Skywatcher dovetails

[Marky1973]

Was I foolish to think that 80mm Skywatcher Tube Rings would work with a Skywatcher dovetail. I'm either doing something wrong or the two things are completely incompatible!

Should have gone with a more expensive dovetail that was flat or the ST80 one....although, even then the bolts will probably still be the wrong pitch... it's madness.... MADNESS!

I feel a return coming on... it'll probably be less stressful to buy an ED80 with its own dovetail....

Spleen vented.

[damnut]

I am with you on this one, they should just work, unless you have a vixen style dovetail. Couple of pics would help but you have all the kit so i guess RTFM does not apply!

[Marky1973]

Yeah, the base of the rings is too wide for the gap between the ridges on the dovetail, so there is a gap, which could be filled, but wouldn't feel solid. And the bolts that come with the bar are too narrow to screw into the holes on the bottom or the top of the rings.

I could turn the rings upside down if the bolts matched. The bolts on the rings have a different pitch to the holes in the bar, so won't go through.

I spent long enough finding ways to connect the rings to mount a guide scope that I think the whole thing will crumble in front of my eyes info try to rearrange that!

Mobile at the moment so no pics!

[John]

I'm trying to get my head round the problem you are having. I've owned a few ST80's and they seem to have worked OK in the tube ring / dovetail bar department

The screw holds on the other side of the tube rings are threaded for 1/4 photographic tripod adapter screws so you do need to use the ones on the other side which I seem to recall are threaded for M6 ?

[John]

I've just realsed that you may be using one of the short type dovetail bars - I can see where the issues might lie with that type. I used to use a medium bar and drill new holes in it to fit the tube ring spacing. I've never found a use for those short dovetail bars to be honest.

[Marky1973]

Hi John. I got a long SW Dovetail - 33.5cm I believe - was £17.99 (ish) from Harrison Telescopes.

Basically, I have the ST80 in its rings mounted on top of the ED70 with a new set of 80mm SW Tube rings - same as the ST80 ones.

So the "bottom" of the rings at the moment is a square, flat section and the top of the rings have a smaller circular mounting around the hole where the photo screw was housed.

The home made mounting bar that connects the scopes is secured to the photo mounts on the ED70 Rings and then into the square, bottom sections of the ST80 rings.

You can sort of see what I mean in this photo - please excuse the Heath Robinson-esque efforts!

When I have more time I'll try turning the tube rings over on the ED70 and finding some different bolts, just didn't have the time tonight and I will need to be re-drilling the mounting bar connecting the scopes and finding bolts that work!... It's not a major disaster, just amazed that there is so much trouble with items that are supposed to work together. The bolts that came with the bar don't seem to fit anywhere other than the bar itself! 

It was really just to have something more substantial that the "shoe" on the ED70 so I had more options for adjusting balance if mucking about with different cameras and such like.

I guess I have a spare now, just in case I find something to do with it 

(I may just be being an idiot of course)

[damnut]

FLO have just posted an st80 dovetail for £11..

[Marky1973]

Yeah, just saw that... wish that had appeared 2 days ago! 

[Marky1973]

Oh to hell with it... bought that and will, by hook or by crook, make this all work in the way I think it should in my head! 

[damnut]

At least you can send it back with FLO

[Marky1973]

Thought it might be useful to hammer the bolts into the other dovetail bar....

[Marky1973]

Well, I won't be able to send anything back now as they are both slightly scratched in a couple of places as I cajoled the whole thing together last night with pure brute strength, determination, half a bar of chocolate, a set up bolts of Tesco and a few expletives. I now have rings "upside down", sawn-off bolts, dovetail bars upside down and stripped screw heads... but, it is done and a lot more solid than it was before.... once I had got past the majorly stupid error of putting one set of rings on the bar with the catch on opposite sides of the bar, I relaxed ready to try it out... oh, and the catches are immaterial - unless you have another bar on top of the tubes and might ever need to open them of course!

Here it is.... it didn't fall off the mount or fall apart, so hopefully, it will hold together for a while....

Of course, next thing will be something like significant cone error (yep James, I just looked it up) which means I'll have to adjust it all. But, until then, I shall enjoy my handywork and thank my lucky stars I bought an NEQ6 to support all this metal!

[goose35]

Having the same issue. I need a solid dovetail bar i can drill out myself as pre drilled ones always seem to have a hole where you dont need it or it overlaps where you do need it and thus cant get a new hole in.

As for the thread sizes dont get me started. Lol

[Marky1973]

Yeah. Hopefully the pain involved in sorting this will put me off upgrading the scope for a while!