Introduction: Russian Birch Table Without Fasteners
The idea for this table was to craft an attractive and usable piece of furniture that was readily reproducible at scale. I didn't know how many I would ultimately need for my studio space and the notion of something I could essentially "copy" on-demand, was compelling.
In the past, I have expediently used utilitarian foldable tables like one sees at bake sales and school registrations. Unfortunately, many of the affordable table designs prevalent today are unable to attend an architectural interior as a legitimate piece of furniture.
I've always admired the modernist design aspiration of creating something both utiliarian and attractive. In this case, there was a clear call for something with more warmth and presence while maintaining affordability.
With this basic premise, I wrote a series of toolpaths to build a table with two sheets of plywood using my Shopbot PRSstandard 96-48 table and no fasteners. You will want to use a single jack hammer and a block with these toolpaths. The gapping of the material is .02" which I've found provides enough friction to maintain good structural integrity while allowing a reasonable effort when assembling the Russian Birch plywood.
Shopbot PRSstandard 96-48 table
1/8" diameter carbide compression bit
2 Sheets of .70" (+/-.01") thick Russian Birch plywood
Single Jack Hammer
Step 1: Tool Uses
The 1/8" diameter carbide compression bit is specialized bit made for working with plywood and other products succeptible to surface chipping. Briefly stated, the compression bit minimizes chipping on both the top and bottom surface of the plywood, by driving the chips from the cut down from the top and up from the bottom.
There are two sheets required to make this table.
The first sheet toolpaths:
S1T1: After zeroing the mill to the top of the plywood and zeroing the X and Y with the proximity switches, this toolpath makes a few light drill marks in the surface of the plywood to indicate safe locations for attaching the polymer nails.
S1T2: This toolpath accomplishes all the cutting required for the table top.
The second sheet toolpaths:
S2T1: This accomplishes the same thing as S1T1 for the second sheet.
S2T2: This toolpaths accomplishes all the through cutting required for the table legs
S2T3: This toolpath places to pockets in the primary table legs and helps to provide some structural integrity to the interface between the spine piece and the two main legs.
After a sheet is milled the utility knife is used to sever plywood tabs that provide work holding during the milling process. The use of this knife is employed immediately after the milling process is complete. See the two attached screenshots that will hopefully serve as a guide for where tabs have been placed. The black dots indicate their locations.
If you run the utility knife through the cut after the milling process is complete you should feel where these tabs exist. A little pressure applied during the cut should produce the satisfying sound of the tabs severing so you can subsequently remove the individual components.
Once the individual components have been cut and liberated from the plywood sheets, you will want to clean up the edges of the plywood where it has been cut with an 8" 4-in-1 rasp. Particular attention should be paid to providing a small rounded edge where the plywood face veneer interacts with the box joint. Failure to do this has the potential to result in some pretty unattractive splintering of the veneer at the most eye-catching locations.
A lot has been written about interior corners with cnc wood milling on the internet. There are a few different solutions for "dog bones" to accommodate the geometric challenges associated with rounded interior corners.
All this cleverness is kind of a waste of time.
A better solution, I've found, is to simply use a small 1/8" bit that produces a very small 1/16" radius at interior corners. This small rounded corner can be easily squared up with a few pulls on the interior corner with a detail saw like the one depicted above.
After trying many different methods, this approach has turned out to be surprisingly easy. If you find yourself having to draw the blade more than five times along the inside corner you are doing something wrong. Because the blade itself is almost 1/16" thick, this simple motion turns out to be all that is required to eliminate any significant interior corner radius and will allow perpendicular box joint cuts to slide together nicely.
Once the pieces have been assembled as shown in the order shown in the attached timelapse, one can sand all the edges to a smooth finish with the sanding block.
This table was made to go together without fasteners and the anticipated finish would be a tongue oil finish or something similar. Alternatively, if one does not anticipate breaking down the table in the future, one can employ wood glue and use any number of more viscous stains.
Step 2: A Video Summary
I have tried uploading the shopbot files, but for some reason I am being told by the server it is an incorrect file type. Feel free to contact me through my webpage at www.studioecesis.com and I can email you the files.
Thanks for checking this out!