Dome build: Top panels continued.

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Saturday: Not a happy bunny. I have been playing with small scraps of 15mm ply. Trying to make the overlapping edge vanish by cutting back the underside. I wanted an overlap because of the low angle [22-23°] of the top tier of panels. It looks as if I'm going to have to cut back the undersides to rest on the highest cross struts. Then trim the overlaps back to the top edge of the lower tier of panels. Sealing the gaps will just have to do. Any upward projection looks awful. The low viewing angle greatly exaggerates the thickness of any overlap. Beveling the top edge, to make the leading edge thinner, is even worse!

Hours later I had shortened the three panels to stop at the next lower panels. I undercut the top panels to rest on the top cross struts for mutual support.

I also pulled the base of the ladder out. Then re-secured it so I could better reach the top of the dome.

Rotating the dome allows me to access the top from the inside stepladders. But my view is blocked once the top panels are fixed in place. I need to be able to see the top of the dome from very close quarters. To accurately measure and mark the panels for trimming.

There is now almost no extra height at the lower edges of the top tier. Which looks far better than before form below. Now I can press on with the rest of the panels in slightly thinner, 12mm, birch ply.

Sunday: Due to my temerity in cutting, it took me 2.5 hours to complete the first 12mm top panel to perfection.  The triangle was too large for either of my DIY, table saw sleds. Though I was able to cut across the bottom, the sides were far too long. So I cut roughly with an electric jigsaw and then trimmed back to the line with a No5 Stanley-Bailey plane. The shorter [side] panels will fit on my largest sled. Anything bigger would tip right off the small table of the DeWalt saw.

It is an odd situation trimming a trapezium or triangle. Cutting the top off lifts the whole panel. Cutting the bottom lowers it. Raising makes the base too wide. Lowering makes the base too narrow. It is a fine balance to achieve the correct dimensions and angles simultaneously. The tops are heavily skewed. The bottoms hardly at all. The 5th panel had to be notched around the right angle of the slit framework and mitered into the bargain. The next panels become straighter and much shorter. Hopefully making life very much easier.

I must have an altitude record for climbing ladders by now! Each panel is costing me at least ten climbs inside and ten climbs on the outside ladder. I'm sick of unplugging and plugging tools in. I was using the miter saw, table saw, jig saw and a router today.

Removing the riving/kerf knife from the DeWalt table saw, just to use the sled, or for half depth cuts is a complete bore too! The cover plate has to be removed and the blade wound up fully. Then a bolt head still deep within the machine has to be loosened enough to allow it to be pressed inwards. So that the knife can  be lifted free. After that the bolt can be re-tightened and the plate replaced. The blade can now be lowered and adjusted for the required depth of cut.  [If you can still remember why you went through all this rigmarole.

These two images show how little of the top tier is visible from the ground. [Upper image] The lower image shows the view from an upstairs window in the house. Eight panels were fitted at this stage.

Don't forget to isolate the saw first. Or your fingers may be sprayed across your face as you poke about deep inside the machine almost touching the razor sharp blade.

I'm prepared to bet that the idiot who designed this daft feature never used a circular saw productively in his entire life. Probably the same bloke, working well above his pay grade, who put the tiny OFF switch hidden away, down under the table. Where it can't be seen, nor reached, except with a white stick and the help of a specially trained guide dog!

Perhaps the overpaid "designer" idiot hoped that this would be a safety feature. Preventing the machine from being turned on by other than the operator themselves. Later machines [US only?] have a tiny red tab over the OFF switch to make it slightly easier to find in the darkness under there. But only for those with arms five feet [1.5m] long. My own answer to the problem of inaccessibility was covered in an earlier post:

 https://fullerscopes.blogspot.com/2018/06/dome-building-dewalt-stop-button-paddle.html

Click on any image for an enlargement.

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