More About Waste Blocks and CA Glue...
Wally Dickerman at Green Valley, Az.
>We've had several posts recently on using CA glue with waste blocks. Here are a few suggestions based on my experience of turning many hundreds of bowls/vessels using waste blocks and CA, plus over 300 students in my classes, nearly all using waste blocks and CA glue. My success rate in not quite, but almost, 100 per cent. I use CA because it's faster and it does the job for me.
When using waste blocks it is essential to have a good mating of both surfaces, just as it is in any glue joint.
I've found that nearly always when a CA joint fails, it's because not enough glue was used. My method is to apply lots of medium viscosity CA to both surfaces, apply accelerator to one surface, and immediately apply the waste block using only firm hand pressure. The blank can be mounted on the lathe immediately.
CA glue bonds well with wet wood. I have't tried Russ's method of using thin glue along with medium, on very wet wood, but I will.
CA glue has a shelf life of 3 to 6 months at room temps after opening. Refrigerating it after opening isn't recommended. Once it starts to thicken it's best to discard it.
Don't use CA glue if it's cold. Less than 50 degrees and it doesn't bond well.
When opening a new bottle of CA, throw away the cap. You'll get fewer plugged spouts without it. When I do get a plugged one I replace it with a clean used one, and put the plugged spout in a glass jar containing acetone, which dissolves the glue.
If you're getting a white residue, it's because you're using too much accelerator, and too soon. A light spritz will do after 30 seconds or so.
A failure can occur when using wood that warps a lot while drying. Perhaps surprisingly, I've seldom had that happen.
I don't trust an endgrain joint, so if I'm turning a small or medium endgrain piece, I turn a 1 inch tenon, 1/4 inch deep, on the blank to fit into a matching hole in the wast block. Makes a stronger joint. Also not a bad idea if you're turning a large bowl.
I use 4/4 or 5/4 alder for waste blocks. Alder almost never warps, so I can count on a good mating surface. Other soft hardwoods such as poplar work well. Never use plywood as it may delaminate. One big advantage in using a waste block, is that after the piece is completely finished inside and out, except for the foot, where I've left "heavy" wood, I can part away some of the waste block and form the foot as shown in the photo...
Wally