Question for Slipjoint makers

Rusty McDonald

Rusty McDonald

Joined
Mar 28, 2007
Messages
1,171
Do you heat treat before or after you grind your blades? I'm not talking about the profile I mean the actual grind of the blade. I have seen several that do and some that don't. Is there any benefit from doing it before? Wouldn't it Eat more Belts that way?

Rusty
 
I make slipjoints only and grind after heat treat. I use blaze to initialize grind, cleanup with cheap AO and blend with either 3M Scotchbrite or trizac. I owuld guess that you could grind 12-15 blades with a Blaze. After heat treat I surface grind with a belt setup and then use a 14" wheel to grind.
 
Hi Rusty

Grind Hi carbon before heat treat and stainless after heat treat. The reasoning is that it has less chance of warping and if it warps and that the tempering temp is so high with stainless that grinding will not affect the temper, do all of your grinding to thickness after the tempering and than grind the bevels. This is the info that I got from Paul Bos and Terry Davis.

As for the belts if you're going to use stainless invest in the good belts I personally use 3M 977F super cubitron belts in 60 and 120 grit. For me they seem to last the longest. I have used the Norton blazes but not enough to make a call as to how good they are.

Hope this Helps

Tony
 
It doesn't get too hot when grinding after heat treat and change the hardness?
 
After HT but be sure you have a dip bucket close at hand and grind without gloves....I'd rather get a finger or thumb a bit too warm than damage the HT'd steel.
Also I like grinding after HT because you take less off a blade HT'd than ground softer.
 
Hi Rusty,

I grind about 60% of the blade before HT with a 60 grit blaze. Leaving a very fat tip! After I start with the 60 and then go straight to a 220 J flex...then finish it out as needed. I like starting my hollow in softer material. :thumbup:
 
The edge heat treatment is adversely effected when machined post heat treatment. For those who want to keep the integrity of heat treatment it needs to be done by hand tools or cooled machines. Dipping the part occasionally in coolant won't work.
 
Let's see some of your famous data to back up those claims. Most knives go to a belt after heat treating, for what it's worth.
 
Dr roman landes conducted scientific studies of this issue. I suggest you study his data and conclusions.
 
Mr. Landes has a similar discussion on another forum, gave some more detail.


http://www.knifeforums.com/forums/showtopic.php?tid/746080/tp/1/

"" Now the rule is, once you did HT on it there is nothing else to be used but water cooled grinding systems, e.g. water cooled Tormek japanese water stones...
Although many makers do different like on the belt physics cant be beaten. And worst it matters!

Now why is it so, the very fine edge of a sharp knife is a very fragil geometric body, that tapers on the one side to "0" and grows on the other side to the body of the whole blade section.

When you grind the fine edge, heat is generated and flows into this body. using a water cooled system takes away this heat by flushing around the affected area. If you leave the coolant away the heat flows directly into the body.

Research has shown (H.Stüdemann, Elauterjung,R.Grube,1980, Research Report Nr. 2923 County Nord Rhein Westfahlen, Solingen Germany,as well as own test)that the heat genarated wo coolant exeeds temperatures of 600°C and more in the area of the edge.

Means the very fine part of your nicely sharpened edge is overheated bejond the tempering maximum of any steel available and herewith softened.

It happens so even on a slow moving freshly equipped beltsander wo coolant.
The resu is a more or less quickls dulling edge at the overtempered areas.

Normally the overheating is not visible by bare eye but can be nicely shown doing microscopic hardness testing where it reveals its effect.

If one thinks dipping it once in a while into the cold water not to overheat it, sorry but one cant be quick enough.

So grind cool to stay sharp longer..

Regards ""
 
nullack said:
Dr roman landes conducted scientific studies of this issue. I suggest you study his data and conclusions.
Click to expand...

The issue here is grinding the blade, not the edge which Mr. Landes is speaking on. Perhaps you need to actually read the topic at hand.

I don't have access to Roman's testing or the report that he references, but I don't see anything about how long the steel is applied to the belt, what speeds or what type of belt is being used. I also don't see how long the steel was subjected to 600C.

Your claim claim assumes that all steels being ground or sharpened after heat treating are going to be tempered at a low heat temper. Since we're dealing with time at temperature, how does this affect a user of high heat tempered steel?
 
blades&grace said:
Hi Rusty,

I grind about 60% of the blade before HT with a 60 grit blaze. Leaving a very fat tip! After I start with the 60 and then go straight to a 220 J flex...then finish it out as needed. I like starting my hollow in softer material. :thumbup:
Click to expand...


This is my method as well, I also put the nail nic in before HT because I Mill mine into the blade instead of grinding it in.. I leave it at a 120g then HT. It has worked for me so far. I think Ill stick with it.

It's good to see there are different methods to get the same result.
 
Either way works fine. Grind after HT is a good way to eliminate a warp. Knife makers are supposed to know not to over heat a HTed blade :)

With that said, I grind 70-80% before and the rest after. I do not like to grind hard steel.
 
Acridsaint I said edge heat treatment. Your straw man tactic won't prove your argument. If your interested in his data and conclusions rather than trolling go and read his data and conclusions
 
We are talking about grinding a blade after heat treatment. I didn't see anywhere in your reply where you changed the subject from that. Your claim was that grinding after heat treatment affects the edge, no where in your statement was there a qualification on how thick the edge would have to be.

There is one person here person who spends his time on the forums telling people how wrong they are about making knives without backing up his claims. I think everyone can agree that there is a troll in the thread, I guess it's just a matter of who.
 
What I like about you AcridSaint is that from time to time you come up with insightful comments and suggestions. You do however have an unfortunate habit of getting grumpy mate and being unnecesarily nasty in your posts, to the point of arguing silly things.

I completely disagree with your assertion there is no data to backup dr Roland landes studies on how machining temps harm the temper. He did metallographic examinations with photographic evidence. If you want to be fair dinkum you should look at his data and conclusions with a calm mind.
 
Firstly - nowhere did I dispute Mr. Landes' claim, in the context of sharpening it may well be true. I did ask a question that you have not addressed, which is how will this affect users of high heat tempered steels. Very nice attempt.

Even machining after heat treatment may indeed harm the temper, it was never argued that it couldn't. My claim is simply that it is not black and white, if you don't use a file or water cooled grinder, you will ruin the temper of a blade. As I said above, where is the time at temp and the thickness of the part being machined? How does it relate to the question at hand? We are talking about grinding the bevels, not sharpening the edge.

Now on to the part where I tell you that it's not my responsibility to gather the data to refute your claims, but yours to support them. If you now want to claim that grinding the blade after heat treat will affect the temper (if you wonder why I say now please look at your post above indicating that you were not talking about this type of machining), then it is indeed your responsibility to back up your assertion.

You have a very interesting habit of your own, you seem to enjoy inserting short quips into a discussion that have no merit within the context of the conversation and then wait for people dispute it. When you can no longer back the position you simply say "that's not what I was saying at all" and try to apply some context that is not within the original discussion. Perhaps it's just that you don't actually read the questions and responses, but most often it sure looks like a troll to me.
 
Mate I said "edge heat treatment" which any reasonable person would take to mean edge heat treatment. You've now accepted dr roman landes studies of this in how machining effects edge heat treatment. If you take the view that is offtopic to the thread, that's your choice to make. It's not mine.
 
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