Now that the first prototype is finished, here are the results of the test run:
Adjusting the blade itself was easy enough : just tapping the blade a little at a time until it cut enough for the finished dowel to go through the exit hole.
I also had a little tweaking to do on the body for the blade to cut properly: I used a small rounding plane and some files to straighten the cone shape (remember how it was slightly crooked at the junction between the cone and the exit hole?). I also adjusted the blade holder to improve as much as I could the escapement of shavings.
Now for the actual result, it is, as I had started to expect since I first clamped a blade on the unfinished tool, somewhat disappointing.
Here is a close up of the resulting surface and you can see how ragged it came out:
In addition to the poor cut quality, shavings also kept jamming themselves either under the blade or between the blade and the holder. I had to back up the tool to clear out the shavings every so often.
Everything is not lost though as this 1st prototype got me thinking and I hope that the next iteration, whenever I find the time to work on it, should have all the more chances to perform properly.
The modification I intent to make on the next prototype are:
- Blade position. As suggested by Thomas and as one can observe from a regular pen sharpener, I will definitely try to place the blade in a more tangential position. The blade is currently too close to being radial. For this prototype, I used the plan from an old Fine Woodworking magazine article (Fine Woodworking #8 or so) and either the drawing was wrong or I did not understand it properly. The more I look at it, the more the blade position looks wrong.
- Geometry and angles. I will use the cone geometry that canadianchips kindly measured on his own tool.
- Blade holder. I will probably loose the blade holder completely, moving from a bevel down configuration to a bevel up configuration for the blade in the process. The blade holder proved to be a hassle, and it keeps trapping shavings that jam the tool. I can easily hold the blade in place with 2 screws and some large washers as the blade has slots cut in. Also, both canadianchips’ tool and Ray Iles rounder (http://www.toolsforworkingwood.com//Merchant/merchant.mvc?Screen=PROD&Store_Code=toolshop&Product_Code=MS-IROUND.XX&Category_Code=CRI ) do not feature any blade holder and do not appear to be any worse for it.
- Body material. The next iteration will not have a platanus/plane tree body but a beech one. Why? simply because I don’t have any more platanus wood and have been given a block of beech that could be used ;)
Thank you everyone who wrote me with encouraging comments.
Until next time,
-- Fabrice - "On est bien bête mais on sent bien quand on se fait mal" - my grandfather