Lazy Susan dob brake

[scogyrd]

I discovered this mod by accident and then found out that it is similar (I presume) to what some manufacturers do so I cannot take any credit for it.

First you will need to do the fixed bolt mod - which you should've all done by now because it does improve the scope's accuracy.

Sky-Watcher SkyLiner 200 Dobsonian Telescope

Mine is similar to this except I used ptfe instead of acrylic (I don't see it makes much difference though) and I removed the plastic bush that goes round the bolt. I would also recommend using steel instead of aluminium because the steel bolt is slowly wearing the aluminium thread away.

Next fit a lazy Susan bearing.

Orion XT10 Dobsonian Azimuth Bearing Lazy Susan modification

Now, when you reassemble the scope you will find it moves far too easily so, if your scope is on uneven ground or the wind picks up, it will move.

I tried to get round this by tightening the bolt but I soon found out that, if I moved the base in one direction, the bolt would loosen itself and, if I moved it the other way, the bolt would tighten to such a point that the base wouldn't move.

Obviously this was no good so I decided to fit a m10 thrust bearing between the bolt and the ptfe and found that I was now able to tighten the bolt as much as I needed (from too free to not moving at all) and it would stay like it.

The only drawback to this was that I now had to carry a spanner with me, in case the bolt ever needs adjusting, so I bought a hand knob to use instead.

IMO the mount is now much better than it was originally. Matching the amount of force it takes to move the scope in az with the amount it takes to move it in alt is as simple as turning a knob, which means I can now move diagonally much easier, and it takes no more force to get the base moving than it does to keep it moving so I hardly ever overshoot the target now: I used to do this quite a lot when using teflon bearings.

Here's some links to the parts (or shops) I used.

10x24x4mm Needle Roller Thrust Bearing

M10 Hand Knob

M10x70 Bolt

Handrail Tube, Tube Inserts Plastic Caps items in B E J Engineering store on eBay!

Trent Plastics Fabrications Ltd - Acrylic, Polycarbonate, Mirror, Colour & Tinted Acrylic, Tube & Rod (Powered by CubeCart)

I hope I've explained myself properly, it really is much simpler than I've made it sound, if not then feel free to ask any questions.

[Damo636]

Nice work and a good guide. I really will have to get around to this mod on my 200p. Turtle Wax is the only modding i have performed on mine!

[scogyrd]

Thank you. Although I probably should've mentioned in the guide that the scope I did this to was a 200p as well.

Judging by the pictures it could do with a good dusting too. It doesn't look that bad in the flesh.

[jimmyjamjoejoe]

Where'd you get the aluminium block?

[scogyrd]

Where'd you get the aluminium block?

Ebay I think. I did that mod a while ago now so I'm not too sure.

TBh I wouldn't recommend aluminium because the threads wear away over time. I intend swapping it for steel sometime soon.