Skywather EQ6 Pier Extension on a pier

[LongJohn54]

When I built my Obsy I set the pier height so that I could sit on my seat at its lowest height and view objects overhead while the scope was vertical.   Unfortunately my back has now decided that this is too low for extended viewing so something had to be done.

Hence the purchase of a Skywatcher 8 inch pier extension.

 

A well wrapped box arrives.

 

Lots of bubblewrap.

 

Out pops the pier extension.  There was nothing else inside the box so a quick visit to http://skywatcher.com/download/manual/ was made and a copy of the instructions was downloaded.

[LongJohn54]

Off with the mount.  As you can see I use a bolt as the azimuth peg.

The bolt head is too large to fit inside the tube.

 

Five minutes with a hacksaw and we have a half head bolt.

 

Using the off-cut bit and a ring spanner it was easy to tighten up the bolt.

 

The extension top now fits nicely into the tube.

[LongJohn54]

Just checking that the mount’s wedge is in good condition.  I use much harder bolts than Skywatcher supply so it’s the wedge that’ll be damaged if I over tighten them.

 

The baseplate is fractionally inset into the tube so that the tube rests on the brake disk.

 

Once tightened it makes a very firm connection.

 

The view inside.

 

[LongJohn54]

The ball race separated.

 

The top plate in place.  Both holes in the top plate are threaded for the standard azimuth peg or you can use a smaller diameter bolt if you want to keep the peg for your tripod.

 

The top plate fitted under the mount and the securing bolt tightened.  This is the weakest part of the system.  Too tight and the ball bearings bind preventing adjustments to the mount in azimuth, too loose and the mount can move on the top plate even when the azimuth bolts are tight against the peg.  After my first attempts at installing the extension I realised that this was the primary source of flex and unwanted movement so I was keen to minimise it as much as possible.

I eventually decided the best method was to leave it just loose enough to rotate the mount. Then get polar aligned with EQMOD.  Then power down, remove all wires and remove the three screws holding the top plate in place.  Carefully lift off the mount and tighten up the securing bolt properly.  Replace the mount and the three screws and wire up then check whether the polar alignment is still accurate with EQMOD.  It took several attempts to get this right as tightening the bolt generally made something move.   By the fourth attempt my arms were about to drop off but this was the one that was successful.  Polaris remained in the middle of the little circle in the polar scope.

 

[LongJohn54]

Set at maximum height for testing.   The extension is built to the same quality, fit and finish as the mount.

 

Once the scope was on and EQMOD and CdC fired up I set about building a fresh point model.  My first alignment star of choice is Mizar as it’s easy to find and unmistakeable in the eyepiece.  Here I’m just resting my phone on the Skywatcher 12.5mm illuminated reticle eyepiece and you can see that the stars are not small round points.  I couldn’t get my phone to focus on both the stars and the crosshairs so I focused on Alcor which seemed to work.   Touching the scope induces some vibration which wasn’t there before the extension was fitted.  However, it settles fairly quickly.  It’s a bit irritating when trying to get finely focused though.

An improvement for use on a pier could be made by drilling out the threads in both plates and dispensing with the ball bearings.  Then use a long bolt fed through the bottom brake disk, through the extension and into the mount.  This should be more rigid than the current assembly.  It would also ruin the extension for use on a tripod.  I’ll see how I get on over the next few months before deciding whether to do it.

One thing has been successful, my back feels better sitting higher up.