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woodblock

Rotating a newtonian on an equatorial mount

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I mentioned this on another post. It is very difficult to rotate the tube in my equatorial mount without completely undoing and lifting the top ring. Even if you undo completely but leave the top ring resting on the tube it won't rotate in one direction and is still hard in the other. In the one direction the friction from the ring causes it to tighten more tightly on the tube and it won't budge.

So I have a plan. Someone kindly sent me a link to a design for some simple floating tube rings which rest against the hard rings and this stops the tube slipping down when you undo the clamps. So that's the first thing but it's still hard to rotate the tube.

So the second idea I had was this. The tube rings clamp around the tube 360 degrees but with the new floating rings to stop the tube slipping down I don't think it's necessary. So I'm thinking of cutting away most of the felt inside the rings and just leave 3 or 4 pads around the circumference. I'm hoping that will allow me to rotate the tube without having to open the clamps completely. What do you think?

Cheers

Steve

 

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I had this problem with my 200pds. After a lot of messing about with various solutions I used my 3d printer to print off four quadrants which I created using SketchUp. My printer bed isn't large enough to print anything larger:

1972261836_ScreenShot2019-11-20at11_35_02.png.37ad90f14d417d22031162b35be4d90d.png

A large Jubilee Hose clamp from ebay was used to keep them in place.

1101442360_slipring1.jpg.295e4def7cbcc33772c9740b9304403b.jpg

I had some Teflon sheet handy, so cut sections of it and fixed them to the side in contact with the rings. Probably would have worked ok with just the PLA but the teflon make it very smooth. Notice I also had to countersink the hinge of the rings so the head of the bolt was clear of the teflon (far left in above photo).

This close up shows the teflon more clearly:

2067591000_slipring2.jpg.96ecaf268cfb67942a6cbf7c143fd4a3.jpg

End result - works well!

Eric.

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Either use above the same jubilee clip with 10mm electrical mini trunking the flat side the jubilee clip fits nice inside.

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Thanks everyone, I've already bought some jubilee clips. I just need some tubing or trunking to finish the job.

Cheers

Steve

 

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