Sorry for double post. The picture size was causing problems so I had to split the entry. In the last blog entry, I completed the feet for the sofa table and the joinery to connect them to the legs. In this entry, I will cut the remaining pieces for the base, complete the joinery and glue it up. It will look like this.
First step is to create for table apron sides. Since the apron stock was only surfaced and jointed on one side, I rip the apron stock to final width.
And cross cut to final length to get 2 R/L sides and 2 F/B sides.
I then chuck up the same profile bit that I used on the legs and route the four sides of each apron work piece.
I have four profiled apron pieces.
Next step is to cut the mortise and loose tenon joinery for the legs. To start, I mark up a center line on each apron piece using a try square and a marking knife. It is important to use the try square so that you mark a consistent line on all pieces or your mortises will not line up.
If you have a precise center mark on the apron piece and use it as a reference to mark the legs from the top, you will guarantee that the leg and the apron top will align. Use the same measurement from the apron, I mark line at same point on leg stock assembly.
Time to cut the mortises. I chuck a 1/4” spiral upcut bit in the plunge router. Install a 1/2” guide bushing (comes with MortisePal). Set spiral bit to cut 3/4” deep. I use the MortisePal for loose tenon joinery. I love this jig. Makes mortise and tenon joinery quick and accurate. I set the jig to cut a 1/4” wide tenon, centered 3/8” from the unprofiled side. I insert the largest mortise template that will fit on the end of my apron stock. Set reference face against the same side for each piece and line up centering mark on jig with center marking on work piece.
I cut the mortises by inserting bushing through template, making a series of plunge cuts and then move the router back and forth a couple of times to make final, clean mortise.
Use the dust collection to remove waste as you go or the mortise will not be a consistent size due to chip build up. If you dont have integral dust removal, you will need route, vacuum and then route a final pass. The results are consistently spaced with nice clean slots.
The end result is 16 mortises cut in about 15 minutes.
Next step is to mill mill the loose tenon stock out of left over plywood. I typically do a large amount in one pass so I can re use in future projects.
First I resaw the plywood to nominal width.
I sneak up on the final fit into the mortise using 1/64” passes in the planer.
In order to fit the rounded edges of the mortise, you must round over the edges of the tenon stock, so I chuck up a 1/8”round over bit.
And rout the round over profile on both edges of one side of the tenon stock. Make sure to use a feather board to press down the thin stock to ensure a consistent profile.
Next step is to set final tenon width. I insert finished side into mortise so you can mark the other side to final width.
I then rip tenon stock to final width and rout the remaining side to fit into the mortise. Nice and tight.
I then use the RAS to cut 8 loose tenons that are (2x mortise depth – 1/8”) to leave room for glue squeeze out.
Because my table will be between the sofa and the wall, I did not add drawers to the design. In order to keep the structure rigid and strong, I will be adding two plywood cross members using sliding dovetail joints.
I will use a straight bit to hog out the bulk of the waste and then a dovetail bit to cut final shape.
I mount the straight bit and set the depth to bit under the final 3/8” height in order to cut the initial pass.
I mark the location of the center lines of the dados on each piece (22” from each end). I then make the line more visible by wrapping blue tape along the edge and around to other side.
I will cut the dados using a panel sled on my router table designed to handle large workpieces. I could have used a T-square dado jig to do this with hand held router but I like the control I get with the sled on the table.
I mark the center line of the bit on the sled backer board and then all I have to do is line up the edges of the blue tape on the work pieces with the blue tape on the fence and I am all set to cut.
I use blue tape on the table to mark the point where I stop the sled in order to cut a stopped dado.
I then chuck the dovetail bit and set the height to 3/8”.
I repeat the previous steps used to cut the straight dados, but since the bulk of the waste has already been removed, I get no burning and nice clean edges.
Leaving the dovetail bit set to exactly the same height, I bury the bit in the fence so that I can cut a tenon on each end of the plywood webbing that I know will be too wide.
I measure the difference in size between the tenon and the dado and adjust fence inward by slightly less than half of the difference in widths. (1/2 because you are taking two passes to cut the tenon – one on each side). I use the micro adjust feature on the incra to get the final fit perfect.
Now comes lots and lots of sanding. Use Random Orbit sander from 100-120-150-180 grit on flat surfaces.
Then use profile blocks to sand same sequence by hand on the profiled sides.
Here goes two hours of your life … wear a dust mask, use plenty of dust collection. I will be building a sanding down draft table as a future shop project.
Now it is time for glue up. A testament to the strength of the miter lock is that I have not had them glued up during any of the sequence so far.
Now glue in loose tenons to legs and short apron sides. I spread glue on the tenon and in the mortise.
I use a spacer block to keep the legs square during glue up. I also glue the feet on at the same time. Note that I only set the assembly on my table saw to take the picture. I never glue up on my tablesaw … NEVER.
I also glue the plywood webbing at the same time.
I line up everything for final assembly.
My clamps were too short, I had to use one clamp on each side, pulling on each other in the middle for the final assembly.
And the base is done. Next step … back to the veneered top.
-- Shawn, I ask in order to learn