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Astro Tech Voyager Alt tension adjust

Started by going_broke, 10/12/2010 09:29PM
Posted 10/12/2010 09:29PM Opening Post
I just acquired a used Astro Tech voyager Alt-Az mount. The slow motion controls work very nicely. There are tension adjust knobs (screws really) for each axis. These screw have very little adjustment range and fall out completely after about 1-2 turns. A few times already, one of tension knobs dropped out on the ground.

So, I'm wondering if any others have run into this and found some solution? I need to push my refractor around on the alt or az axis sometimes for quick or coarse pointing, then use the slow motion controls. I'm not able to have a setting where the motion is smooth and also good holding friction. It would be wonderful to have something like the cam locks similar to Celestron CG-5 mount.

Over at OPT, I played with the Vixen porta-mount (alt-az). There was not a tension knob, but I could slew a telescope around very smoothly and the refractor would hold in place nicely and then use slow motion controls. I think there are set screws you can adjust tension with.
Posted 10/13/2010 03:09AM #1
I have one and found that the 'tension adjust knobs' don't really preform very well as 'tension adjust knobs'. They appear to act as on and off knobs. Once you feel no contact, further loosening has no effect. There is no need to loosen them until they nearly fall out. For me there is no 'set and forget' position, it's loosen to slew, tighten for slo-mo. I use mine with my FS-78 and I have to securely tighten the screws to get enough clutch action for the slo-mo to work. A much lighter scope may behave differently.
I gather from your post that you feel that slewing is too stiff and you would like a lighter touch. There is a way to loosen the slewing tension but it comes at a price, a bit of wobble between the two bearing surfaces. As a side note: even with stiff slewing, if the tension screw is loose, there is no extra stress put on the worm and gear during slewing.

If you would like to play with the tension, this is how to do it.

1. Loosen the 3 black set screws on the part the saddle is mounted on and remove that section. You don't need to remove the saddle. These 3 set screws correspond to the 3 on the polished ring for the azimuth bearing.

2. Loosen clutch and align the 2 holes in the back cut flange with the 2 set screws of the inner ring. Loosen these 2 set screws.

3.Using a spanner wrench or your finger nails turn the inner ring to adjust the tension. Caution, 1/4 turn makes a big difference.

4. Realign the holes with the set screws and tighten them.

5. Check for feel or wobble, repeat steps 2-4 until your happy.

With my mount, I have found that totally eliminating the wobble results in pretty stiff slewing. YMMV

Good luck,

Fujinon 10x70 FMT-SX binocs
Tak FS-78 ƒ/8.1 - 630mm fl.
6" ƒ/6.5 homeground newt. - 981mm fl.
10" ƒ/4.85 homeground dob. - 1231mm fl.