making a dob smoother

[Daniel-K]

Currently I own a sw 350 flexi tube and I love it but one thing that is bugging me is the jerky movement in the alt. It makes keeping things in the ep a challenge

Btw way this is like this when both handles are mot even tite.amy ideas how to improve this

Dan

[NGC 1502]

Hi Dan, the most common fix is by adding a centre bearing pad around the centre bolt.  Needs to be JUST enough to ease the weight from the outer bearings, but not too much, or it will teeter on the new centre bearing, so experimentation is needed.

You can use sheet plastic ( common source is milk cartons ) cut to a circle with a hole in the centre, to go around the bolt.  Works well if you get the right number of discs, but tends to 'bed down' in use and require further tweaking.

Other fixes are a 'lazy susan' roller bearing, should be a more lasting fix.

Hope you sort it, because a sticky Dob is a pain, a smooth one is a joy to use.

Edit - oops sorry, just re-read your post, you said alt, not azimuth.  To ease the altitude, the Teflon bearings need to be closer together for a lighter movement, further apart for more effort needed, not sure if that fix is easy on a SW Dob..........

Regards, Ed.

[Mike73]

Dan get yourself some Sailkote, its non greasy/oily, invisible and the effects lasts for atleast 12 months (I did mine when I first got 16" and I'm just about to strip it down and do it again now 18 months on!) 

You can use it for both alt and azi bearings.

Dont use much of it though, spray it onto a rag and wipe it on, it really is good stuff and could make things too loose if you use to much!

It was recommended to me by Sumerian, top stuff!

[clarkent]

That's a cracking tip.  Thanks Mike73

[knobby]

Pencil lead?

[Daniel-K]

Dan get yourself some Sailkote, its non greasy/oily, invisible and the effects lasts for atleast 12 months (I did mine when I first got 16" and I'm just about to strip it down and do it again now 18 months on!) 

You can use it for both alt and azi bearings.

Dont use much of it though, spray it onto a rag and wipe it on, it really is good stuff and could make things too loose if you use to much!

It was recommended to me by Sumerian, top stuff!

thanks mike ordered some  will give it a bash

[AlexB67]

Like the pencil idea, must give that a try.

Dan, FWIW, I do find it helps, at least I find I can get smooth movement on the 10 inch flexi as long as the tube is not too low, above 45 degrees or so by not over tightening the right handle ( the one on the opposite side where you sit ). This gives better fine adjustment on the near handle where you do sit to get it in the sweet spot. The manual mentions this also as far as I recall.  

[Mike73]

My old 12" Skywatcher suffered from the same problem, sometimes it was ok others it was quite sticky and jerky to move. The only way to really get around the problem is to build a complete new base spreading the alt bearings and and getting rid of the lazy susan for teflon pads, both my Skywatches were great scopes but although the bearings did the job for me they were the biggest let down of those scopes.

The new ES and Skywatcher prototype truss dobs have thought about this and its the reason I like them so much.

Dont OOUK claim their dob bases can be used on their competitors scopes aswell? Might be worth looking at Mikes and see if its possible to put your SW on a OOUK dob base?

Dan I take it your scope is top heavy thats why your tightening the handles to stop it dipping? Have you tried any kind of counter balance on the primary end? It sounds like those tightened handles are more of a problem than the alt bearings.

[AlexB67]

I think the OO tubes are narrower. An OO Dobsonian base will not fit a similar aperture SW scopes I believe. I think Moonshane told me about this some time ago as I looked into that at one time. I could be wrong though. 

[Daniel-K]

well  my sailkote arrived today and i have just put some on the ALT telflon pads and how good is this stuff!

[101nut]

I think the OO tubes are narrower. An OO Dobsonian base will not fit a similar aperture SW scopes I believe. I think Moonshane told me about this some time ago as I looked into that at one time. I could be wrong though. 

My Celestron 10" didn't fit the Orion dob base for that reason. I put some aluminium packing strips in the joints when I assembled it, made slightly longer fixing studs and widened the hinges slightly so the rings fitted and sat true. Nothing too strenuous or irreversible, just a bit of a pain to have to do it and you need to be a bit handy at metal bashing. 

AndyG

[NGC 1502]

I think the OO tubes are narrower. An OO Dobsonian base will not fit a similar aperture SW scopes I believe. I think Moonshane told me about this some time ago as I looked into that at one time. I could be wrong though. 

That's correct, my 10" OO Dob has an 11" tube, narrower than most competitors.  

The OO tube is aluminium however, noticeably lighter than steel tubes, a 10" OO tube weighs about the same as an 8" SW tube.

Regards, Ed.