Skywatcher 150PDS Replacement Spider / Secondary Mirror Holder

thingiverse

This is a scaled up version of davidbroise's Skywatcher 130PDS retrofit. The model isn't geometrically perfect as I did the scaling in blender (The only editor I know how to use), but it works which to me is the most important thing. You will need a couple screws to put it together as the ones which come with the original spider may not work, and it's recommended anyway to replace your collimation screws with thumbscrews to make collimating easier. I would recommend grabbing stainless steel screws / bolts for longevity. In total it should cost a maximum of $20, which is significantly cheaper than the machined replacement spiders you can find online. I can't guarantee this will fit any other telescope than the Skywatcher 150PDS Explorer, and I won't be making one for any other telescope. If it does fit your telescope though let me know and I'll list it here. NOTE: You will need to be VERY comfortable with collimation and all the possible issues as you're going to need to do it from scratch. This video is pretty in-depth and should cover most of it, just be warned it may take some time to perfect - https://www.youtube.com/watch?v=KkX_MHpqozE. Parts: 1. 4x M8x10 Thumbscrews for the telescope mount (https://www.aliexpress.com/item/1005003596895331.html - 1/5pc M3 M4 M5 M6 M8 M10 GB835 304 A2-70 Stainless Steel Knurl Flat Head Hand Tighten Curtain Wall Glass Thumb Screw Bolt DIN653). 2. 1x M5x30mm Bolt to mount the secondary mirror (https://www.aliexpress.com/item/1005002413652525.html - 5pcs-50pcs M1.6 M2 M2.5 M3 M4 M5 M6 304 A2-70 Stainless Steel Black grade 10.9 ISO7380 Hexagon Hex Socket Button Head Screw) 3. 3x M4x30mm Thumbscrews for collimation (https://www.aliexpress.com/item/1005003930418672.html - 1/5x M2 M2.5 M3 M4 M5 M6 M8 M10 304 Stainless Steel A2-70 Knurled Tall Head Thumb Screw Plain Type Metric Manual Adjustment Bolt) Putting everything together (Do this with the telescope horizonal, you don't want to drop anything on the primary mirror): 1. Remove all of the screws holding the white end ring from in front of the spider. 2. Unscrew and remove the thumbscrews holding the original spider in place, be VERY careful to hold the spider while you do this as the mirror will want to fall down otherwise, try not to touch the mirror while you do this. 3. Remove the spider and unscrew the center screw holding the mirror, again make sure you hold don't touch the mirror's surface, but hold the black cylinder it is attached to. You will end up with a spring which we will reuse. 4. Place the spring into the recessed slot on the back of the replacement spider, put the mirror on top and screw it in with the M5 bolt. Leave a couple millimeter gap between the spider and the mirror holder so the collimation screws have some room to work with. 5. Screw in the collimation thumbscrews, they should just touch the back of the mirror's holder. 6. Place the replacement spider into the telescope and screw in the outer ring with the M8 thumbscrews. 7. Do a proper collimation now, you will likely need to rotate the mirror so it is in the correct orientation pointing into the focus tube. Make sure you tighten the collimation screws enough so that the mirror cant freely spin. 8. Reattach the white telescope end-cap / ring, if you bought the same M8 thumbscrews as me they will not fit next to the outside thumbscrews, I instead screwed them in from the inside, it doesn't hold the ring tightly, but it still stops it from coming free of the telescope. If you're looking for a dew shield and you got larger 25mm thumbscrews like me for the outer ring, this (https://www.thingiverse.com/thing:6169282) should fit perfectly. ------------------------------------------------ **UPDATE 2023-08-31** Rotated the vanes so they align with the focuser tube. This prevents the focuser tube from creating an extra (5th) diffraction spike.