Motion mods for dobs

[iceman]

Well my dob base has stayed pretty much stock since I bought it.. My alt motion got really loose and fell down a bit after moving it up - because I think I stretched the springs by storing the OTA in the upright position on my trolley with the springs still in place..

So I disengaged the springs and it's been nice and smooth since then, been a month or two and alt motion hasn't been a problem.

Lately though my az motion has been stiff to get moving, and when trying to manually track (and find) Saturn on a small CMOS chip has been a pain in the rear.

So tonight I did the milk-bottle washer mod to fix the az motion.. Used 5 washers to pack the middle.. It was a bit wobbly on its own without the OTA on, but once the OTA was back on it compressed them enough to give much smoother az motion without wobbling side to side.

It hasn't had a first light yet, but i'm planning to get up early tomorrow morning to catch Saturn and i'll be giving the milk bottle washers a test!

oh and btw, here's a hint.. if you get the milk bottle out of the recycling bin, and it's been there for a few days, block your nose!! Dang that was smelly crusty old milk in the bottom! :)

[Mick]

I trimed the corners of the three teflon pads to 45deg and used a very small amount of inox applied with a cloth on the base only were the pads rub. The az motion is spot on now. (12" scope)

[iceman]

I might have to give that a try too.. What is inox though? Some sort of lubricant?

Anyway i didn't get to give the washers a "first light" this morning, woke up with the alarm at 3:40am, stumbled outside, looked up, clouds :( So I went back to bed.

I have to give the laptop back to the other on-call support person this week too, so my imaging will have to be on-hold this week. Nevermind, it'll give me a chance to just look, instead of playing around with imaging equipment and post-processing :)

[Mick]

Yes inox is a spray lube like WD40. Have you had a look at Comet C/2004 Q2 Machholz yet?

[iceman]

No I haven't.. what time is it rising, and in which direction/constellation?

I've got some wd40 at home, might give that a spray on the base.

[Mick]

Ice, only use a small amount of WD40, spray it on a rag and then us the rag to wipe a tiny amount on the base only were the pads rub. Q2 Machholz is in Columba at the moment, it's around 7.5 mag and rises at 19:64 and clumination is at 2:01 from my location. Finder charts and Comet info can be found here http://www.skyhound.com/sh/comets.html

[iceman]

Thanks for the info! I'll definitely have a look for it when the darn clouds clear :/

Was great to catch LINEAR and NEAT earlier this year in my 11x70 binos before I got my scope.. My 5 yr old son even got a glimpse through the binos :)

[Mick]

I used 7x50's, what a thrill two bright Comets in the sky at once :)