Building the Octagon Pt.5 Support.

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The experts on the CN forums have advised me to improve the location and support of my braces/joists. To that end I have routed a test pocket in the upright stump for a perimeter brace/joist. Satisfied that it would be a useful modification I threw together a crude router jig to achieve some degree of automation and a [far] greater degree of accuracy. 

The braces/joists would be supported by the lower shoulder rather than simply relying on two 4" screws. This raises some issues since I really wanted to keep the lower floor as near as possible to ground level. Cutting a pockets sets a lower limit unless I step the bevel on the joists and make a shorter socket. This would leave some meat on the lower end of the upright posts to support the joists. The higher joists need no such special treatment.

Being able to wheel something straight into a building has certain advantages depending on the surfaces. Deep gravel is a hopeless surface for heavy wheeled objects. A raised floor also risks the problem of wildlife moving in unless well sealed on the perimeter. I planned to add skirting boards which would be lost in the depth of gravel chipping as a first barrier. The self-compacting sand&gravel collects on the soles of footwear and leaves a brown trail across the grass. Hardly very practical!  Aluminium flashing also buried in the gravel would provide an anti-digging barrier while rejecting rain and moisture. Paving slabs are an option but complicated by the shape of the building.

This simple router jig would be slid along the 4"x 4" posts. Then clamped at the next pocket to be cut so that the router can do its thing. With 48 sockets to make I could see serious problems arising if the work was dragged out for too long. Using a  jig was suggested on the CN forum. I initially had doubts because of the weird angles involved but my misgivings proved to be unnecessary. The time saving from using a jig makes the large number of joints a practical proposition.

Involuntarily listening to a neighbour's router is no more fun than listening to their chainsaws. Though revenge is indeed a fine thing! There are others, even closer to home, just looking for an excuse to criticize the serious lack of progress. Withdrawal of goodwill is not something lightly to be countenanced! 😨

Friday: Bank holiday. I trimmed the router's add-on, Tufnol base plate to make it symmetrical. I could then reclaim the missing batten by closing up the width of the jig. I also added a stop batten to act as a fence at the front. Further fine adjustment brought the routed socket to a tight fit on the 45x145mm joists. Cutting an accurate pocket is now very much simpler.

The Head Gardener is now suggesting the observatory building be raised on "stilts." This, she claims, will help to avoid vermin living underneath and damp getting into the lower structure. It will also make the ground floor even higher requiring at least one step and probably two. My own feeling is that it will make the building seem insubstantial instead of a permanent structure. The nearby shed hasn't show sings of infestation or damp. Now I cannot progress with making ground floor joist sockets in the posts until the exact height is known. 

Click on any image for an enlargement.

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