Dovetail bar - how do fit a scope on it

[carastro]

I have a dovetail bar and a deforked ETX which I want to use for planetary imaging.  The ETX needs camera size bolts (? 1/4 whitworth").  I have pinched one of the camera bolts from the one supplied by Skywatcher which fits and found another, but whatever I screw through the dovetail bar the heads protrude so it can't sit flat in the Vixen slot of the mount:

So what are these bolts holes supposed to be for then (the ones halfway down the bar)?

Also any ideas how I can fix the ETX to the dovetail?

[Freddie]

You go the other way, so the thread srews down into the bar not up from the bar into the rings/scope.

[Red Dwarfer]

That`s the exact bar I got on Monday to attach a 130P to a Goto mount ...

I took the screws / bolts sent with it out and used the thicker ones that attached the 130p to the EQ2 mount ...

Try the other way round too as suggested above ...

Good luck . 

[carastro]

I had a feeling that might be the case, but since the scope will be on the other side of the holes I can't screw them in the other way.  Must try to think of an alternative.  

Carole 

[steppenwolf]

When I need to do this, I drill the holes out to remove the threads then countersink the holes from the bottom of the bar. I then use countersunk 1/4" - 20 bolts (or 6mm countersunk bolts as required) to match the threads in the base of the telescope. This work can be done with a standard DIY power drill but a local engineering company could do the work for you easily and cheaply.

[Stub Mandrel]

4 hours ago, carastro said:

what are these bolts holes supposed to be for

Using the bar with a camera tripod.

Yesterday a gorgeous little (7cm) dovetail arrived from China. 1/4 UNC camera thread in the middle with countersunk (from underneath) holes and two M4 screws to suit.

[Alien 13]

I have often been mystified why most dovetail bars are not flat on the top but have an almost v shape, the flat ones being as rare as rocking horse teeth 

Alan

[carastro]

Well l am going to get a friend to countersink the holes to allow for the bolt heads. 

 Carole

[Davey-T]

5 hours ago, Alien 13 said:

I have often been mystified why most dovetail bars are not flat on the top but have an almost v shape, the flat ones being as rare as rocking horse teeth 

Alan

ADM have nice flat tops

Dave

[Stub Mandrel]

A quick check shows a dovetail with the v-top will accept a scope down to about 55mm diameter, while just having the two raised lands would limit it to about 75-80mm diameter, so the answer is probably 'so you can fit small scopes to one'.

[carastro]

I have sorted this.  I found a fairly cheap slotted dovetail on MA with the back of the plate slot being recessed and 1/4" bolts, it fits perfectly.

Carole