Dome build: Doors and shutters.

*

Thursday: Another warm and dry day. I bought enough 4mm ply to make the shutter covers and another 4x8 sheet of 12mm grooved ply for the main doors. The original grooved plywood double doors have gone seriously banana-shaped. So I removed them and have been loading them down on the trailer bed with a 2x4 prop at each end. Some 3/4" x 4" boards will form an internal frame to try and keep the doors flat. The new ply sheet will form a second skin for a more solid sandwich construction.

I used the last of the cartridges of sealer along the edges where the top tier panels meet the slit ribs. Hopefully the dome will now be waterproof.

Friday: Max 67F and sunny. Trimmed the timber for the internal  door frames and plywood skins to size for the main, double doors. Now I just have to glue and screw them all together and rehang them. I discovered the trailer bed was 1/8" concave so used that to my advantage with the badly curved plywood and frame boards. Using the opposing bows to help straighten the outer 12mm ply skin. By sheer luck I was able to make the internal, door frame, horizontal rails from off-cuts of the uprights. For the internal center sections I used up some off-cuts of 10mm grooved ply.

Saturday: Gluing and screwing the main doors together. I wanted the slight curvature of the trailer bed to fight the curvature on the ply. So I left the doors in place and loaded them down with everything heavy I could easily lay my hands on.

They will be ready to move after lunch. Then I can turn them over and screw the opposite skin to the frame. I'm using a clear, foaming PU waterproof glue called Sika 545. It goes on golden yellow, like thick syrup, but bubbles like foam when it escapes from a clamped joint.

Having removed all the "heavy metal" I discovered the doors were bowed the other way from the original ply. So I brought the convex sides together and  clamped them up while the glue set up. The 2m aluminium straight edge can be seen resting on top of the double thickness sandwich. This shows that the top surface is now perfectly flat. What that means when the doors come apart again is anyone's guess. I should have realised that loading the doors with weights would distort the trailer baseboard downwards. I couldn't think of a way to ensure the doors stayed flat while the glue was setting while still allowing a greater thickness to be clamped.

Sunday: I have unclamped the doors after leaving them overnight to find them both bowed by only about 1/4". I can live with that. It will be interesting to see if they keep changing over time. They are remarkably heavy now compared with the original single skin 12mm ply. I'll plane them first before finishing off with a trimming router bit with a journal bearing guide.

Click on any image for an enlargement.

*