Saturday, December 08, 2007

Enormous Fir Brackets

As I mentioned in yesterday's post, I'm working on a set of three enormous fir brackets.  These will fit under the soffit of some huge home.  They will be 20" tall and 6" thick, projecting off the exterior wall about 21" total.  The pattern I'm using is shown below.  I took the full size drawing from our drafting department and glued it to a piece of 1/4" ply to make my pattern. 

After I'd used the fantastic Fay & Eagan 429 (see previous post), I glued-up five 1 13/64" x 15 1/2" x 70" slabs.  Below, you can see one of the slabs in clamps.  I frequently use the printmaking brayer you see on top of the slab to spread large amounts of glue quickly. Stacking all five slabs yields the required 6".

Once all five slabs were glued together, I stacked them one on top of the other and used a caret to mark one edge.  Harrison taught me to use carets in markups because they convey a great deal of information.  In the photo below, the caret indicates 1) the placement of each slab relative to every other; 2) which surfaces receive glue and which do not; and 3) which side I'm working from on each slab.  Someday I'll do a whole post about carets and their multiple uses.

At this point I was almost ready to start gluing, but I knew I needed a way to register the slabs since I'd soon have roughly 30 square feet of wet glue causing them to slip and slide every which way while under pressure.    My solution was to drill two 9/16" holes in opposite corners of the slabs in the waste material.  I could then drop 1/2" dowels into the holes to keep the glued slabs from going cattywompas. In this photo you can also see the considerations I thought about with regard to grain orientation at the ends of the boards.

A coworker helped me spread the glue across the slabs' interior surfaces, I dropped the dowels into their registration holes, and then the whole assembly went into this massive press.  I'm not sure what it was originally designed for or why we have it, but it's handy for face gluing large, heavy pieces like this one.  The red gun at the top is a pneumatic driver that screws the clamps down.  There are four or five clamps per beam, all of which can be located side-to-side.

This last picture shows the assembly under pressure in the press.  The 4-by material is simply blocking we use to keep from having to drive the clamps all the way down.  The air driver makes a hellish racket.  When I go in on Monday, I'll take my huge timber out of clamps and start bandsawing the brackets.

1 comment:

John said...

I just like that you use the word "cattywompas" in a proper sentence.