Thread: Why kill an edge

Just a warning for new honers:

This is a tool in the box, an arrow in the quiver, and is mostly used for specific reasons

If you "Kill the Edge" "Joint" or "Downstroke" whatever the name De Jour is you better know how to hone and set a bevel to bring it back... It is more of an advanced technique


So you've been warned


Thread moved to proper forum at the same time

Originally Posted by JHBBlade

Interesting!

I'm in the middle of muddling my way through a Tuckmar that was NOS, and just does not want to form a nice edge to the bevel.

I can get it to shave okay, but never at the level of my other razors. Fresh off the hone it feels more like a razor with a week and a half under its belt.

Having spent a lot of time looking at the edge in between honing I've come to the conclusion that the edge might be over hardened due to evidence of likely chipping on the very edge of the bevel. Also in some areas the material near the edge looks like it had suffered corrosion at a micro-level. So I'm now taking off material from the bevel until I can get to shave off the 1k. The more material I take off using the 1k, the better the edge of the bevel starts to look,confirming my gut feel that was telling me I need to find fresh steel.......... If I eventually succeed then I'll be in 100% agreement with the 3 killed edge technique!

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Was it a Cell Rot razor?

Some of the Tuckmar scales were notorious for cell rot. If so remove the scales or the rot will continue and can spread to other razors.

If cell rot, continue removing the edge until and if, you get to solid steel.

I've recently learned this. After Glen told me about it and me forgetting (CRS), then another gentleman here told me the same thing a couple weeks ago (Sorry, CRS again), I've now learned that when restoring a blade this has helped get the edge I'm looking for. I've honed and honed to no end and not come out with an edge like I want. Then after killing a couple times, it comes out like it should.

Thanks for the thought Euclid440. I had no idea what cell rot was until you mentioned it now. But no, the remarkable thing is that the Tuckmar blade is very clean and free of rust. All of the original grind marks are perfect and shiny. . There is only about a 1/8" little streak of corrosion that I've seen several times on Silversteel which generally is not a cause for concern. The part of the bevel that had a tiny hole corroded through it was not inline with that corrosion. There was also no corrosion on the non bevel area, only in a small portion of the bevel.

I'm quite grateful for the small chip/hole in the bevel, as it helped me make the decision to remove more material on what seemed a very clean blade. As gssixgun points out, you don't want to be overzealous and remove a lot of steel for no good reason.

Took off about 1/50" to remove the hole in the Bevel. It looks considerably cleaner, and more consistent than before, all along the full length of the blade. Ran out of time to finish, will only tackle it this coming weekend.

I know from what I can see on my better razors with a 100x Carson scope what I'm aiming for. Think I'm now 80% there on this one.



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So if you kill the edge you need to start back at 1k bevel setting ?

Nothing much to add, except that dulling an edge on glass (1-3 strokes, until it loses all cutting ability) will effectively dull the edge, but doesn't kill it; you can pretty much bring it back to where it was before dulling with a decent stropping.

Originally Posted by Legday69

So if you kill the edge you need to start back at 1k bevel setting ?

Yes but as Glenn noted this is an advanced trick or a contest trick.

So yes after rolling the edge to worthless on a water glass you will be resetting the bevel
commonly at 1K. A new blade or very hard blade that chips does need to have its bevel
set on a water stone with a light smooth touch that is unlikely to start fresh chips.
DMT slabs can be a bit harsh on hard easy to chip steel. A lot of slurry methods are
great at not starting fresh chips and cleaning up old chips.

The sides of a lot of old hones are full of side grooves from rounding a french point
or sharpening fish hooks. You cannot catch fish on a dull hook as easy as you can
with a sharp hook. I do not like some french points and calm the point.

The other aspect is that setting a bevel correctly is uncommon.
Many factories finish their razors on rotating hones by hand and do lift
the spine so it is not aligned with the edge and not aligned with the
bevel to the edge. Even tape can upset getting the geometry exactly right.
Three bevel sets early in the life of a good blade should do it.
Old blades with hand honed geometry who knows.

By way of example my first razor and hone... twenty+ years of honing
with a Belgian water stone. The razor and the hone grew to like each other.
The hone was a little sway back but the geometry of the steel and hone
exactly matched.
Had I sent the razor to anyone else to hone it would have required a lot of work.
Had I kept using it all would have been fine.
But then I bought a second razor and a second hone (Norton combo) and
the two old friends were unhappy for a while. It took months to get the old razor
to match a flat 4K or Belgian waterstone hone a little. It took a 1K hone and some
other magic with film on glass to get things to 100%.

If you have a lot of hones and many razors flat is necessary.
If you have one good hone and one good razor... what works is fine.

So skip the water glass and hone as if you need to set the bevel at 1K or 2K.

So if you kill the edge you need to start back at 1k bevel setting ?


It depends on how you Kill the edge, how much pressure you use, how you do it and why.

The job of a 1k is to grind the bevels flat, in the proper angle and get them to meet at the edge.

if you are doing as Jim stated in the 2nd post, and you are doing a fully honing, maybe. But it probably will not take may laps on a 1k, or a 4k should do it. I often reset bevels on a 4k, unless they are new or damaged.

If you are removing the edge because of edge chipping, after honing and need to remove a bit of the edge to get to solid steel, No. Drop down to an 8k and reset the edge. The bevels are already flat and in the proper angle so getting them to meet should only take 10-15 laps.

If you are killing an edge on a finish stone, to strengthen the new edge or remove microchips, kill/joint it on the corner of the finish stone with a single stroke and reset the edge in 10-15 laps on the finisher.

You are just removing the fin to straighten the edge, so it is easy to get the bevels to meeting again, because they are already flat and in the proper orientation.

Originally Posted by gssixgun

Just a warning for new honers:

This is a tool in the box, an arrow in the quiver, and is mostly used for specific reasons

If you "Kill the Edge" "Joint" or "Downstroke" whatever the name De Jour is you better know how to hone and set a bevel to bring it back... It is more of an advanced technique


So you've been warned


Thread moved to proper forum at the same time

Originally Posted by Euclid440

So if you kill the edge you need to start back at 1k bevel setting ?


It depends on how you Kill the edge, how much pressure you use, how you do it and why.

The job of a 1k is to grind the bevels flat, in the proper angle and get them to meet at the edge.

if you are doing as Jim stated in the 2nd post, and you are doing a fully honing, maybe. But it probably will not take may laps on a 1k, or a 4k should do it. I often reset bevels on a 4k, unless they are new or damaged.

If you are removing the edge because of edge chipping, after honing and need to remove a bit of the edge to get to solid steel, No. Drop down to an 8k and reset the edge. The bevels are already flat and in the proper angle so getting them to meet should only take 10-15 laps.

If you are killing an edge on a finish stone, to strengthen the new edge or remove microchips, kill/joint it on the corner of the finish stone with a single stroke and reset the edge in 10-15 laps on the finisher.

You are just removing the fin to straighten the edge, so it is easy to get the bevels to meeting again, because they are already flat and in the proper orientation.

This is exactly why I posted the warning above,,,

Not often I read something that lights a bulb. This one set off a whole series and explained a couple things that have mystified me for years. Thanks Glen et al.