2" shaft mounting Pt.46: Going down below.

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A trial assembly with the RA wormwheel at the bottom of the Polar axis made far more sense. It also showed that I should move the altitude pivot upwards along the PA housing. This would better balance the rather top-heavy appearance. It would also push the wormwheel further away from the base plate, pier and fork. Perhaps even allowing considerably shorter fork tines.  I have sawn off the studs while still leaving a small reserve for unforeseen changes.

Am I a robot?

Rain forced me into the workshop today but at least I had the chain hoist to help me lift things into place. The arrow in the image shows the direction for a new altitude pivot point. If I removed the nearby furniture screw it could rise even further. The [much larger] pivot stud would provide far more compression than the smaller one. So there would be no sacrifice of strength. Once the new pivot point is properly established I can then measure how far I can shorten the fork tines. I am trying to maintain the full radius curve on the top of the fork tines for appearance and maximum friction.

Here I have moved the pivot further up the PA. The highest point was not the most favourable and I had cross studs to avoid.  So I moved it 3/4" down on the same line. I think the whole mounting looks much better balanced now. It is suddenly looking rather impressive [in real life] thanks to the large scale. The tape measure shows the overall height to the top of the saddle is now 40" or 100cm from the base plate.

The mounting's overall balance is now backwards or clockwise seen from this viewpoint. So I had to make up a stub axle which could hold a weight and be locked against falling by tightening the flange bearing grub screws. Adding the OTA, declination axis shaft and counterbalance weights will overcome the imbalance. Allowing for a slight bias to be overcome by the turnbuckle for fine altitude adjustment.

As the fork tines are sloping I have to be careful that the large RA wormwheel does not get any closer. Just cutting off bits of fork would bring the wormwheel nearer. I could cut a more acute angle on the base of the tines. This would tilt them over more and bring the mounting's CofG further within the fork base. While simultaneously moving the wormwheel slightly further away from the base plate and pier. I have made up a cardboard "set square" for 55° to aid rapidly setting the mounting at the correct angle.

Now I ought to make the large pivot stud to get rid of the G-cramp and allow free access to the fork. I'm thinking of boxing in the fork with front and back plates held by cross studs, along much the same lines as the bearing housings. This will help to stiffen the fork more than simply adding channel profiles to the sides. It will also allow greater freedom to fit the dual angle profiles. I used a 12mm [1/2] galvanized stud for the pivot. The nuts look a little 'understated' against this scale of mounting. Some larger washers will help. Perhaps I should step up to the 15mm stud size I used in the bearing housings.

Click on any image for an enlargement.

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