Testing glue strength.
If you missed Bob Spangler’s class on “Woodworking Gluing Essentials” (January 2010), you’ll probably learn a few useful tips from this summary, which Peter Eddy wrote up.
Bob began the class with a discussion of the advantages/disadvantages of different kinds of glue, and how he chooses which glue to use in a particular situation. He uses Titebond II in most furniture-building applications. It has greater water resistance than the original Titebond, and dries flexible rather than hard. Titebond III has even greater water resistance, and would be used for a piece to be used outdoors. Titebond type glues have the advantage of water cleanup of overage on the piece and on tools. Epoxy glues are also good for outdoor applications, but they dry hard and cleanup is more difficult. Bob also discussed a number of other types of glue, ranging from contact cement to “hide glue,” which is used in musical instrument construction because it loses its adhesion when heat is applied.
The course was filled with practical hints about the gluing process. Bob included a graphic demonstration of the strength of glue joints that follow the grain, and the weakness of joints involving end-grain. A student was easily able to break apart with his hands an end-grain glue joint Bob had prepared; the with-the-grain joint was rock-solid.
Bob's trick for keeping boards flat when he's edge-gluing: Clamp thick, straight boards over and under the parts.
Bob's trick for keeping boards flat when he's edge-gluing: Clamp thick, straight boards over and under the parts.
Gluing boards
Bob demonstrated the process of gluing several boards side-to-side to make a wide surface using biscuit joinery, and stressed the importance of correct clamp placement and the use of reinforcing boards of identical thickness to make a flat surface.
He also demonstrated several jigs he has fabricated to make glue-up of his furniture pieces quick and replicable.
Customizing a brush.
One practical idea I took away was making a nice glue-spreading brush by cutting all but ½ inch of the bristles off a plumber’s flux brush.
Step 1: Tape the outside edge of each corner.
Step 2: Turn over taped frame and spread glue on mitered ends.
Step 3: Wrap the frame pieces together.
Step 1: Tape the outside edge of each corner.
Step 2: Turn over taped frame and spread glue on mitered ends.
Step 3: Wrap the frame pieces together.
Gluing picture frames
Bob also showed us a way to make a clamp for a small picture frame using masking tape: you lay the cut pieces of frame molding end-to-end and long side down on the sticky side of the tape, apply a thin coat of glue to both sides of all four corners, then fold the tape up sticking the tape end from side 4 to side 1, and voila!, you have a surprisingly tight jig to hold the frame together while the glue dries.
Gluing veneers
Bob's veneer press
The last few minutes of the class were spent in the veneering area of Bob’s shop where he talked about the veneering process in general, showed us how to join pieces of veneer seamlessly, stressed the importance of applying glue to the substrate, not the veneer, and demonstrated a huge vacuum bag he uses in the gluing process. It exerts one ton of pressure per square foot!
Final thoughts
This was an extremely well conducted learning experience. Bob had obviously thought out what he wanted to demonstrate, had assembled what he needed to do this, and he presented the material clearly. Student questions were welcomed and handled in a way that helped everyone’s learning.
