collimating thumbscrews question

[ultramol]

I have just acquired a SW200p . Unfortunately ! it came with an instruction manual so I guess you can understand why I am so confused. The six screws for adjusting and then tightening the primary mirror are neither the first, second or third option shown in the manual. They are completely different. I did notice though that 3 of the screws have springs on them. Are these the adjusters or the locking screws , which ones do I turn to move the mirror and which to lock it ? Thanks in advance....Geoff

[brantuk]

The ones on springs are the collimating screws - the mirror cage position goes up and down when you turn one and it's supported in place by the spring. The screws next to those are the locking ones.

(you should have three pairs of screws (one collimating and one locking) spaced evenly round the circumference)

[andyman]

Hi geoff the ones with the springs are the adjusters others are locking nuts

[andyman]

Posted same time as brantuck sorry for same reply

[ultramol]

Many thanks for your prompt responses...

[Avocette]

Hi Geoff. Continuing my occasional survey of what types of screws are supplied with which SW scopes, I'd be keen to know a few more details - are they screws requiring a tool to adjust or knurled knobs (and if a tool is required then is this cross head or Allen key type), and finally what age is the scope? Just curious!

By the way you should be pleased to have springs; they're much better than the neoprene O rings that are often fitted to the 200p Skyliner Dob (IMHO).

[ultramol]

Hi Avocette, The screws are the knurled knob type , the larger one with springs and the small one without the springs. Both are turned by hand. I bought the scope on an eq5 mount second hand, The scope was purchased new in May of this year I believe which makes it about 7 or 8 months old. How long in stock at the shop  I could'nt say. It Is in pristine condition. Everyone who has seen it thought it brand new.

hope this is some help to your project

regards....Geoff

[Tinker1947]

The locking screws are not for locking as in that ain't gonna move again, there turned until they touch then a quarter of a turn more......

[moffer]

Am I correct in thinking that it is only the 200p eq5 f5 reflectors are fitted with springs and the 200p f6 dobs have o-rings?

No experience with springs, but the o-rings on my 200p are not much good for holding collimation. I slightly tighten the locking screws but the primary still moves a few mm.  

[moffer]

Should have added that the primary never fails to move a few mm after a short drive to my local darkish site.

[Avocette]

I have personal knowledge that a 200p Dob bought new in 2012 had O rings, otherwise three other scopes of unknown precise age (150p f5, 250px f4.7 Dob and 300p f5 flextube Dob) all had metal knurled knobs and springs. I would speculate that the latest 200p Dob may also have a thinner metal casting for tube end rim than earlier examples since a set of Bob's Knobs and Springs had to be specially tailored (after feedback with Bob) to fit and work properly.