Thin on the Ground

I’ve set a goal for myself this year to improve my planing, and I have come to believe that a hand plane’s quality of set up is largely reflected by the quality of shavings it produces. Obviously, one aims for a tear-out free surface, and a flat surface, without tool marks. Beyond that, the wider and thinner the shaving the better, in terms of achieving a optimal result. The shaving should come out of the plane without curling upward. Like a musical instrument, as you approach that point of ‘perfection’, the greater the number of very minor aspects of set up which come to affect the outcome, and the more demanding and subtle the tuning becomes. It’s the same puzzle with a woodworking router for that matter, or grinding lenses for telescopes.

Developing skill at plane tuning takes time, and I am sure I have a lot to learn yet.  Consistent results remotely approaching this continue to elude me:

I am by and large happy with surface quality when I plane a piece of wood. I can obtain a flat surface and leave no tool marks behind, at least on a good day. Trying to go further than that requires some way to gauge progress, and that means going beyond assessing the surface quality to assessing the shaving itself. Namely, full width, fairly flat, and, by the way, how thick is it? It is difficult to measure very thin shavings with any sort of conventional tool, however Mitutoyo makes a type of digital thickness gauge which is well suited to the task:

This is the tool of choice for those in the Kezurō-kai, a group of Japanese craftspeople who meet several times a year to demonstrate traditional woodworking practice and have a competition to see who can produce the widest, thinnest shaving. there is also a Kezurō-kai newsletter, in which tool metallurgy and nuances of sharpening are discussed in great detail. Mike Laine, A craftsman out in California who runs the company Wooden Heart sent me a stack of Kezurō-kai newsletter back issues, which I have been making my way through slowly. That has partly fired me up to work to improve my planing. I think the key to becoming a craftsman is not to settle for anything, to always strive to learn more and develop better technique. Assume that ‘you don’t know it all’ is a good point to start it would seem. I don’t know it all, and have found that assuming otherwise usually leads to unfortunate outcomes.

The Mitutoyo gauge measures to a refinement of 0.001mm, or 1 micron:

The current record in Japan for thinnest plane shaving, which I take to be a world record, is 0.003mm, or 3 microns – unless, of course, someone has bested that figure in recent months.

For those who experience blank-outs when seeing metric, 3 microns translates to:


I don’t really care to go all-out and strive to match that, as I think it would require an indulgence in kanna-otaku-ness (geeky obsession) to a degree I’m not especially interested in, however I am interested to see where I am at generally at the moment, and then see if I can make some improvements from there. I would definitely like to get into the sub 10 micron zone though. I’m not sure at all at this point how much work lies ahead of me to reach that objective however.

To give a comparison to a commonly encountered item which is considered fairly thin,  I measured a piece of single ply toilet paper. It was 80 microns thick on average.

The measuring gauge is not an inexpensive tool to buy new, however if you are interested in finding one, they do pop up on the used market from time to time. It is model number 547-401:

If I’m not overly appalled at how bad my results are, I may be posting up from time to time over the year to show my progress toward this goal of improved shavings. I guess that wherever I start from in terms of thickness of shaving, I will try to halve that number by the end of the year. Well see – nothing ventured nothing gained.

Thanks for visiting the Carpentry Way.