Sharpening M4, any troubles?

[Tdhurl1103]

Hi guys,

About two months ago I picked up a GB1. I love it a lot and have been using it in the yard and garden for a myriad of tasks. Its a great heavy use folder. I have cut wood/limbs, string, tape, opened plastic bags full of topsoil, as a prunner, and even used it to stir some soil around/a very light digging tool. Any way, the knife preforms well, is very user friendly, but I realized it got dull pretty fast. No real worries though, after all, I am using it pretty hard. What I did not expect was that I would be unable to sharpen it.

For the life of me, I cannot get the entire edge back using the Sharpmaker. I worked on it for about 30 minutes, then, frustrated, set it aside. I came back to it today to try to get the edge back on it, working on it for an hour; no joy. I can get the edge razor sharp at the heel/ricaso up to about a half inch before the belly. Then its dull as crap in the belly. The tip about a quarter inch toward the belly is user edge sharp. When I sharpen I go slow and make sure the edge has contact with the rods. I did notice that the edge seems to "slip" down the rod when it gets to the bellyarea. I started out with the 40 degree, then, like the video says, after no edge I went to the 30 degree. What the **** am I doing wrong, your best guess?

I don't have these issues with my PM2 and Sage1 (S30V) or any of my traditionals in 1095. I do have some issues sharpening 420 or 440 (not sure which steels they are exactly) I have two 1980's era Camillus TL-29s that wont sharpen on the Sharpmaker.

Anyone else have issues sharpening M4?

[paladin]

Offhand I'd say you're not hitting the Apex at that area...

M4 is a little <just a little> more challenging to grind than some might admit, thinking since it develops a patina it's one of those easy to sharpen high carbon old timey slipjoint like steels...

But having said that, no steel is impossible to put a good edge on...you...just....gotta...hit....the....apex...

Probably got a thicker shoulder where you're noticing "dullness." Pretty common for hand sharpened blades to be a bit fat in the belly & sweep area. If you had access to a belt sharpener and about a 1000 grit belt you could take that shoulder down in a heartbeat and be able to fully hit the apex at 40 deg. easy.

Otherwise you're gonna have a good half to three quarters of an hour of grinding with medium rods at 30 deg. holes...a bit shorter if you got the diamond rods...

Keep with it-- you'll get there and it will be AMAZING!!!

[Kenakth]

Hey, I don't have any M4, but I did just finish reprofiling a HAP-40 Stretch (which had the worst factory edge I've ever seen on a knife. >24 deg/side in some parts, <18 deg/side in others along the edge). Sounds like your edge is a wider angle or more worn in the belly than towards the ricasso.

Try putting some black or blue Sharpie marker along the edge of the problem area (I generally just cut into the marker with the section I'm trying to check) and then make a couple light passes on the stones. If the marker doesn't come off near the edge, that means you're not reaching it and you may need to use some course stones in that region, or spend more time with whatever you were using previously.

Hope it helps. If it doesn't, post an update please.

[ImageX]

Try putting some black or blue Sharpie marker along the edge of the problem area (I generally just cut into the marker with the section I'm trying to check) and then make a couple light passes on the stones. If the marker doesn't come off near the edge, that means you're not reaching it and you may need to use some course stones in that region, or spend more time with whatever you were using previously.

This.

A Sharpie will let you know what you are or aren't hitting. I have a GB2 but have only done light touch ups since I haven't used it very hard yet.

[Brock O Lee]

+2

Sharpie is your friend. Coarse stones are your friend too if you don't want to labor for hours and hours to work away a thick shoulder on the SM med stones. They are simply too fine for that type of work. I would suggest something in the range of 150-300 grit. DMT X-coarse or coarse is normally what I would use to grind away a shoulder.

Once the bevels are set your GB would be a much easier to maintain on the SM, as long as you don't let it get very dull.

[abbazaba]

Sharpie and a magnifying glass are key for me.

I reprofiled my GB1 and Mantra to 30 degrees using the diamond rods and it took probably and hour each to get hair popping sharp. I did a 154CM last night and it took only about half an hour. I love the M4 though!

[Surfingringo]

Its not uncommon for the Taichung knives to come with an overly obtuse bevel. The shortest distance between A and B would be to reprofile to 30 degrees with the diamond rods until you are properly apexed then lightly microbevel at 40 degrees.

[dplafoll]

I have a Mantra, and I haven't had any trouble sharpening it. One side was ~15 degrees, and the other was more obtuse, but even with the medium stones I was able to knock the obtuse side down a bit. I'm waiting on some diamond stones, and when they come in I'll really re-profile.
I might suggest sending it to a sharpening service to have them re-profile it to 15 dps and put on a microbevel for you at 20dps, and then you'll pretty much be set. There are services out there that'll do that for not too much money, or you could find someone local. Or you could buy a WorkSharp/Wicked Edge/Edge Pro and get cracking yourself. :D

[toomzz]

M4 is my most beloved steel because it sharpens devilsh sharp. To answer your question; I have no trouble sharpening both my M4 Bradley's.
I started sharpening in 1997 with a sharpmakerset (SM) and since a couple of years I have a wicked edge. I rebeveled both of my GB's back to 15 degrees per side, which works fine.

Wicked edge is easy, SM is another story. I learned to sharpen freehand with the SM-rods. I use both medium, fine and the ultrafine-rods. To maintain the edge of my GBs fine and ultrafine are enough. The last strokes with the ultrafine rods I take a slightly larger angle and gentle stroke the edge. That is one option. The other option is using the rods and finishing with a strop loaded with (for example) green chrome-paste or flexcut gold. That works superb on M4. You can use either a regular leather strop, or leather wheel loaded with your favorite compound.

[bearfacedkiller]

I have not personally seen a Taichung knife that came with an edge under 40 degrees. Significant reprofiling has been neccesary on every one of them. My GB2 and my Bradley Bowie both came with really obtuse bevels that were a bit over 40 degrees. Without seeing your knife I cannot say for sure but I would bet that is your problem. I can't figure out how they are able to make such nice knives in terms of fit and finish but seem to lack the ability to put a decent bevel on them. It sucks but at this point I have just accepted it.

[SG89]

I have not personally seen a Taichung knife that came with an edge under 40 degrees. Significant reprofiling has been neccesary on every one of them. My GB2 and my Bradley Bowie both came with really obtuse bevels that were a bit over 40 degrees. Without seeing your knife I cannot say for sure but I would bet that is your problem. I can't figure out how they are able to make such nice knives in terms of fit and finish but seem to lack the ability to put a decent bevel on them. It sucks but at this point I have just accepted it.

What do you use to measure your bevels?

[bearfacedkiller]

I just put it to the stones. I am quite proficient with both the Sharpmaker as well as pocket stones so I use them and some muscle memory as my guide. That and a sharpie. Both the GB2 and the Bradley Bowie were only hitting the shoulders on the 40 degree setting. I am carrying my GB2 today and absolutely love it but I did have to reprofile it quite a bit to get it where I want it. It is in my eyes still the best value in Spyderco lineup. It is an amazing blade for around $140.

[toomzz]

I am carrying my GB2 today and absolutely love it but I did have to reprofile it quite a bit to get it where I want it. It is in my eyes still the best value in Spyderco lineup. It is an amazing blade for around $140.

+1

[Tdhurl1103]

Thanks. All great suggestions and insight. Much appreciated. I'll give it another go, using the sharpie.

[anagarika]

Another trick is to use strong light directly on the edge apex. I thought I fully apexed my GB1, but inspecting it's edge using my iPhone camera light, saw flat spot reflecting back the light near tip. Back to work until the reflection is gone. At this point (no reflection), the apex thickness should be less than 5 micron, if I recall Cliff saying before.