2" shaft mounting Pt.36: Holding it all together.

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I was struggling with ideas for an attractive and efficient means of holding the axis housings together. Then I found some oversized 8mm [5/16"] hex socket furniture nuts at a DIY superstore. Some 8mm studding [all thread] provided the means to join opposing sides.

Marking suitable points to site the threaded rods suggested a position to pass close to the main studs. The smaller studs would then be denied the ability to move sideways if the housing plates should manage to slide. Not that it would be likely with lengthways compression applied by the large studs. The smaller studs sandwich the side plates between the wider ones. Great care must be taken if I should decide to add more smaller studs at intervals to increase the clamping pressure. Clear room must be left for the large cylinder. Any bolts or studs to hold the housing to the cylinder must be over 6" long.

Each new fixing will increase lateral resistance to plate movement by improving the clamping pressure. Note the scale of the heavy 2" axis shaft and the large and smaller studs in the internal image above.

The images show the general idea. With earlier images taken without side plates to show the "innards."

The final image [left] shows the declination axis standing on end with the side plates firmly clamped in place. Endways movement of all four plates is fully constrained by the sturdy bearing flanges against the pressure applied by the large studs and nuts. The plates cannot move inwards, towards the axis, because they all rest against the large studs along their entire length. Being under tension the sturdy main studs are incredibly stiff and so highly resistant to bending.

I will still need to use long, through bolts [or studs] to join the declination axis housing to the large cylinder. I must avoid the single connecting plate carrying all the [heavy] loads via [only] the resistance of the four smaller [8mm] studs.

The exact location of these long fixing screws is another problem to be solved. The housing plate nearest the polar axis can easily be drilled to match the Tollok bush. Thus providing another level of reinforcement at the joint between the axes. Unfortunately, the screws for the Tollok bush cannot pass right through the declination axis shaft. Which all leaves very little clearance for additional fasteners within the 7" diameter footprint of the cylinder and the stud-filled declination bearing housing.

Nothing must interfere with the mating surfaces of the cylinder and the housing plate. Even the position of this joint along the length of the declination housing needs careful consideration. The declination housing ought to be offset to allow just enough clearance for the large wormwheel and its  worm. Any extra offset must be balanced by even heavier counterweights.

Click on any image for an enlargement.

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