Saturday, February 14, 2015

designing blocker

I am in the process of designing a blocker, or "stock knife" which was one of my objectives at the launch of the school year. The drawing shows the rough forged blank, and the finished shape of the knife above including the hook which attaches it to a large staple driven into a stump. The pointed part is where a turned handle will fit, making it comfortable for use.

A blacksmith friend has offered to help me with this project and believes it will be within my capacity with some careful coaching. I plan to make two or three for use at the Clear Spring School.

I acquired a truck spring as a source of steel, and will use the forge and power hammer at the Eureka Springs School of the Arts. How could anyone be as lucky as I am?

I have also been trying to resolve problems with the makerbot 3-D printer at school. I sent an email to Makerbot support, and have come to the conclusion that part of the wiring harness is at fault. But so far, my email has been ignored. This is not a good sign.

There have been hopes that tools like 3-D printing as it becomes open source and widely available will become a democratizing force. But it is so complex and involves so many layers of unseen technology, that it may leave folks longing for creative work that can understood and made certain by hand and eye.

Simple tools allow us to create directly from the inner eye though the intellect of the skilled hand. The stock knife, or blocker can be one of the tools to facilitate the fulfillment of that process in ways that 3-D printing of plastic will not.  Working with real tools takes practice. On the other hand, you can set up a 3-D printer and right out of the box it will make more plastic until it quits and you are left scratching your head.

Make, fix and create...


  1. Anonymous2:12 PM


    I've enjoyed following your blog for several years now and find your expositions on sloyd enlightening and your positions on modern education depressingly sensible. Thus, I feel a bit chagrined to inform you that your block knife design needs some rethinking. I have two suggestions that will improve the predictability and consequent safety of the knife.

    You've made a good start with the pivot loop in about the right spot. The pivot should be in line with the cutting edge so that the edge doesn't move sideways when the blade rolls.

    My first suggestion is to make the end of the handle below the line of the cutting edge. With the handle above the edge as you apply downward force any inadvertent twist will be compounded as part of the downward force becomes and increasing part of that twist. In effect you have an undesirable positive feedback that rolls the knife. If the handle is below the line of the edge, a twist just provides a predictable steering force. You may not cut straight, but the blade stays in the wood.

    The second suggestion is to mount the handle at right angles to the blade - like the T handle of an auger. Most commercial block knives were made with iron loop handles. A T style handle gives more leverage to steer the blade.

    Have another look at Richard Bazeley's video and you'll see his knife conforms to these design principals.

    Keep blogging. Your work is useful and thought provoking.

    Andrew Adams

  2. Yes, Andrew, I see what you mean and why it makes sense. I'll also consider the T-handle.