APT wedge

[MartinB]

Not many people use wedges on the forum so thought I would write a little review of my recently acquired bit of kit. Bought second hand on Astro Buy and sell. Wedges are designed to allow fork mounted scopes to work in equatorial mode allowing long exposures without field rotation. I have used the Celestron heavy duty wedge which is ok for my relatively small 8"SCT but has fairly clunky ajustments making really accurate drift alignment very difficult.

The APT wedge is an altogether beefier piece of kit weighing in at around 20kg. Although a slightly odd maroon colour it is obviously well engineered and finished. One of the neat aspects of the design is that the whole wedge sits on a pair of rotating discs. This means that the wedge can be firmly seated on the tripod whilst still allowing adjustment in azimuth. A lot of wedges need the tripod bolts to be loosened to allow this.

The wedge is rock solid. The adjustment controls are very smooth enabling very fine adjustment. My first time out I did a quick polar alignment using the finder line up polaris with the appropriate offset. This was pretty accurate. I targeted a southern meridian star and over the next 10mins applied a couple of tweaks then went off to play at imaging with my ED80. When I got back the star was still bang in the middle of the illuminated reticle. I spent another 10 mins on and Eastern star This was still central 10mins later when the clouds rolled in. So a perfectly aligned scope with nothing to see

So delighted with the wedge. Heavy but manageable with accurate controls and carries my NS8 effortlessly.

[geppetto]

Nice addition Martin.

The beefier the better with those things.

Nice touch the AZ adjustment 8)

[daz]

Sounds good Martin.

How about some piccies of it??

[Greg]

Martin,

You couldn't post a pic could you.

Nice to see what a proper wedge looks like.

[Ambermile]

http://myweb.tiscali.co.uk/ambermile/wedges.htm

[MartinB]

That wedge of Arthur's is a beauty. I got the APT second hand on Astro buy and sell. I'll upload a few photos.

[Greg]

Very nice Arthur.

Work of art.

[MartinB]

Here then as promised are some pictures of the wedge. I have put the scope on and show how it is positioned during alignment. Sorry about setting (decoration imminent!) but haven't been able to get out for a looong time.

Initial position for getting a rough polar alignment

Having aligned Eq north align is selected from the hand set. You then move the scope into its index position

Enter into the handset when this is done and you are asked to rotate the scope in azimuth (now RA) to the meridian

Once entered the scope will do a 2 star align routine.

[geppetto]

Thats a nice and sturdy bit of kit Martin

Should help your photography no end

[Ambermile]

Am I the only one thinking Barbie here? Looks nice and solid Martin, and whilst I'm not a fan of welded wedges it does look like a solid bit of kit. I'm intrigued by the two white pads though?

Arthur

[MartinB]

More Sindy I think Arthur, she was always a bit more refined. The white pads are actually eye piece holders. The white inserts are for 1.25", take them out and they take 2".

[Wayne MacKenzie Sr]

@MartinB I see you are staff and assume still active on the forum? You had posted about this wedge which I also have enjoyed for many years. I recently brought it out after over 2 years hiatus to remount my SCT and can’t figure out why it is moving a degree of so left and right, even after bolting down (not sure exactly same bolts) and t/nut has no play to explain it (horizontal fin knob t/nut. Do you remember if you encountered any simular difficulty? Mine is on a meade tripod.)

[MartinB]

I got this wedge second hand in 2006 and I remember that when I received it had a similar problem to yours.  I spoke to the guy I bought it from and he also said he hadn't used it for a couple of years.  The problem was that the plastic/teflon material between the base plates of the mount which allows rotation had perished.  It was a very easy fix, I simply replaced it with a new plastic sheet (from a large margerine tub iirc!).  Worked a treat.  I sold the wedge on many years ago but it was a lovely piece of kit.

[Wayne MacKenzie Sr]

Thank you so much for your reply. I ended up breaking it down completely and found my issue was that the center pin upon which the top plate rotated on had migrated to far up and no longer acted as an axle for the base. While I'm glad I had an opportunity to disassemble clean and re-grease this awesome base, a simply tap tap tap down upon that pin in the middle would have solved my immediate troubles.  I'm being verbose not necessary for you but for those that come after us with the same problems. These bases are mosters and I would not be surprised if I find them still installed 30 years from now. The guy simply built them to last.

[MartinB]

Great stuff, glad you are sorted.