Friction bearing for dobs

[markse68]

I just spotted this on Teleskop-express website and just wondered if anyone has experience with such a device- do they work well? Wondering if the friction is smooth or if it has stiction and if they stay set or work loose?

https://www.teleskop-express.de/shop/product_info.php?products_id=6767#ebericht

Thanks,

Mark

PS happy new year

Edited January 1, 2020 by markse68

[johninderby]

Looks very much like the friction bearing used on GSO deluxe dobs.

https://www.teleskop-express.de/shop/product_info.php/info/p1192_GSO-10-inch-f-5-Dobsonian-Telescope-Deluxe-Version.html

Edited January 1, 2020 by johninderby

[markse68]

Thanks John, using that knowledge I found a few results on CN referring to them but no detailed discussion about them- just that some like them whist others don’t 🤔😂 They certainly look a neat solution and well made 👍 I wonder if they just have too little stiction- the stiction is too close to the friction? I guess a little stiction is useful for giving the right amount of lock when changing eps or in the wind. Yet most of the discussion on alt bearing design on CN are about reducing stiction to make it closer to the friction to prevent jerky motion- something I’d obviously like to minimise in my new dob base design. Maybe there’s just no perfect solution that will please all users

Edited January 1, 2020 by markse68

[johninderby]

I too have read differing opinions on the friction bearings, Mostly positive but not everyone seems happy with them.

I prefer the bearings used on my Bresser dob. Traditional style bearings used mainly on bigger dobs but work well on my 10”

[markse68]

Yes there’s something to be said for the beautiful simplicity of the classic large trunnion + Teflon and Formica solution though I think there’s a bit of an art (or rather science) to getting it right- trunnion diameter/pad spacing/Formica surface texture to match OTA weight and inertia that could be tricky for a diyer to get right without a lot of trial and error. Especially given differences in preference to the balance of stiction/friction. Some sort of adjustment mechanism seems ideal but it would need to not only adjust the kinetic friction but somehow to skew the relationship to stiction too 🤔

[johninderby]

One thing I like with the Bresser is the use of tube rings as well which allow for balancing of the tube and also rotating the tube to get the eyepiece at just the right angle. 

Bresser has used an embossed metal rather than formica but seems to give the same result.

[Science562h]

I believe, that those bearings are made, by GSO for their dobsonians. Ultimately, they are used for Push-To. They might fit the Apertura, Zhumell, Bintell, Omegon, Bresser, Antares, Atronz, & Guang Shen DOB models. 

johninderby, but he can GOTO, Push-To & track, with those bearings & you can't/haven't. He's more right, by picking them.  It's not, about opinions or likes & dislikes; its about technology, making the right decisions & those bearings are simply better. They have full capabilities. Your Bresser is made, by GSO but your rings are totally useless. You can't even transport/move properly or logically.

GET THE BEARINGS, THEY'RE BETTER.

[markse68]

Can you elaborate on “better”? I think people use the classical large journal dob bearings with goto and push-to too? I’m really interested in the comparative “feel” of these- the balance of friction/stiction and how useful the adjustability is?

Mark