Lazy susan question, what type to get?

[Jim09]

I'm building a dobsonian mount for my DIY goto project, not sure what kind of lazy susan to get,  tube is a 200p skywatcher

I've come across three types on ebay so far

(sorry about large images , can;t figure out how to set max width for image uploads )

Can I please get any advice on what type to use?

thank you.

 

1. This seems like the obvious logical choice but I've seen some videos on youtube with not so smooth operation which worries me a bit if that's the case generally with these bearings?

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[cletrac1922]

Jim

Main thing to consider is the load bearing weight of the lazy susan

Needs to be at least 50% above load bearing weight of tube, and other support structures

Be interested to see finished project

Attached pic was taken at a recent club solar viewing day

In background is pic of home made Dob mount, one of our members

Might give you some alternate ideas

John

 

[Jim09]

Thanks John,

Shouldn't be hard to find one for the weight I needed as larger ones are rated nearly 200-300kg , I was more worried  about the smoothness of the rotation from amazon reviews it seems like the type 1 bearings are either hit or a miss so I guess I'll give them a miss and go with type 2 which has decent reviews.

 

[JasonH]

Hi,

How did you get on with this? I'm looking at the same ideas.

Thanks,

Jason

[banjaxed]

I used the type 2 and it works perfectly.

[JasonH]

Nice one. Do you have a link to where you purchased it please? I spoke to a supplier last week and they weren't sure that it would be smooth enough, so I'd be reassured by buying what's worked for you.

Thanks.

[johninderby]

One problem to be aware of with using a lazy susan bearing is it will turn too freely. You may want to add some friction. I found using teflon pads as in a standard dob setup and shimming to just add some resitance to turning helped and made the movement smoother.

Edited November 18, 2019 by johninderby

[banjaxed]

Hi Jason,

 I bought mine from eBay for about £10-£12 from memory and added a small amount of oil to the bearings. I f you find it moves too freely then I just push a piece of sponge in between the base and the moveable base, works for me.

[JasonH]

Interesting, thanks all.

Mine is a Sky-Watcher 200P. The slewing was a bit snatchy with the standard teflon setup, hence why I was looking to upgrade. I tried 5 individual bearings first but they were really poor quality and sounded like they were made from gravel, even after greasing.  I removed them this morning and cleaned everything, again. Back to the original setup and it doesn't seem so bad, compared to the bearings I've removed - I'm sure I'll get fed up with it again though.

The bearing company I spoke to suggested using slewing bearings, which look similar to the type 1 ring bearings, above, however, unlike the type 1 they were prohibitively expensive. I've found a 506mm diameter slewing ring in Germany, for £60 inc. postage, which is still a lot and would cost even more to return if I didn't find it suitable. The base diameter is 520mm.

With the lazy Susan or slewing ring bearing potentially moving too freely and requiring additional friction, I'm concerned that I'll end up losing the smoothness of movement by inadvertently re-adding the snatchy feel.

Not sure which way to go from here.

Edited November 18, 2019 by JasonH

[johninderby]

There are proper bearings but a bit pricy

https://www.teleskop-express.de/shop/product_info.php/info/p1646_Azimut-Roller-Bearing-for-Dobsonian-Teleskopes-D---320mm.html

One of the reasons I now recommend the Bresser dob over the Skywatcher is it has proper alt and az bearings.

Edited November 18, 2019 by johninderby

[JasonH]

I've opted for the furniture sliders route. I fitted eight 38mm diameter sliders around the circumference of the base plate, to avoid catching on the hex bolt heads that protrude from the rocker box.

I'm very pleased with the result, the snatchiness has gone and the feel and friction is great. The sliders came in a pack of 16, I've also replaced the castors on my desk chair and it's much better too. A good use of under £12.

Edited November 20, 2019 by JasonH