Zachariah Posted February 6, 2012 Share Posted February 6, 2012 I am trying to collimate my SW skyliner 150. But the screws holding the secondary mirror are so tight I cannot budge them, despite holding the mount tightly. Looking through the eypiece with a cap everything looks not to bad. But using a laser the secondary is out and the primary. If I grt the primary right everything is out looking down the focus tubeIf I cant shift the screws in the secondary is it best to get as near to perfect using a coll cap and looking diwn the focuser? Link to comment Share on other sites More sharing options...
Kai Posted February 6, 2012 Share Posted February 6, 2012 If you undo the screw in the centre of the secondary 1/2 a turn this will lessen the pressure on the adjustment screws so you can use them.HTH Link to comment Share on other sites More sharing options...
Zachariah Posted February 6, 2012 Author Share Posted February 6, 2012 Thats the screw that I cant budge. I very nearly twisted the spiders. Link to comment Share on other sites More sharing options...
sabana Posted February 6, 2012 Share Posted February 6, 2012 HiJust hold the vane with the other hand. If it then still insists on twisting, you're at the end of the the thread for the bolt that holds the vane, and then you need an extra washer between the tube and the bolt .(This is a common probem so an extra washer is oten advisable). Link to comment Share on other sites More sharing options...
Zachariah Posted February 6, 2012 Author Share Posted February 6, 2012 Well tried that and the ****** will not shift. Link to comment Share on other sites More sharing options...
Kai Posted February 6, 2012 Share Posted February 6, 2012 The im afraid that you are going to have to remove the secondary from the vanes and use a bit more force in holding the secondary (maybe clamped in a vice). Link to comment Share on other sites More sharing options...
Zachariah Posted February 6, 2012 Author Share Posted February 6, 2012 Thanks. But I would have to remove the secondary and the vanes by using the 4 nuts on the outside of the tube. Pretty drastic. I dont have a vice either. Why do they make them so tight Link to comment Share on other sites More sharing options...
stevetynant Posted February 6, 2012 Share Posted February 6, 2012 can you carefully put some WD40 on the nut and let it soak - a very small amount I'm talking and use the straw and perhaps some kind of shield to ensure you don't get any on your mirrors? Link to comment Share on other sites More sharing options...
Kai Posted February 6, 2012 Share Posted February 6, 2012 Pretty drastic. I dont have a vice either. Why do they make them so tightIve found that it the over adjustment of the three grub screws that is the problem rather than the middle screw.If you want to loosen them then you are going to have to bite the bullet im afraid.I dont think that WD40 will work as the screw on the outside are under compression and the middle screw is under tension rather than seized. Link to comment Share on other sites More sharing options...
Mr Q Posted February 6, 2012 Share Posted February 6, 2012 Before you go banannas with the secondary, do a star test to see if the amount the collimation is off is worth the trouble. The link below shows the effects of bad collimation on planetary detail.Thierry Legault - The collimation Link to comment Share on other sites More sharing options...
Peter Drew Posted February 6, 2012 Share Posted February 6, 2012 You have far more chance of freeing one of the three adjusting srews rather than the centre one. The centre screw is being held with the combined pressure of the other three, either one of which, onced freed should release the others. Link to comment Share on other sites More sharing options...
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