Thoughts on axe grinding jigs

A

Au_Craftsman

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Oct 2, 2019
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I set out this week trying to find 1 new axe head to restore but may have gone a bit overboard seeing I now have 9 axe heads and no money haha but that's alright.

Previously I have been using a belt sander to set the bevel and then sandpaper to polish and although I have been improving they still arent 100% perfect and although good enough for work I am trying to get them spot on.

I am planning to build a jig to hopefully fix this, it will be a adjustable height pin at the end of my belt sander so I can use the height to adjust the angle and get a specific grind. I will probably have it about 10cm from the edge of the sander I don't think the distance matters but may be wrong. What size bolt or screw should I use to rest the axe on and what size drill bit / what depth should I use to make the hole it sits in? Thanks very much for the help
 
Without more descriptive detail about how you intend to put it together, the arrangement of the machine and the workpiece, and your intended method of use, or without a diagram to that same effect, it'll be difficult for us to give any sort of constructive input. All that said, I'd personally say just keep working on developing your freehand skill.
 
It's a relatively simple design, there will be the stand going to the ground and a thread at the top of it a bolt can be put into. By twisting the bolt in / out it will change the height of it thus changing the angle it sits at. Thanks definitely will do, I also use the sander for knives so always good to get better at doing it freehand
FortyTwoBlades said:
Without more descriptive detail about how you intend to put it together, the arrangement of the machine and the workpiece, and your intended method of use, or without a diagram to that same effect, it'll be difficult for us to give any sort of constructive input. All that said, I'd personally say just keep working on developing your freehand skill.
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The diagram is of questionable quality haha but I'm sure it conveys the idea.
W1d7Ay6.jpg
 
I have to recommend not using that setup. I only use a belt sander if the steel I'm working is so hard my best files won't cut it. Usually chisels. For axes, even though it's time consuming for sure, I use files. You run no risk of drawing the temper out of the bit. If you are careful you can do it and some guys on here do. But I for one avoid it at all costs.
There's also the fact that using the bolt you'll be grinding a flat angle and that is not the ideal outcome. You want a nice convex grind right at the cutting edge. Check this out;
20200104_141450.jpg
And lastly any grind that's worth having behind the cutting edge is much easier to achieve with a file. And it's fun! Directly working with the steel is a fun way to feel connected to the axe.
Anyway I wasn't going to bother because opinions differ. But after all you asked! So there's my .02c
Good luck man!

Edit; I forgot to add(and this is equally important) that a convex edge will burst a chip much better and not get stuck nearly as often. And that will help the longevity of your hang.
 
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Maybe you're thinking of something like this.

https://www.fs.fed.us/t-d/pubs/htmlpubs/htm08232327/

That will do a decent job if you're happy with a radial grind. On flat-cheeked axes a radial grinbd is as good as any. But on a convex-cheeked axe you're better off with a banana grind or half-banana grind. These are best achievable with a good file followed by stones.
 
Thanks alot I definitely see where you are coming from, I will be also making a jig for hand filing / polishing to repair the edge after the bevel has already been set. To be fair I have ruined a temper before when just learning but can put a decent grind on with a belt sander now that I have some practice. I currently have a convex edge on most of my tools but im hoping with a jig i can get a flat chisel grind which I am told my chop better and is often used on race axes. I know convex is stronger but with a larger collection now I have room to experiment with different grinds. Thanks again for the advice I will make sure to do one with a file too to compare

That being said you have alot more experience than me so you are probably right about using a file instead

Yankee Josh said:
I have to recommend not using that setup. I only use a belt sander if the steel I'm working is so hard my best files won't cut it. Usually chisels. For axes, even though it's time consuming for sure, I use files. You run no risk of drawing the temper out of the bit. If you are careful you can do it and some guys on here do. But I for one avoid it at all costs.
There's also the fact that using the bolt you'll be grinding a flat angle and that is not the ideal outcome. You want a nice convex grind right at the cutting edge. Check this out;
View attachment 1260901
And lastly any grind that's worth having behind the cutting edge is much easier to achieve with a file. And it's fun! Directly working with the steel is a fun way to feel connected to the axe.
Anyway I wasn't going to bother because opinions differ. But after all you asked! So there's my .02c
Good luck man!
Click to expand...
 
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Thanks alot mate that's pretty much what i am planning on except with the head pivoting instead of the grinder.

A perfectly symmetrical radial grind would be a step up from what I have currently although I do agree and will also soon be trying to learn how to Banana grind to see how it performs on local wood.
Square_peg said:
Maybe you're thinking of something like this.

https://www.fs.fed.us/t-d/pubs/htmlpubs/htm08232327/

That will do a decent job if you're happy with a radial grind. On flat-cheeked axes a radial grinbd is as good as any. But on a convex-cheeked axe you're better off with a banana grind or half-banana grind. These are best achievable with a good file followed by stones.
Click to expand...
 
For reference, convex edges are actually thinner than flat-ground edges of equal edge angle. Think of it as being like if you took two identical flat-ground edges and then ground the shoulders off one of them. That's essentially a polygonal version of what's going on with a convex. It's (conceptually) like there's just so many flat facets of continuously reducing angle behind the edge that it causes it to appear as a smooth and continuous curve. When a convex is stronger than a flat grind it's because the edge angle has been made thicker, and so too has the geometry been made thicker, as a result. :)
 
rjdankert said:
FWIW

uKTg0H5.jpg



Bob
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Note how all of these employ a fixed bevel width rather than fixed apex angle, and so each have different angles to them. When bevel width is held fixed, concave is the thinnest geometry and convex is the thickest, but in reality we don't typically impose a limit on the visual bevel width, and so comparisons are best made by comparing the angle at the apex. This illustrates the principle I mentioned where a convex edge that is stronger that a flat one must inherently have resulted from increasing the edge angle rather than keeping it consistent. :)
 
Yes ^. In free hand sharpening there is usually some convexing that takes place. I've looked at my edges for years and yes, it's
present. I could after sharpening remove some shoulder on the edge and make it look even more convex. But what is the need? I'm just going to be slamming it into hard wood for a few hours and sharpen it after a day or two. Besides in a year it will naturally become more convex. DM
 
I'll periodically re-dress the cheeks/bevels of all of my cutting tools as time goes on to make sure they stay in the right range for their context of use, but figuring out which bits to care about and which bits to mostly not bother with sure helps you get straight to work with less dilly-dallying in details that end up having minimal impact in the long run. If you're able to get those "ideal to have" aspects squared away without undue effort then it's great, but if not you're still close enough that you're not suffering significantly for the lack. Bevel setting usually only needs to be done when you first get a tool, then after that just honing work is needed for quite a long time. Once things actually thicken up or you experience damage, that's when it's time to re-bevel, but then it takes a lot less time than the first because the geometry you've got isn't too far off the mark. :cool::thumbsup:
 
FortyTwoBlades said:
I'll periodically re-dress the cheeks/bevels of all of my cutting tools as time goes on to make sure they stay in the right range for their context of use, but figuring out which bits to care about and which bits to mostly not bother with sure helps you get straight to work with less dilly-dallying in details that end up having minimal impact in the long run. If you're able to get those "ideal to have" aspects squared away without undue effort then it's great, but if not you're still close enough that you're not suffering significantly for the lack. Bevel setting usually only needs to be done when you first get a tool, then after that just honing work is needed for quite a long time. Once things actually thicken up or you experience damage, that's when it's time to re-bevel, but then it takes a lot less time than the first because the geometry you've got isn't too far off the mark. :cool::thumbsup:
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Yeah that's a fair point but I am a perfectionist and when restoring the more high quality vintage axes it is preferred to do the best grind possible so it does not diminish the value.

I have been given advice from a very knowledgeable bloke who grinds the professional race axes. Although a convex grind on a knife may be preferred a flat grind is much superior for chopping on an axe and because of this it is used in racing and timber sports. Flat grinds are much better for wood which is why chisels and planes are flat ground and why a flat grind on an a axe is called a chisel.

Not saying you are wrong a convex grind can be good on some axes since it Is more durable so fine for most, but if efficiency is the way to go then usually a flat grind with small micro bevel is what you want.
 
Au_Craftsman said:
I have been given advice from a very knowledgeable bloke who grinds the professional race axes. Although a convex grind on a knife may be preferred a flat grind is much superior for chopping on an axe and because of this it is used in racing and timber sports. Flat grinds are much better for wood which is why chisels and planes are flat ground and why a flat grind on an a axe is called a chisel.
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A flat or even hollow ground bevel for plane blades and chisels is in the first instance to provide a reliable surface against a bench stone for maintaining the cutting edge. Were these bevels convex this would make getting at a keen and precise edge infinitely more difficult given the mechanics of sharpening and whetting them which in theory is a much more controlled action compared to typical work with axes. Remember in all but some specialty planes the iron is mounted bevel down so never even comes in contact with the wood. Perhaps in the case of timber sport there are refinements involved which relate to the particular woods and the nature of competition, OK, they have their reasons but beyond that a convex bevel for axes in most cases is suitable given the percussive nature of their use.
 
Ernest DuBois said:
A flat or even hollow ground bevel for plane blades and chisels is in the first instance to provide a reliable surface against a bench stone for maintaining the cutting edge. Were these bevels convex this would make getting at a keen and precise edge infinitely more difficult given the mechanics of sharpening and whetting them which in theory is a much more controlled action compared to typical work with axes. Remember in all but some specialty planes the iron is mounted bevel down so never even comes in contact with the wood. Perhaps in the case of timber sport there are refinements involved which relate to the particular woods and the nature of competition, OK, they have their reasons but beyond that a convex bevel for axes in most cases is suitable given the percussive nature of their use.
Click to expand...

Yeah I agree they are suitable for most uses but I made it clear before that I was trying to get the best performance. It depends what the goal is.

For an axe which you would prefer to have to maintain less a durable convex is fine but if you want to get the most progress for your time and energy spent chopping then a chisel grind is usually the way to go.

That being said I use a convex on my splitting axes and any axes or hatchets I bring camping. In this case I would rather have a more sturdy edge which is less likely to be damaged and will require less maintenance as repairing your edge after it's chipped from a knot isn't the easiest with just a small stone.

Ideally different types of axes are ground differently even if aiming for performance as a Tassie pattern made for hardwood is very different to an axe made for soft green woods. A 17* angle is fine for pine but if you take that to a redgum here in Australia it's likely to ruin your edge.
 
So correct that the more specialized the action the more an opportunity to refine things and as a rule that conventions are poorly suited to individual conditions. Remembering that in principle the flat bevel will result in a harsher surface left behind because of the absence of a mechanism allowing for the cutting edge exiting the cut. Another way to put it is the convex bevel acting as an effective pivot.
 
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