Estimating survey.

[Dave Shepard]

I'm curious to know how other people estimate the time it takes to cut a frame. I break it down to each timber. For instance, a tie beam might have two tenons @:25 minutes and two brace mortises @:15 minutes. I total the time for the piece, then multiply by the number of like pieces.

Here is a sample timber with a few different types of joints.

20' 8" x8".
11 5" wide 2"/2" rafter seats, 12/12 pitch.
Two corner post mortises, 2" x5" x6" total depth before reducing to 7" final timber.
One center post mortise 2" x7" x6" depth, same as above.
Two brace mortises 2" x8" x4" depth before reduction.

How long would you estimate, and what tools would you use, such as boring machine, drill, chain mortiser etc.



 

[Ljohnsaw]

Great topic!

I asked a similar question quite a while back.  Most of my timbers will be two tenons and 2, 3 or 4 brace pockets.  Braces just two tenons.  I (simply) estimated I could produce one piece per hour, on average.  I multiplied by the number of elements and, IIRC, I would need to spend about 250 man-hours on my frame.  That represents 8 hours a day, 7 days a week, for a full month.  With practice and repetition (I have 50+ rafters to cut and 3x as many bird's mouths), I would hope to improve somewhat ;)