O:T: sharpening old drawknife

K

Kevin the grey

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Aug 26, 2005
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This drawknife has had three owners that I know of so its been through the mill to say the least . It looks like it may have been used to split shingles at one time as the back of the blade has small dents in it along almost its entire length . It is also as dull as a lecture on creative writing ! L:O:L

The area behind the edge is heavily convexed . I know heavily is a relative term . Let us say the radius is more pronounced than upon my B:A:S: Kukuuri . To me this can come from two reasons . First reason being it was used and dulled and the person kept right on using it .
Second would be that the convex is by design of the sharpener .
I hope it is the latter .My question is how would I sharpen it . The blade has two ears where the handles bolt on . This makes it kinda hard to sharpen using the mouse pad and sandpaper technique as the ears would ride on the surface before the blade touches . I could put the mouse pad on a board no wider than the mouse pad therefor allowing the ears to extend below the level of the pad .
Can anyone suggest an easier or better technique than this ? I do not want to reshape the edge into a straight angle as I am learning of the great benefits of a convex edge .
 
A 1" belt sander ending up with a very fine grit belt and/or leather strop. Use a tub of water big enough to dip the whole knife in to keep it cool. Use it with the belt slack, and keep the edge down, so as not to cut the belt (or worse:( ) Roll the knife to maintain the convex shape. This would be my first choice.

If one were going to use stones, it wold be easier to bring the stones to the knife, rather than have it on the bench. It could then be rolled over the convex edge and keep the contour. I believe this is how old-timers did it. I would clamp it securely in a vise for safety reasons.

For fine work, the bottom (flat or convex) side should be flattened and mirror polished up to 2,500 grit SiC paper or a hard Arkansas or water stone. You don't see a lot of drawknives in use because they are tough to sharpen. They do the job though. Made a flintlock pistol stock with one a few years ago. Did 90% of the stock shaping with the drawknife, then went to a spokeshave. Very little sanding after that.
 
Bri in Chi I didn,t see where you expanded upon the strop method you mentioned . On another note I,m pretty good with a stone so I may try to duplicate the convex with that method . I don,t have a belt grinder so that method is out .I get pretty good use out of my draw knife as I scrape hides and am slowly learning to make archery bows with it .
 
Kevin, Brian is spot on when he says to polish the blade to a high finish. The higher the finish the smoother your cuts will be and the less finish work you will have.
Personally I think I'd use a board to fit the draw knife with the mouse pad for the finished edge anyway.

Of course a lot of how I would sharpen it would depend on how hard the old blade is. If a file will cut it then I'd simply rough it in with a good file maybe using it as a draw file and cleaning it frequently with a good file card.
 
The drawknife isn't really shaped to a full convex edge, since the bottom is flat. The convexed top acts more like the chip-breaker in a plane. It's a very different edge-geometry than a khukri. The whole thing depends on a very flat, polished bottom. Just like a chisel or a plane-iron :D
What kinda bows do you make?
 
Think I,ll try stoning then stropping for now as I don,t have suitable sandpaper . Thanks for the good advice on polishing up the whole blade front and back . The back is in good shape except where the previous owner hammered on the spine to split something . The hammer dents will be easy enough to file out . [

I am just starting to learn to make self bows and the guy who teaches me lives 80 miles away so my lessons are few and far between . I made one that he tillered and I am on my second one which I want to do back to belly and board to tillered .I am making pyramid style bows as they are called an automatic tiller design . Its not quite true but it does make tillering easier . I am making them with ash as I have a supply of the best ash the bowyer has ever seen . I hope to get a good piece of hickory one day as I think hickory shoots a heavy arrow really well .
 
I can't imagine why you would want a convex edge on a blade designed to shave, rather than chop. A convex edge is perfect for a heavy edge and hard work....a khukuri for chopping, or a hatchet, or a hunting knife for heavy work. A smaller included edge angle is suitable for softer woods, and a more obtuse angle is better for harder woods. I use a pretty small angle for my paring chisels, but a convex edge would be avoided - like the plague - on a paring chisel, plane iron, etc.

I can't see any advantage to a convex edge on a blade for shaving wood - it would be much easier to get a finer edge on a drawknife with a bevel shaped edge and a microbevel at the edge.

I would use a fine India slip, followed by Arkansas stones. Finally, I'd use a fine leather strop for hardwoods like Maple.
 
We have another opinion here as to the convex edge . The only advantage I could see from my limited experience was durability of the edge . At this time and considering the extent that this edge is radiused (SP) I won,t be reshaping the edge . At least not soon .For one thing I would lose a lot of useable blade and I don,t have the powertool to change it or the good file it would take to do it by hand . I,ll take a medium or coarse stone to it then strop it if I can find an abrasive powder for a good Price ? Does anyone have an idea as to what is an inexpensive abrasive for the strop as well as where to get it ?I think I can use the strop without an abrasive . Isn,t it less efficient dry ?
 
2 cents from bowmaker. I m using drawknife all day. Keep it progressivelly dull. If you sharpen it, itl turn in your hands and dig into wood.
I never sharpen it. Drawkwnife wasnt meant to cut. Its meant to separate layers of wood without cutting in.
No good bowmaker sharpens it.

That might be different when doing exlusivelly carpenters work, but I m using mines for everything and works just fine.

Just keep the blade clean and without teeth and roll ups and it will do.
 
I guess it all depends on the use to which you're going to put it. If you're using the drawknife as essentially a splitting tool, then sure - keep it dull. Probably whatever blade geometry you like will work there.

As a woodworker building furniture, boats etc., I want a sharp drawknife, with a chisel's geometry. A flat polished back, and a bevel like a chisel on the top. I use stones to sharpen my drawknife: one technique is to clamp it in a vise, and move the stone over the blade. I also make a small secondary bevel at the edge, though some don't. For the way I use it, a sharp drawknife is less likely to slip, less likely to injure you, and cuts much more cleanly. If you skew the drawknife as you pull it towards you, you'll get a slicing action; with practice, you can get shavings as thin as from a plane.
 
Yes, true to boot...

I also know how to make thin shavings with drawknife, but in my proffession is essentiall to work in the frame of the wood grain when following the bw back.
Here the chiping off the pieces, rather than shaving is needed.

I also make lot of axe handles and other things, for which I use another drawknife, but I never considered necessary to keep it that "shave my forearm" sharp.

It also depends of how one moves the blade and I m tought to do it different way than furniture makers do.

I always envyed boat and ship builders, as this is work I liked to do, but we dont have any sea.

Jaroslav
 
Thanks for the good tip Tom . A variation on what you suggest is proabably what I,ll do for now .

Hawkwind I,m new at making bows and have never worked with a very sharp drawknife so I couldn,t tell the difference . I guess without seeing the drawknife you can,t tell how really dull it is . I,ve had sharper butter knives . I have been using a stone on it but it is much too fine a stone and the knife just dulls up after ten minutes . I may just take a medum stone and make it progressively sharper until it approaches what I am comfortable working with .
B:T:W: The bowyer I am working with isn,t religious about chasing a growth ring on the back . He says his design is so strong you can violate one growth ring without harming the integrity of the bow . He has one bow with three hundred thousand shots out of it .
 
Hey guys, I just want to give you an idea about another tool to use. Lee Valley Veritas low-angle spokeshave. It is a great spokeshave that can cut convex or concave by reversing part of the tool. It is really a good tool and may work great for what you guys are doing. Lee Valley has a great website, lots of cool and inovative stuff as well as traditional classics.
 
I can see how, for bow work, essentially you want a "riving tool." You want to split the wood rather than cut it, so that you maximize the strength of the piece. The folks who custom make windsor chairs in the traditional way split the wood they use for everything except the seat of the chair, for exactly the same reason. It maximizes the strength of the long/narrow pieces of wood when grain runout is eliminated. Especially important in wood that will be under bending stress, and where you want it to be as light as possible for the strength you need.

BTW, I'm only an amateur furniture maker and boat builder ... though I have plans to do more, as life allows.

t.
 
I can see that. I am a fledgling luthier myself. Some instrument parts are better if they are split out too. Usually there is still some fine shaping though and some minor runout is not bad in most cases for instruments. Just an idea I had, as that tool has really helped me out for some of my applications.
 
Haven't bought one of Veritas' low angle spokeshaves (yet), but they look grand.

Bob, what instruments do you make, or do you want to make? My daughter plays cello ... as I once did too. I'd love to eventually make her an instrument, but that's a long time away.
 
Tom, I am focusing on guitars. That is pretty broad in itself though. I have done an electric from a kit, pretty much just assembly. I am doing a dreadnought acoustic from a kit that is more involved, shaping of parts and the like. I am going to do a two week apprenticeship next month where I will build a jumbo flat-top with William Cumpiano. He sort of wrote THE book on guitar building. He takes a few students every year for one-on-one training. Two years on his waiting list, wait is over next month. After that, I want to try a semi-acoustic electric and then maybe an archtop jazz guitar. I may end up in the cello/violin area yet. I am just taking it a step at a time.
 
Kevin the Grey;

I agree with you about saving blade edge. I'm in no hurry to re-profile edges, unless the work required for the blade demands it, or it must be re-profiled to correct or make it strong enough for the job. I have a 25" AK that Yvsa re-profiled for me. It's edge was too slender in my opinion and might, I say might, have broken under hard use. Now it's re-ground into a nearly convex edge, it is much stronger and probably won't break A break would have hurt the knife, and lost much more of the metal in repair than putting a new bevel on.

But if a khuk arrives that could use a more convex edge, I won't put one on immediately. I use and sharpen the blade as needed, and in this manner over time achieve the edge I want. But the blade has worked for me in the meantime, and my money has been well spent.



munk
 
But if a khuk arrives that could use a more convex edge, I won't put one on immediately. I use and sharpen the blade as needed, and in this manner over time achieve the edge I want. But the blade has worked for me in the meantime, and my money has been well spent.

munk

Kevin
So you are saying I could slowly convex an edge over time as well as take a convex edge off and put a straight bevel on ? In the meantime I would still have a useable tool ? I guess up until the transition is complete the tool would need sharpening a bit more often . As you say at least this method makes use of the blade material instead of just removing it . Do you happen to know do H:I: seax come with a convex edge ? It seems to me it it a hacking / chopping tool with a good point for puncturing.I think a convex edge should loan itself to that except the puncturing part .
 
Kevin,
I won't predict which knives will come with a true convex edge. Some models seem to have this more than others, and some of the edges are not convex but a Sabre grind, as I've learned from the experts here. I think many of the edges are half way to a true convex. When we had the Maoist uprising several years ago, the blades were arriving with thin non convex edges. That is not the case today.

The last three blades from HI I have, have been convex. Yes, you can use your blade and gradually get the edge profile you want, though at some point you may or may not have to remove metal above the actual cutting edge which of course would not have been touched in normal sharpening.


munk
 
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