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Log Joist, step by step.

Started by Dave Shepard, July 22, 2012, 03:11:59 PM

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Dave Shepard

A couple of people have urged me to share some of my timber frame work, not to mention any names or anything, but Piston is at least one of those people, :D so I thought I would put together a couple of pictorials of some of the parts that I am making in the shop. I will also start a thread that I can add to as the work progresses on the overall project.

I am a full time timber framer restoring two New York State Dutch Barns in Western Mass. Both of these barns have been taken down and labeled, inaccurately, and delivered to where I work. Both of these restorations are being overseen by Jack Sobon, who does all of our drawings and specifies the repairs and procedures. Both of these barns are scribe-rule, and are almost entirely Eastern White Pine.



This pictorial is of a new log joist being cut for the floor of the "Canajoharie" barn, as we call it. The log joists are sawn on parallel sides, and the bottom, viewable side, is hewn. The joists are 9'-1 1/4" shoulder to shoulder, and the tenon is 2"/2" from the top or reference face, and 6" wide.


The first step is to snap a line down the center of the joist. Some of the joists are not perfectly straight, so you may have to cheat the line to one side or the other to get it in a good spot. All layout is done from the chalk line.



Next, you need to decide where to put the joist on the log. These logs were 12'-6", so I had room to play, which is good as you can then avoid having to put a tenon in a knot whorl. As you can see, I am crowding the joist to the small end to keep the cross section dimension within spec. There has been a lot of discussion about burning a foot, inch etc. I burn a foot. This joist is 9'-1 1/4" shoulder to shoulder, so I layout 10'-1 1/4". You want to always layout the shoulder to shoulder distance, then layout the tenon from there. That is the critical dimension, the overall length of the tenon, within reason, is not as important. Always use feet and inches when burning a foot. If your dimension is in inches, convert! ;) When you are done with your layout, put 9'-1 1/4" on one shoulder and check the other. If the metal hook is touching the other shoulder line, plus or minus the sloppiness of the hook, you know you got it right. There is no need to worry about the sloppiness of the hook, if you are off, it's going to be more than that. ;) Mark your shoulders on the chalk line.



Use the framing square to layout the shoulders and the end cut on the tenon, as well as the 45 degree reduction.



I lay out the sides of the tenon with a steel rule. I put the 8 on the chalk line and mark three inches out each way. I do this on the tenon shoulder, and the end cut of the timber and connect with the steel rule.



Repeat on the other end and we are ready for the evil blue saw.



I use the big Makita to make my end cuts to save laying out on a round timber, because, in theory, the cut will be perfectly square to my reference face. In theory. :-\ These saws leave a lot to be desired in a number of regards. Do the best you can and finish with a handsaw.



I use a Borneman layout tool to drop the lines down the end to get my tenon layout. Probably the greatest layout tool since the framing square itself. Here, X means remove. In Piston's photos from Heartwood, O is remove, and X is the part you are saving, which is the French system Dave Carlon uses.





Now for the axe work. I have a couple of blocks screwed to a pair of horses that I can clamp the joist on edge for chopping. I chop as close to the line as possible to save on paring.



The only reference you have is the line on the reference face and the line you dropped down the end of the joist. You have to use a square to make sure that the side of the tenon is in dimension.



Use the Big Al tool again to layout the sides of the tenon. Flip the timber 180 degrees and repeat. This one was a little blurry, sorry.



Cut the tenon, drill the peg hole (draw bored to the shoulder). I drill in about 2 1/2" so I don't have to drill from the other side, and taper and chamfer the tenon. This is the last time the joist will be this side up.



Flip the log over and chop the last part of the of the end detail away. Finish the tenon and taper and chamfer. There is some nice mold growing on this one, but it brushes right off with water and a brush. This is not the time of year to be working fresh pine.



Hew the bottom, and add it to the pile.



Altogether, this is about an hour and a half. That doesn't include moving timbers and sweeping up and all the other hidden things that eat up time.
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timberwrestler

Nice Dave.  It's fun doing barny work, where you get to do your finishes with an axe.  I'll make it down there one of these days.  And certainly let me know when they're going up.
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Dave Shepard

No idea when they are going up, but they should both be finished this year, unless we find something else to do outside and put the barn work off for inside work this winter.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Mad Professor

Hi Dave, nice work.


Do you have the timber with the original master scribings for the layout? 

Could do all this with a divider/compass, and to hell with the square and rulers

E.g there should be circle(s) to define the the layout of each tennon, layout starts from the timber centerline/chalkline as above. Each timber has a circle which defines the timber width at hewing......


routestep

Nice work. Would you tell me the cutting tools used. I'm guessing a small hewing axe, a saw, a chisel and hand plane. Maybe not the hand plane.

Also the depth and width of the joist and size of tenon and peg hole. Are the bents only 9 ft apart?

I'd like to build a mini New World Dutch Barn sometime.

Dave Shepard

The tenons are 2"/2" and 4 7/8" long. Peg hole is 1", 2" off the shoulder.

I used a framing square and Big Al tool for layout, 2" chisel and slick, and my 36" scoring axe for the chopping.

These joists are in the narrower outer aisle of the floor. The narrow aisle is 10'-1/4" from the outside of the building to the reference face of the purlin sill. The outside sill is 12" wide, and the joists are housed 1/2" on each end, so the overall shoulder to shoulder length is 9'-1 1/4". The wide aisle is 12'-1/4", so Jack specified oak for that side.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

routestep

A joist with a five inch tenon and a one inch peg. It's really locked in place well.

Thanks for the info. I generally make tenon 3 to 3.24 inches maybe 3.5 and use a 13/16 peg, if I peg it at all. Drop-ins are only 2 to 2.5.

I think I'll lengthen my tenons, might as well go with what stood the test of time. I'll keep my pegs small.

Is that a typical tenon or unique?

Thanks again

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