Reprofiling m390 at 15dps, taking forever

trailhunter

trailhunter

Joined
May 15, 2018
Messages
129
All, just checking in, sharpening my griptilian on m390, it's taking me 40 minutes so far on one side and I feel a small burr forming, using 50 grit diamond, does it usually take this long?
 
It's shouldn't be taking that long,what stones are you using,also if they are the KME Gold Series they should be cutting it just fine,I don't know how much you know about diamond plates such as DMT's or KME Gold Series that are bonding to the plate by electroplating if you have ever pushed really hard trying to make the stone cut faster you may have ruined the stone because it is nothing more then solder holding the diamonds on to the plate.
 
wade7575 said:
It's shouldn't be taking that long,what stones are you using,also if they are the KME Gold Series they should be cutting it just fine,I don't know how much you know about diamond plates such as DMT's or KME Gold Series that are bonding to the plate by electroplating if you have ever pushed really hard trying to make the stone cut faster you may have ruined the stone because it is nothing more then solder holding the diamonds on to the plate.
Click to expand...

Hmm okay, interesting. Yes it's a kme gold beast. I've been on it fairly light. Only letting the weight with some minor pressure on the edges but nothing forceful., I'll keep going at it and see how it turns out
 
There's definitely embedded diamonds, using a microscope I see them as you suggested, I'll clean it up and see how it performs, thanks for suggestions!

 
Anyone know how am I getting these little scratches on the blade? Any recommendation to remove them?

 
What angle are you sharpening at? I'm sure others can offer some suggestions on how to remove the scratches but I think it might be kinda tough.
 
To get rid of the scratch's your going to need a buffing wheel and diamond paste if you ave a dremel tool that should work but don't turn it on wide open because it will just wreck buffing wheel that you choose to use,as far as what grit's to use I don't know I have only heard of people doing this and I have never done it and I did not take note of what diamond paste they used.

Maybe someone here can tell you what Micron would be best,also when you get scratch's like that it's from the abrasive coming off the stone and if you do not clean it off enough it will scratch the blade and you will need to tape the blade.Did the just happen from using the KME stones if so I'd say you may have some diamond coming out,if you used the coarsest diamond KME makes that could be another problem and also sometimes if you apex the edge with a really coarse stone you just end up tearing apart the thinnest part of the edge witch means more work to remove the gouge's.

Also look in you inbox I just you message about a few thing's you asked me and you need to know.
 
wade7575 said:
To get rid of the scratch's your going to need a buffing wheel and diamond paste if you ave a dremel tool that should work but don't turn it on wide open because it will just wreck buffing wheel that you choose to use,as far as what grit's to use I don't know I have only heard of people doing this and I have never done it and I did not take note of what diamond paste they used.

Maybe someone here can tell you what Micron would be best,also when you get scratch's like that it's from the abrasive coming off the stone and if you do not clean it off enough it will scratch the blade and you will need to tape the blade.Did the just happen from using the KME stones if so I'd say you may have some diamond coming out,if you used the coarsest diamond KME makes that could be another problem and also sometimes if you apex the edge with a really coarse stone you just end up tearing apart the thinnest part of the edge witch means more work to remove the gouge's.

Also look in you inbox I just you message about a few thing's you asked me and you need to know.
Click to expand...


Awesome thanks, I'm finishing up, at 1500 now, been at this since 8PM and it's now 12AM. I shaved off a lot of metal but its coming together, I'll check inbox soon and will post pic once its finished
 
That's another reason I really started not liking my KME how slow it is using the 4 inch the stones I know 2 extra inch's does not seem like much but I find it's much faster with an edge pro format stone.
 
Those scratches are most likely caused by you riding the stone past the edge and onto the flats. You might consider using a guide stop or a drill stop on the rod. Or, you should use painter’s tape to protect the blade
 
OK . . . look
Here is what one needs to do to reprofile; abrade the steel BEHIND the edge away so the blade gets thinner there. That is cutting off a significant quantity of metal.
The machinists here will tell you when you do that on say a lathe or a mill the following conditions need to be met :
The tool bit / cutter (your diamonds / honing plate) needs to be as securely fixed as possible with no long linkages between the cutter and the work.
The work (your blade) needs to be EXTREMELY . . . RIDGIDLY . . . fixtured.
The cutter needs to be passed over the work fast enough to remove the metal in a timely manner but there are extremes where bad things happen (the cutter gets destroyed).

So with that in mind lets look at your machining set up.
You have the blade fixtured in a clamp that could not possibly be further from the edge or it would not be contacting the blade. The edge of the blade is hanging out in space and can easily oscillate up and down like a diving board.

Gosh we can stop right there. That is your problem. How did the scratches get on the blade ? The blade defected downward enough that the stone started cutting higher on the blade.

But there's more if we keep going. I am kind of assuming that since you are using that funny sharpening jig, with the diving board clampy thing, that the diamond plate, though very, very coarse is also very short.

That's problem two. To get enough cutter speed (move the few diamonds on that little plate fast enough to remove metal in a timely manner) you would need to flail quite quickly with your arms. Now a thousand strokes a minute looks good for the cameras but can't be much fun on a daily basis.

So . . . what to do ? Use A LOT longer diamond plate.

And finally as far as the rigidity of the cutter . . . that's not bad but you would be better served by getting the plate off the rod or what ever on the jig and put it down on a solid surface like a work bench top or the floor.

Every body mark this moment in the annals of the Blade Forum :
The day the 'Bagmaster recommended HAND sharpening over using a sharpening jig.

Oh yes . . . I've been saying that all along. When I reprofile I use my big old DMT 10 inch long diamond plate and do it free hand because it is VERY FAST ! ! ! !

How ? I just sharpy the whole couple of mm back from the edge ALL ALONG the edge and then run it on the stone and check my progress and STAY A WAYS FROM THE EDGE and remove metal behind the edge.

Goes fast.

As far as ruining the diamonds by pressing hard this will only happen if you contact the diamonds with the edge. As long as you are well back from the edge on the flat or rounded part of the bevel you won't hurt the diamonds if you press quite hard so get your foot up on it and go to town. Kidding about the foot but yes you can press hard.

Now to the scratch removal. Oh man . . . you're screwed !
Sort of.
Forget the Dermal you will only get a lumpy looking blade with shiny scratches still in the blade.

The way to remove the scratches, unfortunately, is to go to the next finer diamond grit from your 50 and use a WIDE fairly firm backing to the abrasive. Think very firm rubber pad. You can get these at automotive paint supply stores for hand rubbing a finish. They come in all different closed cell foam densities. It is like diving suit rubber . . . both softer and much harder.

Put a cloth pad over that and the diamond grit on that and rub for like half your life time. Once the original scratches are blended / removed change to the next finer grit and go again.

Sucks ?
Yes.
If you are serious about removing them you may want to consider sending the knife to Josh of Razor Edge or some one like that and have them put in on their serious power tools (rather than the Barby power tool (Dermal).

Look . . . I've polished knives by hand as I am talking about and they were no where near as tough a steel as the M390.

I hope this helps.
Hang in there.
 
Last edited:
When Wowbagger mentioned making sure about the knife being clamped in and solid so it can't move I completely forgot about another problem with the KME,if you look at the plate that hold's the jaws in place behind there are 2 rivet's and if you use enough pressure you can see the jaws moving up and down and that may also have been a factor,I know other people have complained to me that live near me that they don't like how the jaws move up and down.

What happens is that plate sit's on the rivet's and not right against the frame witch is flat and then it can move because the rivet's are dome shaped.
 
Thanks for the comprehensive reply! I finally finished and its 1:35AM. Damn scratches pissed me off. I locked it down and looking at the angle, I can't comprehend how those scratches got there when the stone is not even close. Anyway, damn it took forever, i went through a chosera set as well as strop to 160000 grit which I doubt had any effect but I got an okay mirror. This is my first time on m390, you definitely need to have a bit more skills than sharpening the good old kitchen knive set, I felt like i was taming a wild beast.

 
trailhunter said:
All, just checking in, sharpening my griptilian on m390, it's taking me 40 minutes so far on one side and I feel a small burr forming, using 50 grit diamond, does it usually take this long?
Click to expand...

50 grit is too coarse a stone to feel for a burr at the apex. You should instead just grind the edges down to the desired angle with the 50 stone without worrying about the apex for now. As Wade said make sure you use very low pressure. Pressure doesn’t cut, the diamonds do so just use low pressure.

Once you have each side set to about 15 degrees you switch to a higher grit stone like the 100 and 140. With these again be light on pressure but you can now start feeling for burrs and apex.
 
wade7575 said:
When Wowbagger mentioned making sure about the knife being clamped in and solid so it can't move I completely forgot about another problem with the KME,if you look at the plate that hold's the jaws in place behind there are 2 rivet's and if you use enough pressure you can see the jaws moving up and down and that may also have been a factor,I know other people have complained to me that live near me that they don't like how the jaws move up and down.

What happens is that plate sit's on the rivet's and not right against the frame witch is flat and then it can move because the rivet's are dome shaped.
Click to expand...


Bummer! Can't wait for the tsprof yo arrive, those clamps look rock solid. One thing I don't like about the kme the handle is a bit loose on the stand and it changes the angle ever so slightly.
 
wade7575 said:
When Wowbagger mentioned making sure about the knife being clamped in and solid so it can't move I completely forgot about another problem with the KME,if you look at the plate that hold's the jaws in place behind there are 2 rivet's and if you use enough pressure you can see the jaws moving up and down and that may also have been a factor,I know other people have complained to me that live near me that they don't like how the jaws move up and down.

What happens is that plate sit's on the rivet's and not right against the frame witch is flat and then it can move because the rivet's are dome shaped.
Click to expand...


Ah okay, I see what you mean. Surprised that wasn't accounted for. Bummer, I really wanted to enjoy the kme but its rough around the edges.
 
Wowbagger said:
OK . . . look
Here is what one needs to do to reprofile; abrade the steel BEHIND the edge away so the blade gets thinner there. That is cutting off a significant quantity of metal.
The machinists here will tell you when you do that on say a lathe or a mill the following conditions need to be met :
The tool bit / cutter (your diamonds / honing plate) needs to be as securely fixed as possible with no long linkages between the cutter and the work.
The work (your blade) needs to be EXTREMELY . . . RIDGIDLY . . . fixtured.
The cutter needs to be passed over the work fast enough to remove the metal in a timely manner but there are extremes where bad things happen (the cutter gets destroyed).

So with that in mind lets look at your machining set up.
You have the blade fixtured in a clamp that could not possibly be further from the edge or it would not be contacting the blade. The edge of the blade is hanging out in space and can easily oscillate up and down like a diving board.

Gosh we can stop right there. That is your problem. How did the scratches get on the blade ? The blade defected downward enough that the stone started cutting higher on the blade.

But there's more if we keep going. I am kind of assuming that since you are using that funny sharpening jig, with the diving board clampy thing, that the diamond plate, though very, very coarse is also very short.

That's problem two. To get enough cutter speed (move the few diamonds on that little plate fast enough to remove metal in a timely manner) you would need to flail quite quickly with your arms. Now a thousand strokes a minute looks good for the cameras but can't be much fun on a daily basis.

So . . . what to do ? Use A LOT longer diamond plate.

And finally as far as the rigidity of the cutter . . . that's not bad but you would be better served by getting the plate off the rod or what ever on the jig and put it down on a solid surface like a work bench top or the floor.

Every body mark this moment in the annals of the Blade Forum :
The day the 'Bagmaster recommended HAND sharpening over using a sharpening jig.

Oh yes . . . I've been saying that all along. When I reprofile I use my big old DMT 10 inch long diamond plate and do it free hand because it is VERY FAST ! ! ! !

How ? I just sharpy the whole couple of mm back from the edge ALL ALONG the edge and then run it on the stone and check my progress and STAY A WAYS FROM THE EDGE and remove metal behind the edge.

Goes fast.

As far as ruining the diamonds by pressing hard this will only happen if you contact the diamonds with the edge. As long as you are well back from the edge on the flat or rounded part of the bevel you won't hurt the diamonds if you press quite hard so get your foot up on it and go to town. Kidding about the foot but yes you can press hard.

Now to the scratch removal. Oh man . . . you're screwed !
Sort of.
Forget the Dermal you will only get a lumpy looking blade with shiny scratches still in the blade.

The way to remove the scratches, unfortunately, is to go to the next finer diamond grit from your 50 and use a WIDE fairly firm backing to the abrasive. Think very firm rubber pad. You can get these at automotive paint supply stores for hand rubbing a finish. They come in all different closed cell foam densities. It is like diving suit rubber . . . both softer and much harder.

Put a cloth pad over that and the diamond grit on that and rub for like half your life time. Once the original scratches are blended / removed change to the next finer grit and go again.

Sucks ?
Yes.
If you are serious about removing them you may want to consider sending the knife to Josh of Razor Edge or some one like that and have them put in on their serious power tools (rather than the Barby power tool (Dermal).

Look . . . I've polished knives by hand as I am talking about and they were no where near as tough a steel as the M390.

I hope this helps.
Hang in there.
Click to expand...

(Sipping on coffee and reading this) Thanks for this info, very informative. It is a lesson learned and I'll take into account feedback for my next reprofile.
 
I started taping the blades with painters tape to avoid scratching blade during sharpening. If you use the knife it will get scratched but I still try to avoid it.
 
Diamonds don't like much pressure, I find it just damages them. I am also finding they like edge trailing strokes better, and so does the knife. With edge trailing strokes the diamonds come into contact with the steel gently, vs running into a sharp edge. Just some observations I have made with my microscope.
 
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