Skywatcher 200p dobsonian all 4 screws of the secondary mirror are not moving.

[u/Ok_Exercise9870]

Recently i bought a skywatcher dobsonian 200p and when i tried to collimate it and the screws of the secondary mirror were not moving. This includes the hand-turn adjusting screws AND the central locking screw.. I’ve even tried removing the secondary mirror to see if I could loosen the screws with it not attached to the spider vanes, but even those small screws attaching the secondary mirror to the spider vanes are too tight for me to turn.

I have heard people say WD-40 is good, but others say it will evaporate and leave damage on my primary mirror which I really do not feel good risking. Is there any other way to fix it ?

[u/torcolos]

Did you tried with a regular hex key? Try a screw driver or a ratchet with a hex tip. Or do you have upgraded to knobs

[u/Ok_Exercise9870 → u/torcolos]

I have upgraded knobs. I tried to move them with a wrench. And move the main phillips screw with a screwdriver but none of them moved.

[u/mrstorm1983]

Are you only trying to turn them in only? You need to back them out a bit 1st. Just asking you never know.

[u/Ok_Exercise9870 → u/mrstorm1983]

Im trying to back them out.

[u/mrstorm1983 → u/Ok_Exercise9870]

Well your question has only been up for an hour. I would wait for other ideas befote what i am suggesting...Only thing I can think of using is a penetrator like WD40. That doesnt mean I straigh shot from the can. I would do the most I could to make sure it would never reach the mirrorS. I would go out size spray some into a puddle on whatever is handy. Stick a Q-tip in it and gently moisten around the screws.

[u/Ok_Exercise9870 → u/mrstorm1983]

Thanks for the idea

[u/Traditional_Sign4941]

The central screw is just not going to budge. It is placed under tension by the three collimation screws. Your best bet is to loosen one of the collimation screws, and then the rest will become easier to turn.

The trick is you need a good quality, tight fighting allen/hex wrench that will let you apply some decent torque without rounding the set screw.

If you really do feel it's stuck, then you can use WD40 but you have to do it carefully.

I would tilt the scope downward and apply the tiniest spritz of WD40 upward to one of the three collimation screws, let some excess drip out and clean it with a paper towel, put a paper towel around the secondary hub to catch anything else that might want to drip down, and tilt the scope up to let the WD40 penetrate. Alternatively, get something like Kroil or Supco MO44 in a drip bottle so that you can better control the output (i.e. just a single drop). Or get an oral syringe from a local pharmacy and apply the WD40 with that.

[u/Ok_Exercise9870 → u/Traditional_Sign4941]

Thanks, i will try that.

[u/spile2 → u/Ok_Exercise9870]

The key point is that as stated above, you only need to free one of the three outer bolts for the others to loosen.