Sharpening

[Rich Stewart]

I got my new sharpening jig and have figured out how to use it fairly well. My question is, is it possible to burn tools so they dull easily? I ground some fingernail grinds on my old chisel and it cut VERY well. Now it seems to get dull faster than before. I dont know if I am becoming obsessed with sharpness or if maybe I burned the tip and it is actually getting dull faster because heat damaged the temper of the tool. I did rather short grinds and waited a minute or so between heavy grinds tp allow it to cool somewhat but I did get bluing on the end of the tool. These are all HSS tools but cheap HSS tools. Sets from PSI and such. How much heat will they take and how can you tell when you might be getting close to that max.

Thanks for any input.

[John Hart]

I was wondering the same thing Rich. I have a tool that I made out of ORS (Old Rusty Steel) and when I first made it, it was sharp and stayed that way for quite a while. But then I over heated it (Bluing) and now it seems like I have to sharpen it more often.

[Bill Stevener]

Oh Boy, I really like the (ORS) cool.:D
Maybe you are just using them more???????

A slight bluing in the HSS should not bother the steel, however I would not recommend making it a practice. When sharpening if you see sparks, generally you are applying to much pressure. you hardly want to hear any noise. Well that also depends on your hearing??????

Bill.>>>>>>>>>>>>>>>>>>>:)

[Dale Thompson]

Rich,
All HSS tools are not the same. Likewise, all surface hardness techniques, usually obtained by heat treating, are not the same. :( I would suggest that your inexpensive HSS chisels, like the HF SET, can hold a very good edge until you penetrate the "surface" heat treating. That is probably the cause of your perceived "dullness".

All tools will "blue" when exposed to excessive heat. On the other hand, the expensive ones like Sorby, Crown, Taylor, etc., are heat treated to a much greater depth and will "recover" faster or, at best, not lose their temper at all unless REALLY abused. :eek:

For learning to sharpen, I am a real fan of inexpensive HSS tools. Why grind away a $70 chisel when you can make the same mistakes and get the same learning experiences from a $5 tool? :confused: :)

For what it's worth, Rich, I would VERY tenderly(usually less than the weight of the tool on the grinder) remove the "blue" on your tools and get to the next level of "temper".

Lastly, you mentioned "heavy grinds". Forget about those until you become an expert sharpener. "Heavy Grinds" should be reserved for "custom" chisels and only done by experts. I am NOT in that category!! :o :)

Dale T.

[Carole Valentine]

Rich, I have found that my fingernail grinds don't hold an edge quite as long as the more traditional grinds. This might be because there is less steel behind it on that type of grind due to the bevel. Then again, it could be just because I use them a lot more than than my traditional gouges! The hardness of the particular steel would also be a factor. I have been told that bluing HSS does not hurt it, but I still try not to do it.

[Carole Valentine]

I was wondering the same thing Rich. I have a tool that I made out of ORS (Old Rusty Steel) and when I first made it, it was sharp and stayed that way for quite a while. But then I over heated it (Bluing) and now it seems like I have to sharpen it more often.

John, that wouldn't be the Ugly Stick would it???? Hope you didn't hurt that baby!:D

[John Hart]

John, that wouldn't be the Ugly Stick would it???? Hope you didn't hurt that baby!:D

Naw. The Ugly Stick is still Rockin' n Rollin'. I don't think I could hurt that thing with a nuke. The one I was having a problem with is a little round nose scraper that I don't use much anymore....Perhaps it should be retired.;)

[Frank Chaffee]

To all the Gentle Men and Gentle Women seeking to maintain that enduring sharp edge on a heat treated tool,
Once the steel has become blue because of over heating, the temper has been lost for some distance up that tools body. Furthermore, the hardness of the metal through that area is substantially less than design crystalline structure.

True, if you grind the shank of say, a chisel beyond the point where the bluing has progressed, you will access metal that is not annealed but is also tempered to a softer state.

Well now I see what a fool I am. Most tools used these days are probably not hardened, quenched and tempered by a person. The working temper is not controlled back from the cutting edge. It is most likely done in an oven so the hardness is homogeneous.

So just grind those back past the burned blue part and keep going.

Frank

[Rich Stewart]

How would one go about grinding back past the bluing without re bluing the part that is being ground past?:confused: Did I just say what I think I said? Did it make a bit of sense? I heard one time that a torch using mapp gas would have a target heat of 1800 degrees. I also heard that HSS chisels could take up to 1800 degrees before being damaged. I don't think I got anywhere near that hot.

[Andy Hoyt]

I'm no expert at this by any means.

My grinder is a fast one (@3300 rpms) and I tend to "get the blues" when I'm impatient and push the tool harder against the wheel to speed up the process. When I'm actually thinking about what I'm doing I just give it a very light touch on the finer grit wheel for just a pass or two.

Only use the coarser grit wheel when I want to alter the shape of the grind.

That said, three questions come to mind. What speed is your grinder running at? And what grit wheels are you using? And how hard and long are you grinding.

[Bernie Weishapl]

Rich I spoke to a turner of 20+ years who said to keep some cold water by the grinder. He said when the gouge starts to get pretty warm or you start to see blue to dip it in the water. He aslo said take light strokes. He said you don't want a lot of sparks or soon you will see blue. I watched him put a fingernail grind on a gouge and never once seen blue. I hope someday I can do that.

[Frank Chaffee]

Rich,
So many of us are learning here.

Search for Bob Smalser’s description of how he knows it is time to dip the tool he is sharpening into a water bucket because the water his assistant is spraying onto the tool is beginning to boil. That is at 212° F. Any tool I have applied to a belt sander I have held with my fingers close to the edge being ground. When is becomes too hot to hold I dip it in the water bucket which is right close handy. A simple matter of self preservation.

But really, a belt sander will only need to be used for removing nicks, chips what have you, or grossly changing shape. When I was a kid I removed those from my ax with a file. Once you have the shape you need on a tool you can maintain it with Arkansas stones or one of the new fangled systems available today.

So in conclusion, I don’t know if the tool you blued and therefore overheated can be reclaimed without heat treating. I do know that I too look forward to the answer to the question you have posed.

Frank

[Mike Ramsey]

This sharpening thing will never be solved!! Some people say Don't quench
HSS in cold water, this should only be done with Carbon, then others say
the opposite :confused:, Oneways Wolverine video demo says to quench? Others
say when the sparks come over the edge it's done? Others say no sparks
should be seen at all? Some say use a high speed grinder, some say use
a low speed grinder There has been some heated debates over that issue
in this forum and others....Sharpening has been my longest learning curve
(so far). I think the quality of the steel is the biggest factor in getting
the best edge from any style of sharpening.

[Kurt Forbes]

Grind past the blueing with a coarse grit wheel 60 or 80 max would be my guess. It will heat up alot less then your 120 grit wheels and just take light passes.
Hss is supposed to hold it's temper even if it gets blue.
Carbon steel will not you either put up with resharpening often or grind past the blueing.

[Bill Stevener]

This may be of some help.

Some time back I added a misting system to my grinder. It's called "Cool Mist" as it applies a fine mist of a cooling agent mixed with water on to the grinding wheel. Operates using compressed air. I use it when changing the configuration or the bevel on the tool. Also when dressing up tools for a neighbor.
The mist keeps the tool cool as well as helps in the elimination and removal of any steel buildup on the wheels. One can grind, remove the tool and feel the end and it is not even warm. I don't remember where I purchased it, but you can Google it.
Works great for me, highly recommend it.

Some photos.

Bill.>>>>>>>>>>>>>>>>>:)

[Rich Stewart]

Thanks everybody for your ideas and suggestions. I will post again at a later time and let you know how I am doing.

[Corey Hallagan]

This was a great post and lots of good info here for a future sharpening bumbler!

Corey

[Dale Thompson]

"Quenching" and "cooling" are two totally different metallurgical treatments. :) "Cooling" is exactly what it implies. A liquid with a high specific heat, such as water, is used to conduct heat away from the metal and prevent the dreaded and normally fatal, for chisels, result known as "annealing". :( "Annealing" is a "softening" of the metal that is BAD for chisels but GOOD if you want to "draw" a flat sheet, or whatever, into a cup. :)

"Quenching" is actually a form of surface hardening where the metal is heated to a high temperature and then dipped into oil or water to bring the temperature down very rapidly. :D The "hardening" effect is due to the fact that the rapid cooling changes the molecular structure of the metal surface. It obviousy becomes more brittle but also considerably harder. :)

The fact that you become "over-aggressive" on your grinder, dip the tool into water and it hisses is NOT "quenching". :( Specific temperatures for specific material compositions are required to achieve the desired "quenching" result. :D :cool:

Dale T.