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Paul Steadman
22nd October 2000, 10:10
G'day Mates,

Are there any metalurgists out there who can tell me if taking a carbon steel sword to a bench grinder for reshaping would effect the tempering or hardening of the blade?

Some time ago I purchased a Tameshigiri-to Katana from Blade Craft in Australia (swords are manufactured in SE Asia...very chunky and excellent work-horses) and my Iai-jutsu Sensei at the time customised it for me (reshaping the point to fun-bari and taking off the shinogi...for tameshigiri practice), he informed me that the heat from the grinding was nominal/minimal and would not effect the blade!

Any comments would be greatly appreciated. Thanks all.

Regards,

Paul Steadman

Dan Harden
22nd October 2000, 14:03
Hi Paul

The question is impossible to answer. I'm sorry

Grinders will build up local heat n different areas depending on the amount of time that any particular area was worked before being allowed to cool off. Therefore, over the length of the blade you could have;

"Spots" completely drawn back to spring temper,
Result
Won't hold and edge and or will set up unequal stresses in the blade

Larger areas that were heated to much on ONE side of the blade with the other not affected at all.He may have drawn areas in the body to a yellow or brown temper ( about 400 to 475deg.) yet other areas not at all. When one side isn't drawn but the same spot on the other side is is sets up unequal stresses in the blade that will give it a propensity to "want" to bend in one direction and an inclination to do so frequently.

and other areas simply unaffected.


Worse yet Paul. There is simply know "practical" way to know. Your not going to Rockwell test every inch of the blade anytime soon are you :)

HEY maybe he knew what he was doing. Wouldn't that be great!


I always chuckle when I see chainsaws sharpened by "Billy the hardware guy" with grinders that draw the temper out and actually bring the temperature up to the red zone. Thus completley destroying ANY ability the blades have of keeping an edge. Ensuring more frequent visits to "Billy."

For others out there. Please realize your SENSEI may know everything about teaching you how to use the sword and absolutly NOTHING! about the blades themselves. Worse yet, they may THINK they do, or may feel they have to respond to your expectations! (can anyone spell E-G-O)
While this may not apply in your case Paul, it may well apply to others.The potential is always there to trust their Sensei, and imbue him with knowledge far beyond the scope of his experience.

Steel is easily ruined in the hands of people who do not know what they are doing. This applies to both the manufacure and the repair of weaponry.


Dan
"who doesn't blindly follow any man" and who sharpens his chainsaw blades by hand.




[Edited by Dan Harden on 10-23-2000 at 05:44 AM]

Richard A Tolson
23rd October 2000, 07:10
Paul,
I am not a metallurgist or even an alchemist :), but I have been a machinist for about fifteen years and I would agree with Dan that grinders, sanders, etc. do not mix with live blades. Leave sharpening/polishing them to the professionals.
However, Organ Grinders are useful for sword testing :).

Cady Goldfield
23rd October 2000, 13:36
Originally posted by Richard A Tolson
However, Organ Grinders are useful for sword testing :).

I prefer mimes, myself.

Richard A Tolson
23rd October 2000, 19:22
Cady,
Hey!!!! My daughter is a Mime. Head for the hills honey, Cady's on the loose :).

Cady Goldfield
23rd October 2000, 20:26
Originally posted by Richard A Tolson
Cady,
Hey!!!! My daughter is a Mime. Head for the hills honey, Cady's on the loose :).

For shame, Richard!! A mime?? What did you do to drive that poor child over the brink?

:D

Cady