Lathe tools hardened the full length

[John K Jordan]

A recent thread on tearout had the little side conversation about whether the Thompson tools are hardened down their full length:

https://sawmillcreek.org/showthread....54#post2999754

Brian's comment about a Sheffield tool maker leaving a small portion of the tool unhardened at the handle end made me wonder about the Thompson steel so I did a little test and simulated a "catastrophic event". Rather than hide this deep in the other thread I thought I'd start a new thread.

To test, I took a new and unused Thompson skew and held 1" of the handle end firmly in the big vice in my little welding shop. To simulate the catastrophic smacked it severely with a heavy hammer multiple times from both sides. I couldn't make the tool break OR bend. When I get time I might call Doug and ask about this.

Man, that steel must be tough! He says he uses 10V steel. From his FAQ:
"WHAT KIND OF STEEL ARE YOU USING? http://thompsonlathetools.com/faq/
The tools are made from the best steel on the market, CPM10V (A-11) a powder metal manufactured by Crucible Materials Corporations with 10% vanadium content to hold an edge longer and has a proven history in woodturning. The steel is hardened to 62-64 Rockwell, triple tempered with a cryogenic treatment between the first and second temper. The cryogenic treatment at this stage transforms the bulk of the retained austenite to martensite and form very fine “eta” carbides much finer than tempering alone, this increases the durability and toughness of the steel. Nothing else can be done to this steel!"
I'm not metallurgist so I don't know how much of this is science and engineering.

I don't know how the Thompson steel and heat treatment compares to the steel the Sheffield tool manufacturer mentioned. Based on my little test and assuming the other tools are similar in toughness, I'm not too concerned with having a type of safety problem the tool manufacturer alluded to (but didn't describe clearly, did he mean if hardened the full length the tool might break at the handle and throw steel somewhere?).

Of course, a catastrophic catch will provide it's own problems!

I do know that certain HSS drill bits are only hardened down the length of the flutes and not at the end held in the chuck. I discovered this with an catastruphic event with a drill press a few years ago when a clamp came loose. The bit was bent about 30-deg from straight. Maybe that's a safety feature to keep them from shattering? Wear safety glasses....

EDIT: forgot to mention - Twice I've seen the result of someone trying to use a big spindle roughing gouge on a bowl blank. Both resulted in a tool snapped in two just above the tang. The tang is small compared to the rest of the tool on many of these roughing gouges. I don't know if anyone was hurt.

JKJ

[Brice Rogers]

The 10V steel must really be strong.

It is easy to check a tool to see how far down it is hardened. I suspect that you've done this. But for others who haven't, just take a file and run it along the tool. On the hardened portion, it should just "skitter" off. On the soft portion it'll dig in and remove material. I think that all of my tools are not hardened all the way down to the bottom.

[bob pfohler]

I love my Thompson tools so it made my eyes water when you said you beat up a $95 skew for the sake of a test.
You don’t deserve that tool and should send it to someone who would appreciate it. That would be me!

[John K Jordan]

It is easy to check a tool to see how far down it is hardened. I suspect that you've done this. But for others who haven't, just take a file and run it along the tool. On the hardened portion, it should just "skitter" off. On the soft portion it'll dig in and remove material. I think that all of my tools are not hardened all the way down to the bottom.

I described that method in the message in the link but it's worth repeating here. I use a triangular file but any metal-cutting file with will work. I found some tools hardened only for the fist inch. Some were not hardened at all. All of these were cheap or no-name brands. I collect old, mostly cheap tools to regrind into special tools as needed or to give away or loan. I made this tool from an old scraper, for cutting a recess to fit a chuck. I angled it so I can easily clear a live center holding a blank jammed against something in the headstock.

Dovetail_B.jpg

I ground it on a CBN wheel with a square corner and grit down the flat side as well as on the face of the wheel.

JKJ

[John K Jordan]

I love my Thompson tools so it made my eyes water when you said you beat up a $95 skew for the sake of a test.
You don’t deserve that tool and should send it to someone who would appreciate it. That would be me!

Yikes, I'd better remember not to mention how many Thompson tools I had at last count. But I beat "on" the skew and can't see any evidence it was beat "up." And it was from the drawer of tools not yet spent time resharpening. (I love Doug but can't handle his grinds!) And hey, it was all for the sake of knowledge!

The next time you drive through TN drop in for a visit and maybe I'll give you that one. Or some wood. Or both. Or a peacock. Since I started incubating peafowl eggs I have a surplus.

peacocks_for_sale_large.jpg

BTW, do you know Mr Thompson sells round rod made of the same hardened 10V steel? I've made several round skews and scrapers and point tools from them. Today I ground a skew from a 3/8" round rod. 'Bout wore me out, even with the 80 grit CBN wheel.

JKJ

[Reed Gray]

Yes, there can be huge differences between the hardening processes. I know the D Way tools have a hole in the base of their shafts because they are hung for the final tempering, so they are hardened for the entire length.

John, I do have a 1 hp Jet belt/disc sander that I keep a 36 grit belt on. I have purchased a number of square ended scraper blanks for customized tools. I think Dave Schweitzer kept a high speed Jet grinder with a 10 inch 60 grit wheel on it.... A brand new 80 grit wheel would be okay, but one that has seen 2 or three years would be fairly slow....

robo hippy

[John K Jordan]

John, I do have a 1 hp Jet belt/disc sander that I keep a 36 grit belt on. I have purchased a number of square ended scraper blanks for customized tools. I think Dave Schweitzer kept a high speed Jet grinder with a 10 inch 60 grit wheel on it.... A brand new 80 grit wheel would be okay, but one that has seen 2 or three years would be fairly slow....

robo hippy

I'll have to try my belt/disk sander. I have one for wood and one for metal.

[Timothy Thorpe Allen]

For initial gross shaping of raw bar stock into a cutting tool, what about clamping the stock in a vise and using an angle grinder? would that be a good way to get to a rough shape that then could be easily refined on a bench grinder (or other sharpening system)?

[Peter Blair]

This is my method and I often cut with a zip cut to start.

[Randy Heinemann]

Just curious why it would matter if the tool was hardened all the way to the handle since, the tool isn't likely to serve its original purpose if enough was sharpened off the steel to get the edge that close to the handle.

[Jeffrey J Smith]

Just curious why it would matter if the tool was hardened all the way to the handle since, the tool isn't likely to serve its original purpose if enough was sharpened off the steel to get the edge that close to the handle.

Nearly all my tools are in handles that can be removed for sharpening. I have used the other end and ground a point tool, round skew or fluteless gouge style tool on it - stores away in the handle while not being used and still have the grind on the other end. Need to be aware of it when using the varigrind, though. I like to use as much of that expensive steel as I can. When it gets really short, 3/8” gouges get a permanent handle and become burnishers...

[John K Jordan]

Just curious why it would matter if the tool was hardened all the way to the handle since, the tool isn't likely to serve its original purpose if enough was sharpened off the steel to get the edge that close to the handle.

Some of the inexpensive tools I've tested were hardened for 1" or less at the tip. It would not be unusual for a woodturner, especially a new woodturner learning sharpening, to grind through 1" and still have a lot of tool shaft left that would otherwise nicely serve it's intended purpose of cutting wood.

JKJ