EQ3-2 vibration but not from tripod

[dcwales2012]

Hi,

Question regarding the EQ3-2 mount.

I have noticed when altering, either the focuser or the RA / DEC fine adjustment my SW EX 150p vibrates a lot. I read the other topic and have found my tripod to be quite rigid, and the mount to tripod knob is tightened securely as are the Azimuth Adjustment Knobs.

The only place I can find any slight movement is when I hold the tube and move it gently the DEC part of the mount moves slightly and vibrates.

My questions are:

How do I get this tightened or cured. Do I unscrew the counterweight rod and use a socket spanner on the nut within the mount, or should I just take out the Polar Alignment blank and use a spanner?

Would making the DEC too tight affect fine adjustment?

If I cant get the DEC to stop vibrating would this be a mount fault?

Currently this vibration is making viewing very annoying because of the time it takes the scope to settle, the object is out of view, then I have to fine adjust again, wait for the vibration to stop, and guess what the object has moved yet again.

Any help would be very much appreciated.

[barkis]

It might well be that you associate the vibrations as emanating from the mount, and you of course could be right.

Is your tripod the aluminium one? If so, try hanging a weight down from it's centre, around 4 or 5 Kgs, and see if the vibrations dampen down quicker.

Don't be tempted to over tighten bolts.

Ron.

[dcwales2012]

Sorry, should have mentioned I have tried the weights.

[JamesF]

Adding weight seems to help for me. As my eyepieces are taken from and replaced in their foam-lined box, I've put some large stones in the eyepiece tray which seems to help a little.

However, any mechanical system like this is always going to have small amounts of movement possible. Gears can't mesh and turn easily if they're tightened up hard against each other. The 150P probably makes that worse because you have heavy components (particularly the mirror, focuser and finder) away from the centre of mass, so any small force on them has a much larger turning moment than the same force nearer the centre.

It may be that there's some backlash in the DEC gearing that can be reduced with adjustment, but the most satisfying solution is probably to add some sort of motorised focuser adjustment. If you have a hunt in the DIY section you should find examples of such a modification.

James

[Parus major]

If you're talking about the play in the Declination axis have a look at this.... http://stargazerslounge.com/discussions-scopes-whole-setups/171668-skywatcher-150pl-owners-tips-mods.html#post2112349

[dcwales2012]

Hi James,

Many thanks for the link.

I'll give this a go.

There is another thing with the DEC. When I turn the fine adjustment knob the DEC sounds like it knocking and there is a horrible binding sound like its rubbing metal against metal. When I compare this to the RA fine adjustment, which is smooth and doesn't appear to cause any judder, I think their is deifnitely a problem with the mount.

I'm not sure I want to tamper with the mount if it still under guarantee, only 3 weeks old. Think I'll ask FLO what they can do about it.

Regards

[Parus major]

Double check with flo but I'm sure the adjustments are intended as user servicable, they eo need tending to every now and again.

[dcwales2012]

Hi James,

I found what the problem was. The grub screw wasn't seated properly, so I took it out cleaned it, oiled it put it back in tightened it and now no more judder. Another Chinese c*ckup.

But many thanks for your help.

Regards

David

[Parus major]

Aye, no bother. The tightening bolts are the ones that cut backlash but tighten the slow mo control, the grub loosens the slow mo so you fiddle until you get the right balance. The nut behind the polar scope cover is if you find there's twisty left/right up down in the puck.