How To First knife heat treating

[Londinium Armoury]

Plus, what oil is recommended for heat treating? Can I go with a simple oil that you can get in a supermarket or do I really have to order some expensive special heat treating oil like Park's 50 Quench oil

Most will recommend you use a dedicated quenching oil like parks 50, but you can use canola oil, peanut oil, or other oils with high flash points. You can also use water, I water quench 1095 because it hardens more than oil, but it has more risks.

 

[weo]

what epoxy is recommended?

In general the longer/slower curing epoxies tend to be stronger. The suggestions above are all good. I made my post in case you didn't want to wait or buy something else if you already had epoxy because you said this knife will never see use, so it doesn't matter how strong the bond is.

just be functional to give the epoxy something to grab onto for more points of contact to keep the handle scales on.

This thinking is where the error is. The holes do not make the bond stronger.

 

[Londinium Armoury]

In general the longer/slower curing epoxies tend to be stronger. The suggestions above are all good. I made my post in case you didn't want to wait or buy something else if you already had epoxy because you said this knife will never see use, so it doesn't matter how strong the bond is.

This thinking is where the error is. The holes do not make the bond stronger.

Are you basing that on any testing? Because from my testing the handles with holes in the tang and half drilled holes in the scales using expanding glues and epoxy proved harder to get off. What testing have you done?

 

[weo]

Are you basing that on any testing?

Did you read the link I posted for the thread that talks about this in detail?

 

[Londinium Armoury]

Did you read the link I posted for the thread that talks about this in detail?

Yes and I refer you to Cushings post in that thread, in particular his mention of crevasse and undercut contact points Vs purely chemical bond between 2 flat surfaces. When you rough up the tang and scales, and then make cuts or holes in both the tang and scales you are creating more layers and points of contact in interlocking fashions, when combined with expanding glues and epoxy that find ways into those cut outs and extra holes they create more lock up points which minimize the purely chemical bond on 2 flat surfaces.

 

[weo]

Yes and I refer you to Cushings post in that thread, in particular his mention of crevasse and undercut contact points Vs purely chemical bond between 2 flat surfaces. When you rough up the tang and scales, and then make cuts or holes in both the tang and scales you are creating more layers and points of contact in interlocking fashions, when combined with expanding glues and epoxy that find ways into those cut outs and extra holes they create more lock up points which minimize the purely chemical bond on 2 flat surfaces.

Yes, and this might make sense, but he also mentions a number of places that with epoxy, you want as thin a layer as possible. This is to minimize the number of defects (air bubbles, dust. etc) that could lead to failure of the bond. Having holes in the tang, while possibly adding the number of undercuts (it's hard to sand these holes), will also leave a large deposit of epoxy that could/will have above mentioned defects.
In post #40 of the thread:

it is the ABSOLUTE NUMBER of defects that are present that presents a problem ..

So to me, drilling holes won't make the bond stronger, but might make it weaker.
Another thing one would need to think about if trying to increase the contact points for epoxy is the size of the holes and thickness of the tang. Let's say a 1/4" hole in 1/8" thick tang. The area of the circle is 0.049" x 2 sides for a total surface area for epoxy of 0.098 square inches. The circumference of the hole is 0.785", multiplied by the thickness 0.125" for a total surface area of 0.098 square inches. hmmm...is there a formula for this??? It looks like if the radius of the hole is larger than the tang thickness, then you actually have less surface area for the epoxy to bond to than if you didn't drill the holes.
Hopefully a math wizard will check my work.

 

[weo]

Are you basing that on any testing? Because from my testing...

Is your testing done under laboratory conditions with controlled parameters measured accurately, or are your results purely subjective? I'm not trying to be a jackass or questioning your experiences, just cautioning against making false conclusions based on inadequate controls. I can think of a number of reasons for one handle to seem harder to break than another without adequate testing controls.

 

[Londinium Armoury]

Yes, and this might make sense, but he also mentions a number of places that with epoxy, you want as thin a layer as possible. This is to minimize the number of defects (air bubbles, dust. etc) that could lead to failure of the bond. Having holes in the tang, while possibly adding the number of undercuts (it's hard to sand these holes), will also leave a large deposit of epoxy that could/will have above mentioned defects.
In post #40 of the thread:

So to me, drilling holes won't make the bond stronger, but might make it weaker.
Another thing one would need to think about if trying to increase the contact points for epoxy is the size of the holes and thickness of the tang. Let's say a 1/4" hole in 1/8" thick tang. The area of the circle is 0.049" x 2 sides for a total surface area for epoxy of 0.098 square inches. The circumference of the hole is 0.785", multiplied by the thickness 0.125" for a total surface area of 0.098 square inches. hmmm...is there a formula for this??? It looks like if the radius of the hole is larger than the tang thickness, then you actually have less surface area for the epoxy to bond to than if you didn't drill the holes.
Hopefully a math wizard will check my work.

That's some interesting info to think about, the holes I drill are 2mm smaller than the thickness of the tang and in some cases 1mm smaller in width than the thickness of the tang. I don't drill lots of them just 1-2 on the top 1-2 on the bottom.

Is your testing done under laboratory conditions with controlled parameters measured accurately, or are your results purely subjective? I'm not trying to be a jackass or questioning your experiences, just cautioning against making false conclusions based on inadequate controls. I can think of a number of reasons for one handle to seem harder to break than another without adequate testing controls.

My testing is the most scientific method known to mankind, under the strictest of controlled enviroments, second to none. Here is my controlled testing method in all its glory. I get a vice and stick my blade in it, then I get a chisel and hammer and smack it a few times. Then I curse because I chipped out the scales and dinged the tang with a deep gouge, then I take a mallet and smack it a controlled number of times until the scales break. Then my vice falls off the table because I didn't bolt it down, and I evade a broken toe by jumping back and kicking my quench tank over.

 

[weo]

My testing is the most scientific method known to mankind...