Cloudy

[seeddamrod]

I've just started making knives from old table saw blades. I am getting cloudy swirls in my blades during sanding. They seem to appear when I go to 220 paper. Bad metal? Bad technique? Help

 

[dwdickey]

Try posting in the makers area

 

[seeddamrod]

ve just started making knives from old table saw blades. I am getting cloudy swirls in my blades during sanding. They seem to appear when I go to 220 paper. Bad metal? Bad technique? Help

 

[RevDevil]

Wrong section, moving to SHoptalk

 

[S.Alexander]

Do you know the steel composition? How are you doing your heat treat? Edge quenching?

Also, pictures may make your question easier to answer.

 

[seeddamrod]

I do not know the steel composition. It was an old 10" table saw blade I found in my grandfather's barn. I been heat treating with my turbo torch and quenching in motor oil. Working on the 3rd knife out of this material and without fail when I get to 220-400 sandpaper the cloudy swirls appear. I don't know how to load the pics :|

 

[kuraki]

You're not sanding with an orbital sander are you? 😋

 

[12345678910]

Show a photo of the table saw blade that includes the teeth

 

[seeddamrod]

You're not sanding with an orbital sander are you? 😋

No. I have a cheap 4x36 vertical sander.

 

[Stacy E. Apelt - Bladesmith]

It could be lots of things, but the most likely is that the steel is not the right type.


Also, your HT is not likely to properly harden steel. The steel needs to be hreated to around 1500F and quenched in something faster than motor oil. For a "backyard HT", try using an AO torch with a rosebud tip and quenching in a gallon of canola oil.

 

[Metalhead0483]

It could be lots of things, but the most likely is that the steel is not the right type.


Also, your HT is not likely to properly harden steel. The steel needs to be hreated to around 1500F and quenched in something faster than motor oil. For a "backyard HT", try using an AO torch with a rosebud tip and quenching in a gallon of canola oil.

Or make an easy one or two brick forge (depending on the size of the blades) using the smaller torch you already have. That's how I started anyway. If the steel is hardenable (not all saw blades are) that should work fairly well.

Pictures of the saw you're using, and of the swirls would help.