Each piece of aluminium plate to be cut is carefully fixed down onto the saw's cast 'table' with the supplied clamp. I then back that up with the 'toe' of an 8" C-clamp [G-cramp] caught under one of the "handles" in the saw's base casting. Naturally I only use just enough tightening effort to ensure the plate I am cutting stays securely in place during the cut. The sheer weight of each plate is halfway to being secure but I don't want my free hand holding the piece of metal in place!
DeWalt could usefully improve its work piece clamping arrangements. Or provide some reinforced clamping areas under the base casting. The post clamp always distorts in use but does seem reasonably secure. It just looks and feels horribly cheap and nasty for such an expensive tool! More of an afterthought by a designer who never cut anything in his life except slicing carrots for a salad.
I had bought the largest of the stainless steel turnbuckles on display for the new mounting but now realise I probably needed the smallest. A similar U-bolt will be fitted to the front plate of the polar axis support fork once I know the ideal location with a rather more suitable size of turnbuckle. In retrospect, a galvanized steel fencing turnbuckle would have been just as good. As it will be hidden well out of sight inside the box formed by the PA support fork and reinforcing plates.
The image shows the view between the fork blades through the missing base plate. The much shorter turnbuckle, I have now purchased, should reach a similar U-bolt in the base plate.
The bearing grub screws are handy to hold the wheel securely provided the applied wormwheel weight does not move the whole bearing in its spherical housing. So I now use a stub of 2" diameter pipe instead of the earlier, and much heavier, solid brass stump. This keeps the wormwheel aligned without the bearing sagging completely out of line as it did with the heavier brass bar. The spherical housing and outer bearing race provides the self-aligning aspect of the bearing. This avoids binding and uneven wear with slight misalignment of the flange housings.
Next I need to drill the massive fork blades for threaded crossbars and furniture nuts. I am continuing to use the same clamping arrangements which I have used on the bearing housings. These have proved to be very secure for simple butt joints between aluminium plates. The tensioned rods [studs] prevent lateral movement of the clamped plates. The steel studs would literally have to sheer before the plate could move inwards. The fork blades are also clamping the Polar Axis at the heavy altitude pivot. This parallel clamping arrangement ensures remarkable stiffness of the butt jointed assembly without pinning or direct bolting between adjoining plates.
While the plated, hex-socket head, flanged, furniture nuts give a neat and slightly unusual appearance which I prefer to using normal nuts, bolts and washers. The depth of the threaded shanks of the furniture nuts probably provide greater security than normal nuts. The flanged heads are designed to avoid the nuts sinking into the usual hardwoods used for assembling furniture. Bed heads are commonly fixed to their bases with these fasteners.
Images to follow when I have obtained a new and much shorter turnbuckle, hopefully tomorrow. While I was cycling to the shops it suddenly occurred to me that I couldn't have a central turnbuckle. Not without blocking access to a central pivot bolt [or nut] on the base plate. I shall have to offset the short, hefty turnbuckle which I bought today. Or provide a suitable hook arrangement on the azimuth pivot bolt itself? A bent, drilled plate is all it really needs to carry the tension loads.
I have yet to decide how best to hold the fork blades to the base plate. There are considerable vertical loads, tipping and torque forces on the base joint. It would be a disaster if the joint gave way. Even flexibility is highly undesirable. The major problem is that the fork is not a fully closed box like the axis, bearing housings. Moreover, some of the surfaces are no opposing each other.