ROCKWELL HARDNESS Scale in woodworking and woodturning: Sam Angelo
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- Опубліковано 14 жов 2024
- With so many variations on High Speed steel, understanding tool quality can be confusing.
Sam has provided some simple detailed information on the Rockwell Hardness scale. Measuring the hardness in tool steel is information that helps woodworkers and woodturners decide which tool to purchase.
This link offers more information on the Rockwell hardness scale:
www.leevalley.c...
Many thanks for the shout out Sam. Everyone I feature on the site and in articles has so much to offer fellow woodturners whether that be emerging new talent or a vast range of skill and knowledge as is the case with your good self.
Sincere thanks for all that you produce and present.
Tom
Tom you are doing some really good work. It is important and can only grow into something held in high esteem.
Sam
Great subject.
Thanks for your time.
Great video we actually had Rockwell hardness test where I worked it was really neat to use and when heat treating a necessity
Enjoy your videos thanks for all the time you put into them
Some very good, sound information Sam, thank you. Great video my friend.
Take care
Mike
Very interesting and well done, Sam!
Very good info Sam! A good refresher!
Take care, Dave
I used to test RHC (rockwell hardness C scale) on shovels and yard tools to see if our heat treating and quenching process was accurate. A RHC score of 55 without tempering causes extremely brittle steel. One demo we would do is throw a heat treated, non-tempered shovel head straight down onto concreate. It would shatter like glass, shards, little sharp pieces, etc. Tempering is something to consider as well, not just RHC.
Thanks, good information. Sam
+WYOMINGWOODTURNER loved the video...lots of good info in it.
Type of steel is something else to consider. Different kinds of steel will harden to different hardnesses and some can be left much harder than others without being brittle. D2 tool steel or 404 stainless for examples have enough alloys added to the steel that they can be left at RC60 & not be brittle. All steels to my knowledge need to be tempered after hardening though to make it be not brittle. (The D2 & 404 I referred to quench to RC65, so drawing out a mere 5 points of hardness is enough to toughen the steel up. O1 quenches out to 58-60 at full hardness and so will be softer after tempering.)
+RealRuler2112 Very true and more good points, though I dont think I would make a turning tool from stainless, would be hard to sharpen depending on the grade, would hold an edge for a long time though. I used mild 1050 steel for the tools I made. Not has good as tool steel but good enough for detailing.
Great video Sam, this is a subject I find very interesting, I wish I could afford a test machine. I recently had to return a couple of bowl gouges which would not hold an edge and I would love to know what the Rockwell hardness was on these compared to others I have from the same manufacturer. All the best, Jim.
Thanks
Sam
You can buy file sets made for this Jimson. You file the piece of steel in question with each file and when it won't bite into the metal anymore, you know that the next one down is about how hard it is. (Not as exact as a Rockwell machine, but much more accessible for regular people.) My father was a metallurgist at GM for over 30 years & has a plethora of stories to tell about heat-treatment of steels...
+RealRuler2112 thanks, I did look at those, perhaps I will get a set.
Thank you so much for sharing.
Great video. You mentioned, and I have heard elsewhere, about how the tip of a turning tool or even a regular chisel might have a different hardness than the rest of it. Does that mean that after a tool has been sharpened over the years and looses an inch or so it is not as good anymore? I ask because I have purchased old chisels before and didn't really take into account the original length versus what they look like now.
Yes that is true. Now I think far more than an inch is hardened. I am not sure how to make sure HOW much is haredened. Just buy good tools. But your old tools will work, certainly. You may have to sharpen more often????
Sam
Great information Sam. I wonder what the number is on my steel plate that I have.
Yep, I have a plate in my neck....propably not steel. haha
Interesting video! Like!
All steel has some carbon included in it it is the process for converting iron to steel . It is the chemical balance between the %of alloying metals and the iron that give steel its different properties. This is also the main problem of asian import steels is they use recycled base stock and do not first exclude the impurities in the shredded metal they use. This leads to inconsistencies between batches. The amounts of carbon, Moly, chrome, Lead, all have effects on the physical properties. The Rockwell test can be done in a number of different modes with different indentors and loads and does not really tell the whole story.
The strength is a balance in the grain structure of the metal Toughness , strength, wear resistance, Malleability . can be indicated in a rough way by the Rockwell number. and a metallurgist can give good indications on how the item will perform under use only if he knows the alloy and heat treatment or lack of in the part
Taking that mower blade as an example it needs to keep a tough edge at the tip (tip speed is regulated by Government safety standards) so it will cut the grass cleanly. but the hub needs to have a great deal of shock resistance because it drives the blade and has the hole stresses the sections between the center and the tip need to have fatigue resistance because they flex a lot.
The properties listed above are all imparted by the manufacturing processes at the factory after which spot testing for Rockwell hardness in different sections will tell if the process worked Same steel from mill different Hardness in different locations because of the process
Thanks
I appreciate the information. The bit about the mower blade being hardened differently at the hub is interesting. I know tools are (or can be) hardened differently at the cutting edge than lower on the shank. I think an important point I would make, is as a consumer of tools, we just don't know how they were made. Maybe sometimes we do. If i but a Doug Thompson tool or a D-way tool, I know they will not break and are top quality. Thanks Sam