Thanks for the information. I have not done a speaker enclosure (or open baffle) before, so I am learning as I go. If nothing else I am very careful when I lay out and cut stuff like this. A very minor mistake can destroy hours of work and many $ in material, so best avoided. It is really useful for me to go through and resolve the whole build in my mind before I start - that way I have already sort of done it, and actually building it is the second time around.

regards -- Roger