Can Someone Explain This????

[NuclearBossHog]

Ok, I was blasting several knives with my sandblaster using fine grits so as not to do any damage. I started with a very fine almond shell stuff. I put this to the following knives:

Two CPM3V fixed blades Heat treated by Paul Boss.

Three Busse Knives of INFI.

The CPM3V knives were bare and when I hit them with the almond shells for about 5 minutes, there was a slight change of look to them. It was working but it would have taken me all day. I then put in the Busse knife and no effect after 5 minutes.

So I went to a coarser grit silica. I put the CPM3V knives in first and it took 3-5 minutes and I was done and got the desired bead blasted look I was looking for, making me happy. As I pulled each knife down I then added the Busse knives and did the same thing. It took me about 4 times longer (about 20 minutes per knife) to get the same finish on them after alread having removed the coating previously. Again I got the desired finish. Actually I should have put the Busse knives in for another couple of minutes to get them perfect, but I was tired of doing this.

Anyway, here is the ISSUE. As I check all the blades, which were all extremely sharp before putting in the blaster, I noticed that the CPM3V blades are blunted now. The INFI knives have no change to the edge. I was very carefull not to directly blast the edges on these knives and always had the edge facing away from me as I did the work.

What happened? I though that wear wise 3V was close to INFI. Is it just the hardness that Paul Boss uses on Heavy use knives is lower than INFI and this is the reason or what?

I found this very interesting.

By the Way I had the blaster set for 110 PSI. Anything under 100 psi didn't even mar the finish on the INFI. Crazy stuff.

I am going to try blasting several different steels next week to see what happens for kicks. I have several Beckers I want to try.

 

[STR]

Anytime you bead blast it will dull the edge from the high pressure dust of the particles flying everywhere, many of which are too small to see with the naked eye. Even the one you say is unchanged was probably affected. They should all be done usually before the final edge is applied but just so you know, most companies stopped bead blasting their blades because of the rusting problems associated with doing so. When bead blasting, you cause micro pits in the steel and these little cavities retain moisture so that even after wiping the blade off from a job involving blood, water, vegetables or fruits, you have not truly wiped it clean and dry. I would not recommend bead blasting high carbon steel at all. You can get away with it on some stainless but even then it will cause surface rust to develop and means more maintainance.

You are not going to be doing yourself or your blades any favors by bead blasting them, and especially the ones like those Beckers of same steel as Cold Steels Carbon V and Case's CV high carbon grade steel. These steels will just be more prone to rust after a bead blasting. Wiping the coating off those blades is a recipe for a terrible looking blade in the future.

 

[Cobalt]

Interesting stuff. I wonder if this shouldn't be in the review forum as this almost might be considered a test. I am not surprised at your results. I took a Vibra-sander to one of my INFI blades just to get the coating off. But because of the grooving n the steel, I had to work it for a very long time before all the coatng came off. INFI was insanely tough to machine. One of the toughest, I think. Stellite 6K may even have more wear resistance. (not 6b or Talonite, they are much softer).

Makes me feel sorry for making Kit Carson grind and finish that huge 14 inch x 1/4 inch U2 he did for me years ago out of 6K. I know he hated having to do that one.

Let us know how your tests go with the other steels. I, for one, find it interesting.:thumbup:

Maybe Cliff should add a sand blaster to his test regimen

 

[averageguy]

"You can get away with it on some stainless but even then it will cause surface rust to develop and means more maintainance."

I agree that bead blasting a high carbon blade doesn't make much sense. But I find that bead blasting stainless (even D2) with ceramic bead hasn't resulted in any noticeable increase in maintenance over a standard satin finish.

 

[Cliff Stamp]

Is it just the hardness that Paul Boss uses on Heavy use knives is lower than INFI and this is the reason or what?

No, they are near identical in hardness, unless you custom ordered Bos to undersoften 3V, it is usually 58-60 HRC. Wear resistance has more to do with type and volume of carbides. INFI is really wear resistant and very difficult to machine.

-Cliff

 

[wetdog1911]

"You can get away with it on some stainless but even then it will cause surface rust to develop and means more maintainance."

I agree that bead blasting a high carbon blade doesn't make much sense. But I find that bead blasting stainless (even D2) with ceramic bead hasn't resulted in any noticeable increase in maintenance over a standard satin finish.

The magic word here is ceramic bead. This is what Kit Carson uses and Busse with his DCBB (Double Cut Bead Blast). The ceramic media actually peens the surface shut. Works great, but few use it as it is very expensive compared to any other media. ZIRBLAST is the trade name.

Rob

 

[Cobalt]

No, they are near identical in hardness, unless you custom ordered Bos to undersoften 3V, it is usually 58-60 HRC. Wear resistance has more to do with type and volume of carbides. INFI is really wear resistant and very difficult to machine.

-Cliff

Yes, I have had custom knifemakers turn me down when I asked them to modify a Busse for me, because I didn't want to wait for the Busse time period. They just din't want to mess with the steel as they had bad experiences before. I have had one knifemaker try to work on a Busse knife and not be able to do it, havng to, then, send it back to Busse, to refinish it and send to me. Insane. This same guy routinely works on 3V and other tough steels.

Like I said, it would be interestng to do a machining wear resistance comparison between INFI and Stellite 6K.