Does home/custom alteration of Spyderco Knives damage the temper?

[SpyderEdgeForever]

I noticed some posts where people took an existing Spyderco model and altered the blade steel to better appeal to them or give them a new function, such as putting an Emerson kindof Wave on a non-Wave blade. My question: Does this in any way damage the overall temper and hardness and strength of the blade and is this not recommended, unless the person has established knife-making machine shop equipment?

[Jazz]

Just run your tools at a slower speed and keep dipping in water to cool and you won't ruin the temper. If you see the steel change color, you got it too hot. Very simple. Happy modding. :)

I just use a Dremel tool and various bits (diamond, sanding drums, etc.). Finish with sandpapers of finer and finer grits, then polish with a felt wheel on the Dremel with polishing compound rubbed in it.

[kennethsime]

I noticed some posts where people took an existing Spyderco model and altered the blade steel to better appeal to them or give them a new function, such as putting an Emerson kindof Wave on a non-Wave blade. My question: Does this in any way damage the overall temper and hardness and strength of the blade and is this not recommended, unless the person has established knife-making machine shop equipment?

Note: I removed the size=3 tag from your text when I quoted you. If you do this for your own benefit, you may be better served in the future by just hitting control (or command on the mac and the + symbol, to increase all of the text on the page in your browser.

You want to avoid high-speed grinders on the edge of your knife, as they can generate enough heat to ruin your temper. Similarly I bet if you had your knife powder-coated or used some other coating process there may be enough heat to damage your temper.

As far as the wave, I'll let others speak to it, but I would just do my best to use something with as low a speed as practical, with plenty of breaks to let the worked surfaces cool.

[setldown]

Note: I removed the size=3 tag from your text when I quoted you. If you do this for your own benefit, you may be better served in the future by just hitting control (or command on the mac and the + symbol, to increase all of the text on the page in your browser.

Nice tip. I feel like my eyes are 30 years younger. :D

[The Mastiff]

Different steels have different tempering temps. Some down in the few hundreds, some up into the thousand degree F range. Know what your tempering temptures are before beginning and keep that in mind. If you need help finding out what those temps are you can just look them up on the manufacturers pages. Likewise many steel suppliers and tool maker websites have that info online.

[JNewell]

Some down in the few hundreds,

Wow...did not know this could be that low! :eek: :) Good info as always, Joe, thanks.

[tonydahose]

i have waved a few knives. I used a giant 3 phase grinder at teh firehouse for most of the steel removal and then a dremel for the hook. I keep a big bucket of water next to me and grind for about 2-3 seconds and then dip. the blade never got hot enough to steam the left over water on the blade. It never changed color and i haven't noticed any change in the blade's cutting abilitiy, chipping, or a deteriation in how long it can hold its edge but this is all personal opinion too. The one big reason i dont think the edge gets its temper messed with it that i am grinding on the spine of the blade which in most cases is a good distance from the edge of the blade.

[Cliff Stamp]

A few clarifications :

1) If you power grind without a coolant you are going to damage the steel, the surface temperatures will exceed not only the tempering temperature but far above it. You can not control this by feel/touch because the steel will cool by heat sinking so your fingers will not feel hot but the steel on the other side can easily exceed the tempering temperature of HSS. Similar the edge/corners will over heat long before the surface will discolor (oxidization) to a large visible extent.

This is in fact so suspectible that you can even damage steel by dry grinding by hand which is why you always should use a lubricant, which also prevents excessive dust so its good for your health as well.

2) If you use intermittent water as a coolant you are only making the situation worse because you are quenching the steel from very high temperatures and very few steels are designed to take such shocks so now you have not only over heated the steel you have micro-cracked it at the surface - at the edge this can be a very bad thing as the cracks will go completely through the steel from one side to the other.

3) Simply because a steel is tempered at a certain temperature does not mean you can raise the steel below that temperature to no effect. There are reactions in steel which take place at certain temperatures, these can still happen and some of them are extremely bad and embrittle the steel and you would want to avoid them at all costs.

As a general rule then :

-do not dry grind

and if you have to :

-do not use water, let the steel air cool

The fact that people so often ignore these simple rules is the main reason why so many knives are extremely brittle at the edge and suffer fracture on trivial events like cutting cardboard at extreme angles at which cross section the knife should be able to cut up bones with no issues.

[JNewell]

More and more interesting and educational.

What, if any, are the implications for how manufacturers put the secondary bevel/final edge on knives? I think this is often done with abrasive belts and similar methods, and IIRC from a few videos I've seen this process appears to generate quite a shower of "sparks" (which I'm sure is not the right word)? I may well have misunderstood the whole process and would be interested in learning more (or reading an explanation elsewhere, if that's more efficient). :spyder:

A few clarifications :

1) If you power grind without a coolant you are going to damage the steel, the surface temperatures will exceed not only the tempering temperature but far above it. You can not control this by feel/touch because the steel will cool by heat sinking so your fingers will not feel hot but the steel on the other side can easily exceed the tempering temperature of HSS. Similar the edge/corners will over heat long before the surface will discolor (oxidization) to a large visible extent.

This is in fact so suspectible that you can even damage steel by dry grinding by hand which is why you always should use a lubricant, which also prevents excessive dust so its good for your health as well.

2) If you use intermittent water as a coolant you are only making the situation worse because you are quenching the steel from very high temperatures and very few steels are designed to take such shocks so now you have not only over heated the steel you have micro-cracked it at the surface - at the edge this can be a very bad thing as the cracks will go completely through the steel from one side to the other.

3) Simply because a steel is tempered at a certain temperature does not mean you can raise the steel below that temperature to no effect. There are reactions in steel which take place at certain temperatures, these can still happen and some of them are extremely bad and embrittle the steel and you would want to avoid them at all costs.

As a general rule then :

-do not dry grind

and if you have to :

-do not use water, let the steel air cool

The fact that people so often ignore these simple rules is the main reason why so many knives are extremely brittle at the edge and suffer fracture on trivial events like cutting cardboard at extreme angles at which cross section the knife should be able to cut up bones with no issues.

[Cliff Stamp]

What, if any, are the implications for how manufacturers put the secondary bevel/final edge on knives?

As the great and wonderful Arnold has said "Don't do that!".

This is the major reason why there is often a dramatic difference in behavior seen after initial edges are sharpened. Often the angle is increased due to the perception of fragility at lower angles and this leads to support for an erroneous conclusion and the common perception that very high edge angles are required when in reality the durability increase is just from moving to quality steel.

However you have to balance this against the cost of wet grinding if you are a manufacturer/maker and ask yourself the simple question of how many people would notice the difference and/or pay for the increase cost/complexity of coolant.

[kennethsime]

Nice tip. I feel like my eyes are 30 years younger. :D

Glad to help!

[kennethsime]

Just run your tools at a slower speed and keep dipping in water to cool and you won't ruin the temper. If you see the steel change color, you got it too hot. Very simple. Happy modding. :)

I just use a Dremel tool and various bits (diamond, sanding drums, etc.). Finish with sandpapers of finer and finer grits, then polish with a felt wheel on the Dremel with polishing compound rubbed in it.

Whoops, you beat me, and with a better answer, too!

[Pockets]

If the spine is heat damaged, that wouldn't affect the edge, would it? Also, damage to the back of the blade could affect the blade's strength, right?

[JNewell]

As the great and wonderful Arnold has said "Don't do that!".

This is the major reason why there is often a dramatic difference in behavior seen after initial edges are sharpened. Often the angle is increased due to the perception of fragility at lower angles and this leads to support for an erroneous conclusion and the common perception that very high edge angles are required when in reality the durability increase is just from moving to quality steel.

However you have to balance this against the cost of wet grinding if you are a manufacturer/maker and ask yourself the simple question of how many people would notice the difference and/or pay for the increase cost/complexity of coolant.

Yes...I have received knives from one of the better known manufacturers that showed bluish color at the edge, which I am pretty sure indicates that the blade was overheated when sharpened.

[Cliff Stamp]

In general, the body of the blade would heat sink long before the edge would be damaged unless the knife was very thin but even then it is very likely you would see the effects of severe over heating on the spine similar to how a spine is drawn with a torch to reduce the temper and requires the edge to be cooled.

[razorsharp]

I noticed some posts where people took an existing Spyderco model and altered the blade steel to better appeal to them or give them a new function, such as putting an Emerson kindof Wave on a non-Wave blade. My question: Does this in any way damage the overall temper and hardness and strength of the blade and is this not recommended, unless the person has established knife-making machine shop equipment?

Keep the steel cool and nothing should happen to the HT

I often regrind my knives so they cut with less resistance

[BAL]

Great tips lead to great tips.

[anagarika]

How about hand filing using diamond files?

[JNewell]

I'm not Cliff, but I think that one's pretty easy - no way to generate enough heat to cause any mischief or concern. :)

[BAL]

I'm not Cliff, but I did stay at a Holiday Inn once.