Est. 1998 — 27 years of woodworking knowledge
Retempering tools and plane blades..
JL
>A friend lost his shop in a fire. He has salvaged all of his chisels, carving gouges and planes (without handles of course). Is it relatively easy to retemper the tools and the plane blades? TIA.
Re: Retempering tools and plane blades.. *LINK*
Barryvabeach
>Sorry to hear about the fire. To answer the question it depends. If the steel is o-1 and it was heated over 4-500 degrees, he will need to harden then temper the blades. To harden, he needs to heat the cutting end ( you do not need to harden the whole tool, the last inch or so should be plenty ) till it reaches cherry red - a great test is to test with a magnet and make sure in is no longer magnetic, then plunge it in oil to rapidly cool it. I use peanut oil, but you can use motor oil or other oil. After the irons are all hardened, you need to temper which means to bring to a defined temp and then to let cool. The higher the temp the softer the tool, the lower the temp the harder but more brittle it will be. If you look around the net, like http://www.hocktools.com/diyht.htm ,or the link below , and other places you can get more details, such as the temp to use for different tools. In general, it is not that hard and it won't cost a fortune in specialty tools - a Maap torch , some firebricks, channel lock or similar long metal pliers, a metal container for the oil , oil, and a fire extinguisher is all it will take. If the tools are a-2 , d-2 or some other variant, it will be much tougher, if not impossible to do it at home.
heat treating info
Re: Retempering tools and plane blades..
r payne
>If he knows the steel used it will be real easy. Simple steels can be done at home, other alloys will need more complex heat treatment which can be accomplished by a pro heat treater.
The most important thing is to know the steel alloy to get the most out of the tool. If the alloy isn't known the process becomes harder. Guessing at the alloy (usually by spark testing) and hoping the heat treat is correct.
ron
Wow, amazing site! Thanks
Frank D. in Montreal
>
Amazing but wrong
Adam Cherubini
>The first sentence in that link is incorrect. So its hard to read on. All steels go non-magnetic at 1350F or so, but this is teh phase change only for .77%C steel. Both higher and lower C steels require more heat to achieve the phase change- more like 150F not 50F
As to the rehardening, O-1 techniques will leave W-1 chisels soft. One must also concern oneself with decarburization and grain/crystal growth.
That said, those tools are doubtlessly shot, so its worth a try. Start by determining which tools are oil hardening and which are water hardening. Do the oil hardening tools first. I recommend buying a $20 1500 F tempilstik (because the magnetic doesn't indicate critical temperature).
Hardening tools isn't hard to do. But its not quite as simple as some would have and there's a surprising amount of misinformation out there, even from trustworthy sources.
Adam
Re: The fire got hot enough..
JL
>so it melted the aluminum bells off the ends of his tablesaw motor. He had puddles of solidified aluminum in the ashes.
He had a rather complete set of carving tools (good ones), some good chisels (Hirsch?), a variety of planes and plane blades.
After the fire had cooled, he collected all the remnants and put them in a bucket of kerosene.
Re: Amazing but wrong
Frank D. in Montreal
>Thanks for that clarification Adam,
and for suggesting the tempilstik.
For anyone interested in knife making, I still think the site is a gold mine of info notwithstanding the fact that there might be the odd nugget of fool's gold. Even great books can have a few doubtful or oversimplified passages.
I agree
Adam Cherubini
>I agree. I only mention it because I tried this technique years ago, figuring it had to be right because it was on the internet, while my education in this subject had to be worthless, and impractical since it was "book learning".
Its actually like a lot of other things I've encountered. Like the woodworkers who don't actually work wood with their tools but are experts, some of the famous blade smiths make knives folks never use. I mean, the handle is made of human bone and has a skull carved in it. The blade looks like a bat's wing. The thing is designed to slay dragons or whatever. So its easy for them to say their blades are tempered this way or that.
I just wanted to fix an old chisel. As I learned, these are two very different pursuits. I use my chisels just about everyday, sharpen them regularly, and I"ve come to know a good one from a bad one. Heating a high carbon steel to non-magnetic, and quenching in oil is a great way to ruin a tool.
But you're right, there's a lot of other stuff on this site that looks correct and is helpful. I don't know about the brine quenches or the temperature of the quenching liquid. But the critical temperatures look like what I think is right.
Adam
P.S. woodworkers should probably concern themselves more with grain size. It may be as responsible or more responsible for chisel performance than a few points on the Rc scale. I never see this mentioned.
Slight disagreement with Adam C.
Patrick Gibbons, Houston, TX
>First the things I do agree with Adam on. There is so much misinformation out there from what I would call very reliable sources. Next, he is dead on concerning differences between water and oil hardening steels. Water hardening steels are better for chisels than oil hardening. Plane blades tend to be O1. If you want the best results you need to go by the steel man. recs for hardening/tempering. The magnet test is a down and dirty way to achieve results under primitive conitions. O1 is fairly forgiving. I believe this is why many smiths will double and triple temper their blades. It will allow more of the proper conditions to result in the blade, i.e. the changing of structures in the steel. My feeling would be that the tools are a total loss now and nothing you do to the blades will make them any worse. The chisels may warp during heat treating. Water quenches faster than oil setting up stress. While carburization is a real problem it will require grinding off the skin of the steel to reach good edge material. Doing it Adam's way is closer to doing it the right way than what I suggest. But I don't know that it matters much in this case.
Oh yea, one other thing...
Patrick Gibbons, Houston, TX
>Smaller chisels tend to warp more owing to their smaller mass. These can be oil hardened to allay some of these tendencies and probably be ok. I think I would write all the tools off on my insurance and then start experimenting with the remains. You can't lose something you've already lost.
Read this book...
Patrick Gibbons, Houston, TX
>Tool Making for Woodworkers, by Ray Larsen
Re: Amazing (period)
Dave Burnard
>Bob Engnath (now passed on) was a very highly respected member of the knifemaking community. I was lucky enough to meet him and get several important pieces of advice from him back when I was just starting down the road I'm on. He was famous for sharing just about everything he knew with anyone who would ask.
I wouldn't discount his simple advice to use a magnet so easily, actually it usually does work, although for higher or lower carbon steels you may not complete the phase transformation. But the tool will mostly harden and that's about all you can ask for on your first try. Just using a magnet isn't really enough, but it's enough to start you down that slippery slope. Also remember with plain carbon steels you only have a couple of seconds to remove the piece from the forge, check it with the magnet, get it into the quenchant and get it cooled down to 400F. Not much room for error so the magnet may not have been the problem.
If you read a bit more it specifically talks about how to do things more precisely - if you have a way to judge temperatures. Most people don't but a everyone has a magnet and that gives you someplace to start. Tempil sticks, thermocouples, and a good eye for color are all part of the game later on.
This legacy site contains a wealth of information about various tool/knifemaking topics. If you're at all interested in tool/knife/sword making this is a great place to start. Also remember that Bob was a knife and sword maker. So although the steels used are often the same, the demands on these implements are different than the demands on a plane blade or chisel and slightly different heat treating techniques are thus in order.
Re: Slight disagreement with Adam C.
Warren in Lancaster, PA
>I have a few experiences which may add to the discussion. In 1981 I retrieved a chisel from a burned out shop. At that time I had no way to heat it so I took it to a blacksmith friend to harden. I did not trust him to temper it so I did that in my oven. I have used the tool ever since.
I once bought some new carving tools and one was softer than the others. I heat treated it three times before I was satisfied; now I am happy. I find the hardening process relatively easy. I judge by color. I think the tempering is harder especially for someone who is sensitive to their tools and can notice if it is not just right. If you find that the tool is too brittle, you can heat it up again just a little hotter. If it is too soft you can harden it again and try again a little cooler on the tempering.
I have hardened with a torch, in a wood stove, and in a forge (real charcoal). I don't like the torch. I think you can see the color better if the room is kind of dark.
Re: I agree
Chris Scholz
>Here is another justification for Adam's post scriptum:
Everyone who has done hardness measurements knows that they are notoriously iffy; NSL figured out (pulication NPL Report CMAM87 dated 2003, Table 4) that the uncertainty of a perfectly well calibrated hardness tester can be +/-0.8 on the Rockwell "C" scale ("working grade hardness tester"; this assumes that hardness references are well maintained, the indenter is not worn, loads are applied correctly and with the correct speed and obviously assuming the operator knows what he/she is doing).
In my view of the world two or so steps of difference in Rockwell C hardness don't make a difference. (I appears that NIST has proposed much tighter standards for hardness testers. If these standards have been ratified I withdraw this comment.)
In addition NIST clearly cautions to compare hardness measurements taking in different countries (no matter if they are called Rockwell "C"). Special publication 960-5 from Jan. 2001 explicitly states (section 8.1.2, p. 56: "At this time, there is no international agreement on a well-defined definition for any Rockwell hardness scale. National definitions are used instead, which are based on national and international test method standards. These definitions vary from country to country. The U.S. national definition of Rockwell hardness, as defined by NIST, is based on the use of the NIST primary reference standardizing machine with a specific indenter and following a specific testing cycle."
Chris, Atlanta, GA
[...]
P.S. woodworkers should probably concern themselves more with grain size. It may be as responsible or more responsible for chisel performance than a few points on the Rc scale. I never see this mentioned.
Re:Thanks all.
JL
>
For Patrick: Slight disagreement with Adam C.
Tom Colligan
>Pat, could you clarify what is the web site you mention; I'm having trouble locating it. Tia, Tom.
If you want the best results you need to go by the steel man. recs for hardening/tempering.
Re: For Patrick: Slight disagreement with Adam C.
Patrick Gibbons, Houston, TX
>I'm sorry, that's not a web site but my attempt to shorten some words. My thought was that one should go by the recommendations of the steel manufacturer. They put out info sheets on what is in the mix, heat treatment, etc. That's more specific than generic conditions for any given steel type.
Tom, here is one of the 'steel' folks that *LINK*
Wiley Horne--So. Cal.
>I think that Patrick was talking about--see the link below. If you pick from the menus across the top of 'cold work steel', 'hot work steel', etc., you will see a submenu of specific alloys come up--A2, D2, O1, etc. Click on one of the alloys and a data sheet will come up with lots of info. on that specific steel.
Re: Tom, here is one of the 'steel' folks that
Phil Joines Krum,TX
>That's some good stuff. Easier to understand than looking it up in Machinery's Handbook which always leaves me scratching my head.