Dmt magna-guide help

cziv · Aug 16, 2011

I have a USMC Ka-Bar that came new with a crappy edge. Pulled out the magna-guide & hones to touch it up.

I have been at it for about 4 hours over a few days and can't raise a burr!

Marked it with sharpie and it's taking it off perfectly. One thing I noticed is that one grind is wider than the other (shiny bevel edge part). I figured that the guide must not be dead center and reversed it this morning and spent about hour & half on it but still have wider grind on one side than the other.

I then figured maybe the spine isn't cut perfectly level and is producing the different width bevels??

Can't do anything about that right?

I'm using the x-coarse hone (it's prime and broken in) but this steel seems insanely hard.

Do you recommend a higher setting (larger inclusive angle) or maybe a lower one (less inclusive angle) or just keep working it? I have it set in the 3rd notch which should be around 40'ish degrees overall, for the size of the blade (measured spine to edge) according to their instructions.

Comments on any and all aspects of this nightmare project are welcome!!

Obsessed with Edges · Aug 16, 2011

On a big, thick blade like that, I'm betting it'll just take some extra time, especially with the small Magna-Guide hones. The wider bevel on one side is probably due to asymmetry in the blade's grind, more metal on one side than the other (relative to the centerline). It's fairly common on most blades, and a lot more noticeable on big blades. Usually more so near the tip.

The first thing I'd do, if you haven't already, is take a very close look at the edge under magnification & bright light. It's likely the edge isn't apexed yet, if you're still not getting a burr. When using the Sharpie to darken the edge, I've often noticed a hair-thin black stripe of it persisting at the very edge, which otherwise wouldn't be seen by the naked eye. It persists most stubbornly out near the tip of the blade, where the bevel is usually much wider and the steel is very thick. The downside of reprofiling a big blade like that, the closer you get to the edge, the wider the bevel gets, and the more metal needs to be removed. The contact area under the hone gets much larger, and the going gets a LOT SLOWER (consider trying to file down a pyramid, from the top down. The area of contact gets exponentially wider, the further down you go).

Make sure you really inspect that edge with the magnifier, so you absolutely know with certainty where you're at. Then, I'd simply put the knife & sharpener down and take a break for a while. When you come back to it, focus initially on the portion of the blade that's closest to being apexed, so you can verify the formation of the burr there. Once you see the burr there, work gradually away from that portion, to raise the burr on the rest of the edge. In all likelihood, if you're like me, the tip of the blade will take the longest to get there. Keep inspecting as you go.

Bottom line, with a BIG blade and small hones, it's just gonna take persistence. Pace yourself, don't work too long at a time, or the results will likely suffer for it.

cziv · Aug 16, 2011

Thanks Obsessed with Edges,

I am experiencing the slowdown that you described. I went out under the bright sunlight with a magnifying glass and confirmed that the sharpie marks I put on this morning are ground off.

I believe I'm getting very close to raising the burr. I think I'm getting close since a quick thumbail scraping test showed both sides of the edge catching & biting in immediately.

I'm going to get back at it again. Thanks a lot for all the pointers!

Be back later with a progress report.

cziv · Aug 17, 2011

The burr came up 15 minutes or so after posting the last time. Followed through, cleaning up both sides until very close and progressesd through hones to xx-fine. It's scary sharp now. I sprayed it down with Rem-Oil hours ago and stored it in the sheath.. :thumbup:

Obsessed with Edges · Aug 17, 2011

cziv said:
The burr came up 15 minutes or so after posting the last time. Followed through, cleaning up both sides until very close and progressesd through hones to xx-fine. It's scary sharp now. I sprayed it down with Rem-Oil hours ago and stored it in the sheath.. :thumbup:

Cool. Glad it all worked out. :thumbup:

I've always been curious about these big Ka-Bars, and wondered how well their 1095 would sharpen up (though, I haven't seen a 1095 blade yet, that wouldn't take a great edge). They look like 'all-business' and no nonsense. Much heavier than any of the knives I could justify for my own uses, but I'm still tempted to give one a try.

iammark · Aug 20, 2011

Hi cziv,

I've got the big, all-black Ka-Bar and did the same thing! I have a Sharpmaker and an Edge Pro. I roughed off the bulk of the steel with the coursest stone in my EP at the Sharpmaker's standard primary bevel angle and worked down to the finest stone in my set. I then moved to the Sharpmaker to put on the secondary bevel with grey and then white stones. It's hair-popping sharp now and it shouldn't be near as much work to touch up in the future using just my SM. I didn't obsess with getting a mirror finish on the primary bevel, so although it looks good and is consistent, it's NOT a 'show-knife', but you could shave a bear with it.

cziv · Aug 20, 2011

iammark said:
Hi cziv,

I've got the big, all-black Ka-Bar and did the same thing! I have a Sharpmaker and an Edge Pro. I roughed off the bulk of the steel with the coursest stone in my EP at the Sharpmaker's standard primary bevel angle and worked down to the finest stone in my set. I then moved to the Sharpmaker to put on the secondary bevel with grey and then white stones. It's hair-popping sharp now and it shouldn't be near as much work to touch up in the future using just my SM. I didn't obsess with getting a mirror finish on the primary bevel, so although it looks good and is consistent, it's NOT a 'show-knife', but you could shave a bear with it.

Thanks for the tip man. I'll keep that in mind. I've found that "for me" 1095 is the easiest steel to put a mirror polish on - witness my 3 Izulas and RC-3 & 4.

The Kab-Bar is almost there, just can use a little more polishing and it'll be there. I don't know if it'll be as rugged as the ESEE's, I cut wire and stuff like that with them and it doesn't even leave a mark on the edge!