Lighbridge primary springs

[Loupy31]

Hi,
I have a 12" LB, I also have the bobs knobs primary kit that includes stiffer springs, I want to set it up so I dont use the locking screws, just the main collimation screws......are the bobs knobs springs stiff enough or do i need to use something stiffer...A young lady by the name of Petra mentioned to me that bunnings had a suitable spring, Ok so what spring is it, or are there other springs i can use and if so what are they and where can i get them.

Regards Peter

[erick]

I looked at Bunnings' springs for another reason. They have a large range of compression (what you want for the LB) and extension springs. All sorts of sizes, gauges etc. Carry in the spring you want to replace and it shouldn't be too hard to come up with a suitable one.

[spacezebra]

Hi Peter

I found the Bunnings Spring packet - it is a C-736 - Utility Compression Spring. 12.706 x 69.860 x 1.829mm.

Cheers Petra

[Loupy31]

HEY Petra,
when you showed them to me I forgot to ask what size or number they where, thanks for that info..........my Moolite focuser leaves the states in the morning, cant wait........the weather her in melbourne has been crap, its because I bought a new scope......BTW is there anything tricky I should know about when installing the focuser or is it just straight foreward.

Cheers Peter

[Tannehill]

My 12" GSO has the same specs as you LB 12 cell, and the Bob's Knob's primary spring kit (and knobs) for you scope and mind are exactly the same. I have the Bob's Knobs primary springs and they work fine.

Despite this, and even if your springs were tighter, you still would probably find some collimation drift without the locking bolts. Even with the bolts, a bumpy car ride leads to the need to tweak things after re-assembly.

Any particular reason you want to forego using the locking bolts? Not that it's a critical feature, because a collimation fanatic will still feel compelled to make adjustment even using them....

s

[spacezebra]

Hi Tannehill

I travelled to Little Desert from Albury with my scope (over 600km without the locking screws) and collimation takes me less than 5 minutes to do, only minor tweaking required as you have said.

I had two separate engineers and the builder of a 30" have a look at the set up and all said separately that with good compression springs - locking screws would not be required.

But at the end of the day it is personal choice and what works for you. Try out different methods and come back to what you feel suits.

Cheers Petra

[Loupy31]

Well Tannehill,
I like simple, and after seeing them in action at vic south, I figured thats the way to go, Now I have been down the "locking screw" road and there are times they are a pain, you get your scope just right once you set it up then you lock the mirror and its out a fraction, so you undo it , back off your collimation knobs and then tighten it, what I am getting at is, it's almost like trial and error , when you have a push pull system...I hope I have explained it well, I am not to good at explaining things. Look how simple the secondary is, 3 screw, ok you have to loosen one tighten the other but you get the idea, I aways collimate after every setup any way so after a road trip I would expect to collimate which brings me to the subject of "Collimators" any recomendations anyone?

Regards Peter :D

[erick]

I reckon this one:-

http://www.iceinspace.com.au/forum/showthread.php?t=24955

[Tannehill]

Sounds good. Can't argue with that - that stiffer springs will make locking bolts less helpful. For sure, those locking bolts do make collimation drift, even with heavy springs that I have. When I watch my barlowed laser image real-time as I turn the locking bolts, the donut moves with even a 1/16" of a turn of that locking bolt, so your system makes sense. In fact, when I tighten those three locking bolts, it's like re-collimating all over again!

I'd say that a relatively inexpereinced person might be lulled into thinking those locking bolts don't affect collimation, and that is misleading, and they'd suffer by not checking afterwards. But, the one advantage is that someone who can't or won't tweak things in the field after transport from home and setup in the field might benefit more from them, provided they realize the above re-collimation issue, because they're more likely to be relatively collimated upon setup with the locking bolts helping to stabilize things....

Regards

Scott

[janoskiss]

Sorry bit late to this thread... anyhoo ... Roger at Bintel Melb knows what to get and where to get it. He's really good with scope mod / ATM advice.