Home Made Dust Cap Advice

Hi Martin - having now seen your scope, I guess it might be easier on you with an erecting finder. I assume you'll have to totally replace the finder - I'm not aware of an adapter for existing finders. And as far as I know, they're not cheap - at least for reasonable quality. Maybe a hundred quid?

The question to ask when you find one and get a price is 'will this make a significant difference for the price' - if yes, go for it, if no, go get a six-pack and have a good evening in in front of the telly on a cloudy night!

Still, you might get a bargain on the second-hand sites. Astromart is good and for the price you'll probably pay here, you'lll saving getting from the US. Also, you shouldn't have to pay import duty and VAT. As long as you know what you're doing (have it sent as a 'gift').

As for a trolley, www.scopebuggy.com do a trolly but I'm not sure it'll do a dob. And its not a very good website so a phone call may be necessary. I think JMI do trolleys 'n stuff as well so give that a whirl. Also, if you create an account in astromart (free) then you can post a 'wanted' ad - I've gotten replies to wanted items which just give me advice! HAndy enough.

Hope this helps - keep asking! I ask my fair share of questions here and the lads are good enough to humour me :lol:

Cheers

Dave McD

Martin, Re your scope bearings.

I have a 16inch dob (truss tube type). In advance of fitting it with a drive system I have fitted ball bearings in place of the teflon. I used these from RS for the altitude and these for the azimuth. The result is really really smooth almost too smooth!! Thinking about your scope I think these might not work with your altitude bearings as there wouldnt be room to fit them. However I highly recommend ball bearings instead of teflon on big scopes like this.

Thanks very much for your advice Dave. I will consider it for the azimuth motion of the rocker box. At the moment in these cold nights the motion as been very stiff and jerky and because of this the vibrations shake the optical alignment a little out of collimation which really annoys me. I dont want to be collimating in the dark throughout every observing session so i need to get this motion smooth and light! Thanks again. Actually do you have any diagrams on how to construct this ball bearing base?

Thanks again!

Martin,

I have a 222mm Dob and find that for the azimuth bearing that if it is too difficult to move then just reduce the distance of the teflon pads from the center axis a bit and try again. Also with the extra weight of your 16" 'scope, you could try increasing the area of teflon to ensure there is no distorsion into the hollows in the textured formica.

For the altitude bearing just moving the pads up or down the curve can increase or decrease the friction. Too little friction here will cause balance problems when changing eyepieces/cameras etc.

Michael Sculy
www.kerryastronomyclub.com

Martin,

Ever consider adding drive motors to that baby?

See

www.bbastrodesigns.com/cot/cot.html for mel bartels excellent DIY system.

Thanks Micheal for that very useful advice, i have never heard that tip before so i will gladly take it on board.

Dave people have suggested this to me before but i prefer the dobsonian style as i do an awful lot of visual sweeping of the sky and this set up is best for my own observing requirments.