TFJ #79 Correction

Hi folks,

I have become aware of an error in my article in issue 79, pertaining to the 4-way splay layout. The error is in a calculation detailed on page 8, and results from applying an incorrect multiplier.

Anyone who goes through the steps to make the sawhorse, as detailed in the article, would likely spot it. My apologies for any confusion that may have ensued as a result - neither I nor any of the proofreaders spotted the problem prior to publication.

Anyhow, if you are contemplating making the splayed sawhorse, Japanese style, then please feel free to contact me and I'll show you the mistake in question and clarify things as need be.

Cheers,

Chris

how many lifetimes did it take for this?

to pass into sacredness and ease. does the function rely on the form?

splayed sawhorse, im working on it.

Sobon is to Ruskin, as Benson is to Violet le Duc

Would this be considered a splayed sawhorse? I'll see if I can get a picture of the top view soon. The legs do have shoulders that the level piece sits on. Then bolted through from leg to leg.

Hi Mo,

This is one application where the grading of timber really matters. A defect in a piece of wood with such a small section and subject to large point loads has the potential to result in dissasterous consequecies for the unwary.

Did you load test each horse ?

Regards

Ken Hume

Hey Ken, To be honest I know nothing of certified grading other than looking for defects and their proportions (knots). I can say that we did visually inspect the pieces.

The other day a couple of us were looking at them discussing whether the half lap cross bracing is in fact doing anything to resist any forces that might want the legs to spread. Since the top of the bracing has a tenon (no pegs) and bolted to those bottom chords are they really doing anything? Is it possible that the half lap combined with the opposing noses of the tenons can keep it from spreading?

I do not know how to load test the sawhorses, but would like to learn. I do assume you are talking of a safer way than "yea that was too much timber".

Hi Mo,

The test could be quite simple. For example, if you are planning to regularly support say 300 lbs at mid span on the horse then you might want to consider applying a test weight of say 600 lbs and if the horse doesn't break then you know that you have a safety factor of at least x2 if the horse is rated for 300 lbs - that is of course provided the horse does not break.

The braces will work provided there is good friction developed at the feet of the legs e.g. say on a concrete floor but if this is placed on a smooth wooden floor with sawdust lubrication then the support developed might not be so great as the legs would be able to spread.

Actually, upon reviewing your photo again there is quite a stack (6 timbers) placed on top of 2 horses which goes a longway to demonstrating the load capacity of the horses.

What do those timbers weigh and how near are you to the point of collapse ?

Regards

Ken Hume

I'm not sure if you're aware if it or not, but that is a Chinese temple in the second posting, not a Japanese one.

Please take a look at issue #79 for pictures and details about how to make. That said, you may wish to check issue #78 as well, for the first article in the series on hoppers, as it is useful knowledge for approaching the splayed leg structure.

~Chris

Derek

Here are some pics. When I was slow this winter I built these saw horses following Chris article. Definitely a fun challenge.

Michael, what is that knotch in the blade of the pull saw to the right, closest to the window? Tim

Tim


A mistake, f*&$$$^%$# up, pick your term, too small a saw for the wood I was cutting.


Mike