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Old 07-09-2019, 10:56 PM
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Bobbyoutback
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Under strength springs

This problem will keep coming up till a simple fix is done when making these dob cells .
I just scored a 12" F/5 GSO Dob , tried collimating it with the supplied small weak springs .
There is mirror shift every time the scope is moved a sort distance .
Even going to a low level to high when setup will shift it a bit .

The compression springs supplied are 12mm OD wide / 13mm long & 1mm wire diameter .
There is a well the springs fit in so we are constricted to the diameter 12mm

Could not find a Aussie supplier of 12mm 20mm 1.2mm wire thickness .
Did find one offshore & have ordered a set .
If they are not stronger i will get some 1.5mm wire size at the same specifications .

Bobby
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Old 08-09-2019, 06:51 AM
Startrek (Martin)
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Try Better Springs in Sydney
They make custom springs in all sizes
Not cheap but did the job and quality that will last
One of the very few locally produced spring company’s left
I replaced all my springs on my 6” newt as the original Taiwanese ones were rubbish
I can collimate in 3 minutes now, so much easier
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Old 08-09-2019, 07:15 AM
glend (Glen)
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Most Bunnings outlets carry a range of suitable springs, they are in the cabinetry section, look for a rack of yellow and white plastic bags with springs in them. Take one of your originals in to compare with what is available. It doesn't matter if you think a particular spring is too long, as they can easily be cut down. Just get the right compression resistance, diametre, etc.

BTW, I used to own a 12" GSO dob and Bunnings supplied my spring upgrade. Cost only a few dollars.
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Old 08-09-2019, 10:01 AM
Startrek (Martin)
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I tried Bunnings in 2 Sydney stores , Hardware and general, mitre 10 , Super cheap auto, Auto Barn etc.... they had springs but not the ones I needed in the correct length , diameter , gauge, and spring tension

Great you found a suitable , quick , low cost replacement at Bunnings
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Old 08-09-2019, 10:12 AM
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Are you able to fit springs with12mm id? The stronger spring could fit over the smaller original and the smaller one will keep it centered.
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Old 08-09-2019, 10:40 AM
glend (Glen)
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Quote:
Originally Posted by Startrek View Post
I tried Bunnings in 2 Sydney stores , Hardware and general, mitre 10 , Super cheap auto, Auto Barn etc.... they had springs but not the ones I needed in the correct length , diameter , gauge, and spring tension

Great you found a suitable , quick , low cost replacement at Bunnings
You missed a key point in my post, the springs Bunnings sell do not need to be the absolute correct length. As long as the diametre is sufficent and the gauge can supply the necessary (stronger) tension, they will do the job. You want a stronger spring. Perhaps some of the many other people who have bought Bunnings springs will pipe up here about their experience.
And in the case of my 12" GSO dob the springs were the correct length for the job.
Maybe Bunnings has changed their stocking approach over the last couple of years, and only stock a subset, but if you go to the company website you can probably find a product number and buy them on eBay.
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Old 08-09-2019, 11:39 AM
Startrek (Martin)
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Thanks for pointing that out Glen
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Old 10-09-2019, 12:39 AM
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Quote:
Originally Posted by doug mc View Post
Are you able to fit springs with12mm id? The stronger spring could fit over the smaller original and the smaller one will keep it centered.
Great idea , Many moons ago i used that concept for air rifles .

I'm going to find the correct springs that fit into the cell resets with enough push-power to fix mirrors from 6" to 16'' so they stay better collimated .

Bobby
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