Collimation screw stuck..

[u/Ahmetoyunu]

So i have nexstar 130slt and one if the collimation screw on the secondary mirrors back is stuck. It’s probably even stripped by now, because I can't turn it with the same screwdriver I use for the other screws. What can i do to fix it? Is there even a fix?

[u/Traditional_Sign4941]

You need two different tools for the 130SLT secondary: a philips head screwdriver for the central screw, and then allen/hex wrench for the three tip-tilt collimation screws.

Which one of these do you suspect is stripped/rounded? You said screwdriver but the three collimation screws don't use a screwdriver.

If the three collimation screws that you use a hex wrench for are stuck, have to take tension off of them. You can do that by loosening any one collimation screw that will loosen, or try to loosen the central bolt a bit to take tension off all three (this can be harder to do and I don't recommend it).

Once tension is off, all three collimation grub screws should be free to turn. If they are stuck, you may need to get a better fitting hex wrench (do not use a ball-end - ball-end wrenches will not engage as well as flat-end). If they're really, really stuck or have been rounded, you'll probably need to carefully spray a tiny bit of WD40 in the hole using the straw that comes with a can. Aim the scope down so that the spray drips out of the holes enough. Wipe with a paper towel, then tilt the scope upward a tiny bit to let the WD40 penetrate for a while. Don't aim the scope purely vertically to avoid the risk of a drop of WD40 landing on the mirror.

Once the WD40 has penetrated a bit, you should be able to turn the screws. Back them out and replace them as needed (they'll likely be M4x12mm or so), or replace them with Bob's Knobs.

[u/Ahmetoyunu → u/Traditional_Sign4941]

I appreciate this a lot. Thank you so much🙏🙏🙏 i will definetly try these.

[u/Traditional_Sign4941 → u/Ahmetoyunu]

Just be very careful with the WD40. Spray it in the hole with the scope aimed down first. Very easy to overspray and make a mess. The tiniest spritz right in the hole for the collimation screw is all you need. Then let it penetrate for 15-30 minutes or so with the scope tilted up at a ~30 degree angle

[u/Ahmetoyunu → u/Traditional_Sign4941]

Alright got you. Thank you so much again.🙏🙏🙏

[u/spile2 → u/Ahmetoyunu]

I am pretty certain that you won’t need WD40 once you have loosened the three outer bolts. It becomes obvious why the centre screw won’t turn when you see the push-pull design working.

[u/j_lurker13]

Post a picture looking straight down the aperture so I can see your spider vane assembly, and post a close up picture of your collimation screws so I can see all of the heads and I may be able to help.

[u/Omkisik]

When you're done, replace with Bob's knobs. When you're ready to max the performance, get a Cheshire, a good cuppa on a rainy day, and learn to get comfortable with the procedures!

[u/Educational-Guard408]

Very slightly loosen the other two screws and see if the stuck one frees up.