St. Peter’s Back Altar – part 4

I had a plan for creating the central dome for this back alter. I was going to create bending forms and laminate a couple sheets of bending plywood to each. This would create the three curved sides. I was a little worried about how to cut the miters to connect all the curved pieces together. That partial plan was formed before I bought the new CNC. It occurred to me that I could create a front and back panel with the exact curves as well as sockets for cross bars. This would give me a form to attach the laminations to and I wouldn’t have to worry about how the miters came together.

It was worth a try anyway. I drew up the panels and set the CNC cutting. It only took a few minutes to cut out both. I left a few tabs to hold the faces in place. When I unclamped the panel, I could cut away those tabs and free up the faces.

I cut a test piece of cherry for a cross bar and it pressed-fit perfectly into place.

While I was cutting and milling 21 more of those, I decided to let the CNC spend some time cutting out a relief carved Dove from a panel of holly. I like it when I can do two different things at the same time.

That carve started with a 1/4″ compression bit that pre-cut away a majority of the waste at high speed. Then I loaded in the 1/16″ ball mill to do all of the finish cutting.

For some reason the 3D model of the Dove had a lot of artifacts that translated into little spikes left behind. These I removed with a Dremel tool. Then I had to do a little hand-sanding to get the dove into shape.

Setting the dove aside, I got back to assembling the structure of the dome. I applied wood glue to each socket.

Then pressed into place 22 identical struts that I cut while the dove was carving.

I applied glue to the opposite face and clamped them together.

After they dried, I cut another piece to set at the peak. This was glued and clamped into place then sanded flush when dry. I also cut and glued into place inserts that fit at the bottom to give me a solid attachment point for the bases.

I cut four 13-5/8″ wide pieces of 1/8″ bending plywood to apply to the sides.

I applied glue to the sides and along each strut before attaching the plywood.

I started at the bottom and attached it with 3/4″ 18 gauge brad nails. About four to six nails into each strut.

I repeated the process on the opposite side as well.

I used my block plane to flush up the sides after the glue dried.

Then I fully coated the second layer of plywood with glue and repeated the attachment process to create a second layer.

When both sides were dry, I planed, then sanded the edges flush to the face.

I did something different with the bottom. I created a step to recess the plywood into. I applied glue to the inside step on both sides.

Then pressed the plywood into place and nailed in on along the edges.

After the second layer was applied by fully coating it with glue and nailing along the edges again, I could sand the the bottom joint flat.

I did a dry-fit to make sure everything stayed square. It sits perfectly flat on top of the cabinets.

I am happy with that. Now I can attach the oak veneer as well as all the trim on the front.