TPoint Flexure War

The initial telescope setup has strange flexure? issues – the TPoint scatterplot has a very distinct N/S distribution. I suspect the various counterweights, which are necessary because the focuser is attached to the rings, which means I cannot rotate the scope. The camera is all threaded connections, resulting in the camera being sideways (assymetric to the scope stack). This in turn requires significant counterweights (about 12 pounds) to balance the scope. I’m not convinced it is well balanced in the end anyway, and probably leads to flexure issues.

Photo Jun 23, 10 23 26 PM

Here you see the large SBig2000XM and the heavy filter wheel. The camera is all threaded mounting, resulting in the filterwheel/camera being sideways. This in turn requires counterweights.

Note 10 lb counterweight to offset SBig sideways camera

Note 10 lb counterweight to offset SBig sideways camera

Here you see the 10 pound counterweight attached via my maple dovetail. The weight is likely an issue, and it might flex on the bolt, and the wood structure maybe flexes as well.

Photo Jun 23, 10 22 16 PM

The 10 pound counterweight needed another counterweight on the opposite side. These two 2 lb weights bolt onto the aluminum dovetail, but might not be as solid as one would like.

Another reason for the 10 pound weight is to counterbalance the Edge11. This scope is crazy back end heavy, necessitating the heavy counterweight. I may be able to reposition the Homeyer cradle to balance the E11 by itself, removing the need for some of the counter weight.

To summarize:

  1. Need to shift E11/cradle
  2. Need to rotate Sky90 so SBig is symmetrically positioned instead of sideways. This requires a new implementation of the focuser on the Sky90.
  3. Eliminate use of maple dovetails.
  4. Minimize counter weights.

All of this yielded the following 354 point Tpoint raw scatterplot


RawOrthoA lot of the poorer data points are in the North.

Here is the resulting supermodel. A lot of the northern points were thrown out


In practice, this would probably be fine for imaging. Maybe some of the northern slews would be off, but I suspect ACP could realign fine. However, I think this is bad enough to prevent ProTrack from guiding.

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