Feet for Dob OTA

[Jim-a]

I've read lots of posts on here outlining various modifications people have made to their dobsonians. I recently bought a second hand 12" Lightbridge - and its only taken just over a week before the mod-bug bit.

When moving the lightbridge about, the only thing to rest the bottom part of the OTA on when taking it off its base are the collimation knobs. Even though it doesn't sit on these for very long (just the time it takes to lift the OTA off, move the base, then put the OTA back) it didn't seem very sensible to rest the whole weight of the mirror and tube on the knobs (even if they are Bob's ! ).

A visit to my local hardware shop and £6 later I had 3 rubber door stops and an assortment of washers, nuts and bolts. Disassembling the scope was pretty straightforward, then it was just a case of drilling three holes, bolting in the new feet and putting it all back together again.

The lower OTA now sits happily on its new feet, with a centimetre or so's clearance between the ground and the collimation knobs.

Now thinking about the next mod - probably something to help balance for different eyepieces etc. Any other suggestions?

[David Smith]

That's a good idea. May have to do something similar.

[JamesF]

That's not a great bit of design to start with really, is it? Especially as not having a solid tube you can't really rest it in a cradle or anything. Or do the standard knobs not protrude as much as Bob's variety?

James

[Jim-a]

not sure what the out-of-the-box, non-bobs-knobs are like as these had been fitted by the previous owner - perhaps someone else can comment?

[Carbon]

I did the exact same thing using hard rubber stops on the bottom.

As for counterweights, I use several felt lined speaker magnets stuck to the lower belly side. There are other fancy ways of DIY counterweights but using large magnets are cheap, easy, and effective for the Lightbridge.