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Help with square rule

Started by Max sawdust, July 17, 2006, 06:28:38 PM

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Max sawdust

 ::) ::)
I seem to be not getting something with square rule joinery.  I understand how to true up an end of a timber by using the reference face but cutting joints and seeing the "timber within the timber"  is giving me a hard time, I keep defaulting to something like scribe rule.  (Lucky the stuff I have done so far involves 8-12' timbers so I can just "ox" them around and measure and fit.)  I am feeling quite dense. ::) 
I want to learn how to understand square rule joinery.
I would like to know how those of you that understand and use square rule learned it; and I am looking for some advice and good reading material on the subject of square rule. ???

Thanks
Max
True Timbers
Cedar Products-Log & Timber Frame Building-Milling-Positive Impact Forestscaping-Cut to Order Lumber

fjc

It is necessary to determine two reference faces (that join to give a reference edge) to utilize square rule. All measurments are pulled from one of these faces. In a three bent frame the two outside gabel ends and wall sides of posts are always the refrence faces. It is necessary to choose one face in a middle bent (the wall outside face and your choice). Because all measurments are pulled from like locations math (ie bent girt and connecting girt measurments) are able to be determined. The gain or decrease in timber size is located to the inside of the building so that it won't interfere with sheathing. For example a 1" housing is not always 1" deep - for an 8" timber it is cut seven inches from the refrence edge making the actual depth unimportant.  Joist, rafter and purlin measurments are pulled from the outside and top. This leaves a flucs surface for sheathing to be applied. Laying out and Cutting Timbers - Jack Sobon - Build a Classic Timber Framed House, Chapter 5 - has a pretty good description. Hope this helps. 

Jim_Rogers

Ask specific questions on what you don't understand about it.
I have posted a book list with many good books on this subject.
Most are available at local bookstores, if not at www.tfguild.orgwww.tfguild.org under publications in the online store.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Max sawdust

Thanks for the good advice fjc, and welcome to this forum, I sure hope I can help you with questions some day ;)  It will have to be on small scale logging, manual saw mills or chain saws, cause I am new to attempting building true TF which I think is a beautiful form of art 8)

Jim I will get more specific, when I am in front of a joint I need to cut.  Thanks for the support and willingness to share your knowledge.  I have several books just looking for the "best" on square rule.  The Sobon shed book is light on square rule so is Benson's timber frame house and Steve's Timber frame construction book I have.  I will check out fjc's recommendations :)
Max
True Timbers
Cedar Products-Log & Timber Frame Building-Milling-Positive Impact Forestscaping-Cut to Order Lumber

Jim_Rogers

Benson's book, the one with the brown cover, lays out timbers by using a system called mapping.
Where you have to keep track of the delivered widths of the timbers and adjust then shoulder to shoulder lengths of adjoining timbers based on these widths.
Not an easy system to use for a first time frame.
Steve Chappell's book uses a system called "mill rule" as he works with all planed timbers and draws the joinery without any housings.
Jack Sobon's two books, one with a red cover the first book, and one with a white cover his last book, both have descriptions of how to do square rule.

To understand square rule you have to understand layout/reference faces. As fjc has mentioned.
The outside of the building, on all sides is a reference face as all the joints have to be flush to the outside so that the timbers won't hold the siding away from them.
The top of all horizontal timbers are the reference faces so that all joints are flush for the flooring to sit flat on them.
The top side of all rafters, at any angle, is the reference face so that all the roof decking will sit flat on them.
For laying out a brace the long side, which is the hypotenuse of the triangle is the reference side.
For the center or interior bents, one side is picked by the designer as the reference face and all interior bents are usually laid out to that side.
All these faces are the usual reference faces.

I have posted some info here on the FF about all this with photos or drawings showing how to label your reference faces so that you can keep track of which side on a timber is the reference face.

Under the list of tools used in timber framing is a story showing most of what I have mentioned.
Here is the link link to story

And you should also read the one about how to layout a brace as it describes how the reference face works on a brace. Here is that link: Brace layout story

Again read up, and then ask specific questions.


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

Max sawdust

Jim,
Thanks very much.  The links are great 8)
I will check out the two Sobon books that I do not own.  I just can not see mill rule working as well.  Even though I own a mill :D  Square rule just seems like the right thing for TF.  Just got to wrap my mind around the timber within a timber thinking ::)

Again THank you.
Max
True Timbers
Cedar Products-Log & Timber Frame Building-Milling-Positive Impact Forestscaping-Cut to Order Lumber

Radar67

Max, I read through Jim's post myself and found them very educational. I have never timber framed, but from what I gather, the timber within a timber thinking is basically picking out the best faces to use as reference faces to do all your measuring from. Jim is this thinking correct?

Stew
"A man's time is the most valuable gift he can give another." TOM

If he can cling to his Blackberry, I can cling to my guns... Me

This will kill you, that will kill you, heck...life will kill you, but you got to live it!

"The man who can comprehend the why, can create the how." SFC J

Raphael

Quote from: Radar67 on July 19, 2006, 08:59:39 PM
I have never timber framed, but from what I gather, the timber within a timber thinking is basically picking out the best faces to use as reference faces to do all your measuring from. Jim is this thinking correct?

That's the basic idea.  Ideally you want to find two straight adjascent faces that meet at 90°, especially in a corner post or beam against an outside wall.

Here's a picture of a less than perfect timber and lines showing one possible perfect timber within it.


This started with no straight faces until I remilled the top.  This is a second floor joist out in the middle of the room so only the face getting flooring needs to be straight and all the joinery must be oriented to that face.
... 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

Jim_Rogers

Stew: you are correct.

Raphael's picture show a good example.

They use the terms "best face" and "best edge" as location names. But sometimes you roll the timber over and put the best "looking" face inward toward the center of the building and the worse looking faces to the outside so that the siding will hide these bad faces. Of course, this can only be done if the timbers are milled somewhat to 90° on each corner, and don't have a lot of bow in them.
We try to look at the quality of the timbers for appearance as well, and try to hide unsightly defects.

Jim Rogers

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

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