Thread: Bintel BT-252
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Old 09-08-2019, 12:51 AM
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mental4astro (Alexander)
kids+wife+scopes=happyman

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Join Date: Jun 2008
Location: sydney, australia
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Improving the quality of action of your dob.

Quote:
Originally Posted by mcdrewsy View Post
Anyone got any suggestions on how to improve this aspect of the scopes performance?
There are a few simple things that will help. This is what you need:

1, Metho
2, GOOD quality car wax. Don't go el-cheapo, get the good stuff, like the Turtle Wax that comes in a tub. The cheap stuff has nasty solvents in it and will not last as long.
3, rag.

You will need to take the OTA off the rocker box. Clean the trunnions (the round altitude bearings on the scope) with metho, and apply the car wax to them and polish them. The little Teflon tabs, ONLY clean them with metho, DO NOT put wax on them.

With the scope off the mount, separate the ground board from the rocker box. If the azimuth bearings use Teflon, clean the pad with metho, and DO NOT put wax on them. The laminate surface the pad push against, clean it with metho and apply the car wax to it and polish it.

If the azimuth bearing uses a Lazy Susanne devise, a LITTLE WD40 is all you can do as these are difficult to clean. I said a LITTLE.

Reassemble the mount, replace the OTA on the mount, and the quality of action of the scope will have greatly improved.

Just be careful not to over tighten the azimuth pivot bolt as this will cause the ground board to pinch at the pivot bolt which will distort the ground board and the way the Teflon pads touch against the rocker box, which will damage the pads and compromise the azimuth action over time making it stiffer and stiffer.

This clean and rewax process is good to do once a year. After the first time that you do this, you will understand the vast difference to the ease of use it makes, and this once a year bit of TLC is well worth the 20 minutes it takes. I have five dobs myself, and I do this to all of them, and it is well worth the little bit of love I give the mount

Alex.

PS, the Dobsons Hole once you've cleaned and waxed the mount is much less problematic. HOWEVER, I find it more of bloody brain tease than anything else as you are challenged to work out the best way to move the scope! If the action of the scope is silky smooth, not stiff and jerky, moving the scope around zenith (dead overhead) is not too hard. One tip is to not move the scope only by the focuser. One hand at the top of the OTA (focuser end), and the other hand down on the rocker box - this two-hand grip on the scope will give you much greater control over it. The mental gymnastics needed to negotiate Dobsons Hole however, man, that can be interesting!

Alex.
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