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Looking for advice on snap line layout #27400 10/16/11 05:46 PM
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danfink Offline OP
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Hi all,

Quick question. I milled some beams with a chainsaw mill, and while they came out great, they are not perfectly square. The structure I am building right now utilizes square rule layout, with joinery spaced 2" from the outside edges. I have very little knowledge in other layout systems, and no experience in centerline, snap line, or scribe. The beams will be used as corner posts, with 5 joints each.

It seems to me that my best option is to use snap-line layout, and space the snap line 2" from my determined outside edge. Sobon describes this process in his Build a Classic Timber Framed House (pgs. 77-78). It entails leveling the piece, then using your framing square to draw level and plumb lines on the butt ends of the timber spaced 1.5" (or I will do 2") from the outside edge that represent a perfectly square (and smaller) inner timber to which the joinery can be laid out to. These lines are drawn on both sides of the timber, then connecting with snap lines.

Any advice on using this system, especially for a newbie, and especially when used in conjunction with a frame that otherwise is all standard square rule?

Also, one member that will be joining into these posts, is a tie beam with 2 thru tenons, and braces at connecting it to the posts. This particul tie beam is a timber milled on two sides, but with live edges on the top and bottom. The timber has a slight curve throughout. For layng this out, should I just snap lines representing its square top and bottom, and cut the joinery to that, including the brace pockets? Any advice for snapping accurate lines on the live-edged underside for the brace joinery?

Thanks so much,
Dan

Re: Looking for advice on snap line layout #27401 10/16/11 09:09 PM
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TIMBEAL Offline
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Hi Dan, from my understanding of snap line square rule, you need not drop lines down the butt ends which means you do not need to level the timber side to side or end to end.

You may instead take the wind out of it by placing a stick in the center of the timber, a level can be used but does not have to register level, it is only to sight to. From one end lay your framing square on the top surface with the tongue hanging down. With a shim, shim the body of the square so it aligns with the level at the center of the timber. Now, gently slide the tongue to the side face of the timber until it just touches at some point on the side face, it may or may not appear square. Now mark 2" on the top face and the side. Without moving the square focus on the other face. Place another square, use the 2" body as you are using 2" references, up so it just touches the top square and mark 2" on the opposite side. You now have 2" marks on 3 faces. Repeat this on the other end. Don't forget to mark the center where the level is setting, trace a line on either side and X it out so you can refer back to it if need be. Snap your lines connecting the respectful marks at the ends. This really only takes a few minutes to do and you have straight lines to work with.

As for the tie, what I do is saw the natural curve with my band mill, as I feed into the timber I follow the natural curve of the timber by raising and lowering the band through the cut. This gives me a flat surface to use. I then snap lines as above, with the timber laid on the side, using the typically wider face as the first, best face. There is a slight deviance. This helps not much for live edge stuff. If you are not scribing the braces in then you will have typical square rule housings, depending on how round the live edge is, the housing will come into the side face, assisting in the layout. A combination of squarers will get the pocket laid out. The next question is how it is cut? Live edges are different but I feel as if I don't have the time to deal with them, heavy wane is bad enough.

You could hew off the live edge, too.

Re: Looking for advice on snap line layout [Re: danfink] #27402 10/16/11 11:57 PM
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Hi Dan , I suggest that you adopt a method that you can visualize and plan all the layout and cutting before you put a stick on the horses. The most direct method, my personal prejudice, is to use level horses and level timbers. Whatever the layout or tooling issues you may have, the use of a level can define plumb or level directly on the stick.

In the case of braces and live edge joinery one cannot have uniform brace length, brace slope and uniform entry points on post and beam. I choose uniform entry distance from the post, uniform brace slope and uniform brace length while allowing the brace entry elevation to vary on the post. What you choose determines layout protocol.

Re: Looking for advice on snap line layout #27405 10/17/11 01:50 AM
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northern hewer Offline
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Hello everyone tonight

Great thread

In my experiences using hewn timber that may be twisted, etc.,
I just placed the timber on horses or timbers, then by sighting visually I would use wedges to try and obtain the most advantageous lay of the timber from one end to the other (splitting the wind)

I would then nail on straight 1 by 2inch stick on one end along a plumb line, (in from the edge about 2.25"), this stick would be long enough to extend above the timber 12 to 16".

Going to the other end of the timber apply another 1 by 2" stick of equal length using one nail keeping the stick in from the edge an equal distance, rotate the stick to line up visually with the far one and fasten securely with a second nail.
Snap a chalk line from end to end

this line is the main line all other lines will square off this line as work progresses

this layout uses only minimal steps and easily adapted to many siuations

NH

Re: Looking for advice on snap line layout [Re: northern hewer] #27410 10/17/11 07:14 AM
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Cecile en Don Wa Offline
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Hello Richard,

I like this method you have described and have one question that also relates to this topic as a whole about the snap line. The question is this, why use an off-set line (2.25", 2" 1" or whatever) which I am guessing represents one or the other cheek of a tenon or side of a mortice, instead of a center line from which the tenon cheek or mortice sides are laid out? Is there a significant advantage of an off-set line over a center line?

Greetings,

Don Wagstaff

Re: Looking for advice on snap line layout #27411 10/17/11 07:34 AM
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TIMBEAL Offline
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Don, the advantage I see is you are already at one edge of the mortice/tenon. No need to measure over to define it. What is the advantage of a center snapped line?

Yes, Roger has a point with the uniform brace lengths. But it is not impossible if the live edges are not real wild, it will complicate things, no doubt. Just remember everything is based on the snapped lines, some mapping may be involved, allowing more error to occur.

Re: Looking for advice on snap line layout [Re: danfink] #27412 10/17/11 01:29 PM
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Dan, the method you describe is pretty much what I was taught. Level your horses, then put your timber on them. Then put a framing square on each end, and use a penny or a nickel to adjust each of them so that the tops are in the same plane. Then mark your 2" mark, and use a combination square to mark 2" down on the side, and on the bottom. The bottom mark is tricky cause your square wants to swing and move. Do that on each end, and snap lines between the marks. I guess, the way others are doing it involves levels and marking the ends, but that's not the way I learned. What you have described for the live edge beam is right on -- basically you're choosing where the level line is on each end, then snapping a line, and laying out everything from the level live you've picked.

Re: Looking for advice on snap line layout #27413 10/17/11 02:04 PM
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Cecile en Don Wa Offline
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Yes, the pre-difined layout line was the one reason I could think of for using an off-centered reference. A center line has always been related to my use of a Japanese carpenters square. Line up the square on the ink line, trace along the opposite edge, flip it over and mark the other side. It has always been good and consistent for me. Another reason, more idiosyncratic, is that a center line is, well, centered. No consideration of left or right, east or west, north or south, up or down, the movement of the sun or rotation of the earth and other pit falls. Maybe I exaggerate... but like I said it suits the broader peculiarities of how I work.

Any other advantages of using an off-center reference line?

Greetings,
Don Wagstaff

Re: Looking for advice on snap line layout #27414 10/17/11 03:29 PM
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D L Bahler Offline
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I do see an advantage to a centered line in that you know no matter where you are, that line marks the ideal center of the timber. I could see a possibility for the occasion of getting lost or confused now and then with an off center line, usually as a matter of error of judgment. With a centered line this is a non issue.


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Re: Looking for advice on snap line layout [Re: D L Bahler] #27416 10/17/11 04:14 PM
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Working in the square rule context, the off center line makes perfect sense since the mortise and tenons are oriented from a reference face ie two inch tenon two inches from reference face. Striking a line two inches from reference identifies reference from proximity, tenon cheeks and mortise side, not at all confusing.

Re: Looking for advice on snap line layout #27417 10/17/11 05:45 PM
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Will B Offline
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I suggest referring to the June 2008 issue of Timber Framing for an article on snap line square rule.
Offsetting the line from a reference face keeps all the timbers (roughly) flush to that face, which is desired for outside walls or top of floors, for example. Using centerlines would center the timbers, and for timbers of varying thicknesses would require some mental gymnastics to offset them back to the flush face or snapping the line to some new datum other than centerline, hence back to "square" one. Unless you want all of your timbers of varying thickness centered.

Re: Looking for advice on snap line layout #27419 10/18/11 12:49 AM
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northern hewer Offline
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Hello everyone tonight:

To each his own I guess, but I agree with Will B. unanimously!

I was always taught to not use a centre line unless for some reason it was necessary, A centre line usually will confuse things big time, because in hewn material layout, you would need to snap more lines than necessary, and mistaken lines could cause mistakes.

As an instructor I would not consider using a centre line layout, but rather start with the 2" offset line from one face (usually the otside) as I referred to in my earlier post. I use 2.25" to allow for rough surfaces in reality.

As Will B referred to above it always keeps the outside surfaces of hewn material (nearly) flush which is normal.

In historical work all braces and girts were set to the outside surfaces of timberframes, even on interior surfaces only occasionally would you see ceiling girts crossing the centres of frameworks set to the middle of the supporting wall posts

The large anchor beams of Dutch barns are one of the occasional centre lined connections with the braces being in line with the large tusk tenons

NH

Re: Looking for advice on snap line layout [Re: D L Bahler] #27420 10/18/11 09:46 AM
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TIMBEAL Offline
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Originally Posted By: D L Bahler
I do see an advantage to a centered line in that you know no matter where you are, that line marks the ideal center of the timber. I could see a possibility for the occasion of getting lost or confused now and then with an off center line, usually as a matter of error of judgment. With a centered line this is a non issue.



DL, have you ever used square rule for working timber? One of the premises to square rule is knowing which face is where, and having the reference edge/snapped line closer to this best face is not confusing, in fact it makes the system more clear.

So, two advantages to snapping lines off center are highlighting the reference sides and delineating the joinery locations.

I am still not convinced a center line is the best location, perhaps there is an occasional exception. And it can be done without pre leveling of the timber, as has been mentioned, pre leveling is just an extra step as is center lines.

Re: Looking for advice on snap line layout #27422 10/18/11 01:24 PM
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Gabel Offline
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An interesting description of traditional square rule is in Hodgson's Light and Heavy Timber Framing Made Easy from 1909.

Here's a link to it on google books: http://books.google.com/books?id=kkk1AAA...ber&f=false

The relevant section starts on page 162, third paragraph.

Re: Looking for advice on snap line layout #27423 10/18/11 05:05 PM
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Dave Shepard Offline
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I agree Tim, referencing the edges/faces is much more important than finding the center lines. When I snap lines for laying out a wonky square rule piece, or for scribing, I level and feather mark the timber, then plumb my top line down on either end, and then put a level line either 1.5" or 2" down on either end and connect the lines. Now I have marks delineating two planes at 90 degrees to one another.


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Re: Looking for advice on snap line layout #27424 10/19/11 01:31 AM
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D L Bahler Offline
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Tim et al,
I should say, I was playing devil's advocate here. I am not necessarily a proponent of center line square rule. I was pointing out a conceivable advantage to some. I have never done center line square rule, but I have dabbled with it in the form of setting out from a primary corner/face. Just a thought I threw out there. Sometimes I do throw out opinions I don't necessarily agree with because I still think they merit consideration!

For the most part, however, I am content to sit back and listen to what you all have to say on this. I don't consider myself any kind of authority on square rule, not even close! SO keep the information flowing, I am certainly soaking it all in.

DLB


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Re: Looking for advice on snap line layout #27426 10/19/11 07:39 AM
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Ken Hume Offline
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Hi,

So far the conversation would appear to revolve around using either square or rectangular section timbers. When round, polygonal, moulded, profiled or tapered timbers are employed then the ability to establish offset lines from references faces will become more problematic and so this might well demonstrate the ultimate value of using centre lines as a method to establish reference planes.

Regards

Ken Hume

Last edited by Ken Hume; 10/19/11 07:40 AM.

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Re: Looking for advice on snap line layout #27430 10/19/11 11:22 PM
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TIMBEAL Offline
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Hi Ken, that is a good example for why we should not get locked into one method. When a certain problem arises we should have a variety of methods to deal with it.

Re: Looking for advice on snap line layout #27431 10/20/11 12:08 AM
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northern hewer Offline
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Hello everyone tonight

Thanks for stepping in Ken with those examples, I thoroughly agree with you.

These types of unusual shapes and conformations might appear and could be handed to you for your attention, in that instance one needs to have alittle something in your experience manual to deal with it.

I once said to my father--"what would I do if I come up against something that I have never done before"--his reply was "when you have enough experience you will be able to figure it out"

How true a statement that was and it carried me through many first run situations, and my Aunt told me as a young man to always listen carefully to your mind when it came to hard calls or problems.

I found that as my career developed and various new challenges emerged I drew on past experiences to solve problems, "Historic Millwrighting" while specialized in itself contains certain aspects of carpentry and timberframing, mainly the getting down to brass tack calculations, common sense and good accurate workmanship.

Anyone of you guys could become a good Historic Millwright--working with wooden drive wheels, line shafts, mill frames, flumes, wooden machinery of many different types--I know this from listening to chatter from all of you!.

NH

Re: Looking for advice on snap line layout [Re: Dave Shepard] #27433 10/20/11 08:24 AM
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Cecile en Don Wa Offline
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Hello,

This seems roughly similar to the way I create guide lines for squaring up timbers with axes.

Greetings,

Don Wagstaff

Re: Looking for advice on snap line layout [Re: Ken Hume] #27449 10/21/11 01:57 PM
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Gabel Offline
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Originally Posted By: Ken Hume
Hi,

So far the conversation would appear to revolve around using either square or rectangular section timbers. When round, polygonal, moulded, profiled or tapered timbers are employed then the ability to establish offset lines from references faces will become more problematic and so this might well demonstrate the ultimate value of using centre lines as a method to establish reference planes.

Regards

Ken Hume


Ken, the examples you mention (all quite rare in traditional American timber work) may well call for center lines, but in most historic square rule applications a center line was not used.

This is what I have seen on old timbers where the lines were still as well as visible. My experience backs up this as I have found that lines which correspond to the tenon/mortise offset (usually 1.5" or 2") saves work by delineating one edge of the joinery.

Re: Looking for advice on snap line layout [Re: danfink] #27577 11/05/11 08:18 AM
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danfink Offline OP
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Hi all,

Thanks for the responses. I ended up snapping two lines on every face that represented where the the distance from the edge that the joinery was spaced to (2") and then the housing (7"). Very easy to do, and very effective.

Now Im on to that curved piece I was telling you all about. Its a tie beam, that spans 14', with a thru tenon on either end that joins it into the posts, and with brace pockets spaced 3' from the shoulders. My plan in to snap lines representing the edge of the thru tenons from the outside face again (2"), and then snap lines defining the top and bottom of the thru tenon. These lines representing the top and bottom of the thru tenon will also show me where the top and bottom edges would be on my theoretical straight inner timber. Since the braces are already cut, and their pockets in the posts, my main concern is that 3' from either shoulder, I need my snapped line to still be on the timber (since the piece is curved, the timber will lose the line in places). If I lose the line at those brace locations, then the pocket I cut for them will be smaller (shallower) than what they need. I also need to make sure that this is true on both sides of the timber, even though the brace is hugged to the outside edge because if I lose more of the line on the inside edge at the brace pocket location, then there would be little meat for the brace peg to come out through. Hope that all makes since.

I write this all in case any of you out there can anticipate any mistakes before they happen in reality. Or in case any of you have any suggestions.

Now, what about snapping lines on curved edges, both convex and concave?

Dan

Re: Looking for advice on snap line layout #27578 11/05/11 09:06 AM
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TIMBEAL Offline
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Dan, snap another line up from the bottom tenon line, so it lays on the timber just beyond where the brace locates. I usually use some random even number, no fractions. What ever it is remember it well. This number you will use to locate the brace on the post, in adjustment to the 36" you are using as the brace leg. It wants to just skim the wane, as it is the housing for the brace.

Now for the post, if you are using 9x9 post and housing to 8". Hold 8" on the shoulder line on the tie beam and mark 36", this is the far end of the brace pocket. Use the reference face as the best face and lay the pocket out on the live edge, no snap lines on this face. Assuming it is a best face and not twisted badly.

Does this fit into what you are doing?

The peg will enter the sawn surface on the ref. face, I care not if it exits in the live edge as it exits the far, dark side.

Re: Looking for advice on snap line layout #27579 11/06/11 12:29 AM
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danfink Offline OP
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Thank you TIMBEAL.

I partially understand. I do not understand the random number part. The brace pocket is already cut on the post. My idea is cut joinery in the curved tie that aligns with the already cut, square rule, non-scribe joinery in its adjacent timbers. I dont understand the random number part, that you use to align the brace to the post. Dont I already know that the brace pocket on the post is 36" down from the shoulder?

Thanks,
Dan

Re: Looking for advice on snap line layout #27580 11/06/11 01:12 AM
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Hi Dan, Now that you have cut the brace pocket on the post before you made the pocket on the tie..... that is an inside curve at knee level or just below. Baseball pun.

I called it random because I don't know how much curve your tie has, and as such, it would be random, I think. In other words what ever number the stick dictates you will use. I try to stick to whole numbers, with out fractions.

I always cut the pocket on the tie first as this will determine where/what the brace location on the post will be. So you can square rule and have all the same length braces.

The number of inches above the bottom snapped line, gaining a third line will determine how many inches off the post brace will be from the 36 inches. As an example if the third snapped line corresponding to the brace location on the tie is 2" up from the bottom line then the post brace mortice will need to be dropped up to 34" instead of the 36".

Now, if you have a 36" leg on the post(now cut) and the difference is 2" on the tie you have to make a brace for a 38" leg, a brace 53-3/4" long. And your brace on the tie gets bumped out to 38", too. The normal brace length for 36" legs comes in at 50-15/16", have you cut all your braces yet? You may need to cut a couple more, if so.

A drawing would make it clearer than my words for sure. Draw it out full scale on the shop floor and see what happens. Then return to the sticks and see how it all relates.

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