I did several dry assemblies to test fit and plan the glue up process. This revealed one segment edges would not mate well with the spacer and its adjacent shelf. I made a new segment for that location. This re-do made me feel that I could improve some of the other segments, but I decided to proceed and call this prototype number two.
Cauls from offcuts were used in addition to band clamps in an attempt to put pressure in the desired directions. I knew the center spacer and its mating segments did not seat as well as I would have liked. I could not get enough pressure to bring that together uniformly. I thought I did reasonable job of getting the segments and shelf fairly tight. The next morning I was shocked to see very large gaps.
I had planned to use epoxy, but since I decided to do the glue ups in very small steps I felt I could get away with yellow glue. Those nice tight tenons seized up rather quickly. Rats. I thought of cutting it apart and redoing what was necessary. After a cooling off period I decided to proceed and do the best I could.
The images below show some of the subsequent glue up steps. Overall effect is not so bad as even semi-close inspection reveals. I believe I will revisit this design fairly soon to see if I can do better.
The poplar shelves, spacers and cross support piece received two coats of pitch black milk paint. The first coat was thicker than ideal, so it was difficult to obtain nice thin covering. I sanded it down somewhat prior to the second coat, which was thinned with additional water.
After the second coat of milk paint, those pieces received several oil/varnish top coats to add some sheen and protection. A number of oil/varnish coats were applied with wet sanding to the walnut elements.
A support base was made up of walnut and poplar. The poplar will later be paint with Pitch Black Milk Paint and given an oil/varnish top coat. This 6/4 walnut board was acquired from Hardwoodtogo.com in one of their surprises packs. The board was severely cupped however since these elements would be about 1-1/4t x 5-1/2w I had enough material to work with. I cut off a suitable length with a panel saw, then ripped to width using the bandsaw.
After smoothing the material, the shape was marked and cut out on bandsaw. Shape was refined and round overs created with rasps, followed with sandpaper.
The poplar cross pieces were milled, taken down to size and end shape cut. The portion that would be between the walnut horizontal elements received a large round over at the router table. The ends were left crisp to create a bit of contrast. The circular shelf unit similarly has soft and hard edges to entertain the eye.
Cross lap joinery was cut using a dado stack at the table saw. A notch for the bottom spacer was created by drilling a 1/2 inch hole and then material cleared out above the hole with my precious Bad Axe 12-inch backsaw.
The assembly was left unglued in case I wish to explore other shapes on the walnut pieces. Finish was applied before glue up of the shelf unit as some areas would be very difficult to reach.
I was fortunate to find some poplar boards wider than 16 inches to use for the three shelves and two spacers (top and bottom). They were cross cut and ripped to rough dimensions, then taken down to 1/2 inch thickness with the drum sander. The boards had significant cupping and a bit of twist so I used the #7 jointer plane to make them flat enough to be stable as they were fed through the drum sander.
Even after making then desired thickness and flat they cupped significantly and differently from day to day depending on temperature. This made fitting a challenge. With many projects the case joinery and construction can restrict that type of movement. In this case I was not totally confident that the structure could exert adequate pressure when and where needed. But I proceeded in hopes that it would work out.
Quarter-inch mortises (through and enclosed as required) were cut with router and edge guide. My initial test fitting was rather messed up. The labels did not seem to make sense. See images below. After some head scratching I realized that the labels were fine, but the middle shelf had been cut too short. Also, one set of mortises was not in proper location. Those were plugged and re-cut. It would not be a problem because they would still be covered by the mating pieces. I had enough extra material to cut, mill and fit a new center shelf. “Measure once, cut twice.” Or something like that.
A bevel up smoother was used on the top and bottom shelves to create bevels matching the curve of the outer circle. The middle shelf was symmetrical as the edge is parallel to the tangent of the circle. Rasps and sand paper were used to create the round overs on all edges.
One image below shows two shelves with early stages of finishing. I will create a later post with more details on the finishing processes I used.
Loose tenons were placed in the mortises and the segments stacked and brought together to verify that they could create something resembling a circle. A few of the mortises were not of uniform depth so I used the Veritas router plane to deepen the mortises to full depth.
Next up was cutting the inside curve with the bandsaw. The initial curve was used to mark the curve on its mating segment. Then I used combination of spokeshave, special sanding block (made from offcut) and card scraper. I didn’t think of the card scraper until pretty fall along the process. That worked pretty well. The spokeshave had mixed results due to the grain situation. The sanding block worked, but took much effort and time.
A full-sized drawing of the circle was created in QuarkXPress. Two different (but easily confused) segment shapes make up this build. Examples of each shape were copied from the overall drawing and printed on 10 mil photo stock with the ink jet printer. These were used to mark shaping as well as location of mortises for loose tenons for each segment set.
A router with fence cut 1/4 inch deep mortises roughly five inches long. Tenons were made of baltic birch plywood. A dry assembly verified the fit.
Bevels were cut at the band saw. For the 22 degree bevel I used a miter gauge. The 68 degree bevels used a shop-made fence to push the material at the appropriate angle.
Loose tenons were also used to join the segments to the shelves and spacers (top and bottom). The top and bottom spacers and middle (largest) shelf used tenons that went from one segment through the shelf and into the adjoining segment. The segments mating to the upper and lower shelves are offset, therefore a tenon went from the segment half way into the shelf. With the opposite side similarly treated.
The 22 degree bevels offered a sort of horizontal surface so each segment was pinched between dogs on my bench. Blue tape was used for mark up rather than trying to see pencil lines on walnut. Mortise dimensions were marked and cut out of the blue tape. A template was attached to the segment using 23 gauge brad nails. [I tried double stick tape but that did not feel secure enough for my taste. Also tried clamping in various manners without success.] The brads worked well as long as I positioned them in good places. I had to be careful that the nails would not leave holes in areas that would be exposed once the curves were cut. I was mostly successful in this, but my brain was on break in a couple of instances.
The 68 degree bevel was too steep to use that same procedure, so I placed them upright in the Moxon vise. It worked pretty well, but was not as stable as I’d like. I had to pay close attention to keeping things balanced to avoid rocking. I was pretty successful with that. Mortises are 3/8 inch deep.
This project may be the ultimate proof that I’m a form over function person. I wanted to create an enclosed book cabinet to house my precious Lost Art Press (http://blog.lostartpress.com) offerings. Some of them are large format and my favorites tend to be quite heavy as they are printed on very high quality stock with top-notch bindings.
As I pondered the shape of this case, I saw a segmented cylinder with proud spacers in a FWW Gallery image. “Hmmm, well, that looks very cool. Something like that could go on top of my book cabinet.” As I explored the shape, I decided to make it into a shelf unit roughly 24 inches in diameter. Having open shelves, I would not use it for long-term book storage, but in time some utility could be found.
I created a full diameter, but shallow prototype of poplar to figure out joinery, sequencing and feasibility. I decided to use walnut for the segments and Pitch Black milk-painted poplar for shelves and accents. I used 8/4 walnut for the segment blanks. Yes, there will be lots of left over material from this build. Cut the board to roughly 7-1/2 x 10 inches, marked sequentially (as they came off the long boards), then matched and marked for the 15 inch deep segments.
I stacked them and put into position to verify positioning and my labeling. It will be very easy to become confused when working on these elements in various positions and orientations.
Next up will be marking the curves and location of loose tenons.