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Complete Disaster....

Rockrae78

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Rockrae78

Rockrae78

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Hi All,

I've only started one other thread (in the beginners section) so apologies if I've put this in the wrong place...

Basically, on the evening of the 10th December, disaster struck and my scope actually slid out of the dovetail on the mount and hit the concrete flags on my patio. Gutted is not the word. I honestly don't know what happened. I'm quite particular about ensuring that all screws etc are tight and these were all checked before going out for the evening. The scope had been out for just over an hour to cool down before it happened. As soon as I started slewing upwards, it literally slid out of the back of the dovetail mounting clamp.

I immediately brought it all inside, to discover that the star pointer had come off - but was still intact with some minor scuffs on the top, the tube also was in perfect shape, without any dents or visible knocks (there is a minor scuff on the rear of the tube at the top), the Baader Hyperion 24mm EP also was intact and - most importantly - the mirrors are still attached and seem fine (there is a black speck on the primary mirror - it's very small but could be a chip and is located to the right of the centre spot) - see attached pics (the speck looks grey in the attached photo). One of the scew heads on the back of the primary mirror is also bent - it is just the head, the screw itself still looks straight to me.

post-24939-0-41741700-1355292033_thumb.j

post-24939-0-79670800-1355292068_thumb.j

post-24939-0-01051400-1355292113_thumb.j

post-24939-0-92167000-1355292155_thumb.j

What concerned me most was that when I went to reattach the tube to the dovetail clamp, the screw was fully inserted and screwed in very tightly - I had to unscrew it completely to be able to slide the dovetail bar back into the clamp. How did it manage to fall out in the first place if it was being held securely in place? Could it have anything to do with the cold temperature, or the humidity levels?

Anyway, after many, many tears (I'm not ashamed to admit I cried! - I also cried during the last episode of Friends and SATC, and when I thought my Manolo Blahniks were ruined after my other half left them in the cellar when we were moving... I thought they'd gone mouldy, but it was only dust), I took my scope out yesterday morning first thing to see what I could see (if anything) and I managed to get the star pointer realigned and got a good look at the television mast that sits atop a hill about a mile behind my house.

It did become apparent though that the scope now needs complete collimation - which I've never done before (I should point out that I've had my scope since July and its never needed collimation so far - as proven when looking through my Cheshire collimator sight tube - all centre spots and cross hairs were always perfectly aligned).

I'm nervous about the collimation - being a complete novice - and have watched a lot of video tutorials on the subject, and I've read numerous chapters in books and articles in leading telescope magazines to try and get my head around the subject.

Out of everything I've read, the following website seemed to give the clearest instructions (most of the concepts are explained in laymen terms):

http://www.astro-bab...ation guide.htm

I'm waiting for the nice postman to bring me some bits and pieces before I start, but I was wondering if any of you nice, clever people have any other nuggets of wisdom to share before I actually embark on this mission (or for that fact, if anyone in the Todmorden area is willing to help me!)?

Please don't judge me too harshly in this, I've berated myself enough... I do take such good care of all my stuff - even the non-astro stuff - and I still can't believe that this has happened... I haven't slept for 2 nights! I don't have the money to replace the whole scope and my other half has spent money he can ill afford on more stuff for me for Christmas and I'm really worried that my scope could be ruined and he could have wasted his money. Has anyone else been through anything like this?

I'm signing off for now, but look forward to hearing your thoughts.

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DoctorD

DoctorD

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Hi

Sorry to hear about your problem - but the important thing is not to panic. It looks like your scope survived with only a little cosmetic damage. A small chip on the primary will make very little difference to the view. Did the Hyperion escape unscathed?

It will definitely need collimating. Astro baby's guide is very good - remember you can collimate indoors at your leisure , take it steady, it's unlikely that the secondary will be far out so check the primary first. If this proves possible to align then check the secondary. The important thing to remember is to make small changes and if you are adjusting the secondary keep the scope horizontal to minimise the risk of dropping a screw driver onto the primary.

You do not mention what mount you have - it's not unknown for screws to loosen when the temperature drops, so retighten as the scope cools. Some mounts have a second screw as added security.

Hope this helps

Paul

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jam1e1

jam1e1

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At the end of my dovetail I've made a bolt stand out so that if does slip, it will catch on that. On top of that got a rock solid adm plate with two tighteners, no problem keeping a 10" scope securely in place.

On collimation YouTube it also there are plenty video guides, eg astronomyshed etc

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Velvet

Velvet

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Hi there

Join the club, this has happened to me too, My Tak 106 did the same thing, but luckily it was on grass. it has

happened 3 times so far, 2 times i managed to catch it. All the screws etc were tightened on mine too and I still

have no idea why it happened. I have put a bolt through the dovetail now so it cannot slide past a certain

point.

So do not feel you are alone in this, it is not just you! hope everything collimates OK, I am sure it will :)

velvet

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leelee970

leelee970

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Really sorry to hear about your accident.

Believe me; I’ve done really silly things – like spill my drink over the laptop. I’ve also had accidents so no one on this site will judge you.

Sounds like you got away with just a few scruffs – phew.

You’ll most certainly need to collimate the scope but it’s not as scary as you think – you’ve done the research, got/getting the tools, just take your time and remember “small” adjustments at a time. Good luck.

As a precaution I drilled a number of small “craters” (for want of a better word) along the edge of the dovetail bar, just enough of an indentation to allow the clamping bolt tip to sit in. worth a try.

Lee

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Carbon Brush

Carbon Brush

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I might know someone who has a friend who could have had a scope slide out once.

In this case it was a big Russian lump, about 20Kg. It hit the obsy wood floor, so bounced.

The result was a paint chip where it fell against the pillar, and virtually no loss of collimation.

The owner needed to lie down and take deep breaths though!

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Rockrae78

Rockrae78

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Hi Guys,

Many thanks for the responses! I promise I really am trying hard not to panic! :eek:

When I was looking at the mast, the image was so crisp and clear that I figured the mirror - even if it is a chip - has survived reasonably unscathed. I was most relieved to note this! With regards to the EP, it also seems fine. This was the EP I used to take a look through the scope and I saw a tiny bird land on the top of the aerial part of the mast. I then compared this to the stock 25mm EP that came with the scope and the two views were similar (a slight reduction in quality in the stock EP but since its not as good as the Hyperion, this was to be expected. It does seem to have some dust or dirt around the edges, but I've ordered a lens cleaning pen from FLO which should arrive today. Keep your fingers crossed for me.

I'm planning on starting the collimation on Thursday morning - I have the whole day free so, as you say, I can complete this at my leisure.

I have looked down the focus tube both with and without the Cheshire to see how far out everything is... The secondary is no longer centrally located as you look down the focus tube and is is also no longer round in shape - it's much more oval. The cross arms of the spider is still aligned with the central spot on the primary mirror, but they are way off to the left. I can still see the clips on the mirror too.

Now, here's what could be a silly question - when I looked at the mast, the image wasn't fully upside down - it was upside down, but diagonally instead of straight (when I first aligned the star pointer I used this mast, so I know it should be fully upside down and not at an angle as a result of the fact that its on a hill). Does this mean that secondary needs rotating, or do you think this is a result of one of the screw heads on the primary mirror being bent? Is there a possibility that this means that the primary mirror has rotated?

It is the standard mount that came with the scope. I will now be checking the screw throughout my sessions, as well as at the beginning and end of each session (which was what I was doing) so thanks for the tip!

This sounds like a very sensible and very good idea but I have no idea how I would go about it. The dovetail clamp is on the motorised part of the mount so I wouldn't want to made any modifications to this in case it affects the quality of the GoTo functions. I could look at attaching something to the dovetail bar itself but my DIY skills are pretty poor so I will have to do a lot of research in this area. I've attached photos of the mount so you can see what I mean.

post-24939-0-28075600-1355302729_thumb.j

post-24939-0-22927100-1355302775_thumb.j

Thanks to everyone for sharing your stories. This really has made me feel better and that I'm not the only one its happened to!

I'll let you know how I get on!

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Rockrae78

Rockrae78

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You could replace the dovetail bar for something longer.

http://www.firstligh...ing-plates.html

Lee

I am liking this idea. If I got one longer than the dovetail mount I could use the pre-drilled holes at either end to attach bolts to ensure that the scope can't completely slide out should this happen again. I will measure this up and try to ensure that these bars will fit the clamp. Thanks for this. Much appreciated.

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astrofox

astrofox

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Unlike losmandy plates there appears to be several slightly differing versions of the "standard" Vixen dovetail. Like others in this thread a safety bolt should be considered as a basic standard on this dovetail. Not had one slide completly out yet but had some near misses early on.

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Brian Nordstrom

Brian Nordstrom

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OUCH ! I feel for you , I had the same thing happen a few years ago when my C102 slid out , but luckly on to grass and no damage , but I nearly choked on my heart ! , its a scary thing seeing it slip and fall .

Glad the optics are ok , only a columination required , WHEW! you were lucky .

I like the idea of a longer dovetail and a bolt at the top to stop the whole thing falling to the ground again , if it ever happens again ( If it was me I would look carefully at the holder , there must be a problem there ? ) .

On a lighter side , the bruises on the tube are now " Battle Scars " and she is a surviver .

Brian.

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NGC 1502

NGC 1502

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No need to feel ashamed of crying, most of would have done the same, and please don't beat yourself up, all of us have done something similar at some point.

It does sound as though the damage is cosmetic. The speck near the centre of the primary mirror is unlikely to be a chip, probably a fleck of paint or similar has landed on the mirror when the scope hit the ground. The 'angled' view of the TV aerial is normal, if you look again, rotate the tube in the mount, and the aerial will appear at a different angle, not caused by a rotated secondary.

Collimation and some careful use of some paint will get you sorted hopefully.

All the best, Ed.

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ollypenrice

ollypenrice

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Unlike losmandy plates there appears to be several slightly differing versions of the "standard" Vixen dovetail. Like others in this thread a safety bolt should be considered as a basic standard on this dovetail. Not had one slide completly out yet but had some near misses early on.

I think it may even be worse for Losmandy. This has come up quite often. The 'Losmandy Dovetail' has a notoriously wide variety of interpretations, probably more than Vixen. Because the Vixen has a deep section it seems to be fairly tolerant but Losmandy's have to be right. When they are right they are better than Vixen, certainly.

Yet another vote for a dovetail long enough to have stopper bolts attached. Put them at bothy ends. WHen you are setting up and balancing the danger comes from both directions.

Temperature certainly has a lot ot do with the loosening of the lockscrews.

Some dovetails, like the Altair Astro ones, have long recessed slots in the bottom making it possible to put tube rings etc in a wide variety of positions. This is a great idea.

Olly

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Rockrae78

Rockrae78

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I suppose I won't know this for definite until I've done a star test, but the fact that I got a clear image of the TV mast gives me hope that optics have indeed survived intact! I know I'm very lucky in this respect.

Basically, its a tripod with a fork arm on top. The dovetail bar slides into what looks like a 'C' clamp on the fork arm (see pics above). The screw that secures the dovetail bar doesn't actually go through the bar, it merely 'closes' the arms of the 'C' around the bar. so i effect, this is the only thing that holds the OTA in place. My other half pointed out that its possibly not the best design in the world, but I'm so happy with the scope (and let's face it, it's a testament to Celestron that the tube's are very robust!), that I don't want to slag Celestron off too much. I'm sure that there is a perfectly valid reason for designing it this way and they know more than I do!

That really made me smile!

I can't do this. The OTA is attached via a fixed dovetail bar and not with any rings so the tube won't rotate in the mount. Once I've collimated, I'll check it again and hopefully, it won't be doing it anymore!

I am already looking into the many different ways to attach a safety bolt onto the dovetail bar, and this is something I hadn't even considered.

I would like to say a mahoosive "THANK YOU" to you all for your kind words and excellent advice. I have been in a bit of a state about this, but since I've read your replies, I feel like I can breathe properly again!

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Rockrae78

Rockrae78

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Peter, I will take you up on that! What time do you open on Saturday evening?

I will still have a go at collimating it in the meantime - after all, I should learn how to do this since I own a Newtonian!

The only thing that I'm still very concerned about is the bent head of the screw attached to the primary. I'm really not sure how much this will affect my attempts at collimating!

It would also be good to have a professional look at the dovetail bar and maybe provide suggestions as to the best way to attach so,e safety bolts to ensure that this doesn't happen again!

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astrofox

astrofox

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I think it may even be worse for Losmandy. This has come up quite often. The 'Losmandy Dovetail' has a notoriously wide variety of interpretations, probably more than Vixen. Because the Vixen has a deep section it seems to be fairly tolerant but Losmandy's have to be right. When they are right they are better than Vixen, certainly.

Yet another vote for a dovetail long enough to have stopper bolts attached. Put them at bothy ends. WHen you are setting up and balancing the danger comes from both directions.

Temperature certainly has a lot ot do with the loosening of the lockscrews.

Some dovetails, like the Altair Astro ones, have long recessed slots in the bottom making it possible to put tube rings etc in a wide variety of positions. This is a great idea.

Olly

Thats true my losmandy mounting plate came already fitted with a safety screw. Copied the idea ever since.
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Rockrae78

Rockrae78

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Many, many thanks to Peter and the guys up at The Astronomy Centre in Todmorden... Was struggling with the collimation but Peter sorted it in less than 5 minutes!

I also want to say thank you again for all the help, advice and encouraging comments that everyone left. On reflection, maybe this thread should have been called 'Not such a disaster after all!'.

I'm ready for the next clear night now! Phew!

Will definitely be back up to the observatory on the next decent Saturday night. Loved having a look round the observatory! Everyone was so friendly and helpful, I recommend everyone to visit if its within travelling distance!

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Steve Ward

Steve Ward

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Glad you're sorted.

You say . . . " What concerned me most was that when I went to reattach the tube to the dovetail clamp, the screw was fully inserted and screwed in very tightly - I had to unscrew it completely to be able to slide the dovetail bar back into the clamp. How did it manage to fall out in the first place if it was being held securely in place?"

This would lead me to believe that the dovetail bar was not properly clamped in the first place , may well have been inserted askew and the clamp bolt managed to partially catch a grip on the underside of the bar.

I know this is possible on the 3 ribbed type of bar as I very nearly fell foul of this the first time I put my 200PDS on the HEQ5Pro , pure instinct made me look closely before letting go.

Temperature would not loosen the grip and then tighten the bolt right up again . . .

Just a thought.

Steve.

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Rockrae78

Rockrae78

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Hi Steve,

Thanks for your comments. I will certainly bear that in mind. The screw itself doesn't touch the dovetail bar, it just tightens the clamp around the bar. I had used the scope the previous night for about 7 hours with no problems. It was literally carried inside, left as is, then taken back out again the following night. The only thing I did was to tighten the screws on the mount and fork arm at the end of the session, then at the beginning of the next session. I think I've only dismantled the scope and mount about 3 times - and one of them was today to take it to the observatory. I would have thought it would have failed before now if it wasn't being held in properly. I was thinking that maybe the plastic (and it is plastic) dovetail bar might have contracted in the cold and that was why it slipped out. It was about -3oC on the night in question! It was also very damp that night, which might have further lubricated the dovetail bar.

I went out for about 5 minutes tonight, just to do a star test, and found myself checking it each time I slewed to something else! Starting to get paranoid! I have now ordered a new dovetail bar, which will need modifying slightly, that I will be attaching as soon as possible - along with some safety bolts!

Thanks again for your help!

PS) Star test was perfect... All is well in my world once again!

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