Tool steel

[Kim]

For you clever guys who are tempering your tool steel, this info may be of use.

http://www.hocktools.com/diyht.htm

Cheers

Kim

[DarwinStrings]

Thanks Kim, one tip I picked up in there was to use oil first then check and if that is no good then go to the water. So far I have been okay with the water though. I have a project or two on the drawing board using old leaf springs so I will do them in peanut or maybe canola(cheaper) oil first then test (as you do cause the test is so simple). I did have a bit of warping with the dovetail chisel but as the sides taper to almost nothing I expected that and just had to regrind it cold after heat treatment.

Jim

[Puff]

Jim - try the local fish and chippie for used oil at no cost.
Leaf springs are gold

[Kim]

Ron Hock recommends peanut oil because it is pure and therefore has a very high flash point. This is the same reason it is the oil of choice in Asian restaurants where it is ladled into thin steel woks that sit bluing on powerful high output gas burners...the more pure the oil the less smoke and therefore the less chance of fire.

Cheers

Kim

[DarwinStrings]

I checked it out and it seems that Canola has a higher smoke point but a lower flash than peanut (about 10 higher smoke and 20 lower flash), I reckon when talking about dropping glowing hot pieces of metal into oil I will be standing back with long tongs no matter which I choose. Either way they are higher than petro-chemical oils which is the point Hock makes.

Purity would be a interesting one when it come to buying cooking oil and I wonder how you would know or guarantee it, I am not sure about peanut oil as I don't buy it but canola (rape seed) is about as cheap as you can get so I wonder if it would be anything but pure unless there is a cheaper oil they might add to it.

Interestingly if you disregard oil as a hardening quench and you quench the wrong sort of steel in water you might at worse get fracturing or warping and then you will know it was one for oil quenching.

Check this out and towards the end you will see a guy quenching a Auriou hand picked rasp, what do you reckon he is quenching it in?


youtu.be/

Jim

[kiwigeo]

Check this out and towards the end you will see a guy quenching a Auriou hand picked rasp, what do you reckon he is quenching it in?

Jim

Moet?

[DarwinStrings]

You reckon that is why they are 100 bucks a pop plus Martin?

Jim

[sebastiaan56]

Having worked in the edible oil industry I can tell you definitively that all oils go through the same filters, 10um from memory. If it is clear in the bottle its going to be the same as another clear oil in a bottle. Some peanut oils will shed remnant protein after big temperature variations. It is impossible to filter it out but accounts for 100ths of a percent by analysis. I dont think that will affect your heat treatment process.

Blade forums have a lot of gurus in these subject on them if you need more information.

[kiwigeo]

You reckon that is why they are 100 bucks a pop plus Martin?

Jim

Ive got two of their rasps and theyre as classy as a bottle of Moet.......

[Alastair]

Edible oils is also my game.

Regarding smoke point, and flash point, there is not a huge difference between the various oils. It is in fact the purity which is the most significant. In particular the chemical purity. Unrefined and degraded oils contain high levels of free fatty acids, from breakdown of the oil. It is these which lower smoke and flash point, and are removed in the refining process.

With that perspective, any pure refined veg oil will probably work well. Two to steer away from would be peanut, and Extra Virgin Olive oil, as these are marketed in their non-refined state, to preserve the natural flavour, and thus will tend to have lower smoke points. They do smell better however.

For the same reason, the used oil from the corner chipper will be cheap, but suggest you check your fire insurance, as it will be the most likely to ignite.

[Kim]

Ron Hock recommends peanut oil because it is pure and therefore has a very high flash point. This is the same reason it is the oil of choice in Asian restaurants where it is ladled into thin steel woks that sit bluing on powerful high output gas burners...the more pure the oil the less smoke and therefore the less chance of fire.

Cheers

Kim

Regardless of who has worked in the edible oil industry and what your research on the net may tell you, I can tell you from personal experience that peanut oil for frying, the standard stuff you buy from the super market, is more often than not refined, and in general kitchen use, has among the highest smoke/flash point of 'any' commonly available cooking oil. I guess that is why Ron Hock recommends it. Yes he does mention that it smells nice, but that is secondary to the flash point concern so I stand by what I wrote above.

I do agree that 'unrefined' peanut oil has a very low smoke/flash point, but as I understand to get 'unrefined' peanut, one would need to look for it specifically probably in a bio-dynamic health food shop or a supplier of lower grade oils to the food manufacturing industry as all but the very cheapest oils at the supermarket are refined.

The chart at the attached link seems to indicate that safflower oil offers best 'bang' for buck. It is readily available and @ 266c has a smoke point 34c higher than refined peanut oil. Ron Hock has been at this for a while so the bottom line is regardless of what oil you use, long tongs are indeed the order of the day.

http://www.cookingforengineers.com/arti ... rious-Fats

Cheers

Kim

[Alastair]

Something also to be wary of is the "unsaturation" of the oil. This is what contributes to the gummy residue you will find on friers etc. From that perspective, peanut is very good, and safflower, linseed, soya and canola the worst.

Regardless of who has worked in the edible oil industry and what your research on the net may tell you, I can tell you from personal experience that peanut oil for frying, the standard stuff you buy from the super market, is more often than not refined, and in general kitchen use, has among the highest smoke/flash point of 'any' commonly available cooking oil. I guess that is why Ron Hock recommends it. Yes he does mention that it smells nice, but that is secondary to the flash point concern so I stand by what I wrote above.

I do agree that 'unrefined' peanut oil has a very low smoke/flash point, but as I understand to get 'unrefined' peanut, one would need to look for it specifically probably in a bio-dynamic health food shop or a supplier of lower grade oils to the food manufacturing industry as all but the very cheapest oils at the supermarket are refined.

The chart at the attached link seems to indicate that safflower oil offers best 'bang' for buck. It is readily available and @ 266c has a smoke point 34c higher than refined peanut oil. Ron Hock has been at this for a while so the bottom line is regardless of what oil you use, long tongs are indeed the order of the day.

http://www.cookingforengineers.com/arti ... rious-Fats

Cheers

Kim

[DarwinStrings]

I would wonder, regardless of what anyone recommends why you would be concerned about a 20 or so degree difference in flash point. When you are using a oil with a flash of between (from what I can find on the net) say, 250 and 280 degrees Celsius and you are quenching a piece of red hot steel in it at about 800 degree Celsius, like I said "long tongs". For my money though and with the small amount of amateur toying with hardening steel non commercially I do, I don't have to guarantee to anybody that it is Rockwell 61, I reckon I will stick to water and if I find a chunk of steel that I really want to use and it doesn't respond well to water then I will use the canola oil that I buy cheap to use as chainsaw bar oil as it is already in my shed. The old fish and chip oil sounds cheap but it is already all spoken for as people living "out bush" here have formed a long queue outside the fish and chip shop to fuel there gennies.

As for those Auriou rasps and their "special" heat treating process, "special" as quoted from the Lie-Nielsen advertising blurb, that had me really curious. Oil and water are old hat, I did that in high school as I imagine many of you my age or older did. Whatever it is it doesn't seem to bubble like water and steam when he is quenching and it doesn't smoke the way oil will when you quench red hot steel in it. So because curiosity got me I read and read and read about the options on the net (yawn) and my guess in the end, which may be totally wrong is Mercury. So in my quest to make a few tools of my own rather than buying them I doubt I will be using the "special" method that Auriou rasps use unless anyone has a spare vat of Mercury laying about and secondly where do you find a "Barleycorn pick" or how do you make something that hard yourself. Jesus! when a idea dives into my head, sometimes I wish it would just float on out the other side without a second thought, it is not as if I don't have a pile of other thing on my "to do" list anyway.

Jim

Life is good when you are amongst the wood, then get sidetracked by another medium.

[Kim]

So because curiosity got me I read and read and read about the options on the net (yawn) and my guess in the end, which may be totally wrong is Mercury. So in my quest to make a few tools of my own rather than buying them I doubt I will be using the "special" method that Auriou rasps use unless anyone has a spare vat of Mercury laying about and secondly where do you find a "Barleycorn pick" or how do you make something that hard yourself. Jesus! when a idea dives into my head, sometimes I wish it would just float on out the other side without a second thought, it is not as if I don't have a pile of other thing on my "to do" list anyway.

Hallelujah to that brother.

As for the mercury theory, it is very heat reactive stuff, (thinking thermometers). We all know that it is in fact a metal that is liquid at room temperature and from what I seem to recall (read:could not be bothered looking up to confirm) it gases off or vaporizes at low temp so aside from the OH&S issue, it would be really expensive having to top up the pot all the time or require quite a complicated filtration and capture process so perhaps this explains the cost of the famous french rasps?

On an aside, if you look at the tool time thread: viewtopic.php?f=1&t=3138 I had posted a small tale of Mr Eric Anton Berg and part of that tale reads:

The success for the products was based on his use of a very high quality plain carbon steel in combination with the hardening operation. He also knew that the forging was of great importance for the quality of the finished product. Therefore Mr Berg very soon established good contacts with the leading experts of steel, forging and heat-treatment. For example can men-tioned that melted lead was used for heating the tools for hardening which gives a very uniform temperature and which also was carefully controlled.

Must say that I have very little experience in this field however the thought of using a lead bath to establish an even heat in the tool prior to the quench really makes sense to me. I would imagine that this method would also control the heat well enough to avoid the concern of crystallization that Ron Hock mentions in his article.

Cheers

Kim

[auscab]

Do you guys know why oil is used or brine or water ?

The flash point thing is just a luxury ,the less it catches fire the more comfortable the work environment,
or more safe.

all the stuff i have read just says old motor oil and a cover, a lid, of course tongs and all the rest to do with safety

cheers Rob

[matthew]

"In 1903 Mr Berg died only 47 years old."

Lead poisoning?

[Kim]

"In 1903 Mr Berg died only 47 years old."

Lead poisoning?

Yes........probably

[DarwinStrings]

Wonder if he cut off his ear like Vincent too Matthew.

Now there's a point Kim, that Auriou quench may be lead too

Do you guys know why oil is used or brine or water ?

It seems oil slows down the quench to stop cracking in some steel Rob and Brine speeds up the quench by helping the water not, sort of boil off as fast from the surface of the hot steel.

As for motor oil I have been trying to limit my contact with petrochemicals nowadays, not sure why I bother though as I smoked like a chimney for 30 years, have been covered in asbestos and my fair share of organochlorine in the building game. Also I can buy canola a bit cheaper than motor oil or chain bar oil for that matter.

Jim

[Kim]

Now there's a point Kim, that Auriou quench may be lead too
Jim

I thought about that too Jim but then thought with a melting point of 327.46 ° C, the 'quenching' effect may not be sufficient to harden the steel as I believe that is still well above the tempering heat no?....Before you answer I have a general announcement to make.

PLEASE NOTE: Everything I say on the topic of metallurgy is based solely upon inexperience and assumption.

Cheers

Kim

[auscab]

Wonder if he cut off his ear like Vincent too Matthew.

Do you guys know why oil is used or brine or water ?

It seems oil slows down the quench to stop cracking in some steel Rob and Brine speeds up the quench by helping the water not, sort of boil off as fast from the surface of the hot steel.

As for motor oil I have been trying to limit my contact with petrochemicals nowadays, not sure why I bother though as I smoked like a chimney for 30 years, have been covered in asbestos and my fair share of organochlorine in the building game. Also I can buy canola a bit cheaper than motor oil or chain bar oil for that matter.

Jim

My understanding is ,

yes possibly cracking,but mainly,
Oil will quench leaving the tool edge,or outside hardness hard [depends on the quench temp] but with a softer core,cuts but takes more abuse.
probably distorts less ? when quenching

Brine is in between,

and water more hard all the way through,

I've done it as a hobby ,
never with oil, I did a rebate plane blade once that I cut from an old smoothing plane blade,the 1870s type that has tool steel welded at the front,quenched it about three times but it would not hold an edge, think it was crumbling off .
I maybe should have used oil on that. have had good success turning band saw blades in to odd springs for secret drawers.

cheers Rob

[DarwinStrings]

Same as Kim said from me too note my use of the words "guess" and "maybe"

Rob I think you might find that "distorts less" and cracking are related. Did you temper the plane blade, if you did not then that may explain why your blade was "crumbling off" as you would have left it too brittle maybe. Brine makes better contact with the steel so is a faster or maybe its better put that it is more efficient than water. I read about a "super quench" that uses soap and well as salt to quench even faster. Some light reading if you are keen Rob is HERE and HERE

I guess that depends on the lead Kim, if it is alloyed with a bit of tin then that makes solder which has a even lower melt and as it seems these guys like to keep their methods secret my 8 year old daughters guess is probably as good as mine. The melting temp of solder would enable it to be a tempering medium I guess. Bugga, I should never get in a chat with you cause now I need to read more and more stuff about stuff I'll probably never need to know

Jim

[Kim]

Bugga, I should never get in a chat with you cause now I need to read more and more stuff about stuff I'll probably never need to know

Jim

Same as you ya bugga.. shudup and leave me alone!!!


So, my mate Mr Google just told me that 'tin' has a melting point of 232°C and a boiling point of 2270°C.....That makes the boiling point well above the crucial 788°C to 815.5°C that my other mate Ron Hock tells me is required to harden hi carbon steel. This means that if one had a good pyrometer handy or a magnet near by, one could potentially use molten tin, or lead in a crucible bath to take the steel evenly and accurately up to the currie point. But as the melting point of tin is well above the desired temperature drop to below 150°F that Ronnie reckons we need to affect the quench, it's no good for that as you need to get the steel cooler quicker. The 'temper' point (light straw) is 325°F or 163°C. As mentioned the melting point of tin is 232°C or 450°F, so molten tin is too hot to use for a temper bath but I reckon hot sand would work a treat.

Speaking of currie, I must get dinner on for the girls.

Cheers

Kim

[DarwinStrings]

I meant adding tin to lead as an alloy and getting solder which comes much closer to melting at tempering temperatures, some solders do around 250-260 F. As far as I can tell, that "straw colour" is not a accurate tempering gauge as different steel alloys temper differently at different temperatures (it is fine for rough enough is good enough mugs like me) Some steels might like that pretty purpley colour with the browny spots

Jim

The currie point is about five minutes away as my partner just got home so I am off to steam some veggies to go with it.

[auscab]

Same as Kim said from me too note my use of the words "guess" and "maybe"

Rob I think you might find that "distorts less" and cracking are related. Did you temper the plane blade, if you did not then that may explain why your blade was "crumbling off" as you would have left it too brittle maybe. Brine makes better contact with the steel so is a faster or maybe its better put that it is more efficient than water. I read about a "super quench" that uses soap and well as salt to quench even faster. Some light reading if you are keen Rob is HERE and HERE

I guess that depends on the lead Kim, if it is alloyed with a bit of tin then that makes solder which has a even lower melt and as it seems these guys like to keep their methods secret my 8 year old daughters guess is probably as good as mine. The melting temp of solder would enable it to be a tempering medium I guess. Bugga, I should never get in a chat with you cause now I need to read more and more stuff about stuff I'll probably never need to know

Jim

I understand the "guess" and "maybe" I didn't see it ,but I understand where your coming from,

"Rob I think you might find that "distorts less" and cracking are related."

Have you heard of the Khyber pass ?

Q. Temper the Blade?
A. Yes , I didn't put that bit in ,quenched and tempered it three different ways, all in water at different heats

The rest ,your right on , I'm running on memory from fifteen years back here, from books,
that to do with the particulars of heat treating

cheers Rob

[DarwinStrings]

My aim wasn't to be rude Rob, it just seemed to me that you were separating cracking and distorting/warping as if they were different and I was just pointing out that they are the same thing just different degrees. Oil quenching stops or minimises cracking/warping of some steel other steel is fine in water as it can take the fast quench.

Jim