Type of edge needed on drawknife

K

Kevin the grey

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Aug 26, 2005
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I am slowly learning to shave out a tomahawk handle useing a drawknife .
I am slowly bringing back the convex edge to an acceptable state . I have been advised that to shave curves it would be wise to put a few degress edge on the back of the blade . I suppose this is to facilitate the angling of the blade into the curve . Would it be necessary to do this to a drawknife that is going to be used on the gentle curve of the top of the hawk handle . If so how many degrees ?
 
If you face the bevel towards the wood so the flat back is facing you, it is easier to cut curves. Back bevels are generally really small as in a few degrees. You need to increase them if the bevel sinks in too aggressively, it is pretty easy to judge by feel. This is generally more of an issue on rather extreme curves though than gentle slopes, working the inside of an arm rest for a rocking chair for example.

-Cliff
 
As usual a great answer . I see that the few degrees on the opposite side will tend to equalise the other sides tendency to draw the knife into the wood .

This drawknife has been batonned by something hard and so the spine will take a little filing to give me a clean slate to start with . Its not badly damaged .
 
Yes, there is also versatility in the assymmetry of the design because you can face the dubbed back bevel into or away from the wood and get a different responce. Spines get beat up a lot, I have seen a lot of nice small hatchets which were mangled that way, the eyes usually deform and crack. This usually happens through lack of experience using a carving hatchet for kindling. The good thing though is that often the damage is cosmetic and now there is little demand for such tools given the ease of power machining wood so they are pretty cheap to get used. I picked up two spokeshaves last week which were just being thrown out having not been used in probably 20 years. It is not trouble for find scads of old sharpening stones that way which just need some lapping.

-Cliff
 
You can boil the oil out of a stone, I have done this, the oil gets in the steam though so don't do it inside. Alvin has also baked it out on many occasions as noted on rec.knives. If the surface is just gummed up then you can reset it on a piece of concrete with some fine sand. You can also use really coarse sandpaper, or actual lapping compounds on a piece of glass.

-Cliff
 
Yes, I typically use a concrete block and fine beach sand. I have tried coarse silicon carbide lapping powder on a glass lapping plate and it was no better. However I generally don't use ultra fine stones, you probably don't want to take a 30000 grit $600 Shapton to a concrete + sand.

-Cliff
 
Its hard to tell how coarse it is because of the loaded up oil in the surface . I got it with a few small cylindrical and triangular stones that clink when touched with metal and are quite light . I got a nice small Norton stone in a plastic slip case and two sizeable stones . One in wood box holder and another loose in kind of an oil paper .
 
You can't really damage a stone with a coarse lapping, the one reason you would not do it to a really fine stone would be that it would wear away too much of the surface and the gauges it would leave would make the finish the stone produces rougher than optimal. Of course if the stone is loaded or dished or chipped, then you grind it flat and clean first. Same principle basically as reshaping a heavily damaged edge with a file before you think about actually sharpening. I am looking for the older arkansas stones. I want to try the clear ones.

-Cliff
 
You can also soak the stone in mineral spirits to disolve out the oil and other assorted gummy residues. I use cheap A/O stones to resurface my good stones. They can be found for around $2 a piece. I even resurface the A/O on my belt grinder as long as they are 6" or less in length.
 
Yes, I have a hard black one and a soft white one, I have never seen any of the translucent ones locally. I have lots of stones though, just something I keep an eye out for.

Aluminum oxide is one of the more common sharpening abrasives commonly refered to as AO, silicon carbide (SiC) another, and CrO is a fine abrasive which is a mixture of chromium oxide and aluminum oxide.

-Cliff
 
I delved in my file tool box and came out with a few different files to try on the drawknife . These bite in a little bit more . It still feels like they are almost skating on the edge . They do a bit better job . The drawknife is shaving wood now . The poplar is a pleasure to shave . It almost shaves like ash . It tends to dig in occasionaly which is not like ash . This may be due to the file job I did or the fact that I am working with a slim tree trunk as opposed to almost blemish free lumber . My hawk handle is slowly taking shape . I am mostly doing this free hand with the occasional glance at my original handle . This is opposed to stopping taking close looks and pencil shading the areas that need wood removed . I will soon have to resort to the pencil method for the final touch ups . Itsa a pleasure to be shaving .
 
If a file is actualy cutting the edge of your draw knife then someone did not harden it correctly. That is the test to see how good an edge heat treated/hardened. If the file digs in then it is not hard enough.

I designed and built a stone file system so I can free hand put on an edge or sharpen knives and hawks. It also can be used to stone finish a knife. It puts a nasty wicked edge on my draw knives to!

http://groups.msn.com/Brentscustomknives/stonefile.msnw?action=ShowPhoto&PhotoID=257
 
B Finnigan do you clamp the drawknife in a vice and two hand the stone file on it ? Those look like nice stones . You designed it from scratch ?
 
I use two 3/8" pieces of hardwood with a hole drilled through both of them. I then put a 1/4" carriage bolt with a wing nut and sandwich the draw knife between the two pieces. Then secure the whole thing in a vise and start sharpening.

Yes the stone file is my own invention. I got tired of using stones as a file but not having enough control so i needed a secure mounting system for them. It also keeps your fingers farther away from the edge.:eek:
 
Kevin the grey said:
Yes I have concerns sometimes when sharpening that blade and fingers are a little too close sometime .
Click to expand...

When I use the files to bring back the edge on my drawknife I get a "wire edge " (if I a musing the right terminology) all along the edge of the blade . The thing is this edge is not consistant . There are gaps in that the edge ends up looking like a serrated blade . It is my theory because the blade nedds so much work it causes the gaps . I am being fairly careful to keep the blade level when passing over the file . I don,t think the blade itself is perfectly flat . That might be a contributing factor . I don,t think that is the main question as the gaps are all along the blade . What do you think ?
 
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