AX SHARPENING WITH POWER TOOLS

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I just started working on a Kelly Perfect DB. It has clearly been profiled to have a felling side and a splitting side. Much of my work so far has been to try and correct the edge geometry. This is my complaint against using grinders to sharpen axes. The round shape of the wheel against the edge of the bit can create a concave edge, not to mention a sloppy curve on the bit.) This was the case on the felling side of my Kelly Perfect. (Sorry, I should have taken photos.) I spent quite a while filing out the concave spots. Additionally, because the felling edge was concave and therefore too thin, the toe was chipped, which required additional filing. Similarly, the heel on the splitting side had a bit of a chip that needed remediation. Aside from the loss of temper concern, I think the electric grinder facilitates poor edge geometry and poor bit curvature. I don't think you can achieve a concave edge with a flat bastard file or a belt sander!
 
Curt Hal said:
I just started working on a Kelly Perfect DB. It has clearly been profiled to have a felling side and a splitting side. Much of my work so far has been to try and correct the edge geometry. This is my complaint against using grinders to sharpen axes. The round shape of the wheel against the edge of the bit can create a concave edge, not to mention a sloppy curve on the bit.) This was the case on the felling side of my Kelly Perfect. (Sorry, I should have taken photos.) I spent quite a while filing out the concave spots. Additionally, because the felling edge was concave and therefore too thin, the toe was chipped, which required additional filing. Similarly, the heel on the splitting side had a bit of a chip that needed remediation. Aside from the loss of temper concern, I think the electric grinder facilitates poor edge geometry and poor bit curvature. I don't think you can achieve a concave edge with a flat bastard file or a belt sander!
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Notice in my video earlier how I pulse the bit back and forth on the contact wheel? That prevents forming a hollow, and creates a nicely blended convex instead. People who produce a hollow when using a grinder on axes are just doin' it wrong. :)
 
Very interesting. You know, now that you mention the "pulsing" technique, I wonder whether the people saying you can't get a convex on paper wheels just haven't tried it. I don't see any reason why it wouldn't work on those.
 
Honestly it's easier to get a convex on wheels than it is to get a hollow. On something like axes you have enough material to be creating a groove that you can then track into, but otherwise holding a consistent spot takes a pretty steady hand.
 
Moonw said:
Makes sense.
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Yeah--the angle of approach is measured from the tangent to the contact point. So if your hand position is moving forward or back without running parallel with the arc of the wheel you're totally changing your angle.
 
Curt Hal said:
I just started working on a Kelly Perfect DB. It has clearly been profiled to have a felling side and a splitting side. Much of my work so far has been to try and correct the edge geometry. This is my complaint against using grinders to sharpen axes. The round shape of the wheel against the edge of the bit can create a concave edge, not to mention a sloppy curve on the bit.) This was the case on the felling side of my Kelly Perfect. (Sorry, I should have taken photos.) I spent quite a while filing out the concave spots. Additionally, because the felling edge was concave and therefore too thin, the toe was chipped, which required additional filing. Similarly, the heel on the splitting side had a bit of a chip that needed remediation. Aside from the loss of temper concern, I think the electric grinder facilitates poor edge geometry and poor bit curvature. I don't think you can achieve a concave edge with a flat bastard file or a belt sander!
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My apologies for not being clear. I didn't use a grinder on the Kelly Perfect. The former owner did. In restoring this axehead, I am having to fix, using a file, the mess the former owner made of it.
 
Kevin Houtzager said:
Try using a smaller contact wheel and use something to lean on, like you would with a lathe. It's should work fine that way. I won't say its easy though! Why you would want a concave edge on an axe is beyond me though
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I think you misunderstood me--I wasn't in any way saying that a concave on an axe was a good thing. I was only remarking on how it's actually more difficult to produce a hollow on most edged tools using a wheel than it is to produce a convex. We just see it on axes a lot because there's so much material there for the wheel to make a channel in and then track from there.
 
Curt Hal said:
I just started working on a Kelly Perfect DB. It has clearly been profiled to have a felling side and a splitting side. Much of my work so far has been to try and correct the edge geometry. This is my complaint against using grinders to sharpen axes. The round shape of the wheel against the edge of the bit can create a concave edge, not to mention a sloppy curve on the bit.) This was the case on the felling side of my Kelly Perfect. (Sorry, I should have taken photos.) I spent quite a while filing out the concave spots. Additionally, because the felling edge was concave and therefore too thin, the toe was chipped, which required additional filing. Similarly, the heel on the splitting side had a bit of a chip that needed remediation. Aside from the loss of temper concern, I think the electric grinder facilitates poor edge geometry and poor bit curvature. I don't think you can achieve a concave edge with a flat bastard file or a belt sander!
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It's just amazing how many vintage axes are like this. It's the first thing I look at when I pick up a vintage axe. How much work is it going to take, can it be done and is the temper ruined.
It seems that most of the vintage axes I see have suffered from incorrect sharpening on small wheeled bench grinders. Some are just worse than others.
 
Its pretty easy to tell what the last guy used to sharpen an axe. And while I don't dispute that its possible to sharpen an axe correctly with one of those high speed, small wheeled bench grinders I can tell you how many I have found that were sharpened correctly using one. That number is zero. I can also tell you how many I have found that were ruined by incorrectly sharpening by hand. That number is also zero.

I stay away from the really bad ones but I have some examples of what those bench grinders do. Lots of hallow ground edges. Some of these have been fixed as best I could, others as found. The ones I hate the most is when they use them to thin the cheeks. I just can't fix that and those are the ones that don't really show up in the picture, but they are the most damaged ones. I can't add material to fix messed up geometry.






 
Ugh--I hate the "knapped"-looking chatter marks made by the improper use of bench grinders. Arguably, though, you may have come across heads that were properly maintained using a grinder and simply never known it. Those grinding wheels should be used for doing the heavy lifting only, and finished with a file or stone, so if done right then all the signs of it would be gone.
 
FortyTwoBlades said:
Ugh--I hate the "knapped"-looking chatter marks made by the improper use of bench grinders. Arguably, though, you may have come across heads that were properly maintained using a grinder and simply never known it. Those grinding wheels should be used for doing the heavy lifting only, and finished with a file or stone, so if done right then all the signs of it would be gone.
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This seems like it might be a source of some common ground?
 
FortyTwoBlades said:
Ugh--I hate the "knapped"-looking chatter marks made by the improper use of bench grinders. Arguably, though, you may have come across heads that were properly maintained using a grinder and simply never known it. Those grinding wheels should be used for doing the heavy lifting only, and finished with a file or stone, so if done right then all the signs of it would be gone.
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Don't forget about angle grinders! Even worse :eek:
 
Park Swan said:
Don't forget about angle grinders! Even worse :eek:
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When I have a bunch of pulaskis to sharpen for our local trail crew I reach for the angle grinder and flap discs. Like other powered methods you don't have to ruin temper if you're careful - and I am. You can power thru a pile of pulaskis in no time. If we didn't use power tools it just wouldn't get done.

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I like, prefer, and use files/stones most often. However, I have a few heads right now (Craftsman boy's axe, and a no-name of unknown quality) that I simply cant file no matter which ones I use. The heads are just too hard and I can't get the file to bite unfortunately. My files are vintage us Nicholsons and a big Heller that's never really let me down until now. It may getting dull unfortunatley :(. I managed to file the Craftsman initially, but only to get an "okay" profile on it more suited to splitting. It has a really nice high centerline, so to really get it to be a nice thin chopper, I think I'm going to need to grab the angle grinder and 36-grit flap disk to thin it out. I won't be near the edge and will keep it cool with water and a rag. (Full disclosure, I have blued a thin wire edge on an axe a while back with the flap disk when I wasn't being careful). I didn't ruin the temper of the edge itself, but it can happen for sure.

I've even tried stones...the Lansk Heavy Duty and the Baryonyx American Mutt coarse stones. They work, but slowly. It would takes hours and hours to get to where I want the head with the stones alone. My last resort is now the angle grinder int he interest of effort required. The axe should hold an excellent edge though based on this!
 
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