Wednesday, March 3

Back Panel Assembly

My first activity this morning was to remove the clamps from the three panel blanks I glued up yesterday evening and scrape the glue squeeze-out off. Then I ran them through the surface planer a few times to remove any ridges that appeared where the pieces got glued together. I was careful to get the face surface as well lined up as possible, but because the pieces were not all exactly the same thickness, the back sides were not all even. I was going to have to plane the assembly anyway… Once the panels were smoothed out I used the wide drum sanded to do bring them down to finished thickness. The drum sander works much more slowly (can’t remove as much material in one pass) than the planer, but the planer also have more tendency to chip out the wood, especially where the wood is highly figured. By sanding them for that last 1/16” I can remove the chips and get a nice smooth surface. Then I remove the splitter from the table saw, install a fine tooth blade and the big cross-cut sled for squaring up the blanks. Next I get out my lay-out tools and take very careful measurements from the clamped up back frame and transfer them onto the back panel parts. These panels will be trapezoidal shaped – narrower at the top than at the bottom – so I have to find the center at the top and bottom edges and measure out from the center points to find the edges. That means finding the needed width (including the part buried in the grooves) divide that in half and measure that distance out from the center point. I cut the panels on the cross-cut sled by using the slot in the bottom of the sled to line up with the pencil lines on the panels, then press down hard and hope it doesn’t slip while I cut. I do use a stop block clamped to the front rail to keep the base of the panel in position – and on the longest panel another block clamped to the back rail helps a lot. Here’s a neat trick. In frame and panel work, the panels must be allowed to float in the slots, not be glued in or when the panel contracts in dry weather it will crack. To make sure the corners of the panel do not get glued in place accidentally by squeeze-out from the mortise and tenon joint, I dog-ear the panel corners. That way there is no wood right where the glue would squeeze out and the panel can’t accidentally get pinned by the corners. I DO have to be careful not to cut away so much that the dog-ear pokes out of the groove – we want a nice solid look to the panel. I test fit everything, adjust if necessary, then take it all apart again and do the finish sanding of the panels and the inside faces of the rails and stiles (the narrow faces adjacent to the panels). It’s much easier to sand these now than after everything is glued together. When that’s done I assemble it again, putting glue in the joints and clamping the parts snugly together. The final step is to use a rule to measure across the diagonals to be sure they are the same length. If not, and these were off by 3/32nds inch, I can pull the frame into alignment with a clamp across the long diagonal.
I’ll let this assembly sit overnight, so I’m done for the day. See you tomorrow.

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