# Turning tool transformation.....?



## MatthewZS (Feb 15, 2011)

Anyone have any reasons why a seldom used tool couldn't be re-ground into a more often used "configuration"?

Thanks.


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## cnccutter (Feb 15, 2011)

non other than your not at the grinder already... I regrind shapes all the time.

Erik


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## dl351 (Feb 16, 2011)

Just make sure to keep a bucket of water handy so you don't overheat the tool and ruin the temper!


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## LarryDNJR (Feb 16, 2011)

dl351 said:


> Just make sure to keep a bucket of water handy so you don't overheat the tool and ruin the temper!




I've heard that dousing the tool in a bucket of water to cool it down actually stresses the metal and decreases the strength of it.  Advice I've been told is to let the tool come to a resting temp from grinding then rework it again.


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## nava1uni (Feb 16, 2011)

LarryDNJR said:


> dl351 said:
> 
> 
> > Just make sure to keep a bucket of water handy so you don't overheat the tool and ruin the temper!
> ...



I have also read and been told that dousing tools causes stress to the metal and that HSS metal can't get hot enough on a grinder to cause it to lose it's temper.  I regrind shapes a lot.  I buy tools at garage sales and then regrind them into whatever shape I want.


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## truckerdave (Feb 16, 2011)

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dl351 said:


> Just make sure to keep a bucket of water handy so you don't overheat the tool and ruin the temper!





LarryDNJR said:


> dl351 said:
> 
> 
> > Just make sure to keep a bucket of water handy so you don't overheat the tool and ruin the temper!
> ...





nava1uni said:


> LarryDNJR said:
> 
> 
> > dl351 said:
> ...



So who is correct?
You can't all be right!
Anyone work with metal out there care to take a stab at such a pointy question?


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## Curly (Feb 16, 2011)

Heating carbon steel without quenching until it begins to turn colour softens the edges. High speed steel was designed to cut metal until very hot without loosing its hardness. Pretty much all the turning tools these days are high speed steel. When you quench high speed steel when hot they form micro crystalline cracks at the edge which results in them breaking down faster. They get dull. :wink:

So quench the carbon steel often before they get hot. Don't quench high speed steel.

To reduce or prevent the steel from getting hot in the first place use the correct wheels for sharpening and dress them often.

Pete


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## bradh (Feb 16, 2011)

Curly said:


> Heating carbon steel without quenching until it begins to turn colour softens the edges. High speed steel was designed to cut metal until very hot without loosing its hardness. Pretty much all the turning tools these days are high speed steel. When you quench high speed steel when hot they form micro crystalline cracks at the edge which results in them breaking down faster. They get dull. :wink:
> 
> So quench the carbon steel often before they get hot. Don't quench high speed steel.
> 
> ...


    Pete is correct here. HSS is designed to get hot, and quenching it cracks the steel and weakens it. If you need to cool it, quench the handle end, not the cutting end of the steel.
    Carbon steel is the opposite, it looses harness when heated, this steel is better kept cool when grinding, it is tricky to recover the hardness after carbon steel is heated.
    The mechanical and thermal properties of steels is a complex subject, huge textbooks are written on the subject of steel.
Here is a decent discussion on grinding HSS on a machinist forum:
http://www.practicalmachinist.com/vb/general-archive/grinding-hss-hot-89869/
Here is a short discussion on the properties of HSS:
http://www.ehow.com/list_6128773_physical-properties-high-speed-steel.html


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## Rangertrek (Feb 16, 2011)

Thanks for this discussion and the good information.


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## ed4copies (Feb 16, 2011)

Can any of you "metal guys" tell me:  Is there a difference in quality among HSS edges?

If I buy a "name brand" HSS, is it likely to be BETTER than a cheap HSS??  If so, what is the difference?

Thanks for any input--I have often wondered about this.


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## THarvey (Feb 16, 2011)

bradh said:


> Curly said:
> 
> 
> > Heating carbon steel without quenching until it begins to turn colour softens the edges. High speed steel was designed to cut metal until very hot without loosing its hardness. Pretty much all the turning tools these days are high speed steel. When you quench high speed steel when hot they form micro crystalline cracks at the edge which results in them breaking down faster. They get dull. :wink:
> ...



I prefer to use oil instead of water.  I know some people that use motor oil, I don't.  I keep a quart of olive oil (in a quart paint can) near my grinder.

I like olive oil for a few reasons:


It cools the steel similar to water.
It is not as likely to blow back on you when extremely hot steel is thrust into it, like water can.
It is far less likely to flame than a petroleum based oil.
It does not discolor the steel like motor oil.

When the olive oil begins to look dirty, I pour the oil in my compost bin then wash and refill the can.  After a few rounds, I replace the can.

I buy the empty paint cans at Lowe's for a $1.25, or so.


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## Padre (Feb 16, 2011)

Great discussion!!

To the original question:  I have re-ground 3 tools with no inherent ill effects.  I didn't quench either.


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## jskeen (Feb 16, 2011)

For a few years a long time ago I lived and breathed this stuff when I was making knives.  From what I can remember (which is sometimes a little iffy, I've been to a few Pink Floyd and Grateful Dead shows between then and now). 

Bottom line is that like any mass produced product, the price is set as much on demand and quantity as quality.  Limited market for ultra specialized material = high price, huge demand for a high quality material brings the price down very quickly without having to sacrifice quality.  HSS or "high speed steel" is made in huge quantities in computer controlled processes that are very accurate.  The quality control of these products is one of the most precise industrial processes in existence, almost on par with gem cutting or pharmaceutical manufacturing.  End result to the consumer, is that you can buy a very inexpensive HSS tool, and the metal will be exactly the same as a tool that you pay 10x the price for based on name.  There is almost no measurable difference in performance between generic HSS and most name brand tools.  

Now, there are exceptions.  There are LOTS of different formulas and degrees of quality control in tool steels, but the general rule holds, "until you get into the very high end, specialized steels, you will not be able to tell the difference"  a $10 hss tool will usually perform just as well as a $60 one.  Now that is very subjective in reality, and if you just laid out the $60 for a new tool, odds are you will very likely "feel" like it performs better than your old $10 one, but can you PROVE it?  

Now the corollary to that is, Are there tools that are better?  My humble opinion is YES, there are materials Like CPM or "powder metal" steels,  or Cryo processed tools, or other high end, "niche market" steels that will objectively outperform standard HSS tools.  But they COST!  And those objectively measured performance improvement MAY not necessarily translate directly to better wood turning performance for YOU.  Not to say that they won't, but they MIGHT not for YOU.  Lots of variables come into play.  

So, all of that comes down to a very objectively demonstrable fact.  I do not own a turning tool that I paid more than $15 for, and most were purchased used for way less than that.  If I had the money (which I don't) to go out and buy a "high end" tool, I would get a carbide tool from one of our members long before I'd end up with a big name "Endorsed" tool.  YMMV of course.


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## Rchan63 (Feb 16, 2011)

ed4copies said:


> Can any of you "metal guys" tell me: Is there a difference in quality among HSS edges?
> 
> If I buy a "name brand" HSS, is it likely to be BETTER than a cheap HSS?? If so, what is the difference?
> 
> Thanks for any input--I have often wondered about this.


 
I remember hearing better HSS tools (brand names)are tempered through the entire tool while cheap HSS tools are not. Don't quote me on this it's just something I remember. On the side note being a cheap New Englander I use HF lathe tools:biggrin: @ somwhere $45.00 for a whole set


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## jskeen (Feb 16, 2011)

Rchan63 said:


> ed4copies said:
> 
> 
> > Can any of you "metal guys" tell me: Is there a difference in quality among HSS edges?
> ...



I find it very unlikely that this is a true statement.  Not that you heard it somewhere, that I fully believe, but that the statement is in fact true.  It is probably a distortion of the fact that very old carbon steel tools were often heat treated and tempered by hand with methods that could produce tools that were only hardened on the business end.  

modern tool steels are almost always heat treated (which includes both the hardening, and subsequent tempering to bring the steel to the desired final hardness without being brittle) in computer controlled electric ovens using multi step formulas which include very precise ramp times to given temperatures, and specific soak times to produce the optimum performance from the entire length of the tool.  

Again, not speaking with my pointy hat on, so no claim of infalibility here, just a reasonably informed opinion.  Feel free to comment, dispute, append or even call me names, I don't mind at all.


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## j.d.sackett (Feb 16, 2011)

ed4copies said:


> Can any of you "metal guys" tell me: Is there a difference in quality among HSS edges?
> 
> If I buy a "name brand" HSS, is it likely to be BETTER than a cheap HSS?? If so, what is the difference?
> 
> Thanks for any input--I have often wondered about this.


 
yes there is. i buy a lot of tool bits and have found american made stays sharp longer. chinese ones work ok though, depends on what youre cutting. also some hss has cobalt alloyed into them, super hard, good stuff. i have ground many hss bits and turned them blue before quenching, no problem. heat does not effect hss like carbide. carbide will heat crack if quenched, never had that problem with hss and i cut steel, stainless, aluminum, 4140, etc. regards, j.d.


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## bradh (Feb 16, 2011)

Rchan63 said:


> ed4copies said:
> 
> 
> > Can any of you "metal guys" tell me: Is there a difference in quality among HSS edges?
> ...


   We are getting deeper into those steel textbooks here. 
The $45 set is likely high carbon steel. These steels get there hardness from the high carbon content and heat treating. You loose the heat treating when you heat the tool too much on the grinder.
    Some terms to help you understand steels:
higher hardness usually means you need sharpen less, but also usually means brittleness.
Brittleness is the opposite of ductile. A brittle steel is usually less tough. A steel which lacks toughness can shatter under a shock load.
   An ideal tool steel is hard (holds an edge longer), tough (takes a shock load), and ductile (bends rather than snap).
   There are a number of grades of HSS. These grades have different alloy mixes and have slightly different properties due to the alloys. All HSS grades stand up well to heat.
    If you are interested in understanding more about HSS, try this short description of HSS alloys:
http://www.ehow.com/list_5966728_chemical-properties-high-speed-steel.html


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## arioux (Feb 16, 2011)

A bit of reading, this explain teh varoius HSS type (M...)

http://en.wikipedia.org/wiki/High_speed_steel

For the original question, i regrind most of my tool to  a profile i'm confortable with.  Angle and fluting curve are always chaged to fit my turning habit and techniques.


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## dl351 (Feb 16, 2011)

Holy smokes!  This thread has grown a lot since I posted!

There is a wealth of information here.  I was speaking from experience of regrinding already heat treated knives.  I guess that falls into carbon steels.  With knives, I live by the rule of not letting it heat up to the point where I can't touch it because of the heat.  I assumed the same would work for high speed steels.  You know what they say about assuming, though!  That being said, I'm pretty sure you can ruin the heat treat of any steel with too much heat.  How much heat is too much?  I'm not sure for high speed steel.

I did a quick search and it seems like a few of us might be right.  It seems that dipping in water while it is still "cool" enough to touch is fine, but the grinding of high speed steel will take forever that way.  Apparently it can get up to a low glowing point without a problem.  It is then that you do not want to dip it into any liquid to cool it.  It can handle that kind of heat, but not the thermal shock at that point.  If I was clearer on what I meant (dunking in water before it got too hot to touch), there could have been less confustion.

I love these forums!  They're a great place to learn and spark learning!


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## KenV (Feb 16, 2011)

Most of what we do with hand held tools on lathes for wood, brass, etc. is an adaptation of materials and products developed, and produced for other industies.  High speed steels are metal working steels and are a key part of the tool steels used in metal working.   As with most adaptations, there are a few compromises along the way, and when people start to seek lowest cost, there are additional trade-offs made for quality and consistency.

There are some standard designations for these steels that are use to note a range of alloy and heat treat characteristics --- one of the more common of these is "M2".   

Depening on where the "melt" was at in the presence of the more expensive metals for the alloy, or the amount of impurities, the properties will fall into a range of generally similar charastics.   There are differences between bottom end and top end of a designation, and some steel may be more "M2 Like" than meeting the specifications.  (This is where some of the weaknesses of self certification can be seen.)

So with temper on HSS steels in the 1100 degree F range, it is hard to lose temper in grinding and use.   

Some metals added to the alloy provide toughness -- notably cobalt for machine steels used for machining tough stuff like cast iron.   

Generally --  you will be able to develop a sharper edge on high carbon steel (also called drill rod, O-1 steel W-1 Steel, or A-1 steel)  O= oil; W=water; and A= air as the recommended quench material for hardening.  than you will get on HSS.   One expects to get a long service run with HSS though.  

High carbon turning tools were the tool of woodturning until about 30 years ago.   There are a lot of them around.  They cut like a dream, but not for very long before they "could be sharper".

You can grind, hone, sharpen, buff, polish, etc but the smoothness of the edge and the application of the edge geometery to the materials is where it is all happening.  Makes a difference between rough removals and finish cuts too.


Back to the original question -- any lump of highspeed steel can be ground and shaped to most any format desired.   Edge geometry, shape, and approach to the work are the key variables.  Think about the bevel for support and control of the amout of cut, and the intended use.   

Have some fun, but think about what will happen when you do it wrong and get a monster catch.


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## titan2 (Feb 16, 2011)

bradh said:


> Curly said:
> 
> 
> > Heating carbon steel without quenching until it begins to turn colour softens the edges. High speed steel was designed to cut metal until very hot without loosing its hardness. Pretty much all the turning tools these days are high speed steel. When you quench high speed steel when hot they form micro crystalline cracks at the edge which results in them breaking down faster. They get dull. :wink:
> ...


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## KenV (Feb 16, 2011)

"Once you have the shape you want on your tool you can harden the steel by taking a torch to it and get it to an even color.....you're look for a 'Straw' color. "


I have always had to get the steel to an even medium red --  a common test is the point were a magnet no longer will attract the steel.

Plunging the red hot steel into the oil/water/ or air cooling (depending on the steel) will cause the hardening.  

The "straw color" is a smiths guide to the tempering of the hardness to reduce brittleness.   I just use the oven at about 375 degrees F and do not try to read the color.


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## Lenny (Feb 16, 2011)

bradh said:


> The $45 set is likely high carbon steel.


 
They ARE indeed HSS and make for a very decent starter set! 
http://www.harborfreight.com/8-piece-high-speed-steel-wood-lathe-chisel-set-47066.html


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## MatthewZS (Feb 16, 2011)

Great Green Gravy all the information!  This was exactly what I was looking for tho, I wasn't sure there wasn't some tempering/heat treating tricks played with turning tools that I would be mucking up by re-grinding.  Thank you to everyone who's replied for the thorough covering of the issue


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## j.d.sackett (Feb 16, 2011)

I have always had to get the steel to an even medium red -- a common test is the point were a magnet no longer will attract the steel.

Plunging the red hot steel into the oil/water/ or air cooling (depending on the steel) will cause the hardening. 

The "straw color" is a smiths guide to the tempering of the hardness to reduce brittleness. I just use the oven at about 375 degrees F and do not try to read the color.[/quote]

ken is exactly right. to harden you need to get it a dark cherry red, then quench. if alloy is unknown, i always try oil first. if it doesn't harden up, i use water. cook it in the oven,( i use 350* but 375 is good, probably harder when done), for an hour and set it on a cooling rack to cool. makes for excellent cutters. i made a boring tool out of an old chinese 1" end wrench. hardened and tempered as above and it is a great cutter. have used it on lots of aluminum and several pieces of mild steel and have yet to resharpen it. an old wrench could make very good wood cutting tools once shaped and tempered. can get em cheap at yard sales too. regards, j.d.


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## bradh (Feb 17, 2011)

KenV said:


> "Once you have the shape you want on your tool you can harden the steel by taking a torch to it and get it to an even color.....you're look for a 'Straw' color. "
> 
> I have always had to get the steel to an even medium red --  a common test is the point were a magnet no longer will attract the steel.
> 
> ...



This quenching process will harden the steel dramatically and reduce the need to sharpen. This is the first part of hardening by heat treating. The problem here is the steel crystallizes into a grain structure called Martinsite; very hard, but also very brittle. Proper heat treating should also temper the steel. Tempering is a process where the steel is re-heated and held at a medium temperature and allows the steel grain structure to reform into a Bainite type grain. At this point the steel has lost a little hardness, but looses it's brittleness. 
  Here is a good article on heat treating, including a temperature chart for tempering:
http://www.threeplanes.net/toolsteel.html

You guys are really testing my memory retention from all those Engineering class lectures I sat through almost 30 years ago.


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## bradh (Feb 17, 2011)

Lenny said:


> bradh said:
> 
> 
> > The $45 set is likely high carbon steel.
> ...


   I stand corrected, thanks.
   The steel industry in China has improved dramatically in the last 10 years. While I was searching for some links to use, I found some info on new lower cost grades of HSS developed by the Chinese steel industry. The source claimed similar HSS performance at lower cost. 
  We are likely to see more and more lower cost tools now starting to use HSS instead of high carbon steel.


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## phillywood (Feb 17, 2011)

I can very much appreciate this thread as a newbie to this trade. I have some background in engineering ,but not to this extent, However, I have a qsn. about some Sorbey tools I have aquired recently frm a freind who's dad was a turner, and I can not tell which one of these metals I've got on these tools. All it says on the shanks of these tools is shefield metal which doesn't tell me what it is. In addition, I am sure that these tools are not very recently made, would any of you can tell me what I ahve and what's the best way to recognize them or do I need to post pic.s of them for you to see? 
Thanks.


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## Rchan63 (Feb 17, 2011)

Here is something I found on line.

Generally the high carbon tool steels produce a complex, white, bursting spark when placed on the grinding wheel. The high speed steels tend to have individual, orange sparks. 

Richard


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## titan2 (Feb 17, 2011)

phillywood said:


> I can very much appreciate this thread as a newbie to this trade. I have some background in engineering ,but not to this extent, However, I have a qsn. about some Sorbey tools I have aquired recently frm a freind who's dad was a turner, and I can not tell which one of these metals I've got on these tools. All it says on the shanks of these tools is shefield metal which doesn't tell me what it is. In addition, I am sure that these tools are not very recently made, would any of you can tell me what I ahve and what's the best way to recognize them or do I need to post pic.s of them for you to see?
> Thanks.


 
Contact Sorbey.....they'll be able to tell you.


Barney


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## Fred (Feb 17, 2011)

I GRIND my lawn mower blades and I SHARPEN, CHANGE SHAPES, ETC. of my cutting tools on a Tormek. It may take a bit of time, but when finished I am ready to go from then on.

No problem with any heat, wasting of metal on a grinder, the repeatability of cutting edges and such are not a problem when done using the proper jig and a wet system.

And to top it all off, I don't care what kind/type of steel it is either. It is just scary sharp when it comes off the Tormek and the tools cut longer for me when done this way.


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## LeeR (Feb 17, 2011)

Lenny said:


> bradh said:
> 
> 
> > The $45 set is likely high carbon steel.
> ...


 
I bought the HF set a few years ago, but just got a lathe a few months ago, so I am new to turning. I do consider these a good set to learn on. They hold their sharpness well, and at their low price, you can use them as a set to practice learning to sharpen, and not fret when you make a mistake and have to regrind.  I bought a mini-sized Spindlemaster, but found I've learned to like using full-sized tools for pen turning better. While I see the benefit of small tools for very intricate turning, I think the investment in this inexpensive full-sized set was a good one.


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