This years lesson: Know Your Wood! I wanted to do a Bell ornament highlighted in red, so I selected Bloodwood for the silhouette and Aspen for the back. I got lucky and fooled by my first prototype that was 3.5″ tall. Cut out the Bloodwood silhouette on the first try, quickly made and Aspen back and I thought I was good to go. However the Bloodwood silhouette kept breaking on multiple attempts to produce additional copies. I tried tweaking the design by thickening some area of the silhouette and still had many failures. I then enlarged the design to 4.25″ with no greater success. Pieces of the silhouette kept flying off during the machining process. There also was much adjustment of the mounting of the blank to try to support the piece while machining. Finally in despair it occurred to me to “read the directions”.
This is what the Ocooch Hardwoods website (my go to source for thin stock) had to say about Bloodwood:
Janka Hardness: 2900 lbs/ft Avg.
General Workability: Bloodwood is very hard and can have a pronounced blunting effect on cutters. It can be problematic to glue due to natural oils in the wood. Bloodwood is somewhat brittle and can split or crack if not pre-drilled when nailing or screwing. Applying finish produces a brilliant red surface. Bloodwood is good for woodturning.
So it ends up Bloodwood is incredibly hard and brittle. No wonder by silhouettes kept breaking. As an aside, Aspen while very white is a very soft wood with a Janka Hardness: 420 lbs/ft, which accounts for the great deal of fuzz along all the cuts. With Christmas rapidly approaching I switched to 1/8″ Baltic birch plywood, figuring the alternating grain orientation of the layers would reduce the splitting. It worked like a charm. It worked so well I went into full production mode, using the tiling function in Vcarve to layout and cut eight copies in one go.
After cutting cutting the backs out of Baltic birch plywood as well, I stained the silhouettes with Minwax Sedona Red 222, glued on the backs and sprayed on several coats of clear semi-gloss polyurethane. You can see the results below, with the one successful smaller Bloodwood version and four of the final Baltic birch plywood version.
It took a lot longer than I expected to produce the ornaments this year, but I learned my lesson to understand the characteristics of the wood I select before I start a project.