Belt Sander VS Edge Temper

[KFLEISIG]

I have seen a lot of references to using a belt sander for re-profiling, but I thought that the heat generated by a power sander would ruin the temper on the edge. Am I wrong?

 

[Bill DeShivs]

A belt sander should be used with light, quick strokes. The blade should be cooled in water frequently.
If the above is done, edge temper will be OK. If you bear down on a bench grinder (or belt sander) until the steel gets hot and turns color, then you will ruin the edge, at least.
Bill

 

[Nosmo]

A belt sander can potentially ruin the appearance of a blade.
Even in the hands of experts, it can and does have a tendency to throw blades around the shop.
Even experts overheat edges. Once overheated, ( blue) grinding off the colour will not repair the damage.

 

[db]

There are some who beleive no matter how careful you are with power sharpening it will wreck the temper on the very tip of the edge. I'm not sure about that but I have quit useing power to sharpen because I enjoy hand sharpening.

 

[Cliff Stamp]

There are some who beleive no matter how careful you are with power sharpening it will wreck the temper on the very tip of the edge.

There are people who believe anything, repeating rumors with no facts tends to be hardly productive and just continues the meaningless propogation of misinformation. In order to damage the temper on a knife you have to exceed its tempering temperature or subject it to high heats for a *long* time.

Due to the high conductivity of metal the rest of the knife will protect the knife edge by acting as a heat sink. Lots of makers use power equipment to sharpen their knives and they are known for very high quality edges, R.J. Martin, Dozer, etc. . Most damage comes from simply being careless or cheap, grinding on heavily worn belts, pressing really hard to speed up the grinding on such belts, etc..

Note as well that not all steels have the same heat resistance, you will mangle 1095 at temperatures which will be ignored by HSS and you DON'T quench HSS in water to cool it when grinding as this would actually damage it far more than the heat off the belts.

-Cliff

 

[Ben Dover]

I will start this post by identifying myself as an AMATEUR among professionals, and state uneqivocally that any "advice" I give should be taken with a large grain of salt!! Having said that, I do not believe that I would ever use any kind of power tool for sharpening a properly profiled edge.

However, after asking a similar question of Cliff Stamp, and getting some EXCELLENT advice, I will probably buy a belt sander for REPROFILING only!

With very light, quick, strokes on the belt and proper cooling I'm no longer "afraid" to reprofile with a sander.

BUT: I'm going to do at least a dozen old beaters, before I try it with my good knives.

Ben

 

[Cliff Stamp]

Generally even extremely blunt knives only need minimal metal removal. Getting specific, I can take a knife down to about 5% of optimal sharpness and to restore it you are looking at five passes per side on a 1200 DMT hone and then burr removal. Even one pass on a belt sander is way more metal removed. I see it just as a shaping tool, unless you had to sharpen a lot of knives in a hurry and didn't care about wasting lots of metal.

-Cliff

 

[Bill DeShivs]

There are some who beleive no matter how careful you are with power sharpening it will wreck the temper on the very tip of the edge. I'm not sure about that but I have quit useing power to sharpen because I enjoy hand sharpening.

Custom knives are made on belt sanders!
Bill

 

[db]

SO Cliffproov that it doesn't harm the temper at the very tip of the edge. I think the guy should know all the info then make his own choice. Can you proov the very thin end of the edge doesn't over heat way before you see a color change or feel the heat? Instead of always argueing why don't you try and help inform. there are many makers who hand sharpen and some do it so not to heat the edge and some have there own reasons for hand sharpening. Even Alvin J. recomends not useing power to sharpen his thin 1095 blades because they can over heat before you know it is happening. And that is no rumor or misinformation. Take your own advice and quit spreading your opinions as facts witch they aren't..

 

[Cliff Stamp]

...proov that it doesn't harm the temper at the very tip of the edge.

As I noted this is trivially false simply by considering the work of Martin and Dozier and Hossom. All of whom are noted for high sharpness and edge retention and all use power equipment. All you have to do is simply use one of their knives to know the assertion is false. Or simply look at the wealth of people who have, unless you think everyone is lying about their experiences then your assertion is false. No one could possibly believe that.

I think the guy should know all the info then make his own choice.

You didn't provide any info you are just spreading rumors and disinformation.

Can you proov the very thin end of the edge doesn't over heat way before you see a color change or feel the heat?

I ran edge retention tests on belt sanded and hand sanded profiles on the exact same knife years ago. I was actually not looking at that issue specifically but rather was the edge micro-serrations formed differently under high speed belt sanding. It isn't. David Rishar's entry into the WGS was done on a belt sander and not only was it the sharpest push cutting edge to date it had the best push cutting edge retention. Easily passing Ben Dale's hand sharpened edge. Even one blade completely disproves your assertion and it is obvious that there are many from looking at the massive amount of makers and manufacturers who use them.

Even Alvin J. recomends not useing power to sharpen his thin 1095 blades because they can over heat before you know it is happening.

The edge is under 0.005" thick and ground at 5 degrees per side, if you start sharpening that on power equipment then over heating is going to be the least of your worries because you will quickly grind the edge right off. You are working in the thousands and a belt sander essentially makes 75 passes on a bench stone per second.

Yes, it is difficult to grind without cooling when the edge is under 0.005" and ground at 5 degrees per side with a wide contact area because then the edge can't heat sink because the metal right behind it is getting heated as well. So grinding right flat to the blade with such profiles takes a very light touch. But again sharpening in this manner is insensible for other reasons and the knife profile is radically different from the majority of knives.

Note for example how Alvin says to use them and see if this would hold for all knives. Of course it would not, nor would you bring it up when someone was discussing how to use knives. Note that he also does not place any such restrictions on the HSS knives he makes, though again sharpening them on such equipment would be very wasteful. He also doesn't just make very thin hollow grinds. I have convex ground knives from him and he is now working on a larger camp pattern.

In general though I see belt sanding sharpening as very wasteful given the massive speed of metal removal. The heat isn't the concern, the lifetime of the knife is due to how much metal is wasted. You can sharpen very well on belt sanders as many makers have illustrated. Of course there will always be those who ignore facts and those who continue to spread such rumors with no support. It would be of benefit when such statements were made that it was clear there there was no evidence, but this of course would make it transparent and obvious that it should be ignored.

-Cliff

 

[db]

Over heating by power grinding isn’t my opinion. If you tried reading my post and understanding what you have read you’d know that. But what is written doesn’t seem to matter to you you just rather argue and not even try and clear up or answer simple questions. Many knives from factories and from custom makers get over heated at the edge from power sharpening that is why you see the edge holding and/or sharpness improve after a few good sharpenings. You haven't prooved that it doesn't, and it seems you haven't even really tested for it. Yes Alvin has said that power sharpening can over heat an edge before you know it has happened and not only for the thin ones even for the unground blanks. Before you know it is happening is the real point. Quit trying to misinform and confuse that point. The fact that belt grinders can and do over heat the edge is neither rumor nor misinforming. For you to accuse me of misinforming or spreading rumors is laughable coming from you. It’s you Cliff who was removed as a moderator on these forums for misinforming and spreading rumors, not me.

I’m so glad that school is starting soon and hopefully the special internet experts will have a little less time on there hands to argue on the forums.

 

[Bill DeShivs]

DB
I am not speaking for Cliff, but for myself. I have made knives for a long time, I design knives, I restore knives.
Any tool can be misused. As far as power equipment overheating blades- this is a blanket statement used by makers to keep "Bubba" from going out to the bench grinder and ruining his knife. Power sharpening is for people with experience, not the average guy. I doubt there are many "average guys" reading this forum.
I know how to use a belt grinder. I don't recommend most people using one, unless they are: seriously into sharpening (most here seem to be), willing to learn to use tools properly, and capable of basic understanding of what the tools are capable of.
Bill DeShivs

 

[db]

Bill very good post, and I agree with it. As you can tell by my first post I have sharpened wwith power, belt sander, and have quit using it because I enjoy hand sharpening. That is the only reason I don’t use it any more to sharpen. Lets not assume most people reading this are above average in sharpening. Many who really need advice are trying to learn how to sharpen and really we all could use a reminder on the risks of any method.

 

[hardheart]

As you can tell by my first post I have sharpened wwith power, belt sander, and have quit using it because I enjoy hand sharpening. That is the only reason I don’t use it any more to sharpen.

How many tips did you damage the temper on using power equipment?

And how many production knives aren't sharpened on power equipment, but by hand?

 

[Broos]

With just a little care, a belt sander will not damage the edge.

 

[Cliff Stamp]

Many knives from factories and from custom makers get over heated at the edge from power sharpening that is why you see the edge holding and/or sharpness improve after a few good sharpenings.

There are many reasons why edges stabilize after sharpening beyond overheating during grinding. Assuming it is due to sharpening on power equipment is a gross over simplification and again just spreads rumors and misinformation. Have you actually seen the test results which show that to be the reason. No. Just one more case of assumptions presented as facts.

The fact that belt grinders can and do over heat the edge is neither rumor nor misinforming.

No, but this isn't what you said of course which was :

There are some who beleive no matter how careful you are with power sharpening it will wreck the temper on the very tip of the edge.

It is very different to state that you can damage something by abuse or ignorance than it is to imply it is impossible to do without damage even with experience/skill. As I noted, even one example contrary to your assertion proves it to be false, learn some basic logic.

It’s you Cliff who was removed as a moderator on these forums for misinforming and spreading rumors, not me.

I still have the emails where Mike decided he didn't want me as a moderator and those were not the reasons. But keep lying db, it seems to be what you are good at.

-Cliff

 

[db]

"
Cliff said...
I still have the emails where Mike decided he didn't want me as a moderator and those were not the reasons. But keep lying db, it seems to be what you are
good at.

You can personally atack me all you want, I'm not bothered by it. I don't know what Mike told you in email nor do I care. However, I do know what Mike told me in the chat room and those aren't the only reasons you were removed but they are some of them.

 

[db]

Some reason my last post posted before I was done here is the rest.
“
Cliff said…
There are many reasons why edges stabilize after sharpening beyond overheating during grinding. Assuming it is due to sharpening on power equipment is a
gross over simplification and again just spreads rumors and misinformation. Have you actually seen the test results which show that to be the reason. No.
Have you seen the test results that say it doesn’t happen? You know as well as I do that it does happen and that is a fact not a rumor. Is it always the reason and can there be others, sure and I never said there wasn’t.

Originally Posted by db
There are some who beleive no matter how careful you are with power sharpening it will wreck the temper on the very tip of the edge.

It is very different to state that you can damage something by abuse or ignorance than it is to imply it is impossible to do without damage even with experience/skill.
As I noted, even one example contrary to your assertion proves it to be false, learn some basic logic.
There are many people who think that and Say it. If you could read you’d also know I said..
“I'm not sure about
that”

I think you’re the one trying to misinform. Try reading a post and understanding it before running off and acuseing a person of spreading rumors, misinforming, and lying. I think this thread shows you’re the one who does those not me.
If you see the need to personally atack me fine I'm done defending myself from your childish remarks.

 

[Cliff Stamp]

Stating you are lying when you are lying isn't an attack db. You are the one making the personal attacks with your snide school remarks. Of course you don't care what Mike said to me in the emails because it negates what you said and you are far more interested in propogating misinformation than anything else. You can't even see that Bill disagreed with your assertion in the above and that it is completely false that you can't sharpen a knife with power equipment without overheating the blade. That is complete nonsense. Yes there are makers who believe it. There are makers who believe that you should not quench spring steels but should let them air cool because quenching them makes them brittle. If someone asks about hardening 5160 should you bring this up "so they have all the information" of course not because it is false. But keep repeating heresay and rumors, at least you are consistent. As long as you can make the thread about me you can drive a fog over your misinformation.

-Cliff

 

[Jerry Hossom]

Well, I have made a couple knives; I also use and recommend a belt sander for sharpening knives. Can you screw it up? Sure. Is it difficult to avoid screwing it up? No, it just takes some common sense.

A small belt sander is a wonderful sharpening tool, and I have taught a goodly number of people how to use one to sharpen knives. It completely reprofiles an edge or tunes it to a hair popping fineness in minutes. As for removing too much steel, a 15 micron belt doesn't remove nearly as much steel as some of the more aggressive DMT stones. And no, I don't get a royalty from Harbor Freight to say this...?

If you take only one pass and immediately quench the blade in some water, you will NOT overheat the edge. Sure, I guess if you really lean into it you probably could, but that sorta gets back to the common sense thing. As you become more experienced (about 5 blades, maybe), you will learn how hot the edge gets after what amount of sanding/pressure. Every time to make that pass, briefly hold the edge between your fingers before you dip it in the water. If it only feels a little warm, you don't have a problem. If it's hot, you toasted your blade.

Tool steels and high alloy steels tolerate heat differently. High alloy steels are usually a bit more tolerant of heat before you affect the temper. Tool steels, tempered at 350-500F, will lose their temper if those temperatures are exceeded. In case you have'n't tried it, 350-500F feels more than "a little warm". What protects that last tiny feathery part of the edge is that big heat sink behind it (the blade), which very quickly draws heat away from the edge.

Why use a belt sander besides the fact that it's easier, faster and more reliable for an inexperienced person to get a good edge? It gives you a nice, parabolic convex edge which is generally more durable than fine straight bevels. A convex edge may not pop hairs quite as crisply as a fine flat bevel when both are new, but months later the convex edge will still be cutting.

For about $80 you can have a sharpening system that will sharpen every knife in your kitchen drawer in under an hour. Your neighbors will love you. That's about $40 for the sander (Harbor Freight) and another $30-40 for some belts, including a leather belt which, used with some polishing compound, is by itself a priceless addition to every knife lovers tool box. Stropping is a lost art; the power sander with a leather belt makes it doable by anyone... with a little common sense.

For those who don't know me, it is not every day of the week that Cliff and I are singing from the same song book, even if we're not on the same page.

Oh yeah, Lee Valley Tools for those belts. www.leevalley.com Nice people.