laminating arched beams for a cabin
Howdy all,
I would like to spend this winter making gothic arch beams to build a cabin next summer. I plan to build a very big table and form to laminate these beams. 2 questions:
1: what glue would you use? I made curved laminations for my greenhouse roof 3 years ago, and I used Titebond exterior glue. So far so good, but it isn’t carrying much of a load. Just the plastic film and the odd 2 inch snowfall lasting a day or 2. I was wondering if a standard wood glue would do the trick, or if I should consider something more along the lines of a WestSystem epoxy. Any thoughts?
2: I googled every combination of words I could think of looking for gothic arch cabin plans, but all I get is greenhouses and stone arches. I think I’ve got a decent idea so far a a plan goes, but I sure would like to compare it to other plans. Does anyone know of a location for gothic arch cabin plans? Nothing huge, maybe around 20′ x 30′. Thanks in advance for your help.
Replies
Glue choices:
Polyurethane glue would be a good choice -- long open time and waterproof. Titebond makes one (available at HD) or you can go with "gorilla glue" -- they're both polyurethane glues. Another option would be a slow-setting epoxy.
For a good article on glue selection, see FWW #176 (April 2005).
Plans:
Never heard of a Gothic arch cabin, so I can't help you out there.
1.Resourcinal is a traditional choice for lamination. Titiebond tends to creep. Epoxy works but is expensive and somewhat brittle.
2.Gothic arches are easily drawn. Draw 2 overlapping circles then two arches using the midpoint spanning the center of the circles.
I'm sure you can build structurally-sound beams. Building inspectors are likely to have less faith. If you plan to have inspections during the construction of this cabin, check with the building department before you get too committed to building the beams yourself.
I bet Frenchy would have something to add here, might want to post a query to him.
Most of my experience with arches has been in rockwork. What I know is that the semicircle arch would be the easiest to do in wood. Because of the point at the top of the gothic arch, this would require the joining of two bent pieces, which would mean you would have to use a floating tenon or some other mechanical means of connection. My favorite type of arch is the Catenary. This is the shape a chain makes when suspended from two points. It was the shape preferred by the Sumerians in their arch construction and is also used in the construction of modern day bridges. It would also be readily adapted to the bent lamination process.
My experience has been that the PVA glues like Titebond are very suitable for bent laminations. Creep has never given me any problems and the fact that they are so easy to use and clean up makes the whole endeaveor bearable. Bill Lindau
Just my thoughts..
If the beams will be structural (as in really support the roof or something) I believe that NO woodworking glue is made for structural loads.. Or at least just they don't want the liability.
Folks at Breaktime should know better than I..
Edited 10/5/2005 7:06 am ET by WillGeorge
if it were me and i have built a lot of wooden boats, i would use epoxy. it is very strong and water proof. if you can't afford to do it right the first time how can you afford to redo it the 2nd time. there are cheaper epoxy's out there other than west systen. epoxy stays very flexable aand strong over time as long as the sun doesn't get to it. it has no uv protection. so under a roof or painted you'll be good to go. if you have any question as to the strength of your arches add an extra laminate for added strength. hope this helps
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