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Cheap Collimation Tool


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Hi all,

Got a bit bored so I decided to put an old SR4 EP to a more productive use than its original application (which is, let’s face it, a little poor).

Here is how.

Unscrew the barrel and then unscrew the lens housing. Throwaway the lenses (I use the term loosely), you now have a Collimating tool, well almost. You will find the EP aperture a little big to be very precise, so you need to make it smaller but still centred. Here is how.

Find an old dried out pen, the sort that twist to expose the nib.

Open up the pen and on top of the ink tube is a black bit of plastic that is used to engage with the twist mechanism. Pull that bit off and discard the rest of the pen.

The black bit of the pen has a thread one end, the other end is plain. Take the threaded grommet that kept the lenses in place (the bit you unscrewed to take the lenses out) and push the plain end of the pen bit into the grommets inside end (the bit that would touch the lenses when assembled) and then push the threaded end of the pen bit through the EP hole from the inside and screw up the grommet.

Now you will have about 15mm of black plastic sticking out of the top of the EP, cut flush with EP and clean up any burs…and there you have it.

Cheap but effective.

EDIT: The black ring around the top of the EP barrel (in photo 1) is just an O-ring to help take the EP from the focuser; anyone who has one of these EPs will know how difficult it is to get them out.



Edited by sbooder
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