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Primary Mirror (Skywatcher Skyliner 200P) - Collimation

mrjonathanbrown

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mrjonathanbrown

mrjonathanbrown

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Hi guys hope all is well, I recently purchased a cheshire premium eyepiece (FLO) and well I can't seem to figure out

how I "shimmy" the primary mirror - This post is probably best suited for someone who has or did use to have a skyliner 200P (dob) There are three screws for a phillips screwdriver and 6 holes three of the holes are smaller than the other three I've tried putting an allan key inside them but nothing happens it doesn't get grip on anything.

Do I remove the the screws?

Many Thanks Jonathan

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Charic

Charic

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If you turn the Alan screws anti-clockwise, they should come clean out( just to show that they will unscrew - once your adjusted, replace them, as they don't normally get removed, just unlocked and re-locked) The Philips screws are your mirror adjusters. Once the mirror is adjusted the Alan bolts are there to maintain  locking to the mirror cell, the cell won't fall out. They may be tight? Once the primary mirror is set, just re-insert the Alan bolts and nip them up ever so lightly, if you over-do it, you will upset the mirror position and will need to adjust the mirror again!

This is a popular item to read......  http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm Hope it helps. Read it a few times first though.

Where you say it doesn't grip anything, the Alan bolts just press against the mirror cell when locked home, If the mirror cell was too far up the tube from the adjusting end (unlikely) the Alan bolts would fall inside. Make sure you have the correct Alan bolt adjuster, my Skyliner one was slightly too small, therefore no adjustment ?

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oldpink

oldpink

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you should have 3 screws with springs these are adjusters and normally have a large head for finger adjusting
and 3 locking screws the locking screws don't move anything so moving them changes nothing
its the adjusters that move the mirror into position during the collimation procedure once collimation is sorted lock the locking screws

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Tinker1947

Tinker1947

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When collimating my Newt the locking screws were turn until they touched the mirror no tention applied, thats as far as they need to go, as for getting the mirror lined up i used a laser (baader) took maybe a minute on a bad day, just remember which way you turn the screws to move the mirror and go the opposite way next time or you end up with the mirror moving either up the tube or down the tube depending on the way you turn them, keep turning the same way and you end up needing extension tubes because of focus shift or the focuser turn right down so there's next to no adjustment left.

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Charic

Charic

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forget the springs, their only rubber on the Philips adjusters ( you cant normally see them unless you remove the adjusters. DONT do that yet) My concern here is that the Alan bolts wont tighten or lock for you. If they don't lock or tighten, then unscrew them, and they should come right out. I`m wanting you to ensure there is some movement when you insert the Alan key into the bolts( my supplied Alan key was the wrong fit?)  If the actual bolt doesn't turn then get a new Alan key. If the bolts do turn, but don't tighten, or come out, then the threads on the scope could be bare, therefore, the bolts wont go in/out.

Only interested in the Alan bolts at present.

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mrjonathanbrown

mrjonathanbrown

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Charic I can't even see allan bolts I see 6 holes 2 sets - three holes are smaller than the other set of holes and then there are three sets of screws for a phillips screwdriver, when inserting an allan key into any of the six holes nothing happens it does seem the allan key is to skinny.. but on one set of the holes I can see the allan key go through in touches nothing.. il post photo after this post. 

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Charic

Charic

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at the base of the telescope there are six holes on the Skyliner 200P The Philips screws are your primary adjusters, they tilt and align the mirror. The small bolts inside the holes adjacent to the adjusters are your locking bolts.

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Charic

Charic

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Ok is this a brand new telescope or second hand. Some folk do away with the alan bolts? They may not even be there?

Your right about the Philips, they are the adjusters, and the hole next to each adjuster should contain one Alan bolt. They are the locks

can you shine a mag-light or something bright into the holes, you should see the hexagonal slot for the Alan key if the bolt is there. If its not there, the mirror cell will still be ok to use and set-up

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Charic

Charic

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IMG 0152 the hole above the Philips is the Lock, Its too dark to see in the pic, but should be an Alan bolt in there.

gently push your Alan key into the hole, and see if you can spy it touching the base of the mirror. If that's the case, the Alan bolt is missing? The Alan bolt is also black I believe, without stripping mine down.

Measure the Alan key on the inside of the base ring against the  base of the mirror. If held correctly, it should be at the same depth if inserted into the hole. If by any luck, you #cant push the key through, the bolt is in there, but the key is the wrong size?

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Charic

Charic

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ok......just checked my scope again and your picture. It does look like the black is the Alan bolt. Can you try to fit the Alan key, but use a torch to examine that the key is fitting, and whether the bolt turns. I think you just have the wrong key. My scope was supplied with 3 Alan Keys, which is one more than normal, and only the smallest one for the secondary mirror fitted. NONE fitted the Alan bolts on the Primary mirror. The other very small hole below the Philips screw in your image, is a mount hole for a base plate?

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mrjonathanbrown

mrjonathanbrown

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@Charlic sorry for the late reply, your spot on I think - basically its a case of my allan key is just to small I can make out the shape of the darker hole and it looks similar to a allan key lining it will be a trip down the road to asda for me tonight and get this resolved haha. 

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Charic

Charic

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Does the Alan bolt come out now? if that's the case, or tightens, just loosen all three adjusters, then , if your following the collimating guide from Astrobaby, adjust your primary, then just nip up the Alan bolts just enough to hold and no more, or you'll shift the mirror out of alignment.

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mrjonathanbrown

mrjonathanbrown

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Thanks for all the responses. The new allan key fits :) happy days, I've been up all night trying to collimate my scope and all i've done is make it worse!! I've not even started on the primary mirror lol - still working on the secondary I've moved it way to much that its confused me now. I've read umpteen collimation guides (don't think thats helped) I reverted back to skywatcher manual and I found that method impossible. 

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buzzlightyear

buzzlightyear

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Ok but they are usually factory set and hard to knock out of position compared to the primary.

I've seen some good YouTube videos to collimate that seem wayside to follow than typed words with diagrams.

Good luck tho chap and hope it's sorted soon.

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Tinker1947

Tinker1947

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Read the various collimation help files, take a few notes on a piece of paper, do things in the right order, i spent quite  few hours getting it right the first time then things go easier , now 10 minutes if i had the secondary mirror in my hand and had to align it, keep at it in a short while you wonder what all the fuss is about.....

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