Hi Rudy,

Is there really a fundamental difference between what is called mill rule and square rule ? and if yes what are the key differences.

Regards

Ken Hume

Ken,
There may be those whose opinion differs but my learning says mill rule and edge rule are the same - of course this implies perfect timbers too. Square rule inserts a virtual beam inside the physical log so you have a constant to measure from.
Emmett

The timber I've bought so far (for braces) has been correct +/- 2mm (between 1/16" and 1/8"). If I can be assured of the same tolerances for the big stuff, is that good enough to use mill rule?

Ken,

Not really.

With square rule you are truing the timbers at the joints to make them perfectly dimensional and square.

Now if you have the saw mill or planer mill do this work for you by accurately sawing or sizing with a planer and you either use timber free from or assume your timber is free from wind and bow and un-square faces, then that can save you a bit of work as you don't have to size and square up the timbers at each half of each joint. That's mill rule.

Both rely on perfect geometry at the joints, the difference is whether that is accomplished by milling the whole stick perfectly or by perfectly cutting reductions, gains, and housings at the joints.

Griffon,

As for your question. There is not a simple answer. Some would say yes, some would say no.

For me to mill rule, the timbers need to be better than 1/16 of dimension and 1/16 of square (on an 8 or 10" face). Just as critically, you must have minimal sweep and no wind. And you always need to adjust things with mill rule when you are putting them together -- you just haven't accounted for irregularities up front, so you must pay at assembly.

The short answer is that if 2mm is good enough for you on this particular project, then mill rule is fine. (No value judgment intended, everyone has their own tolerances and values.)

Mill rule is fast, I will say that.

GH

Hi Emmett and Gabel,

Your advice and understanding is fairly simple and straightforward and so makes perfect sense.

Thank you for that clarification.

Regards

Ken Hume

mill rule contains structural housings, square rule contains lots of housing to that perfect timber. housings that are required for braces in square rule, may not be required in mill rule.

Thanks Gabel, thats very useful. I'm scratching my head to know exactly what are 'wind' and 'sweep' but I wouldn't trouble you to respond; I can see that any error from squareness or trueness will call for adjustment or result in un-even faces.

I think mill rule will be good enough

Wind as in a winding river, not as in the wind cries mary



and sweep as in not straight.

i hope this terminology is right

mo

I surveyed a barn which had a very small percentage of the joints relieved in the square rule method. That is, it was mostly mill rule. However, I still called it a square rule frame even though only two or three members needed the square rule to find the "inner timber" of the "out of tolerance" timbers. Just my opinion.

Jim

Griffon,

Wind is twist. Something that has wind is said to be wound as in "wound up like a spring".

Sweep is bow, as in long bow, not ship's bow.

gh

Well said, all. Yet I can't resist!
IMHO: Square Rule is the means by which we layout and cut a "perfect" (dimensionally accurate and square) timber frame from "imperfect timbers". Reductions and dimensioning from a reference edge are tools that compensate for dimensional variations in timbers (i.e. an 8x8 that's 7-7/8 X 8-3/16 gets reduced to 7-1/2 X 7-1/2 AT THE JOINT.) This ensures that your reference edge-to- reference edge dimensions are correct. When a timber is straight and square, laying out from an edge will be sufficient to achieve this ("edge" rule or "mill" rule, I think of this as sort of a subset of square rule).
If the edges or faces are not straight and/or square we need to establish straight and square planes to use as references. This is when we snap lines on the stick to define these planes. I've heard this called "snap line square rule" or "true square rule" or just "square rule" as opposed to "edge" or "mill" rule.
I think most of us are on the same page but we have the usual vernacular differences. He calls it a wind brace, she calls it a knee brace. (***Not intended to start a discussion on different kinds of braces!***)
There you have it. Fee: $0.02 (waived)

Hi all,

here is something that is bothering me. If one works with old beams or hand hewn beams you would ecpect them to not be square and/or straight in which case square rule would be applied.

Now if I am ordering beams from the mill and have size variations of up to 1/2" than I wonder why we are using saw mills in the first place.
Remembering back in Germany. If we ordered say a 10x20 (4"x6") than we received a 10x20. You could measure it whereever you wanted it was always 10x20. And those beams were not cut on a fancy mill. So does that means the saw mills here are so crappy or is it the mill operators? I doubt the beams would shrink that unevenly in a short period of time.

Maybe this should have been a seperate discussion but when I read Dan's post I could not help but ask.

Being a sawyer, I try as best I can to make sure my timbers are within a 1/8" tolerance. But wood can move while milling, and even though the mill and blade travel in a straight line the wood can shift in even the best of mills. This shifting can cause the timber to be of different sizes from one end to the other.
Being careful to read the log and watch for stress being relieved and making the cuts in the right order or on the right side to compensate for stress relief is an important part of being a sawyer.
Doing this correctly is important.
Some sawyers sit in a booth and don't get that close to a timber to notice that it has shifted due to stress.
Personally if your timber are out 1/2"; I'd have a serious talk with your sawyer or lumber supplier and let them know this is un-acceptable. Or find another sawmill....

Jim Rogers

I agree with Jim, sawing to 1/8 or 1/4 is good quality sawing, and produces timbers that will be useable for timberframing. Wood definitely moves as you saw it.

EH, are the timber rough-sawn off the mill, or have they been planed? The big circle mills are less accurate than the small bandmills like Jim Rogers and I run. They are designed to pump out the lumber in a hurry. This is why a 2"x4" is actually 1.5"x3.5". That way they can have a large margin for error coming off of the mill and just plane it down to a consistant size. When I saw out an 8"x8", it is usually right on, unless I miscalculated the scale reading, but it takes me a lot longer to make it than a circle mill.


Dave

In my week long introductory timber framing class last week, they called out method square rule. The project timbers we used were very nice, planed, and accurate to within 1/16th or better. The also had very little crown (bow?). We marked our outside face and the top as our reference faces and made all measurements from those faces. This makes sense so that you are basically using the same face of all the timbers of your bent as a reference plan and therefore all measurements being made from this same plane will assure that the mortise and tenons align to this plane (and the top reference plan. Then as long as you make the other two faces of the mortice or tennon square and to the correct dimension, it will all fit together correctly. From reading this post, it sounds like mill rule and edge rule are the same thing just a different name. Is that correct?

what i don't understand is how one can project a perfectly square and lengthwise true shape into a non-perfect piece of wood from one edge. this is what sobon seems to suggest in his book as a way of dealing with hewn timbers. but where do you lay thearm of the square? if that one outside edge you layout from is not perfect, then your 7X7, though it may be a perfect square, may not be aligned along the length of the tree.

the only way to do it exactly seems to be with chalk lines. and even they are a little fuzzy.

the reference has to somehow remain a perfect, symbolic abstraction through the whole process- i.e. map out the ends of the log with vertical and horizontal axes- ideally the center of the tree- use this to square the timber, assume that the timber is neither square nor straight, refer back to the central axis to lay out chalk lines, and use a standardized measure to layout joints from those projected lines.

and then a check opens up 1/16 of a inch and the timber is that much wider.

Hi all;

In the old text books to "take a timber out of wind" (as in winding) they instruct the tradesman to re hew the timber so that you have 2 square sides, and then placing the timber on trestles and blocking it from movement, you would continue to smooth off spots along the length of the timber to coincide with the position of the each mortise location, using a square and straight pieces to sight over on each end of the timber.

This does work amazingly good in practice, and will allow you to utilize timbers that are quite twisted and that have long sweeps.

"It is always good practice anyway to hew or broadaxe timbers oversize to allow for adjustment such as that above should the timbers move in the drying process that usually occurs during the time that the timbers are being readied for the carpentry to begin."

The above instructions appear in a book written by Willam E Bell in 1858 titled "Carpentry Made Easy"

You will also notice that timberframing is referred to as "Carpentry" not timberframing as we refer in our modern world.

NH

I am just a newby and I have a rather large pile of oak timbers just beginning to find a new existance in a TF addition to my home. On paper everything can be calculated in theory, but when you pull out a timber as I did last week ( for the first time ever) you very quickly find out that the timbers are not even close to the perfect wood you want. They have distortion from he time when they left the mill ( bandsaw) cut by an excelent sawyer. They were stacked and stickered but still checked and distorted over time.
In my case I started with a bent girt and two posts. For reference I chose the top center of the bent girt as my reference and made that level ( or vertical plumb as the timber is on it's side), and then marked the tenons level and on center as best I could. I housed the un-square end of the girt in the post when now I see I could have squared up the girt end first.
on future similar connections I think I will do this.
Very interesting discussion on this topic. I would like to learn a bit more about Japaneese framing techniques who seem to enjoy the challenge of working with timbers that have almost no straight lines anywhere except perhaps in the joint itself.
Any reference books to suggest?? Dave (in NJ)

Hi Dave,

A good start point would be to read "Building The Japanese House Today" by Peggy Landers Len Brackett (ISBN 0-8109-5931-3) which will provide all the inspiration that you need to strive to achieve excellence in your own work. Len's daughter Aya has provided stunning photographs of Len's work in the book.

For specific layout and cutting techniques you would do well to consult Timber Framing Nos. 26, 28 & 29 where Michael Anderson discusses and illustrates Simitsuke - Koya Gumi (marking) plus Michael also featured again in TF 39 & 40 where he discusses the Japanese timber framed building traditional practices.

My son visited both these guys in California earlier this year and came away much inspired by their competence in the field of Japanese framing and lifestyles. As I write the scent from a piece of Port Orford cedar hand planed by Len dilicately scents the air of my office.

Breathe deep and strive for perfection !

Regards

Ken Hume

Hi derek and others

your comment about that the houses were of "framed timber" was correctly put, but you will notice no doubt in the text of the book that the tradesmen were not referred to as "timberframers" but "carpenters"

NH

From what I understand, they were (are) one in the same - the German term Zimmerman means carpenter and timberframer...there is no difference. That's the way the homes were built. Timberframed by "carpenters".
(Would that make me a zimmerfrau?)

Good Sunday to all, and to Ken Hume and his son, for a wonderfly bright breezy day in central New Jersey. Four days of rain (here) forced break in cutting, I can feel a rythem to the blue grass on Brookdale Community College and and to the way the sun goes right down the mortis I cut earlier, and how the rays of the oak truely radiate out of the heart of the wood post.It was a fairly clean cut 2.876 X 8-5/8 in center of post ABOVE the bent girt connection, 24 inches off (33-15/18 H) The beam /post connection was the first I cut right below it and today that hole does look like crap. No lie. The braces above are added because I wanted to reinforce the bent girt connection from tear out. I had also installed lower braces below the girt 36 in off, They were my first angled (45') open half lap. I didnt quite understand the concept of the tapered dove tail that should not pull out, but the 4x6 oak braces arnt ever going anywhere. They add so much regidity to the P/B connection it's visually amazing,

I guess I chopped about a dozen joints so far and I am finding my tools work better than me, but are open to ease of control. I can move large amounts of material (not unlike excavation of soils) and you can moderate taking chipsand shavings. I need to know what chisel works well at shaving the bottom of a deep mortise. I would bet a bent or crank chisel/
I have that makes i guess about twenty cuts on both M &T's. The tenon cut well enough w/ my Milwaukee circular saw. It takes a lot of control and the base is not square or straight. I avoid cutting too deep and I try to angle the cuts away from the lines so there is wood left for future cuts if required. Leaving the line should be a rule. My T's are all rough cut 2 in wide. A bit heavier than Benson mentions, but I liked their massiveness. I know understand the price you pay for ego is loss of strength in Post. A smaller t would ment less loss on the post.
I also cut birds mouth connections at the top of the posts (148 in. oal) which werr 30 in. over the top of the BG. girtTops are flush. The timbers I chose initially was a hickory 6x7 13 ft long. It was straight, well mottled w/ ingron bark rays, and probably stronger than the oak on hand. I actually started markimg and flipping it around,(w/ my torn shoulder)and I knew if I substituted any wood for the oak I would be comprimizing on a value that could only lead to other mandated future compromizezs you dont want to do. Rule 2, Never compromize. (at least with wood) wait. think, measure, think, roll it around,
When you finally getready to drill the first hole and take a cut, all you can do is think positive. It will work (the other rule 1)
I am plagued by two bad shouldes and 55 years of playing. I remeber when we were kids. We used to jump off trees and roofs just because we could. and not get injured too bad. I loved climbing way up in a wild crerry and rolling down over the honneysuckel vines that were thick next to our house in Little Silver. We were indestructable. Local youth club (gang) Kids.

I agree with you Ken, I need to think Japaneese. Locally (in Hopewell PA) the Nokashima Gallary demonstrates the concept of using the living wood as a partner in providing visible strength and beauty with comfort and functionality.
If I get outside now, I can finish the second cut into the BG, and cut the T's on the brace, I have abot 6 or 7 4x6's 12 ft that can make long braces, and also cut down for the short braces which are 4x5 all oak.
I fell into the timber by way of a guy clearing his pasture. 60 treeswere felled, pressure washed, and de-stumped. we cut a lot of fire wood, some I wish now I didnt waste.
There is enough hickory for a good project on it's own. It also burns like gasoline. I cut 8X8's 12' for benches to stack the timbers on. They were arranged on concrete blocks and all leveled. Did I ever mention thenk God and Cat for their D70 crane! Our last milling was 10 oaks cut int 13x13 cants so I could get them stackecd before winter. Them logs is heavy!

I would like to find out about the availability of good cedar for interior sheating or other use. Two Alaska folks now departed were the brothers Ken and Jerry Kard ( dad George). Ken lived in Ankorage and was a suer photographer. Jerry was excepent as well and moved to Hawaii with his work. RIP guys.

I will hunt for the names you mentioned. I would like windows and pannels which reflect a Japaneese style. I want to avoid commercial double hung if possible. Do like the big glass pannels.

Be talking soon. I want to post this but aint sure how. O well.