Reprofiling woes

D

drebs

Joined
Dec 6, 2014
Messages
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So I’m reprofiling a Gayle Bradley 1 M4 62.5 RC back to 15 dps from the factory edge


So I started out on this with a 80 grit moldmaster hard silicone carbide Congress stone on the edge pro .. setting the edge to 15 dps reprofiling the knife from the factory edge ... have never used this knife since I got it years ago.

The first photo shows the edge I created moving the shoulders back after grinding on them (widening the bevel up from the edge towards the spine ) . It took me 10-15 minutes of doing this till I got a burr on the back side.

j5smeM6


https://imgur.com/gallery/j5smeM6

sorry I Tired for awhile to upload these pics to here this was the best I could come up with.

(2nd pic)Now when I flipped it over to do the other side in 20 passes or so the burr flipped even though I hadn’t even begun to move the shoulders back . It’s said once a burr is created to go back to the other side. However I have not established the regrind on this side, have not grinded the shoulders back like the other side how did the burr flip? I should just be grinding on shoulders. Yes I double checked the angle 3 times with a cube. I am holding the knife in same position as a hollow grind can rock on the platform depending on how held, and the angle set screw did not move either.


Should I cut into the wire burr and remove it and continue reprofiling until the shoulders move back or leave the burr and continue?


Also the stone is not cutting near as well as the first side, clogged I assume even though it’s been soaking before and had soapy water sprayed on every minute. How would I unclog? Lapping stone? If so what kind?


Thanks for the input!
 
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If I'm understanding you correctly, it sounds like the grinds are different on each side. That is common on factory knives. Spyderco's are typically in the 15-18dps range so one side might already be at 15 and hence the burr. So, you might only need to grind in that one side that is not at 15dps.

Did you color the edge with a marker? That will tell you the story. If you'r raising a burr on that side and cleaning off the bulk of the marker, it is already where you want it.
 
Looks like you have a bit more grinding to do on the Spyder side.

If it is not cutting as aggressively as before the stone is probably glazed.

Do you have any SiC grit?
If not you could lightly take a 12-16p nail and slightly abraded the surface of the stone a little.
That has helped me in the past on old Norton stones.
 
Almost all factory knife bevels are uneven side to side... for instance one side 13 degrees, the other side 18 degrees.
Sometimes the bevels are uneven tip to heel, like tip is 18 degrees, tapering down to 13 degrees at the heel. This can be different side to side.
Sometimes the edge is wavy.
Sometimes the primary grind is off side to side.
Sometimes there's a combination or all the above.

Interpreting where sharpie marks are removed along the edge with a few passes can tell you a lot about what you're dealing with.

I'm not familiar with the stones you're using, other than them being silicon carbide.
I use oil on my 2x8 SiC benchstone.

I'm not a fan of 1 inch wide stones, especially for repair work, except in rare circumstances.
 
Sounds like you overdid the first side, you should have worked both sides sorta evenly to get your burr. To dress your stone I would vote for loose abrasive on a flatish surface. The harder the abrasive the longer it will last, softer abrasives will still work, for dressing that is. Isn't the Moldmaster for polishing EDMed surfaces? If so that would explain why it is not friable enough for knife sharpening.
 
Diemaker said:
Isn't the Moldmaster for polishing EDMed surfaces? If so that would explain why it is not friable enough for knife sharpening.
Click to expand...

That seems like an overly broad statement. BORIDE AS-9, Orange EDM, and Golden Star are all good stones for knife sharpening, and all are listed as EDM stones. The Moldmaster stones specifically are favored by some highly experienced sharpeners like Jim Ankerson.
 
Diemaker said:
Sounds like you overdid the first side, you should have worked both sides sorta evenly to get your burr. To dress your stone I would vote for loose abrasive on a flatish surface. The harder the abrasive the longer it will last, softer abrasives will still work, for dressing that is. Isn't the Moldmaster for polishing EDMed surfaces? If so that would explain why it is not friable enough for knife sharpening.
Click to expand...


Hearing this statement makes the most sense to me. Hearing the edges were different grinds from the factory ... very true but they were very uniform in how far back they went, could have been a degree of 2 different but extremely similar( now undeniably and obviously very different) When I grinded the first side the shoulders moved away back from the edge to the spine (the bevel visually got very taller) now the other side the shoulders hadn’t even began to move back when the burr flipped. So diemaker being this is the case I over did one side how to proceed? How does one know when the shoulders are properly set as the burr usually indicates this, in this specific case the burr has lied.

I cannot work off the burr concept as it’s already flipped but I haven’t established the 15 dps... (thank you old biker for putting the pics up on here and not a like I tried for a long time!) In the pics you can see how far back one edge is moved on the .016 bte Gayle Bradley (NOTE: pic is overly conservative in the photo angle that shows knife angle, the edges are much more far apart in person than the pic shows), the first pic shows the first grind I made, I grinded until it raised a burr along the whole edge . Like I said it took 15 mins and you can also see how much I moved the shoulders back. The second pic was 1 min, the shoulders not moved at all and the burr already flipped.

EDIT: Just closed my eyes and laid down, the burr can’t lie when you logically think about it so I’m kinda scratching my head now,unless there is an aspect I don’t understand? Could I have formed such a long burr that I hit the edge of the burr before I hit the shoulder of the second side and folded it back to the other side?. Any advice would be appreciated. Didn’t know this could happen

EDIT 2 : this knife is a hollow grind does that change anything ?
 
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I wouldn’t worry about the burr. Your bevels are not even because the bevel is off centre, it is also decreasing in size as you move towards the tip because the relative thickness behind the edge at the tip. The knife probably has a distal taper, but the thickness behind the edge is still thicker than at the heel.

If the blade varies in thickness down its length then the bevel will vary in thickness.

if you continue to grind the side with the small bevel, the apex will start to centralise and then your bevels will even up
 
sickpuppy1 said:
To me the Spyderco side looks like a much steeper angle than the Gayle Bradley side. Definitely use a marker to see how it’s cutting.

the side I grinded has a lower dps (the grind is taller as I pushed the shoulders back) the factory side is a higher dps and steeper if it’s asl slope
Click to expand...
 
I
willc said:
Looks like you have a bit more grinding to do on the Spyder side.

If it is not cutting as aggressively as before the stone is probably glazed.

Do you have any SiC grit?
If not you could lightly take a 12-16p nail and slightly abraded the surface of the stone a little.
That has helped me in the past on old Norton stones.
Click to expand...


I do have sIC grit from edge pro but I believe it’s 60 grit, they sell 60 and 240 which would be best for a 80 grit stone. Also it’s my impression the hard silicone carbibe stones from Congress (moldmasters) are harder than edge pro stones as per Jim Ankerson if I recall correctly. So I hope they work.
 
drebs said:
EDIT: Just closed my eyes and laid down, the burr can’t lie when you logically think about it so I’m kinda scratching my head now,unless there is an aspect I don’t understand?
Click to expand...

Yes, there is another concept you don't understand. The burr only tells you when "grinding has reached the edge". The burr can not know where the CENTER of the blade is. It can not see the edge bevel width. The burr just forms when you grind until an edge forms.

Imagine this: You start with a knife that has a completely squared off edge. There are no existing edge bevels. If you look at the blade in cross section, you are going to be grinding on a rectangle; not a triangle. So you start on one side and begin grinding.

After grinding for a short time, you now have an angled bevel on one side. If you look at the side you are grinding on, you'll now see an edge bevel forming. But there's no edge yet. You have a long way to go.

After a while, you look at the blade in cross section again, and you see that you are almost to the center of the blade. It's almost time to stop if you want to have your edge be in the center of the blade. Now if you can't see the cross section of the blade (which human beings really can't; this is a thought experiment), then you might just keep right on grinding past the center.

Eventually, if you kept grinding on only one side, you would reach the other side. ...and now your rectangle would have one existing squared off side, and your new angled side would reach ALL THE WAY over to that side. Your edge would obviously be way off center at this point.

You have done a mild version of what I just described. You ground only one side and have off centered your edge. The way to correct it is to grind on the "short side" until the bevel widths are approximately even.

When doing a big grinding job (like a reprofile), it's advisable to only grind on one side for a medium length of time. Maybe 1 to 2 minutes of continuous grinding by hand. Then switch sides, do an equal amount, and switch again. Monitoring your edge bevel width can help you a lot here too. Keep looking at those edge bevels as you grind. Try to keep them approximately equal as you go.

Good luck to you.

Brian.
 
B
bgentry said:
Yes, there is another concept you don't understand. The burr only tells you when "grinding has reached the edge". The burr can not know where the CENTER of the blade is. It can not see the edge bevel width. The burr just forms when you grind until an edge forms.

Imagine this: You start with a knife that has a completely squared off edge. There are no existing edge bevels. If you look at the blade in cross section, you are going to be grinding on a rectangle; not a triangle. So you start on one side and begin grinding.

After grinding for a short time, you now have an angled bevel on one side. If you look at the side you are grinding on, you'll now see an edge bevel forming. But there's no edge yet. You have a long way to go.

After a while, you look at the blade in cross section again, and you see that you are almost to the center of the blade. It's almost time to stop if you want to have your edge be in the center of the blade. Now if you can't see the cross section of the blade (which human beings really can't; this is a thought experiment), then you might just keep right on grinding past the center.

Eventually, if you kept grinding on only one side, you would reach the other side. ...and now your rectangle would have one existing squared off side, and your new angled side would reach ALL THE WAY over to that side. Your edge would obviously be way off center at this point.

You have done a mild version of what I just described. You ground only one side and have off centered your edge. The way to correct it is to grind on the "short side" until the bevel widths are approximately even.

When doing a big grinding job (like a reprofile), it's advisable to only grind on one side for a medium length of time. Maybe 1 to 2 minutes of continuous grinding by hand. Then switch sides, do an equal amount, and switch again. Monitoring your edge bevel width can help you a lot here too. Keep looking at those edge bevels as you grind. Try to keep them approximately equal as you go.

Good luck to you.

Brian.
Click to expand...

Brain thank you! This all finally makes sense now. And a great lesson appreciate it
 
bgentry said:
You ground only one side and have off centered your edge.
Click to expand...
Yes, I forgot about off centered edge. I've found these from the factory too, although this one might have been self inflicted.

Both sides can be at the same angle with more grind on 1 side, resulting in off centered edge.
 
jpm2 said:
Yes, I forgot about off centered edge. I've found these from the factory too, although this one might have been self inflicted.

Both sides can be at the same angle with more grind on 1 side, resulting in off centered edge.
Click to expand...

Since I’m at going to 15 degrees on the side I’m about to recenter ... im prob going to touch it on the belt grinder (that I modified to work the exact same way as the Ken onion knife grinding attachment, I’m actually going to make a tutorial , not to toot my own horn but because I’ve learned so much from here and YouTube and feel like I’ve never been able to give anything back or share expirnece like so many other do which is what makes all this work ) at 17 degrees to knock the burr off with a 60 grit ceramic belt . However I don’t know if that will rip the burr off giving me no apex but one way or another that weakened steel will have to come off.

or should I just grind on the side I haven’t then go back to the side I already have with the burr and flip it back to the middle and lightly cut into high grit stones removing the burr?
 
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I really wouldn’t stress too much about the burr and the actual sharpening of the knife until you are happy with the orientation of your apex. Post this you can concentrate on actually getting the thing sharp...

I’ve no experience with powered sharpening but I think typically the final steps are completed using a combination of leather belts and compounds. Also from what I’ve heard taking that final step using a powered system is typically harder than on a stone and by hand.

I’d stick with your stones and remove the burr on those when you actually get down to sharpening
 
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