Stiff RA & Dec Axes

[astromole]

Can anyone advise me on a relatively simple way to ease the stiffness in the axes of an EQ3-2 mount. I've looked carefully at a description of a strip/regrease/rebuild of a HEQ5 mount. This seems to be a bit beyond my comfort zone, but before I fit dual motor drives I would like to ease the movement in the axes, particularly the dec axis.

As always any help to this old newbie is most appreciated.

Frank

[astromole]

Well, I bit the bullet and carried out a partial disassembly/reassembly of the v. stiff RA axis....not the whole thing, just the plate which holds the worm gear against the large toothed wheel on the axis itself. A bit of careful examination and thought revealed how this bit of the apparatus works and how the 4 allen key bolts and the grub screw all work together to set the worm gear with the ideal pressure as it meshes with the RA axis gear. I can only say that after several goes I managed to achieve a compromise between stiff and sloppy which is a whole lot better than before.

I know photos would help but briefly this is how I managed it:

1) Loosen the 2 allen key bolts which hold the worm gear carrying plate vertically (ie the 2 WITHOUT the grub screw)

2) Fully loosen the grub screw between the other 2 allen key bolts. Be careful it doesn't drop out and get lost on the carpet!

3) Loosen the 2 allen key bolts on either side of the grub screw until the worm carrying plate is uniformly loose.

4) The idea now would seem to be to tighten the 2 allen key bolts (on either side of the grub screw) uniformly so that the worm gear meshes at 90 degress with the main large toothed wheel on the axis, and with an appropriate pressure.

5) This is where a bit of trial and error takes place. As I see it the grub screw acts as a stop to the allen key bolts once they have been tightened and set where you want them. However, I found that tightening the grub screw also makes slight changes to the pressure applied between the worm gear and main gear on the axis. This is where the trial and error comes in. You have to balance the tightening of the allen key bolts with the action of the grub screw. (This may be just a function of the age of my mount)

6) Once you've reached a reasonable compromise between too stiff and too sloppy, you then tighten up the other 2 (vertical) allen key bolts (the ones without the grub screw.

7) Finished??? Well not quite... Carrying out 6) above also applies some changes to the settings you've achieved. The only way I resolved it was to make slight adjustments at 4), 5) and 6) again until, as I said, I reached a compromise between too stiff and too sloppy.

Incidentally I also took the opportunity to inspect the condition of the gears and to apply a little lithium grease.

Flushed with success I applied my new-found knowledge to the Dec axis. Now I'm not saying I've done the correct thing but I've found out a whole lot more about the mechanics of my EQ3-2 mount and the result is a definite improvement on its former performance.

I still think it will be some time before I attempt a full strip and rebuild. I do wish Synta would publish a proper workshop manual, or at least an exploded diagram of their mounts' interior.

Tinker on dudes!!

Frank

[philsail1]

You did well there Frank - and you explain the tricky bit of balancing the final adjustments between the horizontal and vertical allen bolts. I understood your description perfectly because I made the same adjustments on my Celestron CG5 mount - and was faced with the final tricky balancing adjustments. I couldn't have explained it as well as yourself.

Good one, as it will give others the confidence to make the adjustments to their mounts stiff axis.

Very satisfying when it all comes right!

Regards,

philsail1.