Introducing the K4
Several years ago, I was given a rare opportunity to live with, and study, a very rare plane. A Spiers thumb plane. To be honest, I did not really appreciate this opportunity until several weeks into my time with it. I knew it was rare and therefore valuable, but I underestimated the design and functionality of it. I thought my first infill was ordinary - an un-handled Spiers coffin shaped smoother... this plane looked even more basic.
Until I used it.
It was a pretty amazing experience. Everything was exactly where it needed to be. There was an amazing relationship between the sneck of the iron, the top of the lever cap screw and the empty area at the front of the plane. There was a complex and deliberate relationship between these points and they all worked together to provide a very comfortable experience. I was pretty shocked and was once again reminded that simple looking, does not mean that complex design thought did not go into something. I kept this experience tucked away until the time was right.
As I have been exploring the K-series of planes, it made sense to consider a really small plane - a true one handed plane. This was the goal for the K4.
I outlined the specs I was after. It needed to feel like that Spiers thumb plane - the relationships between the elements was critical. I wanted it to be taller - like the XSNo.4. The extra height allows it to fill out your hand a bit more and provides a place to put your fingers (along the edges of the plane). I have a few traditional block planes and they are great until I want to use them in the middle of a surface - they are so squat that I spend more time figuring out where to put my fingers than actually working. And my fingers are always cramped up anyway.
If possible, I wanted it to have a similar front pad design to the rest of the K-series planes. I also thought the angle to the rear infill would be an advantage for getting the geometry right for a one handed grip.
The plane would be 4-1/2" long with a 1-1/4" wide blade. I opted for a 52.5 degree bed angle again.
It was a real challenge to get everything into such a small plane body. The lever cap design needed some serious modification to allow it to fit inside this small space and be functional yet still look like the lever caps in the other K-series planes. The scoop on the front pad is not at all functional from the standpoint that you cannot get your finger in it, but it does serve a very important practical purpose. It allows the top surface of the pad to be wider allowing the plane to be used with 2 hands if you want. It is wide and long enough that you can 'pinch' it for planing an edge.
The sides and sole are 01 tool steel, the lever cap and screw are bronze and the infill is Desert Ironwood.
A few photos of the K4 with a few other planes to give a sense of scale...
(with a Lie Nielsen 'Violin plane')
(with the XSNo.4)
(with the K7)
(with the K9)
Here is the grip that I use with the K4. The palm of my hand fits comfortably against the angled rear infill. The tip of the blade tucks into my hand. I can feel it, but am not putting pressure on it - the top of the lever cap screw is slightly higher and helps facilitate the natural curve of one’s hand. The distance to the front pad is also key - as is it’s height and shape. Typically one handed planes have a depression in the front grip - suggesting your index finger rests inside it. I have often found the geometry of that depression to be too low - tilting your hand a little too far forward and down. The idea behind not having a depression is to allow for a larger variety of finger positions and the height of it should keep your wrist in a more natural position (less stress during use).
I will have the K4 with me at WIA this year, and am looking forward to people trying it out and giving me feedback. It feels great when I use it, but nothing beats getting tools in the hands of other woodworkers to really test it. If you are going to WIA this year, please stop in, say hi to Joe (Steiner) and I and try out the K4 or any of the other planes.