HEQ5 Pro mount head movement on the tripod...

[Centus]

Hi,

I am still getting used to my new HEQ5 Pro (loving it so far) and last night, after finally getting the polar alignment spot on (viewed Saturn through a 10mm eyepiece + 5X Telextender on my 1200mm Newtonian for several minutes without any discernible motion!!!), I accidentally touched the back of the scope, and to my horror noticed the mount head has some freedom of motion in the azimuth on the tripod.

I was sure it was stupid me not tightening the azimuth bolts down, but when I checked they were tightly screwed.

When I played with it a bit more I noticed the motion is actually on the other side of the mount head, not the front where the Az bolts are, but the back where there is nothing.

I tried tightening the main mount bolt on the bottom but that one was also tightly screwed.

Of course this ruined my night as after spending an hour getting the PA in check I had to re-do it all over again

Any ideas?

Thanks!

[IanL]

I don't understand exactly what you mean by "the motion is actually on the other side of the mount head".

If the head is properly seated on the tripod, it should only be capable of rotation in Az by pivoting around the central bolt. If it is pivoting around the Az adjuster pillar (which is what you seem to be saying), then the head can't be properly seated on the tripod base. There should be a circular depression around the central bolt, and on the bottom of the mount head there should be a corresponding circular projection that sits inside it.

If you don't have these two lined up, then the central bolt wouldn't screw in to the bottom of the mount head; it might feel like it is fully tighened because it is trying to lift the whole of the mount head, counterweights and scope upwards as you tighten it. Not a good situation at all! It should be pretty obvious though, as there would be a gap between the mount head and the tripod on one side (opposite the Az ajduster in this case).

If that isn't the problem, the other thing to check that the pillar the Az ajuster screws bear on is also properly fitted. It screws in to the top of the tripod; there are two holes on opposite sides of the tripod so you can unscrew the small pillar, put it on the other side and so reverse the orientation of the legs if required. If it wasn't screwed in tightly then I guess you might end up with some play.

Finally, make sure that you unscrew both Az adjusters a fair way before you put the mount head on the tripod. If they are close together, then they might sit on top of the adjuster pillar insead of fitting around it, and that could lead to the problem above of not having the central bolt properly lined up.

I really can't think of anything else that can go wrong; it's a pretty simple system.

[E621Keith]

Not too sure about the exact nature of the problem, but the M10 main bolt on the tripod does not stop rotation in Alt-Az, That's the job of the Alt-Az fine adjustment screw that you used for polar alignment. You need to tighten both screws so it clamps onto the small pillar protruding from the tripod. If the head is not properly seated on the tripod, your alt-az bolt may be resting on the pillar rather than positioned to the side of it.

[Roy_E]

I had a similar problem some time ago with my NEQ6, and that was caused by the peg that the AZ adjusters act against being loose.

[Centus]

Thank you guys, I tested most of these things, but one option may be my problem - the azimuth peg being loose.. I was not aware it had a screw, I'll check that later tonight.

Thanks!

[Centus]

Hmm, finally got around to checking the theories, found out it was non of the above...

It was the mount head base being smaller than the hole in the tripod by a little, so it had a little play in the hole, I'm not sure if this is a defect in the specific mount I got or if it's something normal, but I ended up adding some tape around the base of the mount head so that it fits more tightly in the hole, now when everything is bolted down there is zero play.

This shouldn't cause any problems with alignment, right? assuming the mount head is polar aligned the connection between it and the tripod is irrelevant, right?

Thanks!

[IanL]

Hmm, finally got around to checking the theories, found out it was non of the above...

It was the mount head base being smaller than the hole in the tripod by a little, so it had a little play in the hole, I'm not sure if this is a defect in the specific mount I got or if it's something normal, but I ended up adding some tape around the base of the mount head so that it fits more tightly in the hole, now when everything is bolted down there is zero play.

This shouldn't cause any problems with alignment, right? assuming the mount head is polar aligned the connection between it and the tripod is irrelevant, right?

I have an NEQ6 not a HEQ5 but that doesn't sound right to me. Clearly there has to be some clearance between the hole and the base to fit them together, but even without the main bolt in place, you should only be able to rotate the head, any lateral movement should be minimal. How much movement are we talking here? Fraction of a mm or a lot more? If it is a lot, and the mount is new I'd speak to your dealer about it; could be a manufacturing defect.

As you have already found, it does cause a problem with the alignment, in that you can't get it to hold. On my NEQ6 with the main bolt fully tightened, even if the Az adjusters are slackened off, the head does not rotate when moderate force is applied (ok if I used the scope as a lever and put my back in to it, maybe it would move but not from a slight bump or from motion of the scope/mount head).

You tape fix might be ok, but if the tape compresses over time you may be back to square one, so I'd get it looked at if that is an option. If it isn't an option, maybe look at increasing the friction between the mount base and the tripod head somehow? You would want it to rotate easily when the main bolt is loosened slightly but not move when the bolt is tightened. Maybe some kind of large, thin washer between the two might work.

[Centus]

Hi Ian,

Thanks for the response, I think it was somewhere around 2-3mm of motion, I will call my dealer just to make sure this is expected, didn't know if it was reasonable or not.

As for a washer fix, I like this idea, I might go with a spring washer, that should do the trick, assuming my dealer says it's OK.

Thanks again all.