Square rule hammer beam frame

[David M]

Im familiar with the concepts of center line rule method (James Mitchell ISBA) for laying out hammer beam bents.

Has anyone had much experience on adaptability to a square rule method with the  appropriate gains?

Would it all end up too unsightly?

I'd love to come up with a handy 12' wide 12/12 hammer beam bent design utilizing square rule method. Ideally 7x7 stock of #2 mixed oak or similar.

Any input or guidance as always much appreciated. 

[Brad_bb]

Welcome David! I see you're fairly new.  If you don't mind, take a minute and add your location to your profile.  It will then show up in all your posts so we know whereabouts you are, what kind of wood is available to you, your weather conditions etc.  This helps in tailoring answers to questions.

So you want to make a 12 foot wide hammer beam bent?  Well you shouldn't even need a steel tension rod for that width.  You may know that hammer beam bents tend to create outward thrust, which is why in the old days, the medieval churches that used them had big stone buttresses at the base to resist the thrust.  

I had to investigate what center line rule method was.  
https://www.youtube.com/watch?v=VzEq9bEx500
If this guys was doing it right, it looks like just another way of laying out the joinery, similar to snap line square rule.  This method is good if you have timber that is not sufficiently straight(and or square).  With the smaller bent that you're doing, and thus smaller material, I would hope that your material is sufficiently straight that you can use regular square rule.  Or if not, can you straighten your material, with a planer etc.?  Put a string line on it to check it.  You can also look at twist with a couple framing squares.

[David M]

Brad, 
 
 Thanks, yes I will go ahead and update that.

 Im deep in timber country of eastern WV, I have about any species of hardwood I could want available easily and cheaply as well as a handy inventory of white pine and red spruce stands that were planted in the 40's-50's that are coming to harvestable age.

I usually mill the timbers myself and have everything needed to get the stock as straight as I'd like (12" beam planer). I enjoy and have become custom to the speed and general handiness of SR layout. Ideally in the next year or two I would transition to full scale layout scribe, but until then I distance scribe some components.

The niche I prefer to work in is smaller frames that are more widely attainable to a larger client base. That being said ornate smaller hammer beams have been on the list of things to play with for a bit now.

The only thing I see as immediate issue is that hard and fast suggestion Steve C makes in his book about bringing the lower hammer brace into the post at 2/3rds. That may be problematic as with a 12/12 and 12' wide it would put it quite low and obviously a head injury waiting to happen. So I would gather that issue may be partially addressed by increasing the post width to compensate for the bending forces and raising that joint out of the way. 

Provided the sill is framed in timber as well I suppose simply making sure the short sill join is designed for tension (ie wedge half dovetail) would help with any spreading issue much as a tie below a plate would in a common rafter system...