That darn burr

[Curtis Niedermier]

I recently purchased a set of mid-grade skew chisels for cleaning up half-blind dovetails. They were far from sharp and needed to be flattened and polished.

It all went great until I was trying to finish the sharpening. The burr I developed was massive. Not hard, but it kept getting "longer" off the chisel's edge. I managed to work most of it off, but I had a lot of trouble completely removing the burr. I ended up going back and forth from bevel to bottom a bunch if times and still felt like it just wouldn't break free. I think the steel is soft enough that even my polishing stone made a good burr.

So the point of this post is this: I don't have a strop or any lapping compound. How else can I remove the burr and get that ultra polished edge? I never have this problem on my LV PM-V11 tools.

[Jim Koepke]

When a blade being sharpened develops a burr, it is time to stop honing. Sometimes the burr doesn't extend across the full edge. For me, the honing stops to deal with the burr, then the honing is adjusted if need be and continued until the burr extends the full width of the edge. Once that is accomplished it is time to move to the next stone, remove the burr and continue working the bevel, ymmv.

Once a burr occurs, there isn't much reason to continue working the bevel unless one is trying to change the angle of the full bevel.

Maybe something is being missed by me in this case. How is it a massive burr developed?

This has me thinking about going out to my shop and turning a pair of 1/4" chisels into skew chisels.

jtk

[Mark Draper]

Use the back side of an old belt and some automotive polishing compound. Wet or dry 3m sandpaper don't get duller it gets finer and comes in grades to 1000 grit or more. I take contact cement and glue it to a softwood, works great.

[george wilson]

Use a much finer stone.

[Tony Shea]

Not sure what ur chisels are butit kinda sounds like the steel might be really soft if your polishing stone isnt getting rid of the burr. Depends what ur finish stone is though.

[Winton Applegate]

Burr
Yah they can be tenacious.
Mostly I get a bur when honing the A2 blades. Partly because I am using water stones which do not like it if you push the blade into the stone as if shaving off some thing on the stone.
Contrast that with O1 and sharpening on a hard Arkansas stone. You can go both directions or even just push the blade into the stone and the wire edge is worn away. The O1 just doesn't develop such an invincible foil like thing to start with.


At the stage you are at with the big wire edge you could try the following on your finest stone:
Be sure your stones are really flat.
Flip back and forth more often from bevel to back.
Use very light downward force between the stone and the blade.
Don't go even a full stroke/stone's length before flipping to the other side. Even getting down to like a quarter of the stone's length then do the same on the other side.
Keep the pores of the stone really clean and fresh and the stone well wet. I am not a big fan of "slurry" I tend to get rid of it as soon as it forms. I want fresh, hard, fixed abrasive cutting my blade as opposed to rounded, flexy/mud pile stuff that rolls around under the blade rather than CUT the steel.


All the sloppy problem areas I mentioned above : non flat, too much downward force, too long a pass and flexy mud bearings . . .

may contribute to DRAWING OUT a flap of foil from the edge rather than make it thinner and thinner and cut it off.


At the worst you could go back to a coarser stone to remove the wire edge, now that you know from it forming to start with that you have succeeded in getting rid of the wear bevel and edge rounding, then go finer and finer stones flipping the blade more often, keeping the stone pores clean and less downward force.


Stropping on a cheep, too soft leather is the easy way out but half way wears out the edge in the process. because the facet gets rounded. Actually partially reestablishing the wear bevel.


You will know you are on the right track with your methods when you see the wire edge coming off on the stone in the form of tiny, tiny, tiny fragments of metal a little at a time.


I used to see that on the Norton 8000 after I polished the edge on it, cleaned the stone with a nagura stone and water and rinsed it and then went after the final fragments of the wire edge with progressively shorter passes on the 8000 and more frequent flips back and forth and lighter and lighter pressure.


Now I do the same thing on a Shapton 8000 and by the time I am on the Shapton 15000, if I choose to even go that fine, there is no wire edge visible under the magnification visor I tend to use.


I suppose you could finish up your A2 blades on a hard Ark and go against the edge but I find the Ark tends to get polished from the A2 blade and stops cutting, at this point you are technically BURNISHING the blade and to take the polish off the ark and get it cutting again is tedious because it is so hard it takes a diamond plate and more work than I am willing to put into it to get 'er dressed again.


Or you could just snap that wire edge off on your palm and chant to your self :
"sharp tools are a CRUTCH" "Only inexperienced internet woodworker wimps use sharp tools"

I am still chuckling from that one.

[bridger berdel]

I wonder if these mid priced chisels will behave better after you have sharpened past the factory edge a bit. run them hard for a bit and sharpen often and let us know if they start behaving better.

what make are they?

[Hilton Ralphs]

I recently purchased a set of mid-grade skew chisels for cleaning up half-blind dovetails. They were far from sharp and needed to be flattened and polished.


What make are they? Lee Valley sells a set of cranked left, right and straight chisels but they are junk. Useful for cleaning up glue but it's probably cheaper buying a flea-market special for this.

The Narex set looks pretty good and the one that Joel sells also appears to be a bargain.

[george wilson]

What I mean is,hone the burr off using a much finer grit of stone than you used previously. Push the chisel forward to remove the burr. The finer stone will hone the burr thinner so it falls off. Does sound like your chisel is too soft.

[Jim Matthews]

Strop on a piece of hard maple, using a little auto body polishing compound.

Toothpaste is also a mild abrasive.
I've had mixed results with Bon-Ami cleanser, which is nearly pure Diatomaceous Earth.

It takes considerable force to strop on leather, charged with polishing Oxides.
I recommend having the strop clamped, or blocked so it can't wander...

[Ed Looney]

Try increasing the sharpening angle by a degree or two on a 8000 or higher polishing stone. The higher angle should focus the polishing where the burr meets what will be finished edge.

Ed

[Robert Hazelwood]

Ideally, you can anticipate when you are going to reach the apex and stop just before the burr forms. Then get a little closer on the next grit, finally apexing on a very high grit where the burr will be very small. If you make a big honkin' burr on a coarse grit stone it is always tough to remove.

An idea I picked up from the knife community is to actually remove the old edge prior to beginning sharpening (by taking a few strokes at a very high angle, close to 90 degrees). The idea is that the old edge is composed of fatigue-weakened metal and if it is not removed, the new edge will be made of weakened metal, which would be more prone to burr-formation and would not hold up as well in use.

Another tip is when you reach the fine grit stone, take a few high-angle passes (maybe 40-50 degrees) to cut off the burr. You'll form a tiny micro bevel. Then back sharpen at your intended angle until the microbevel is removed. Alternating strokes into the stone (rather than back and forth) seem to do the best job of cutting off the burr, so I like to finish with them.

It's better, IMO, to remove the burr via abrasion on the stones, rather than breaking it off on a strop. In theory that should leave a cleaner and more resilient edge. The strop should simply polish the edge beyond what the stones can do. However it takes a lot of time and care to get a perfect edge straight off of the stones and it's probably more economical of effort to just do a sufficient job on the stones and strop.

The poster who mentioned the chisels performing better after a few sharpenings has a good point. Factory edges are usually sharpened on a belt sander and power buffed and often get overheated in the process, softening the bit of steel right at the edge.