Hand Tools Archive

Still more on cap irons, Warren will be amused

Bill Tindall
Working with Mia today on the translation of the article Kato and Kawai wrote for students learning to set up a plane. ( I am not translating the shaving bender into the words "cap iron". That was done by Kato in the English abstract of the paper.)

Warren will like their conclusion: "After an analysis of the use of hand planes we can say that setting the cap iron can not be done right the first time(by eye). You must take a test shaving and judge the effect of the cap iron little by little with precise adjustments." This statement seems to be wisdom to ponder.

In this work they made a ton of precise mechanical measurements on the plane blade as it planed hardwood and softwood lumber. However, the most sensitive measurement for how the cap iron was working[to prevent tear-out in case any doubts remain as to what the shaving bender is for] was the how the shaving appeared! There was a sharp departure from a flat shaving to one that was scrunched up accordion style as the cap iron was moved ever closer to the blade tip. They quantified this effect by measuring the length of the shaving to the length of the wood it came from and calculated a "scrunched factor".

What I failed to find was what the target scrunch factor was. I will seek clarification from Professor Kawai. I suppose one wants the cap iron set as close as possible but not so close the shaving compresses into an accordion.

Maybe Stu can seek some more info here at the planning symposium.

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