Finishing CPM 3V

[Justin Presson]

Need some input guys.

I have a large blade, like 17"overall.
Im using cpm 3v and I have never used this steel but everyone says its a bear to finish. Im just trying to set myself up for succes after heat treat.

Can anyone give me reccomendations on finish you lay down before heat treat and after and maybe what belts you are using?

Thanks
Justin

 

[EdCaffreyMS]

3V finishes a lot like CruForge....... once heat treated it's simply a pain....especially when it comes to hand finishing. I suspect this is why you see a lot of "scotchbrite" finishes on knives made from it!

When it comes to the finish pre-heat treat, it's basically "six of one, half a dozen of the other" thing. Personally I just leave the finish at 120 before heat treat, and after heat treat start with a 50 grit, grind to the point where there just enough left to run up through 600 grit. With either 3V or CruForge, it doesn't seem to matter much whether I'm using AO or SC paper..... I go through a lot of it compared to finishing other steels. I'm not sure that I've ever actually "finished" a blade of either 3V or CruForge....more like "gave up" on them.

 

[Justin Presson]

3V finishes a lot like CruForge....... once heat treated it's simply a pain....especially when it comes to hand finishing. I suspect this is why you see a lot of "scotchbrite" finishes on knives made from it!

When it comes to the finish pre-heat treat, it's basically "six of one, half a dozen of the other" thing. Personally I just leave the finish at 120 before heat treat, and after heat treat start with a 50 grit, grind to the point where there just enough left to run up through 600 grit. With either 3V or CruForge, it doesn't seem to matter much whether I'm using AO or SC paper..... I go through a lot of it compared to finishing other steels. I'm not sure that I've ever actually "finished" a blade of either 3V or CruForge....more like "gave up" on them.

Thanks Ed, I assume you are finishing your edge thickness pretty close to the dimensions you want before heat treat?

 

[EdCaffreyMS]

I assume you are finishing your edge thickness pretty close to the dimensions you want before heat treat?

That's part of the "6 of one, half a dozen of another"..... if you finish the edge too thin, you run a high risk of warping in the heat treat, that can't be repaired...... but if you leave the edge thick, as I tend to do, you've got a lot of work (and belts) in finish grinding. I've gone both routes, and after loosing a few blades because I ground the edges too thin prior to heat treat (they warped beyond repair) I tend to always keep things thick pre-heat treat....but that presents the other set of issues. Although I've made a number of blades from 3V, I choose not to use it anymore, because the overall "cons" out weigh it's "pros" to me. Partially the same for CruForge..... but with it, the fact that it may or may not ever be available once the current supply is gone, it what steered me away from it.