What does this spark from a saw blade tell?

M

masa

Joined
Feb 3, 2005
Messages
191
Sorry I am unable to get better photos of it while sanding. It is of unknown origin, any insight on what it might be?

p7qqkjP.jpg

sy6BtoA.jpg
 
That means high carbon knife steel. Play with it and learn its character. Cut some small strips and quench in various coolants. Have fun.

What exactly are you sanding? Is that a bandsaw blade?
 
Last edited:
What kind of saw blade ?

circular saw blade ?

Let's see a good photo of the blade itself, the blade tips.

If you can see the carbide tips on the saw blade then it[s worthless as knife steel



spark testing is really subjective
spark+test.jpg
sy6BtoA.jpg
 
Last edited:
The starburst at the end of the lines is indicative of high carbon steel. Try a piece of mild steel and you will see globs at the end of the lines. The more lines in the cluster the higher the carbon content. People with a lot of experience can tell the alloying agents contained in the steel. Thats not I.
 
It tells me that it might be some sort of possibly-decent steel. At least at the edge. Or maybe not...
Fred.Rowe said:
The starburst at the end of the lines is indicative of high carbon steel.
Click to expand...

Maybe.

I can get sparks like that off of a cheap case-hardened file or lawnmower blade if I push it hard enough, and I do not get many sparks at all from annealed O1 or 1084 or D2 or 440C or 1095 or CPM-154 or CTS-XHP or CPM-3V or Elmax (all of which have plenty carbon to make good hard blades).

I have pretty close to zero faith in spark-testing as a way to determine steel quality. There are many more factors involved than just carbon content or
if the spark branches out or not.

Mostly, your pics tell me that it was a saw-blade at one point. We have no idea if it was a really good saw-blade. If you want to make some really good knives without relying on guess-work and investing in pro-level HT, spend $20 and buy a bar or two of 1084.
 
Last edited:
I am with James. It tells you it is hard and has carbon. It takes a lot more than some sparks to say that it is a good knife steel.
 
it comes from a power hack saw blade. I thought that most are hss but it doesn't seem so.
 
I have a bunch of them and have heard they are similar to M4. Ones I have are hard to grind and can get pretty hot and stay hard.
 
In that case, I would try grinding the teeth only to see if it is a bimetal blade. With HSS teeth welded to a steel body.
 
You can make a better "guess" if you can see the entire spark stream. Looking at the burst, by themselves, is not as informative. I like to spark test in a dark room using a big cup stone on a grinder to produce the sparks. Put comparitive samples in the vise and grind them, switching one from the other. I've been fooled on more than one occasion.
I have a spark test book, with nothing but pics in it of different metals being tested; it gives an idea of what it might be, but I think it takes a lot of experience to make a positive identification. You can learn a lot more with carbon steels by testing them as quenched.
 
You must log in or register to reply here.
Back
Top