Brace Layout Question and Answers

[Jim_Rogers]

Tony_T:
You can buy the magazine online, but you can't access the articles online.
If you want the magazine, go to the guild website www.tfguild.org and click on the online store and go to publications, and you should be able to list what back issues you want and purchase them.
Hope this helps.
Jim Rogers

[Jim Haslip]

Hayton,

The (RED) Timber Frame Joinery & Design Book from the Guild has several articles about Hip and Valley Framing written by Ed Levin based on some info from the Compqgnon du Devoir, the French trade guild, using compass layout to determine roof angles instead of Framing Squares. There are 3 articles.

I believe this "RED" book has been superceded by a newer version.
I haven't seen the new one.
Michelle or Sue at the TFG office would be a good place to start looking for a copy.
Ask them if the same articles are in the "Green" book.

[hayton1960]

Hi again Jim
That method of developing roof seat cuts/plumb cuts/hip cuts etc on scaled down paper was the first way I was shown to do roofing calculations (from a stick framing point of view) But I found it inacurate-too much transferring from drawing to bevel board, bevel board to sliding bevel etc too much room for acumulated error. I like to work on a full sale if possible (must be a throwback to my digitising days!!) What I like about the french drawing method is that the floor drawing IS the finished dimension of the component, not a scaled down or abstract representation of it. I think on Marcs site he shows you how to make a giant 360 degree protracter on the floor with a large compass, all the 90 deg, 45 deg, 30 deg etc etc
PS I bought what I thought was a good (Stanley) roofing square-cost me about £24 (about $45-$50) The numbers stamped on it are wrong (some of them are repeated where they shouldnt be!)
Cheers Jonathan

[Jim_Rogers]

Jonathan:
Take that square back, and get a good one.......

Jim:
The new book, the GREEN book has articles in it since the red book was published.

Currently reading it.....
Just picked up my copy at the conference.

Jim Rogers

[Jim_Rogers]

bump to the top

[Jim_Rogers]

bump

[mmhailey]

This thread is invaluable Jim.  

I am drawing and redesigning ( sketchup) a set of plans I have, and I was in the process of drawing the braces and housings, when I noticed the Tenons are a bit different from the ones depicted in this thread.  Here is a sketchup pic of the two bearing ends.





Am I missing something?  Isn't the one from the plans a lot more work with the chisel, and less bearing surface? The one on the right with the 1 1/2" tenon is from the plans. I do know that this set of plans has no housings and all the dimensions are showing full size timbers 8X8 4X6 etc.

Any one see a problem with changing the braces to housed, and 2" tenon

[Jim_Rogers]

mm:
The reason why one tenon is 2" and the other maybe 1 1/2" could be that the braces are 4" on the 2" tenon and 3" on the 1 1/2" tenon.

Not sure.
But the rule usually is that the tenon on a timber is 1/4 the thickness so if you have a 8x8 then tenon is 2", and a 6x6 the tenon is 1 1/2". But when you're working with 8x8 then usually braces are 4x6 and then they just use a 2" tenon as the layout is already 2" off the layout face and then 2" thick, which puts the tenon flush with the inside of the brace and makes it easy to layout and cut.

When you're working with 6x6's then the braces are usually 3x5 or 3x6 and then the tenon is 1 1/2" so that also make the tenon flush with the inside.

Some people who work with planned timbers so that every side is smooth and have truly 90° corners don't house their timbers or braces. So they just cut a brace to fit flush up against the post or tie beam. So only a mortise is needed, But the cuts have to be prefect or the gap will show, and it' looks like h-e double hockey sticks.....L-L..... Housings hide a lot of imperfections.

Some people like their braces to be centered on the post and one the tie beam so the center the brace tenon and mortise as well.

As I have mentioned and some people don't do this at all, but most frame plans have a set of rules that each joint have to follow, such as creating housings down to the next 1/2" in size smaller inner timber. That is the key to doing "square rule" joinery with rough sawn timbers.

Hope that helps.

Jim Rogers

[mmhailey]

Thanks Jim,

I have redrawn the braces with a 2" tenon, and the 2" bearing surface, and 1/2" housing.





The brace from the plans is a 4X6 into a 8X8 post and tie. The plans show the brace flush with the outside of the frame.
Actually the 1 1/4" brace tenon was the only small one I find. The rest throughout are 2" tenons.

We built this frame when I attended a workshop, and I do remember that the brace stock was planed, probably to an exact 4X6. My guess that is the reason for no housing. 

[witterbound]

IMO, un-housed braces with shoulders on two sides are very difficult to cut and fit.  The shoulders have to be parallel to each other when you are cutting them, then if the timber isn't perfectly square, one shoulder may fit and the other one won't. 
Then if your timber shrinks, it can pull away from the tight shoulder you've fit.    I believe it's much easier to get a clean look by only having one shoulder, and housing it (which isn't that much work to do).

[Mad Professor]

You can lay them out with a divider from irregular wood if needed same as is with posts and ties

Mate them to the posts using the same divider settings using the true post/tie (e.g. a housing).

Best to set up a 3/4/5 triangle on the post and tie to make sure they are square. Use the centerlines and the divider

[Piston]

Jim,
When milling timbers for braces should I mill them 1/8ths inch thicker?  So if I want a 4x6 brace do I mill it 4 1/8thx6?  I think you told me this before but I get confused on which timbers to cut slightly over sized and which ones not to? 

I know you had mentioned to mill certain timbers slightly larger to allow for shrinkage, and I believe the braces were included in that list.  I'm glad this thread came up again. 

[Jim_Rogers]

Jim,
When milling timbers for braces should I mill them 1/8ths inch thicker?  So if I want a 4x6 brace do I mill it 4 1/8thx6?   

Yes, we mill all brace stock thicker then the layout dimensions, that is 2" off the layout face and then 2" thick makes 4" and to allow for width shrinkage, we add 1/8" to make it 4 1/8".
On 1 1/2" by 1 1/2" layout for 3x5 braces we add 1/8" as well.

[Piston]

Thanks Jim....
I think you said that if I had to ask you a third time then you were gonna tell me to get lost!!! That was my second time asking so since it's written down now I should be okay  :D

[Jim_Rogers]

It's, if you ask me a third time, I'll tell you to write it down...... :D :P

[Aikenback]

Hi, in my opinion it seems to me that its most important to use drier wood to avoid gaps. If you don't house the kneebrace you risk the "heel" of the 45 deg. cut opening up as the material shrinks across the grain. The angle appears to become steeper ( over 45deg as the material shrinks towards the "toe". If you house the joint, the housing can shrink away from the housed material and leave a gap. I personally save and use my driest, oldest leftovers and mill them to my brace size and draw bore a little bit with excellent results. I think moisture content is important here. I don't have any experience with oak just yet, is it too hard to work if it is too dry?
Blake

[Mad Professor]

If any body is interested.,

I have the layouts for the top/bottoms of  ( common 45 o braces) braces and the the other sides of how the post and plates mate.  All laid out with a divider.

These are based on several unit circles, with these unit circles, scribed into one of the principal beams as a reference; for construction and future repairs, much like the old buildings were laid out.  The tennons and mortices also had their own circles/diameters for proper layout.

It is all old geometry that most have forgot.  Applying it to irregular timbers/logs requires  references, level and plumb, after you have established a small smooth surface.

[jimdad07]

Great thread, thought it could use a bump.

[Carpenter]

     Thanks for the bump.  I've read this thread 5 or 6 times at least and even laid out and cut several braces and I've still learned something just from re-reading the thread. 

      Could somebody do a tutorial on a 3-4-5 brace layout?  I've been using google sketchup for years, ( but I just recently learned how to really use it) I watched a you-tube tutorial on how to make components for a timber frame building.  He was drawing a Jack Sobon picnic shelter, I happen to have the book with the picnic shelter plans in it as well.  It's in Fourteen Small Timber Frames.  Jack used 3-4-5 braces for this shelter.  Which of course peaked my interest being a carpenter I use the 3-4-5 rule regularly, and I like the way they look.  So, I drew out a rather complex building using 3-4-5 braces, then after downloading Timber Frame Rubies I was able to make shop drawings of the components.  I noticed that with my square rule frame rules of downsizing the frame by 1/2" that the 3/8" layout for the braces did not hold true.  The end of the brace with the 53.2 degree angle is app 3/8" off the reference face, but the end with the 36.8 degree angle is approximately 5/16" off the reference face.  The length is easy of course.  I'm sure I can get the angles right with the framing square.  The dis-advantage might be that once cut, one is definitely left and one is definitely right.  And, do they brace against sideways motion as well as a 45 degree brace? 

     I have not actually cut any 3-4-5 braces or brace pockets yet.  Am I missing something?  That's just what it looks like in the sketchup drawing.  Anyway, I know some of you have cut 3-4-5 braces and could probably help me out. 

     

[Roger Nair]

It's all about choices and priorities.  What you have discovered in the deviations from a 45 degree brace can be worked around.

All braces have handedness, even 45 degree braces, the brace on the left of the post is the mirror image of the post on the right.  Since the ends of a 45 brace are mirror images of each other, the brace just needs to be flipped end to end to fit the pocket.  One option is to cut the brace with a centered tenon with equal shoulders on each side of the tenon eliminates handedness but forces you to a centered layout in the post and beams.  The other option is define handedness and count and cut the braces with handedness.

The other choice relates to brace  pocket depth and the offset of the layout line to the edge of the timber.  I choose to have even depth of brace pocket and layout the post and beams in the manner of Jim's lesson, however as you have noticed the offset from  the brace edge varies with the angle.  So to layout, calculate the offset ( 3/8 and 5/16 by your example).  Mark the offset on one brace end.  With a furring strip and screws filed sharp, set up a fixed trammel at the brace length.  Nestle one end of the trammel in the marked offset and scratch an arc at the other end and the scratch other offset intersecting the arc.  That locates your braces critical dimensions.  In theory, angle layout should be from a line connecting the end points not the edge, so draw the line and do the layout.  Also layout from the edge and compare, you could at this point tweak the angle from the edge if needed.

That is what I basically do.

[Jim_Rogers]

I have attempted to draw, in my professional timber frame design program, a 3-4-5 brace layout.
I doing so I established some rules that I tried to have the joints follow. For example the housings or joints of the brace pockets would be 1/2" under the size of the timber. A standard that I usually use.
Then I drew out the points, one down 4' and one over 3'. I told the program to connect these points with a brace, including tenons and 1/2 housings.
The results gives me a brace which has a 3/8" layout line parallel to the arris of the brace. But the legs of the triangle are not all 3-4-5.
See drawing:



 

The three foot leg comes out a little longer as well as the 5' hypotenuse.

So you have to ask yourself, "what do I want?"

Do I want something that is easy to layout and cut?
Or do I want something that is exact?

If you want exact then you're going to have to adjust your housings depths, angles and brace layout line to the exact locations.

If it was me, I'd do it my way and just tell everyone that it is a 3-4-5 brace layout and no one will be able to see these very minor distance variations.

Jim Rogers
PS or do it Roger's way.

[Roger Nair]

My dad often said, "There are two ways of doing things, the right way or Roger's way."  What I do know is dad was wrong, there are many ways, the manner in which we work as individuals is so varied.  However, Jim, I just do not follow why you deviate from 3-4-5, the goal is to have easy dimensions 3-4-5 and consistent pocket depth and to have the surface of the brace merge with the surface of the post and beam.  What you have outlined fails on two counts.  You need to examine what happens at the joint at a close scale.  The different angles of approach at the joint require a different set back of the critical dimensions, no tweaking of the brace leg will solve the condition unless the tweaking brings you to even brace legs.

[Jim_Rogers]

Roger:
All I'm saying is what the program showed me when I dimensioned the drawing it created.
The drawing is there and if it doesn't work then it doesn't.
I would have to try it to verify that it did or didn't.
But I have found in the past that what the program says is true, it has been true.
Jim Rogers

[Roger Nair]

Jim, your results are based on the way your Jerry program figures problems of slope.  The Germans work on degrees of arc rather than whole number slope.  So what might have happened is that a 4/3 slope is rounded to angles 37 and 53.  the calculation is tan37 times 4 feet equals 3.0142 feet which gets rounded to 3' 1/8" but 3' 5/32"  is closer.  There are rounding errors the true figures are expressed in never ending decimal fractions.

[Jim_Rogers]

Jim, your results are based on the way your Jerry program figures problems of slope.  The Germans work on degrees of arc rather than whole number slope.  So what might have happened is that a 4/3 slope is rounded to angles 37 and 53.  the calculation is arctan37 times 4 feet equals 3.0142 feet which gets rounded to 3' 1/8" but 3' 5/32"  is closer.  There are rounding errors the true figures are expressed in never ending decimal fractions.

This is true, but we have to have number/dimensions we can work with using our regular layout tools.
I have a ruler that has 32nds and 64ths but I rarely use it in timber framing.

Jim Rogers