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Lazy susan bearing on a dob mount.

Daz Type-R

By Daz Type-R
in Discussions - Mounts

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Daz Type-R

Daz Type-R

Posted
Posted

Hi all.

It has got to the point where I am sick and tired of my dob base's lack of small adjustments. When trying to follow Jupiter the other night, I kept nudging the scope either too far so Jupiter was no longer in the fov, or not enough.

I have tried WD-40, polish etc etc but to no avail.

So on that note, found this bearing company who sell a 12 inch lazy susan bearing, can you think of any downsides to fitting this to my dob base? (web site link below)......

http://simplybearings.co.uk/shop/product_info.php?products_id=42341

It has screw holes to attach the bearing to the top and bottom parts of my dob base and is only 8mm thick, should not add too much weight to the scope and base, which is good.

So can you guys think of any bad points, apart from screwing into the base?

Cheers,

Darren.

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garethmob

garethmob

Posted
Posted

the lazy susen is one of the mods a few members actually do to their bases, the other being using ebonary star worksurface.

there shouldnt be any bad points as far as im aware, just make sure it moves fluidly but with enough friction to be any use (you wouldnt want it wizzing around in circles expess as ur trying to show some one a dso would u :)

im actually going to add one to mine when i get around to "building" it

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johninderby

johninderby

Posted
Posted

I've used both the lazy susan bearing and the ebonystar and find the ebonystar is the way to go as it gives just the right amount of friction but no stickion.

The lazy susan bearing does need some form of added friction to be usable though. With just the bearing the scope will revolve constantly and it is impossible to use. I added some Teflon chair glide pads around the bearing and made up thin washers from milk jugs to go under the chair glides to raise them up just enough to take some of the weight of the scope and to give just enough friction.

You can get the ebonystar in pre-cut disks ready to glue down from Telescope Service, but it's also a good idea to replace the Teflon pads on the base with better quality ones.

http://www.teleskop-express.de/shop/product_info.php/info/p3876_Ebony-Star-Ring-D-40cm-zum-Selbstbau-von-Gleitlagern.html

John

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Daz Type-R

Daz Type-R

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John, quite possibly the most helpfull reply ever. :)

Thank you very much, much appreciated.

Think I will go down the lazy susan option with extra Teflon pads stacked up, that seems the cheaper option, currently saving for good quality ep's at the mo as the stock ones are killing me, nearly as much as the sticky dob base :(

Did you just cut up plastic milk bottle cartons to build up the Teflon pads and where did you get the Teflon pads from (if you don't mind me asking)

Cheers,

Darren.

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johninderby

johninderby

Posted
Posted

They were called Slide Glides, which are Teflon coated. You can get them in 1" dia as well. Pretty well all DIY places such as B&Q etc. stock them. Important point is that you want the ones with the centre hole in them so that you can screw them down, and that way just put the polythene "washers" that you've cut from a milk jug underneath them.

http://www.amazon.co.uk/Slide-Glides-Pack-Ultra-Low-Friction-Screw-/dp/B002NQMV74/ref=sr_1_1?s=kitchen&ie=UTF8&qid=1315235226&sr=1-1

They are the same ones as in the photo, except that I stuck the centre circle from a self-adhesive CD label on top to get the resistance just right. I put some Turtle Wax polish on the stick on circle. Probably defeats the purpose of the Teflon coating really, but it works! It's a bit of a fiddly job as the thickness of a piece of paper can make all the difference.

BTW you only need to fasten the Lazy Susan bearing to the bottom (ground board) as the centre bolt that already holds the base and groundboard together will of course keep everything centered.

John

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  • 3 weeks later...
Daz Type-R

Daz Type-R

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Sorry, bringing this old topic up again. I am about to buy the lazy susan bearing and the teflon pads and I have just had a thought about the centre bolt, will it be long enough to cater for the base and groundboard with a lazy susan bearing or do I need to purchase a longer bolt?

Cheers.

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  • 4 weeks later...
xyz

xyz

Posted
Posted

I added a lazy susan to my Skywatcher 8". I needed a longer centre bolt. To provide some friction I simply pushed in a chunk of foam (foam kitchen scouring pad with the green scratchy stuff cut off). I also often push in a small wedge of wood as a sort of "weak handbrake" between the two base discs - it just keeps it firmly still when I have found the target.

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tms48

tms48

Posted
Posted

You can fit one without using screws or drilling holes. I mounted mine by removing the original pads, and carefully centered the complete lazy susan in position on the lower base section. Using the original bolt and collar as guides I placed the top base section in postion and checked it rotated evenly with no wobbles. I then tightend the bolt with just enough tension to ensure I get no unwanted rotation due to wind etc. It works pefectly and I can return the base to its original condition if needed, now I just need to get rid of the slight altitude sticktion which prior to fitting the lazy susan I did not notice

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peterbolson

peterbolson

Posted
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I may be being thick but I can't see where you can put the 50mm pads that John recommended. There is only 45mm from the outer edge of the outermost screw heads to the margin of the base, and much less between the heads inside of this. I've tried the bits of foam that xyz suggested & they do seem to add some friction so I'll stick with them for the moment. The lazy susan is definately a vast improvement.

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spaceboy

spaceboy

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I ended up asking myself this question some time ago http://stargazerslounge.com/beginners-help-advice/120992-good-link-dob-bearings.html I went with the cheaper LS bearing and has worked out fine. I used 2 circles of carpet tile placed back to back with the axle bolt going straight through the center. This means the tighter I do the bolt the more friction I have enabling me to adjust the tension easily. This came in handy one windy night :)

The most beneficial mod I found when considering smoothing up the AZ movement is to secure the axle bolt to the bottom board and restrict the sideways movement of the top board as this is one of the main causes of sticktion. Sky-Watcher SkyLiner 200 Dobsonian Telescope

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  • 1 month later...
Grunthos

Grunthos

Posted
Posted

You can get the ebonystar in pre-cut disks ready to glue down from Telescope Service, but it's also a good idea to replace the Teflon pads on the base with better quality ones.

http://www.teleskop-express.de/shop/product_info.php/info/p3876_Ebony-Star-Ring-D-40cm-zum-Selbstbau-von-Gleitlagern.html

This link no longer working.

Are the rings available elsewhere? (can;t seem to find any)

Thanks in advance.

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johninderby

johninderby

Posted
Posted

Not a suitable mod for a Synscan dob unfortunately. :)

The stiffness is caused by the drive system. This scope isn't really designed for manual use. Yes you can push it around, but this is only for moving it quickly to a new position instead of waiting for the motors.

John

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Grunthos

Grunthos

Posted
Posted
Not a suitable mod for a Synscan dob unfortunately. :(

I thought so...(couldn't work out the mechanics of having a super slick action and a synscan goto system)

Let's look on the bright side. One less mod on my list of things to do. :)

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  • 2 years later...
michaeldurban

michaeldurban

Posted
Posted

Nice explanation of mods John..!

I immediately ordered a 12" Lazy Wife..I mean Susan.

And hello everyone...

I'm michael, from Durban, and new...Although I have been following

your adventures since two years.

I finally registered.

Oh..My scope is a SW 10" flextube..and because of this (and other)

forums I have already made the following mods.

- custom made springs for sec. and prim. mirror

- flattened out the focusser tube

- Flocked the whole scope with car upholstery (yes, works wonders!)

- re-centered the mirror spot

- made a cooling fan

- re-painted the base to matte black

- had new SW-logo stickers made

- made my own dew-cap and dewshield for my Telrad.

- And became (after much cursing) a collimation guru (well...almost)

In short, without forums like these, us newbie's could never get of the ground.

Hope I'm not hijacking this thread but..Thank you.

Having said that,

I will follow the guide for installing the LS and let you know how it goes!

cheers!

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michaeldurban

michaeldurban

Posted
Posted

Hello everyone (newbie here..!)

well.. i started my little project..setting circles for my Dob

(ehh..my wife said : Here name is  Calpernia !)

And so she is...my Dob's new name..

Anyway..

I've had Calpernia for six months now...and we were quite impressed with

her 10" aperture. She was delivered by Skywatcher, and is of the flexible kind..

I am upgrading her with setting circles...

and I will take pictures as I go along...(although decent..)

First of all, I live in South Africa. Apart from the ANC there is not much you can

get here (did I break a rule already?),

There are no eyepieces available (well, that's not entirely true, there are two), few scopes, few accessories

and even less DIY stuff.

I recall one day I went to the local hardware store (bear in my 'local..') and asked for simple

rubber washers (with a hole in the middle).

The (not so bright) attendant looked at me with alien eyes and responded : ..eeehhhh...

Anyaway...this is not europe, everything I have done so far is by ingenuity and import...

So... setting circles.

I did go to the local print shop and handed over a PDF file (which I cannot attach to this

discussion as I haven't reached for the elusive 50 posts yet.)

But you know where to get it I think, CN, astronomyforum.

I think Astrobaby has a few.. (hello astrobaby :kiss: )

I also ordered a lazy susan bearing -which, in itself is a whole new story, ever tried ordering a bearing named :

Lazy Susan in South Africa?  No?  well, you're in for a few good laughs-

I ordered it from Cape Town, together with a digital inclinometer (they had it !)

And so, after using house/garden and kitchen appliances I have what you call

a Home-made Dobsonian.

Flocking I made from black car upholstery (works surpisingly well..)

I repainted the white base to matte black (uhh...so it looks like the new model, and

also less light reflectivity...damn albedo's!!)

had new springs made, and did a bunch of other stuff..

I hope I didn't hijack this thread (hijacking is common in SA..so excuse me).

Just want to thank all the forum contributors for helping me indirectly...

You never knew..., but you kept me thinking at night..dreaming

Cheers..!!

michael

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