Vixen GP mount question

[F15Rules]

Hi all, 

Could anyone please advise me what diameter and length the two adjustment bolts are on a GP mount?

It's the pair of bolts at the base of the mount that work against the single bolt on the opposite side of the mount to adjust the latitude setting of the polar axis..I need to source a pair of missing ones for a mount I've had as a project for a while.

If anyone has a pair surplus to their needs...?😊

I attach some photos that I hope might help..

Thanks in advance,

Dave

Edited December 16, 2020 by F15Rules
Photos added

[DaveL59]

Assuming it's similar to the EQ5 then yeah it's to tune the polar alignment on the AX axis, acts against a pin in the tripod head. I don't have any spare but could check the thread on the EQ5 if that helps. Could be different in the Vixen tho so hopefully someone who has one can give a more accurate measure.

 

edit - oops my bad, just re-read and you're after the ones for the 2 empty screw holes. Shouldn't there be a plate there that is bolted by those two and also has a large bolt that acts against the cam to drive the latitude angle?

Like this...

Edited December 16, 2020 by DaveL59

[F15Rules]

Thanks Dave.

I don't think I've seen such a plate on a Vixen GP before.. however I did find this short thread..

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.cloudynights.com/topic/651821-vixen-gpdx-and-gpd2-latitude-adjustment-bolts-question/&ved=2ahUKEwjc6NDzy9PtAhUKAcAKHQZOB4UQFjAAegQIBBAB&usg=AOvVaw1Y_QSlbhDmpZK7v6WNaUKz

..it might explain why mine had the two empty (but threaded) holes. I believe they may be M10 size, I will try to guage how deep they are and see if I can source replacements..

Dave

[Ibbo!]

I will have a look at mine tomorrow afternoon and measure up for you if no body comes in beforehand.

[John]

20 minutes ago, F15Rules said:

Thanks Dave.

I don't think I've seen such a plate on a Vixen GP before.. however I did find this short thread..

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.cloudynights.com/topic/651821-vixen-gpdx-and-gpd2-latitude-adjustment-bolts-question/&ved=2ahUKEwjc6NDzy9PtAhUKAcAKHQZOB4UQFjAAegQIBBAB&usg=AOvVaw1Y_QSlbhDmpZK7v6WNaUKz

..it might explain why mine had the two empty (but threaded) holes. I believe they may be M10 size, I will try to guage how deep they are and see if I can source replacements..

Dave

The odd thing is that I've seen that plate on some GP's but not others. I've recently sold a GP but I can't for the life of me recall if it had the plate or not

That "Cloudynights" thread seems to about the GP-DX  / GPD2 mounts which have a different design for the latitude adjustment bolts and their mountings.

Back to the GP mounts, is that plate removed to allow the mount head to be used in alt-azimuth mode ?. (I maybe incorrect on that)

 

Edited December 16, 2020 by John

[F15Rules]

Thanks John,

I actually meant to cut and paste this link..

If you search "Any Vixen GP2 owners here" on the Mounts forum - it's from 2013 I think..

I don't think GPs could be used in Altaz mode, there's no facility for the mount to rotate through 360 degrees horizontally as would usually be the case?

Dave

Edited December 17, 2020 by F15Rules

[John]

3 minutes ago, F15Rules said:

Thanks John,

I actually meant to cut and paste this link..

If you search "Any Vixen GP2 owners here" on the Mounts forum - it's from 2013 I think..

I don't think GPs could be used in Altaz mode, there's no facility for the mount to rotate through 369 degrees horizontally as would usually be the case?

Dave

I think you are right Dave. It was the older SP that could do the alt-az thing.

I've just found a photo of my GP and it did have a plate where those 2 holes are on your mount. One of the latitude adjustment bolts runs though it like the EQ5.

I only sold the mount a few weeks ago and I've forgotten the details of what it looked like already

 

 

[AdeKing]

I've just dug my GP out and the plate setup is identical to the EQ5.

The bolts look like they're M6 based on the cap size but I'll dismantle it and pull out the digital caliper tomorrow as it's too late now.

I have a box full of machine bolts so if I have some the right length I'll pop them in the post for you.

Just need to work out where I've put the digital caliper gauge as typically I've found its case but it's empty.  One day I'll learn to put things back in their correct place, in the meantime I'll have to keep searching.

Ade

[Ibbo!]

Well this is embarassing, I have just been out to look at mine and there is no plate.

In my defence it has been sat on that tripod in the same place for about 3 years its my alternative mount that is semi perm.

Sorry no help from me.

[DaveL59]

There was someone selling bits off an EQ5 in the classifieds, ok it'd be white but if its the same size might be a quick cheap option if they still have that bit, unless you already have that kicking around in a drawer/tin somewhere or want to fabricate from scratch.

[AdeKing]

7 hours ago, DaveL59 said:

There was someone selling bits off an EQ5 in the classifieds, ok it'd be white but if its the same size might be a quick cheap option if they still have that bit, unless you already have that kicking around in a drawer/tin somewhere or want to fabricate from scratch.

Good shout Dave, though I've just searched for it and the thread seems to have completely vanished from SGL, not just moved to the Completed for sale forum.

I know it existed and that I posted in it as I got a white plastic RA cover for future use on my GPD2, but the thread doesn't show up in my history any more.

@Alicja was the original seller, might be worth a PM.

[AdeKing]

8 hours ago, Ibbo! said:

Well this is embarassing, I have just been out to look at mine and there is no plate.

In my defence it has been sat on that tripod in the same place for about 3 years its my alternative mount that is semi perm.

Sorry no help from me.

Interesting, how were you previously adjusting the altitude of the RA axis Steve?

Seems an odd part to be missing from both GP mounts unless they're the result of failed attempts to convert to Alt Az use.

Edit: Have now read the "Any Vixen GP2 Owners on Here" thread mentioned above and that might well answer the question as to why its missing, apparently some GP2s were shipped without the second latitude adjustment bolt as it got in the way of the motors when used in places at low latitudes, I imagine its the same for the GP.

Maybe your mounts have made their way to the UK from more exotic places guys. 

Ade

Edited December 17, 2020 by AdeKing
Details added.

[AdeKing]

Dave (@F15Rules) I've just quickly removed the latitude adjuster plate from my GP before starting work.

The two bolts securing the latitude adjuster plate are indeed M6 and have a 12mm threaded shaft.

I've had a very quick search through my nuts and bolts box and might be able to locate a couple of M6 x 16mm bolts, though I can't guarantee it.  I certainly don't have any as short as 12mm though I'm afraid.

If you want me to send you the dimensions of the original vixen plate then let me know.

Ade

[John]

You might think that the small plate had never been on Dave's GP. There is no wear mark on the lug which the 12mm bolt would bear against to hold the latitude angle of the mount

 

[michael.h.f.wilkinson]

For what it's worth, my (black) Vixen GP mount that came with the Celestron GP-C8 does have the plate in question. I suppose it is not really necessary, but I do rather prefer securing the polar axis with both adjustment bolts tightened, rather than gravity doing the job of the second bolt

[DaveL59]

33 minutes ago, John said:

You might think that the small plate had never been on Dave's GP. There is no wear mark on the lug which the 12mm bolt would bear against to hold the latitude angle of the mount

 

That was my thought too John, no witness marks from the bolt on the cam so perhaps the offset weight of the head & counterweight was enough to keep things safely in place against the rear bolt, at least for visual.

[Ibbo!]

This is mine and of course its not a GP but a GPD

 

[AdeKing]

1 hour ago, Ibbo! said:

This is mine and of course its not a GP but a GPD

 

Ah, I see, so you're not missing anything, that arrangement is identical to the GPD2 that I also have, which was I believe the last incarnation of the GPD/GPDX.

6 hours ago, DaveL59 said:

That was my thought too John, no witness marks from the bolt on the cam so perhaps the offset weight of the head & counterweight was enough to keep things safely in place against the rear bolt, at least for visual.

Thinking about it when I'm not tired I can see that the second latitude bolt (on the counterweight side of the mount) is not really necessary as you say gravity and the counterweight should keep it in position when set up and operating.

But it leaves potential for pinching of cold fingers (ouch) when attaching to the tripod.

7 hours ago, John said:

You might think that the small plate had never been on Dave's GP. There is no wear mark on the lug which the 12mm bolt would bear against to hold the latitude angle of the mount

I agree about the lack of wear, it does suggest that it's never been fitted.

6 hours ago, michael.h.f.wilkinson said:

For what it's worth, my (black) Vixen GP mount that came with the Celestron GP-C8 does have the plate in question. I suppose it is not really necessary, but I do rather prefer securing the polar axis with both adjustment bolts tightened, rather than gravity doing the job of the second bolt

As above, now I'm fully awake and alert I can see that it's not really needed.

[F15Rules]

Firstly, thanks guys for all the replies! 

I'm sorry for the delayed response, we had to dash to the Midlands and back today due to a family health emergency, just got back.

I also messaged Pete Gamby, who used to represent Vixen while Opticron had the Vixen UK distributorship.

Pete confirmed that a batch of GPs were shipped without the plate and bolts..it was thought that these mounts were originally destined for low latitude regions where the presence of the adjustment plate and bolts could have interfered with the operation of the polar axis: however, these mounts came to Europe by mistake, and Opticron bought in a small supply of bolt sets to ship to their GP customers. Sadly, they have all long since gone.

Ade, thanks for confirming the bolts are M6 (my electronic calipers have died! - rubbish anyway!). Yes please, I'd love a pair if you have some please, I will pm you, also about the plate.👍.

Several of you have suggested the bolts may not be needed, that gravity can do the job? 

As I haven't got the mount on a tripod so far, I can't move the mount manually to a lower latitude setting at the moment, only to a higher setting with the bolt on the opposite side which pushes the mount higher.. I need to put it on a tripod to get enough torque to push back manually in the downward direction.

I agree with John that it looks as though my mount never had these bolts and plate fitted as there are no bolt marks where you'd expect them to be. So presumably any past user(s) must have been able to push the mount manually to their local setting.

Anyway, a lot of food for thought here and I will take up Ade's kind offer of the bolts and see what can be done about the plate..I may have a small metal plate that could work .. I could drill the two M6 end holes myself, but of course a central bolt hole would need to be tapped for the bolt thread, which I'm not able to do.

My grateful thanks to all who responded, you're a great bunch!

I'll post again to show whatever solution I come up with👍😊

Dave

Edited December 17, 2020 by F15Rules
Additional text info

[DaveL59]

hi Dave

hope the family is ok, not fun to have to dash off in current times. I put my daughter thru that a couple months ago in fact, gave the family a scare for sure!

[MercianDabbler]

34 minutes ago, F15Rules said:

Anyway, a lot of food for thought here and I will take up Ade's kind offer of the bolts and see what can be done about the plate..I may have a small metal plate that could work .. I could drill the two M6 end holes myself, but of course a central bolt hole would need to be tapped for the bolt thread, which I'm not able to do.

Assuming the central one is also M6 then I am able to drill and tap if you like. M6 is the biggest I have though.

I'd need the dimensions though - my mount is an SP which has a completely different arrangement.

 

[philj]

20 hours ago, John said:

The odd thing is that I've seen that plate on some GP's but not others. I've recently sold a GP but I can't for the life of me recall if it had the plate or not

That "Cloudynights" thread seems to about the GP-DX  / GPD2 mounts which have a different design for the latitude adjustment bolts and their mountings.

Back to the GP mounts, is that plate removed to allow the mount head to be used in alt-azimuth mode ?. (I maybe incorrect on that)

 

Your old mount has the plate John

[F15Rules]

3 hours ago, MercianDabbler said:

Assuming the central one is also M6 then I am able to drill and tap if you like. M6 is the biggest I have though.

I'd need the dimensions though - my mount is an SP which has a completely different arrangement.

 

That's very kind of you, MercianDabbler ( great handle!👍).

If I need to take you up on your kind offer I will send you a private mail message.

Dave

[DaveL59]

On my EQ5 the alt adjuster bolts are 8mmx1.25 if that helps. I'd doubt that M6 would be up to the job, but then again on that side it's only really preventing the head tilting downwards as the other bolt is the one carrying the real load.

[F15Rules]

Hi again all,

Just to share a happy ending to this mini saga...

I'm delighted to say that Ade (King) has really come up trumps for me..he has fabricated a new plate and drilled and tapped holes for the plate, as well as supplying the two 6mm bolts, one for each end of the plate.  It arrived this morning👍.

I found an 8mm hex bolt in my bits box for the central bolt where the "Tommy bar bolt" would have been. It all works perfectly, and I am really indebted to Ade for his kindness in doing this for me, with no charge, and he wouldn't even accept the cost of first class signed for postage! - a Top Man, thanks so much , Ade!.

I know that this plate might not strictly be essential, but I feel much happier knowing that the new plate, and having bolts on reach side of the polar axis will keep the latitude setting firm and no chance of slippage.

I'll probably just paint the plate in Hammerite black to finish it off.

I've attached a couple of pics showing Ade's handiwork😊👍

Dave

Edited January 29, 2021 by F15Rules
Correction of bolt sizes