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joint dimensions on odd sized timbers

Started by son reech, January 23, 2007, 12:37:06 AM

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son reech

i'm going to build a 12x16 shed as per jack sobons book.  if i use 7x7 timbers, could i still use the joint dimensions described in the book, or would it be better to reduce them to a smaller size?  i believe the rule of thumb is 2" for 8x8, and 1 1/2"  for 6x6.  so which way would you go for 7x7,  better to have bigger joints, or is that removing too much wood?
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Raphael

If you stick strictly to the rule of thumb the answer is 1¾".
What species are you working with?
... he was middle aged,
and the truth hit him like a man with no parachute.
--Godley & Creme

Stihl 066, MS 362 C-M & 24+ feet of Logosol M7 mill

Stumpkin

I have found in old barn frames that the 2" M&T is the general rule of thumb even in 6x6 material. I find 2" bits for old boring machines more often than 1 1/2", I've never seen a 1 3/4" bit but I have one that is 2 3/4".  Tom
"Do we know what we're doing and why?"
"No"
"Do we care?"
"We'll work it all out as we go along. Let our practice form our doctrine, thus assuring precise theoretical coherence."      Ed Abbey

son reech

i'm working with doug fir, and i plan on using the square rule method jack describes in the book.  so if i cut 1" shoulders on all the joints, that leaves 6" of wood.  i'd rather just go with the dimensions in the book than having to recalculate all the joints.  either way i, i think i'll stick with the standard 1 1/2 and 2" mortices.  don't ya think that's the way to go?
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Jim_Rogers

Quote from: son reech on January 23, 2007, 08:41:52 PM
I'm working with Doug fir, and i plan on using the square rule method jack describes in the book.  so if i cut 1" shoulders on all the joints, that leaves 6" of wood.  I'd rather just go with the dimensions in the book than having to recalculate all the joints.  either way i, i think I'll stick with the standard 1 1/2 and 2" mortises.  don't ya think that's the way to go?
When Jack wrote that book, many years ago, he planned on people using this design to make bigger structures than the 12' x 16' garden shed. So, he planned on having the 1" housings for these larger structures.
When we made this shed, just recently, we changed the housing to 1/2" in all joints of the frame.
This did change some of the shoulder to shoulder lengths of some of the timbers but this is nothing too hard to keep track of.

As we intend to cover the roof rafters with 2" tongue and v-groove lumber, which as we all know finishes at 1 1/2" thick, we reduced the number and spacing of the rafters from a pair every 2' to a pair every 4'. But you should only do this if you're using thick roof decking.
If you're going to do 1" boards or something like that, then you'll need rafters every 2'.

When doing this frame with 7x7 stock, layout can be done at 1 1/2" off the layout face and 1 1/2" thick, tenons and matching mortises without any problem.

But as Jack's first book states, if you widen or lengthen the frame, of the garden shed, you need to follow his recommendations for beam sizing and extra post placements.

It's a great first project.
Have fun, and keep asking questions......

Jim Rogers

Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

son reech

jim, are you using 3/4" pegs for 1 1/2"m&ts?  and what is the concern with 4' rafter spacing for 1" boards?  my intention is to space the rafters 4', and use 1x4 boards every 4" as nailers for cedar shingles.
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Jim_Rogers

Yes 3/4" pegs for 1 1/2" tenons are standard.

4' span for boards is too much. Especially with any snow load. 2' span boards could be ok. I'm not familiar with your area so I don't know your snow load or wind load. You may need to consult with someone familiar with your area.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

son reech

o.k., jim that makes sense.  we usually don't get much snow in these parts, but you never know.  the only reason i was going to space the rafters at 4' was to save time milling and cutting joints.  but i guess the more you cut, the better you get, right?  thanks for the advice
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