Near disaster last night scope fell off mount!

[Gohan75]

Hi, i recently bought a 2nd hand HEq5 Pro. My first purchase was a Skywatcher 130p on an eq3, so i simply removed the scopes rings and mounting plate and connected to my heq5. I am not sure if i am doing this correctly as last night the scope literally fell off the mount whilst i was imaging with a barlowed DSLR! Luckily it landed in a bush so there was no damage. I am just wondering if i am connecting the scope correctly as when i tighten the screws on the heq5 plate it seems to want to push the scope mounting plate up and out of the mount connection so i have to try to keep it in place as i tighten. Do i need a different dovetail plate or something? Or was it a case of it not being tightened enough? I am also concerned i am damaging the screws by tightening them too much?  Any advise appreciated. 

Sorry the photo isnt great i hope you get the idea.

[Cornelius Varley]

I think you probably didn't have the dovetail located properly on the mount before tightening the screws (done it myself). To ensure you don't do it again leave the dovetail & rings attached to the mount or attach the dovetail & rings before adding the telescope.

[emadmoussa]

Ouch! Glad no damage happened.

I'd suggest either you replace the saddle with a better clamp system. Or like Peter suggested, make sure the scope is mounted 100% correctly, I had my refractor slipping before simply because I didn't see this little misalignment, or leave the dovetail and rings on if you only have this telescope.

[nmoushon]

I have the HEQ5 and I've had a similar instant when the plate wasn't up against the far wall of the mount so when i tightened it one side didnt tighten all the way. Not I also try moving the scope once I have tightened it down. With one hand on it of course. Just to double check and then when it doesnt move I got back and try to tighten the knobs even more. The little movement frees up any friction that was preventing it to be as snug a fit as possible. Especially if its cold out side and you get a bit of cold welding going on sometimes. Glad you were able to catch the scope though.

[Moonshane]

if you look at the left side of the clamp, the paint has been chipped off the top 'corners' which suggests to me that it was not seated correctly. as others have said, make sure it is placed to the left of the dovetail clamp and then take up the slack with the bolts. the bolts should move not the dovetail bar during this process.

[Gohan75]

Thanks for the advise. Thinking about it i have been connecting the dovetail plate whilst the scope is attached, which i always struggle to do. Now in hindsight that seems like a stupid thing to do, ha!

I will defiantly be making sure i get it correctly placed from now on as that was a scary moment, especially considering its my girlfriends camera!

I was just making sure i defiantly had the correct dovetail bar for that dovetail plate as the whole thing seems a strange way of connecting such precious and heavy equipment. 

[Moonshane]

what I used to do for the short time I had eq mounts was have the bolts at the top and put the dovetail in horizontally. that way, gravity puts the dovetail in the right spot.

[Gohan75]

The thing is the dovetail bar seems too thick, like the the plate doesn't have enough depth to fit the whole bar in. Im not sure iif its supposed to be like that. 

[Sleepy Kiki]

Ouch! Glad no damage happened.

I'd suggest either you replace the saddle with a better clamp system. Or like Peter suggested, make sure the scope is mounted 100% correctly, I had my refractor slipping before simply because I didn't see this little misalignment, or leave the dovetail and rings on if you only have this telescope.

Another vote for changing the HEQ5's clamp, I upgraded to the ADM Dual Saddle and was worth every penny.... no more dovetail bite marks!

[Astro Imp]

That is scary, good to hear no real damage caused.

When I first had my gear I used to leave the rings attached to the scope and put the whole lot into the clamp. Second time out I nearly dropped the lot because the dovetail wasn't seated properly. I don't do that any more, dovetail and rings first then mount the tube in the rings. 

[Gohan75]

Yeah i think i am going to be doing that from now on! As tight as possible as well.  

Thinking about it, looking through my images that day i notice i odd wobble and movement between the images, it must have been in the process of moving out of place! Will these images be OK to stack still or do they have to be perfectly aligned?

I have been looking at new saddles, its something i will have to consider. Although the amount of different saddles and bars is overwhelming for a newbie like me! Let alone how to fit them ect..

[Stargazer33]

Silly question time, but have you got the dovetail on the right way up?  I can't really tell from the photo but it looks like the widest part of the dovetail (cross section) is towards the OTA. The narrowest part of the dovetail should be toward the OTA and the widest part away from it. As you tighten the bolts they should pull the dovetail down into the mount, not push it up and out!

[Gohan75]

Bryan, thats probably the most thought provoking question all day! I bet you any  money i have been stupid enough to attach it the wrong way around! thanks for pointing that out i will have to check that ASAP!!

[M4lcs67]

I was concerned when I got my CG5, C9.25 combo last year as the connecting plate on the CG5 was/is pretty rubbish in my opinion. Not safe at all and all you have is a couple of screws digging and gouging into the soft aluminium dovetail bar of the ota and ripe for working loose and the whole lot falling to the ground and smashing to pieces, so I invested in an ADM replacement saddle for the CG5. Yes, expensive, but alot more secure as it doesn't point-load onto the dovetail bar, but spreads the load evenly over the full-length of the bar and doesn't damage it. Job sorted. Nice and safe now. Also Gohan75. Love your avatar. The late great Carl Sagan. Brilliant...

[Gohan75]

Malc, he's the reason I fell in love with astronomy. A great man indeed. Yeah I think I will have to consider a new Saddle like you say the whole thing feels like a compromise!

[LukeSkywatcher]

Glad there's no damage. Its very easy to attach scope to dovetail and think its sitting correctly. Then you let go of scope and it falls out of dovetail. Happens to me a bit. Thankfully my hands were close to the scope and it only falls into my hands. I wouldnt worry about the marks on the dovetail..............thats standard cosmetic damage.

[Gohan75]

Having inspected the dovetail bar it seems its completely flat, ie straight and does not have a wide section at the top and a low section at the bottom. This means it doesn't fit in no matter which way i put it. I think i need a new dovetail.

[knobby]

Mmmmm a dovetail that isn't a dovetail?

[LukeSkywatcher]

Mmmmm a dovetail that isn't a dovetail?

Those images sure do look like things dont fit.

[Alien 13]

Thats not good is it the skywatcher one because mine was a nice aluminium job easy to drill if you needed more holes.

[brantuk]

That's deffo not a dovetail bar - dovetails don't have a square section - here's some proper dovetail bars:

http://www.firstlightoptics.com/dovetail-bars/skywatcher-dovetail-mounting-plates.html

http://www.firstlightoptics.com/dovetail-bars/william-optics-vixen-compatible-long-dovetail-plate.html

Note the different styles. The chunkier ones take more weight. Some dovetails are designed to screw onto the ota. Hth

[Stargazer33]

Having inspected the dovetail bar it seems its completely flat, ie straight and does not have a wide section at the top and a low section at the bottom. This means it doesn't fit in no matter which way i put it. I think i need a new dovetail.

Ooh! That doesn't look right!     No wonder your scope fell off!  Good job there was no damage and you have now identified the problem so it won't happen again.

I too have upgraded to the ADM dual mount saddle - fits both Vixen and Losmandy dovetails and grips along the whole length of the saddle with two sprung loaded thumb screws pushing an angled plate against the adjusting side of the saddle. Very secure - as long as you locate the dovetail properly which once or twice I haven't, rushing to set up in the dark!    I do however keep a hold of the OTA and give it a good hard rock before letting go completely.

[Gohan75]

haha yeh. Well at least i know now. Thanks for all your advise everyone. I will be getting a new dovetail bar. Will consider an ADM saddle at a later date when i have some money!