5.1.2022 Skate wheel, shutter bogies success.

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Wednesday 5th 36-40F, rather cloudy with occasional sunny periods and showers.

Finally, it was mild, dry and bright enough to do some work out of doors. First I used the 360° laser level to check the bottom of the dome skirt was level. This required some minor changes in the stacks of timber packing. 

Frost heave and wet weather had altered the dome's level by about 12mm or about 1/2". The dome is far too heavy to lift by hand power. So I use lengths of 2x4 to lever up the edge so I can slide bits of plywood or timber under the skirt. When I was satisfied with the skirt I lifted the laser on timber blocks. This allowed me to and check the plywood base ring was still level. All was well.

Now I clamped a straight piece of batten across the skate wheel bogies to ensure they were straight and on the same track. Then I drilled through and bolted the skate board, bogie brackets to the shutter ribs. Using M8 stainless steel screws. I shall use stainless steel, Nyloc nuts and the correct length of screws, when I am satisfied with the fit of the shutters.

First shutter opening tests showed a problem. The rollers were lifting the shutters too much when they were fully open. For a quick fix I swapped the larch running board to a thinner one. Much better. I can easily adjust the brackets slightly up and down on the shutter ribs to get the levels exactly right. 

The shutter ribs must be concentric with the slit ribs and parallel. It is easy to tell the difference at a glance by examining the ribs from the inside or outside the dome. The shutters are very sensitive to roller level because of their considerable height. Causing them to tip with serious errors of level across the base due to their considerable "leverage." Easily adjusted via the fixing brackets.

The rolling movement, when opening and closing the shutters, is now completely effortless. A huge improvement over the constant struggle with drawer slides. Where the top and bottom slides had minds of their own!

The shutters needed to be opened and closed by pushing high up on the shutter ribs. Which suggests that the heavy duty, drawer slides have much more friction than the large, skate wheels. 

Time to think about guide rollers in channels to take the place of the upper slides. Though I have serious doubts about simple, vertical rollers working properly. There is a 2m+ horizontal offset between the tracks of upper and lower rollers. Which means the upper rollers will apply considerable torque. So that auto-guiding via single upper rollers [like a sliding gate or door] is very unlikely to work as desired. The shutters will wander outwards at the bottom if there is no restraint. 

I still favour a lower channel for steering the shutters. Though I shall have to fit scrapers. To clear snow and leaves from the outer ends of the channel as the shutters open. 

Both images, above, were taken with each shutter fully open. This view will vanish once the open triangles are filled in with spare, GRP, dome material. I am in no hurry to close these triangles because they offer easy access when the shutters are closed. Provided I duck down low enough not to hit my head for the hundredth time!

Until now it was quite a struggle to close the shutters in a hurry. Hence the long delays on this part of the dome construction. It is not a simple matter to design a new feature if there is no material to achieve it. Most of my project's construction metal is scrap. Scrap metal may be relatively affordable but it is not remotely easy to find exactly what one needs.  I tend to buy clean aluminium when it is available. This shows the scrap metal yard staff that I am serious. Rather than picky.

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