As far as I know, most axes have convex edge. But Tormek changes it into hollow. Is this OK?
I think axe jig should be able to handle convex edge.
Quote from: sharpco on November 26, 2017, 01:28:01 PM
As far as I know, most axes have convex edge. But Tormek changes it into hollow. Is this OK?
I think axe jig should be able to handle convex edge.
Not being an ax user, (and the only ones I've sharpened I used an angle grinder on, 'cause that's all there was)... I'll take a total guess here... that the overall blade shape/geometry of the ax will determine how well it cuts... not the final edge put on by the Tormek.
At some point, you may have to re-establish the overall profile of the
knife ax. ;) This may require another sharpening (actually grinding) method.
The axe jig is one of two Tormek jigs I do not own. I have been tempted, however, since I do not own an axe, I have not purchased one. Neither have I sharpened an axe.
I am curious to read the replies. As I recall, some of us have successfully sharpened axes with the Tormek.
At first glance, it would seem challenging to grind a convex bevel with a convex wheel.
Ken
If you look at a new ax you will see that the blade consists of the two surfaces that meet to the form the edge, and they are nearly, if not completely, flat. The slight hollow grind of the Tormek grindstone is close enough to flat across the blade, as it's only a few millimeters wide.
The convex part you are talking about is the cheek. As you move away from the edge into the cheek the steel gets thicker, and those surfaces are not flat. A felling ax is concave if I recall correctly, but a splitting maul is indeed convex. This cheek profile is shaped differently for different axes, but it has little to do with the shape of the profile of the blade, and the blade is the portion you grind on when you sharpen the ax. I would think that if an ax has been sharpened so many times that the shape of the cheek is no longer what it should be to do the job properly, it's probably time for a new ax. I suppose it would be appropriate under some circumstances to try to reshape the profile, but a Tormek would not be sell suited to this task.
As Herman says, not all axes have convex bevel - splitting axes do, but carpenter's axe do not.
Convex bevel is advantageous with striking blades like splitting axes, which are hindered by a concave bevel edge. Those tools don't work as well with a hollow grind because the shape of the bevel "stops" the force of the stroke.
Check our procedure for sharpening hatchet & carpenter's axe http://knifegrinders.com.au/06Procedures_axe.htm (http://knifegrinders.com.au/06Procedures_axe.htm)
Thank you, all.
I'll try it with Tormek when I need to sharpen the ax later.
Quote from: wootz on November 27, 2017, 02:23:29 AM
Check our procedure for sharpening hatchet & carpenter's axe http://knifegrinders.com.au/06Procedures_axe.htm (http://knifegrinders.com.au/06Procedures_axe.htm)
Wootz, what do you mean by "25 degrees included"? From the photograph it looks like you're sharpening at a 25° bevel angle, which would put the edge angle at 50°. I'm just curious about your terminology.
Herman, you gave me a fit of a panic attack, but I rechecked that webpage and see nothing wrong.
25 degrees included is the standard for axes, we sharpen them at 12-13 degrees per side.
For example, see page 29 of the American edition for Ax grinding:
http://knifegrinders.com.au/dropbox/Ax_grinding.pdf (http://knifegrinders.com.au/dropbox/Ax_grinding.pdf)
If you still see a misfit in any our photos please do let me know.
Wow! No wonder you can shave with them!
I would think that with an angle that small the edge wouldn't hold up to chopping. Certainly a wood chisel, cleaver, or kitchen knife wouldn't.
My Fiskars splitting axe has double concave blade geometry. The included cutting edge angle is between 25 and 30 degrees.
Jan
Just got a T-8, and after doing my lathe chisels, I started attacking other things I had lying around, like this axe I picked up at a garage sale a couple of years ago, and which had just been gathering dust in my shop since the edge was so severely damaged. The head was too big for the axe jig, so I just worked it on the tool-rest -- somewhat clumsily, initially, as you can see by the multiple bevels. But eventually I got a nice sharp edge. Haven't tested it out on wood yet, but it slices the heck out of paper!
Welcome to the forum ear3, and thanks for sharing your results. I like your old axe. For splitting purposes the bevel is OK.
Sometimes I use a small clamp to better define the stop. For me it works better than the index finger stop, especially when reshaping the axe.
Jan
Thanks for the screw clamp idea. When I first tried with the universal support, I actually tried rigging up a plywood jig that approximated the radius of the axe and clamping it to the head, but the topography of the head was such that it wasn't stable. But the screw clamp might be an elegant solution with the built in radius of the clamp jaw.
BTW, I didn't realize the Festool screwclamps were simply rebranded Protool ones, but I guess that makes sense given the merger of the companies.
Jan is the master of ingenuity! ;D
Ear3, you are correct, the screw clamp shown was made by Protool.
When the circular flat end of the clamp's screw roles without slipping along the USB, than the points of the edge trace a curve called extended cycloid.
Jan
P.S. Click the image to start or stop the animation.
Quote from: Jan on December 06, 2017, 10:06:25 PM
Ear3, you are correct, the screw clamp shown was made by Protool.
When the circular flat end of the clamp's screw roles without slipping along the USB, than the points of the edge trace a curve called extended cycloid.
Jan
P.S. Click the image to start or stop the animation.
Your posts always make me think (and I had to sleep on this one), ??? but this doesn't affect the ax head being sharpened, does it? (Unless the head was actually attached to the circle at a point, and following that path you show...
(https://forum.tormek.com/index.php?action=dlattach;topic=3448.0;attach=1428)
... if it did, I'd think you'd see little "arches" on the ax, (since the radius isn't the same)? ???
(Either way, I learned something new!) :)
CB, you are correct, there is whole system of scratches on the axe bevel.
The animated cycloid is not very instructive, because in reality the radius of the clamp jaw is many times smaller than the distance between the USB and the LOC, where the axe meets the stone.
Jan
Quote from: Jan on December 07, 2017, 06:53:37 PM
CB, you are correct, there is whole system of scratches on the axe bevel.
The animated cycloid is not very instructive, because in reality the radius of the clamp jaw is many times smaller than the distance between the USB and the LOC, where the axe meets the stone.
Jan
I will have to ponder this one for a while... unless the ax was actually attached to the rotating wheel... I'm not seeing it. ???
(But, you know me... sometimes it takes a while). ;)
CB, your understanding is correct. My description was probably not accurate enough, you know I am an alien. ;)
When the screw of the clamp is tighten, then the wheel of the clamp jaw is firmly attached to the axe head.
Jan
Quote from: Jan on December 07, 2017, 11:19:27 PM
CB, your understanding is correct. My description was probably not accurate enough, you know I am an alien. ;)
When the screw of the clamp is tighten, then the wheel of the clamp jaw is firmly attached to the axe head.
Jan
Your description is fine... I just have to think and get a bit more detail. :o
I think I understand it now. :)
I have honed the bevel of the old axe (shown in reply #16) on the honing wheel and measured BESS sharpness. The score is now 230 gf, which is quite good value for such a thick blade with 35° included edge angle.
Jan