 230 grit scratch pattern intact (while still being able to abrade the burr away)

For my bling & bite edges done with 15 micron mono diamond on a Paper Wheel i generally use 0,25 mono diamond compound on a Paper Wheel for burr removal, unless a customer wants to see more bling than bite, then i tend to use 1 micron mono diamond on a Paper Wheel.

If i had to start again (knowing what i know now) with just a standard set of Razor Edge Paper Wheels coated with 180 grit SiC & that small block of white aluminum oxide i would most likely exchange the aluminum oxide for 0,5 micron mono diamond compound.
But i would probably try 0,25 micron first to see if that would work sufficiently. (probably not)

Brock O Lee · Feb 19, 2016

Rhinoknives1 said:
Toothy, Micro Teeth are from of Appox 120 grit or less, Belt wheel

I would not be surprised if that's the case. The Spyderco factory edges feel more toothy than a Sharpmaker diamond edge (+- 400 grit IIRC), which is normally how I like to finish my EDC's.