jowl posts

[hayton1960]

Hello everybody
I was wondering please, what experiences does any of you gentlemen have with jowl posts?
What is the best way to get up some jowl posts? I made some 1/8 scale; by laminating a wedge piece to a regular post, others I have hewen from a solid 3x2. How important is it that the jowl post is all one piece? Is it feasible to just have a post that tapers from square at the foot to jowl depth at the top with no jowl step at all in between (like a giant wedge)? If you DID laminate one, would it possibly need some steel reinforcement bolts or pins to prevent splitting, which they are prone to do at that point anyway? What does anyone think?
Cheers Jonathan ;)

[Jim_Rogers]

The shed that we're currently working on, here at my workshops, has two jowl posts.
I cut them with my sawmill.
What I did was I figured that I wanted an 8x8 at the bottom and a 8x12 at the top.
I milled a log that was big and I made it 8x 12 end to end with the heart off center so that it would be in the center of the 8x8 part or 8x8 side.
Then I laid out the lines I wanted the jowl cut to using a framing square.
Once I had these lines drawn I cut a relief cut with a chain saw, and made a end cut to this relief cut.
This produced a timber with an 8x8 end and a 8x12 end with a squared off step in it about 4' or so down from one end.
I wanted a bevel transition from 8 to 12 so I blocked up the 8x8 end until the bevel line was level to the saw table and made the bevel cut to remove a wedge shaped piece.

Here is what the post came out looking like:



We have cut some joints in it and it and it's mate will frame the doorway in our project, but they will only be seen from the inside looking out.

If you want to add a piece to a post to make it look like a jowl this piece would be called a corbel.

What you'd do is create a mortise pocket for it and a shoulder for it to set on and then peg it to the post this would make it look like this:



It's not as strong as a single piece but it will do....

Hope this helps.

Jim Rogers

[hayton1960]

Hi Jim, thanks for your reply
Your excellent corbel diagram just got me to thinking even some cruck truss type constructions use a blade that is almost like a extra long corbel?? I reckon a corbel is a brace that fills the entire corner and has a bigger surface area in the wood connection? I like the look of that, more complex joinery though, swings and roundabouts I reckon! Good way to use up a stumpy little offcut!
Is it feasible to use a tying joint in a cruck bent on the little cruck spur (opposite ends to the 1/2 lap dovetai ends) to support the plate and rafters etc?
Mind you Jim, the more I think about it, I very much like the concept of the dropped tie beams with a queen post/purlin type arrangement as in the Dutch manner. It makes more sense to get better use of upstairs space (with a low vertical wall instead of triangular wall/floor junction) Then again theres more risk of the posts cracking at there top sections with that arrangement! Six of one, half a dozen of the other! Thats one reason I am spending time cutting various different joints, studying diferent designs and construction types etc, let go of preconceived ideas etc I love and respect our joinery traditions, and practise a lot setting out/cutting etc (all by hand); but when I build my frame, I want it to still have a cotemporay feel to it, be energy efficient, and be as free of chemicals/plastics/resins/solvents etc as it can be.
Thanks again for your tireless encouragement Jim, I apreciate it a lot
Cheers, Jonathan
Ps Jim will you "post" a picture of the 2 jowlers in your workshop when your done fitting them up? Looking forward to your write up of fitting the curved pine braces as well ;D

[mark davidson]

I've cut jowled posts right on the sawmill before, just like Jim I start with a 8x12 or whatever the full original size is. Then choose the side to jowl and cut with the sawmill(bandsaw) to a bit short of the beginning of the jowl(now, back off the sawmill into the kerf, this may require some back and forth sawing as you're getting close to the end of cut). Then fire up the chainsaw(or even the circular saw if you're close enough to power) and cut the waste piece off(should make a 4x8 brace), now you're done with the sawmill, get the adze/chainsaw/whatever(angle grinder??) and shape the jowl as you like.... probably only possible with a bandsaw mill??? 

[Jim_Rogers]

Jonathan:
I don't have much experience, yet, with cruck construction so, I can't comment on the ideas you've mentioned.

Recently I received a request for another story about layout and drilling peg holes. Saturday, while it was raining outside, at one of my regular workshops held here at my sawmill yard and shop, we photographed a step by step set of procedures for laying out and cutting a brace mortise, including drilling peg holes in both the mortise and tenon on the brace. This took 58 photos to complete. It took several hours just to write the step by step procedures. (This is something I've wanted to do for sometime).

I have inserted the photos into the story and have printed it for my records. It took 41 pages, to print.

I have reduced all the photos for uploading to the FF.

However, I'm leaving today to go to the Eastern Conference of the TFG (Timber framers guild) and won't be back to my desk until Monday the 17th. On Tuesday the 18th, I suppose to move my sawmill to a job some two hours away and saw there for three days, staying over at a local motel. Possibly moving the sawmill back here around Monday the 24th or so.

This will not leave me any time to upload the photos or post the story until then. :( :( :( :( :'( :'( :'( :'(

After this is done, and or at our next workshop we'll be creating two collar beams with round edges, similar to laying out the curved braces. At that time I'll take a series of photographs showing how this is done and then write that story.

It really isn't that hard to do, you could try it yourself if you're interested.
Just get two matching curved pieces, create a standard brace of the size you want to use, lay it on top of the curved pieces to identify the center of the curve on both so they match, in size and shape. Then lay a straight edge across the center of the arch and draw two lines, one on each end. These two lines will be the 3/8" layout line as described in my story already posted about how to layout a brace corner. From there you just layout and cut the brace ends on the curved pieces using the 3/8" layout line as your hypotenuse of the triangle.

Once the curved braces are completed, you layout a standard mortise pocket for the brace on your post and beam. Lay the curved brace over these pockets and see how much longer the mortise has to be expanded to fit the brace tenon. Cut the mortise longer toward the 90° corner and fit the brace to the longer mortise. The mortises in that frame were around 19" long.

Not really hard at all.

One thing I thought I'd do next time I'd lay one out was to go to the hardware store and buy one of those huge squares that sheet rock men use to cut sheet rock. The legs on that square are very long and would work well to use to compare tenon shoulders to see if they are 90° to each other.


Have fun and don't post to many question for me, for a while........


Jim Rogers

[hayton1960]

Thanks for your replies gentlemen
I wondered how they got out jowl posts 7 or 8 hundred years ago, no power saws, not even big pit saws. I guess they cut the flared section by chopping out a wedge shaped section to establish the jowl flare, then split off the "waste" with metal or wood wedges, then clean up with adze or side axe??
Jim, my apologies for adding to your workload! I hope you (and anyone else who is attending the guild conference) has a great time!
Cheers, Jonathan ;)

[Tony_T]

Thanks for your replies gentlemen
I wondered how they got out jowl posts 7 or 8 hundred years ago, no power saws, not even big pit saws. I guess they cut the flared section by chopping out a wedge shaped section to establish the jowl flare, then split off the "waste" with metal or wood wedges, then clean up with adze or side axe??
Jim, my apologies for adding to your workload! I hope you (and anyone else who is attending the guild conference) has a great time!
Cheers, Jonathan ;)

In the old days when they hewed timbers by hand jowled posts were cut from the butt log of the tree.  The jowled portion was actually obtained from where the tree flared out at the base .  That is the post after being hewn was upside down in relation to how the tree grew.  This supposedly gave the jowled portion greater strenght as the grain of the wood followed the jowl portion but the remainder of the post had grain paralell to the post.  Layout on the log for hewing was done using chalkline (charcoal line) , dividing compass, and plumbbob , with an axe/adze used to square off the log. 

When milling a timber (as described in posts above) I suppose you could also use the butt end of a log to get the same effect (grain structure) but the flaring of the butt is usually problematic when trying to saw things. 

[hayton1960]

Hi Tony,
Thankyou for your reply
How you mention it, it makes sense to use the natural shape of the tree, same as using natural curved limbss to make braces and knees etc.

Talking of old chalklines, I recently saw a picture of a chalk reel recovered from the Mary Rose ship. It sank about 450 years ago. It just looked like a bobbin they use for sewing thread, almost like an old type wood fishing reel.

Cheers, Jonathan ;D

[hayton1960]

Hi Jim
I trust you had an awesome time at the guild conference.
You know what, if it rains it pours! You mentioned about corbels a while back. I just spent a week in a barn/farm complex in Suffolk where there were corbels literally everywhere you looked. (I uploaded some pictures). These were BIG babies, the only one I could get safely close enough to measure was 40"x46". They were fixed with iron bolts, not able to ascertain wether there was aditional tenons, stub tenons etc (my diagnostical skills are minimal to say the least). The barn we stayed in was as badly damaged as the one in the photos before it was repaired. They jacked it up on acrow props, built a new concrete floor, plinth wall under it etc, laid an entire new wall plate (sill). The rafters were all made from re-used timbers. 99% oke throughout but I saw one length of pitch pine being used for a plate. The top ends of the queen posts were in a dovetail form like on a kingpost.
If you ever get to visit England Jim, Suffolk is definately worth a visit, excellent timber frames from 5,6,7 hundred years ago, still maintained to a high standard. I saw a part renovated/part new frame going up. Fought my way through torential rain, mud and general crap to get some pictures of the tying joints (the jowl posts were about 16"x12" at their tops), only to discover I'd left my nicad batteries at home :D : Oh and I was so disapointed when we went to visit Coggeshall barn, the Grandaddy of them all, now a National Trust monument (on a par with Stonehenge, Blenheim Palace etc), because it was closed to the public for the winter earlier in October :'( Enjoy the pictures!
Cheers, Jonathan

[mark davidson]

thanks jonathan,
I'm a great lover of english framing, always good to see pics.

[krusty]

Question for y'all....

When using such a post how large do you make the lower portion of the top seat? If you have an 8x12 post top, do you have an 8x6 section for the top plate or an 8x8 section? Thus leaving onlu a 4" tenon max for tie beam of sorts?

If you go with an 8x6 section you would have to notch the top plate down to 6" wide for it to fit of course.

Home that makes sense!

[Jim_Rogers]

krusty:
If you go to the TFG (Timber Framers Guild) website and download Part two on this page:
Link to Historic Joinery page

You'll see a drawing like this:



and others.

You'll have to figure out what size you need based on the sizes of all the other timbers that will be joining the jowl post.

Hope this helps.

Jim Rogers

[Tony_T]

I've read the Jack Sobon article Jim mentions above.  Lots of nice ideas for joinery using jowl posts.  Also note that the principal rafters can be mated directly to the tie beam which prevents any outward force being transmitted to the plate. I've seen posts split at the top tennon due to the thrust of the plate from very heavy snow loads in some old barns.

[Jim_Rogers]

I've transfered some pictures from one computer to the other to show you the jowled posts as they were drawn in the frame we're cutting.
Here they are from the outside:



Apparently I had already posted this view in my gallery and didn't remember it.

Here is another view looking out the doorway from inside:



When we fit up the wall or a bent with them in it I'll take some photos and post them.

Jim Rogers

[Jim Haslip]

Jim,
What's the reason for the Jowled posts in that design?

Is it cosmetic? Or do the jowls let you carry a wider span?

Just curious...

[Jim_Rogers]

For fun.......
Just wanted to see if I could cut one on my mill......
And after cutting one, I wanted to use it, so I cut another one so that they could "frame" the doorway......
This design makes this shed frame special and different.....
And did I mention just for fun......

Jim Rogers

PS. I've been sending you emails did you get them?
If not maybe you should send me one with your current email address......again.....

[Gabel Holder]

Hello all,

I strongly agree that jowl posts should be fashioned from a butt log with signigicant flare so that the grain will be continuous up through the teazle.  Otherwise you have a weak shear plane.  This becomes a major issue in a traditional english tying joint because as the plate shrinks, the teazle takes the entire load of the tie beam which because the principal rafters foots into the tie is pretty much all of the roof load.  Couple that with a short grain shear plane and you guessed it--   pop goes the teazle!!

To avoid this we use flared butt logs for jowled posts and leave a 1/4" gap between the shoulders of the teazle tenon and the bottom of the tie.   (A procedure I learned from some very good English framers.)  That way the plate supports the roof load and the continuous grain of the main part of the post supports the plate -- no shear worries unless the pricipal rafter lands too far inboard on the tie beam.

Jonathan,  great pictures.  Like Mark, I am a huge fan of traditional English oak framing.  I was in Oxfordshire in July at the Carpenters Fellowship rendezvous and a few of us slipped over to Great Coxwell to see the barn.  Incredible!!  I will never be the same.  We also looked at several other barns and houses and every where I looked you could see the grain running up the posts and into the teazle -- obviously they used flared logs.  Those guys were pretty sharp.  They knew wood.

Cheers,

Gabel

[mark davidson]

Gabel,
thanks for your post, I'm about to cut my first ETJ frame and the 1/4" gap makes good sense. I was also wondering about the mortise for the teazle tenon, it could be a bit longer(on the plate side) than neccessary to account for the horizontal shrinkage? Also sounds best to leave the teazle unpegged?
I have cedar for posts(no shortage of flare for the joinery), and most of the rest is white pine. The frame will be a pavillion for a skateboard park. I'm toying with the idea of leaving the teazle tenon side of the posts in the round....
thanks again to gabel and to johnathan for starting the thread,
-Mark.

[hayton1960]

Hello Gabe
Thanks for that very useful insight; now you mention it, it makes more sense. "Natures laminations"
Theres some nice old frames here in the UK which I have only begun to apreciate in recent years (I used to think my Dad was a boring old nutcase when he tried to get me interested in old wood stuff when I was a boy)  :D