Substitute Sbig ST4 Desicannt Ring

[meade expert]

Hi All

For those with broken SBIG ST4 disicannt rings there is a way to manufacture a replacement.

The ring is 33mm by 23mm by 4mm thick. It is in technical terms an ANNULUS.

Surprisingly....there are at reject shops some stickytape plastic inserts that meet these dimensions almost exactly.

They are 33mm by 25mm by 10mm thick. They have a channel that is 2.2mm wide and 3mm deep (thats where you can pack tiny silica gel beads !)

So what you do is sandpaper down the ring till its about 3.5mm on its shallowest end and pack the beads into the deeper end, leaving a 0.5mm gap for air to get into the beads once it has been inserted into the nose piece slot.

Voila ! your replacement ring....and it works well!

[Dennis]

A nice bit of astro DIY and very useful information - well done!

Cheers

Dennis

[meade expert]

Hi All

Here's another solution that can be adapted to replace the $100 desiccant ring SBIG charges for the ST4.
It can also be used for any CCD project that needs low profile desiccant.
It is a plastic board impregnated with silica gel that can absorb quite a lot of moisture and comes in various thicknesses.
Just cut to desired shape!

http://www.agmcontainer.com/desiccan...rbingboard.htm