Skywatcher Explorer 200PDS Mirror Removal Tutorial?

[tehmac]

Hi all,

Now that I have a Skywatcher Explorer 200PDS, can anyone link me to a good tutorial or manual or anything that would explain how to remove the primary and secondary mirror? I want to make sure I absolutely do it perfectly and avoid any pitfalls if I do decide to go ahead with removing it. I know re-collimation is to be expected, but I'd appreciate knowing exactly which screws are the correct ones, how easy it is to get it back in etc.

I am struggling to find anything online.

Thanks.

[MarkyD]

The Secondary can be removed either by unscrewing the center screw on the back of the mirror mount (there is a spring over the bolt so careful) or easier to remove the spider as an assembly and work on the bench.  The primary is best if you remove the carrier by removing the 6 screws holding it on and then lifting the tube off of the carrier leaving the mirror cell on the floor.

With the secondary work on it with the OTA horizontal so any dropped screws etc don't fall onto the primary - it has been done (not by me) and it does make a grown man cry

Removal is described here as part of how to flock a newt

http://www.cloudynights.com/page/articles/cat/articles/how-to/flocking-a-newtonian-r780

[Ricochet]

Why do you want to remove the mirrors? For cleaning? Even though the scope is second hand I would suggest that there is a 95% chance that it is completely unneccesary and you would be better off leaving them as they are. 

[tehmac]

3 hours ago, MarkyD said:

The Secondary can be removed either by unscrewing the center screw on the back of the mirror mount (there is a spring over the bolt so careful) or easier to remove the spider as an assembly and work on the bench.  The primary is best if you remove the carrier by removing the 4 screws holding it on and then lifting the tube off of the carrier leaving the mirror cell on the floor.

With the secondary work on it with the OTA horizontal so any dropped screws etc don't fall onto the primary - it has been done (not by me) and it does make a grown man cry

Removal is described here as part of how to flock a newt

http://www.cloudynights.com/page/articles/cat/articles/how-to/flocking-a-newtonian-r780

Thanks, Mark. So in the below image of the secondary, I presume it is the four round chunky knobs at each side of the spider legs that I remove (presumably by hand) and it just comes out easily?

On the primary photo, I am unsure which screws do what. Can you tell me what the short round silver ones do, what the thinner taller silver ones do, and what the black tiny screws on the actual black OTA itself do? 

Many thanks.

[xtreemchaos]

undo the black screws on the ota side nearest the mirror cell there should be six, you could do with somebody holding the white mirror cell while you do it so it dont fall out, the large silver knob are collimation adjustment and the smaller silver knobs are for locking the mirror after collimation. charl

[MarkyD]

The 4 knurled knobs do indeed hold the spider.  Undo all 4 and the spider will come out.  If you take the white collar off (6 black cross head screws) it will come out slightly easier.  The screws for the primary cell are the 6 black cross heads.  the silver knobs and screws are the collimation adjusters.  You don't need to take them out.

Stand the OTA upright on the mirror collar and take the 6 cross heads out.  Then lift the tube off leaving the mirror cell on the floor is the easiest way to remove it.  I also marked the position of the tube to collar with a marker to replace in the same position.

[tehmac]

26 minutes ago, xtreemchaos said:

undo the black screws on the ota side nearest the mirror cell there should be six, you could do with somebody holding the white mirror cell while you do it so it dont fall out, the large silver knob are collimation adjustment and the smaller silver knobs are for locking the mirror after collimation. charl

Thanks for the details explanations guys. So if I wanted to get the mirror out to do a clean such as this, I would need to take all the collimating screws out also I guess, in order to leave only the mirror. I'm wanting to learn how to collimate everything anyway (needs to be learned sometime), so I guess it's not too big a deal. I don't think I could bathe the mirror with the whole primary cell attached to the mirror still once the OTA is off.

 

[xtreemchaos]

when you get the mirror cell out you will see 3 clips holding the mirror to the cell, each clip has 2 screws, undo them carefully you dont want a slip with the screwdriver and scratch the mirror, and then the mirror should just lift out.  charl.

[tehmac]

Can the whole spider assembly with the secondary mirror be submerged in water. Are there any problems with doing this?

[Singlin]

I replaced the 6 screws holding the clips with better grade stainless steel ones as half of mine sheared when I unscrewed them.I have to confess that I cleaned my mirror about 4 times and still looks as good as new. 

[xtreemchaos]

i carnt tell you about the spider washing, ive allways cleaned mine in place with a bit of lens cleaner ,90% of the time you only need to blow the dust off with a rocket blower, removing the spider can end up giving you more trouble than it worth, the 200p has a offset 2nd mirror which can be a pain to get back in line, i dont know if the pds is the same but its best to check. charl.

[MarkyD]

9 minutes ago, xtreemchaos said:

i carnt tell you about the spider washing, ive allways cleaned mine in place with a bit of lens cleaner ,90% of the time you only need to blow the dust off with a rocket blower, removing the spider can end up giving you more trouble than it worth, the 200p has a offset 2nd mirror which can be a pain to get back in line, i dont know if the pds is the same but its best to check. charl.

The offset is built into the secondary mount.  I set the spiders central to the tube on mine

[triton1]

I also replaced the screws holding the mirror clips in but with Allen head ones this made it easier to undo in future,less likely to slip off with a key than a screwdriver.Don,t forget to leave a slight gap under the clips when replacing the pimary(folded cigarette paper) to stop mirror pinch.