I am back with a new update which brings us to the current state of the project.
First of all, thanks to everyone who shared their interest on this experiment.
As I basically make it up as I go along, any advice, past experience or actual tool description is very welcome.
I did not have a spare blade lying around so I bought a cheap (still it is high carbon steel and appears to hold an edge decently) block plane blade. I chose a block plane blade as the metal is thicker than many bevel down bench plane blades and the width matched the dimensions of the tool.
Here is the blade straight out of the parcel, with a mark on it to show the desired angle :
As you can imagine from the above picture, shaping the blade to the correct angle, flattening the back and then honing the bevel took a little while (about 1 hour) It would have been much quicker if I had owned a coarse dry grinder instead of my relatively smooth and slow wet grinder.
Here is the result :
Obviously it does not show on the picture but I managed to get the edge really sharp. Bevel angle came out about 30 degree which looks kind of right.
The next step will be to recess the blade holder (or the actual body itself, I do not know yet) so that it can be screwed back onto the body and its height comes back to what it used to be before I kerfed it with my saw. (does anyone even understand this sentence ?).
In other words, if I screw the blade holder back on like it is now and without the blade, it will come 1 kerf short of the top of the body. The goal is to recess the blade of its thickness minus the original saw kerf which should garantee that the top of the blade holder ends up flush with the top of the body (which is required for the bored hole and cone to keep their proper shapes).
I could not resist a quick test with a 22mm dowel and the blade clamped on the body alone :
The blade on the picture appears almost square accross but it was really the same angle as penciled above.
This quick try was rather disappointing as you may see on the picture that there was very heavy tear out when I gave the dowel a few turns.So far the various explanations I am considering for the tear out are :
- The blade geometry within the tool might be bad. Right now, the blade is almost radial to the cone and I am considering wheter the finish might be smoother with a lower angle, so that the blade gets more tangential to the cone.
- The blade might be sticking out too much from the surface of the cone, creating chatter. If I could take a smaller shaving out of the dowel, there might be less tear out. This is probably linked to the irregular shape of the cone, a straighter cone (especially near the transition bewteen the cone and the bored hole) might enable a thinner shaving.
From there, my next course of action will be to continue with the current iteration of the tool (recessing the blade holder or the body to accomodate for the blade) and see the results. If I still get heavy tear out, I will try to correct the shape of the cone by hand with gouges or rasps and then if it still does not work, I will probably try to find another blank of wood to experiment with different blade angles and locations.
If anyone owns a wooden or metal rounding plane, I would be very interested in some information regarding its geometry. I am particularly interested in rounding planes by Ray Iles (http://www.toolsforworkingwood.com//Merchant/merchant.mvc?Screen=PROD&Store_Code=toolshop&Product_Code=MS-IROUND.XX&Category_Code=CRI) if anyone owns one.
Until next time,
-- Fabrice - "On est bien bête mais on sent bien quand on se fait mal" - my grandfather