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Mar 21

On Geometry

drawing a volute
Today’s woodworker has a lot more help when it comes to working out the tricky angles of some furniture joints, roof geometry or the wind and rise of a set of stairs he is constructing. Back in the day, school geometry lessons fed straight into the knowledge needed in an apprenticeship and carpenters found themselves learning on the job and learning what was needed to be able to draft calculations in their heads.
A lot of this knowledge has been lost as technology has taken over somewhat, but I find myself increasingly fascinated in the various calculations one can learn to estimate precise cutting angles.
Following on from my post about French ‘guitardes’ and ‘L’art du Trait‘, I have been researching knowledge about plane geometry and it’s use in carpentry and joinery.
Over on ‘A Woodworker’s Musings’, D.B.Blaney not only seems to know a lot more about this in practice than me, but has also constructed some fine models. I love the pictures of loftsmen in the mould loft at Harland and Wolff shipyards. You can see the large drawings on the floor from the loftsmen.
I contacted Mr Blaney about this great post and asked if he had some reference on how to get re-aquainted with plane geometry and it’s use. He recommended some books:

A Treatise on Stairbuilding and Handrailing by W & A Mowat
A Builder’s Companion by Asher Benjamin
Basic Perspective Drawing by John Montague
and also Chris Hall’s website, The Carpentry Way.
(I have also been told a recent book called A Simplified Guide to Custom Stairbuilding and Tangent Handrailing by George Di Cristina is also excellent)

This brought me onto Googling tangent stairbuilding and I hit upon a four-part series online by ThisIsCarpentry, which explains how geometry is used in tangent handrailing and crafting a proper volute.
Tangent Handrailing
Drawing a volute
Carving a volute

I’m sure there’s a lot more out there, any recommendations for making a start are gratefully received. I did also buy the new book from Lost Art Press, ‘By Hand & Eye‘, but overall I didn’t think it was put together very well, or was that helpful. I believe the authors are currently making an accompanying ‘workbook’ to explain the workings better. Read into that what you will, but not one of LAP’s better books, in my opinion.

2 comments

  1. Scott

    Construction Geometry is a good basic starting point too.
    http://www.leevalley.com/US/wood/page.aspx?p=42817&cat=1,46096,46109&ap=3

  2. Jeremy

    While I haven’t delved deep into the exact French method I believe it’s mostly partial secondary auxiliary projection views as I learned in various old school drafting courses, but laid out all overtop of each other to conserve paper space. I would look to dusty old drafting books as well as sheet metal layout guide/handbooks aimed at tradesman pre-CAD era

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