Lazy Susan??

[Paulus17]

i am thinking of adding the Lazy Susan to my Dob base.

But could i ask you for your experience when modded?

What size LS do i need?

Does it really make much difference to rotating the base?

Are the LSs sealed,will damp air,dew/moist get inside the bearing and start it to sieze up over time??

Are there better quality ones i should get and ones to avoid,i have been looking at the Axminster ones?

Cheers folks

[glowjet]

I am not a Dob user, but I have used them and as far as a Dob is concerned the larger the better I should think to avoid any chance of wobble. As far as quality is concerned I would doubt there is a lot of difference between manufactures, but they are nomally just made from pressed mild steel with steel ball bearings for the furniture market, so you would need to provide for access to allow generous coatings of WD40 from time to time. I don't doubt your friendly Dob user will be along in due course to advise a little more on size for a given scope

John.

[JamesF]

Kriege and Berry suggest that a "lazy susan" style bearing doesn't work very well (I think they're of the opinion that it' doesn't have sufficient friction) and that formica running on teflon pads is a better arrangement. Not having got that far with my dob build yet, I can't say one way or another. I'm not completely convinced that the same rules necessarily apply to an 8" dob as a 32" dob, but it wouldn't seem like the end of the world to assume that they do.

James

[johninderby]

This thread has plenty of info on the subject.

John

[sunshine185]

What size is the dob? I have a 10" and the biggest lazy Susan I could fit would be 12" diameter I think to avoid hiring the screws that hold the base together.

[umadog]

If you use Formica and Teflon you will get a good balance between static and dynamic friction. It won't need tuning (the LS probably will), it won't need milk bottle tops, and it don't need lubricating. I bought my bearing surfaces years ago for an 8" build from Beacon Hill.

[johninderby]

12" is the perfect size for a 250PX and the bearing is only fastened to the ground board.

Here's a photo of a 250PX base fitted with a 12" Lazy Susan.

John

[JamesF]

Ahhh. I can feel light bulbs coming on. Dimly, but on, nonetheless

The upper section of the mount just rests on the top of the LS bearing and has a bolt to go through the centre hole to keep it all in place, John?

[johninderby]

Ahhh. I can feel light bulbs coming on. Dimly, but on, nonetheless

The upper section of the mount just rests on the top of the LS bearing and has a bolt to go through the centre hole to keep it all in place, John?

Spot on.

The only fiddly bit with the set-up is getting the three pads to the right height to apply just enough friction so that the bearing doesn't spin too easily. Without some sort of added friction it spins so easily that just a touch will make the scope revolve about ten times.

For bigger dobs I prefer the Ebonystar and teflon system but on 6" to 10" dobs the Lazy Susan is very effective.

John

[Paulus17]

Thanks for the replies folks

Not sure now whether to do this mod as by just adding the LS you still need a certain amount of friction to stop it spinning round.

My Dob at the moment,after adjusting/waxing it meself when i got it,does rotate fairly easily and smoothly,so how would the LS improve on that??

[knobby]

Check the thread in my sig, loads of info