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DIY Wedge and Tripod


After deciding I would like to take astro photos with my LX200, I realised I would need an equatorial wedge. In the UK the Meade Superwedge costs nearly 500! I needed an alternative. After a web search I found a couple of wedge designs which were constructed from wood. A few hours later I had sketched out my own adjustable wedge made from exterior grade plywood.

Construction notes

I wanted to use plywood around 20mm thick, however I ended up laminating two piece of 9mm plywood to give me 18mm. This did have one advantage, it led to the innovation of the adjustable scope base plate utilising single piece threaded rod for the latitude adjustment. This was easily accomplished as I simply routed a 5mm deep slot in the two halves of the latitude plate and then laminated them together with the threaded rod inside. I used stainless steel and galvanised hardware to ensure good weather resistance. The remaining construction was straightforward, each component was cut out, painted with preservative and then screwed and glued together. Finally a crude latitude adjuster was fitted by using a bolt threaded in the latitude plate and resting on the wedge base.

In use

Originally I designed the wedge to fit my DIY tripod which as a complete assembly was to remain outside with a weatherproof cover. However once I had constructed my observatory the tripod was made redundant and the wedge would be used inside.

The wedge was attached to the observatory pier using a 12mm SS bolt, loosening this gave azimuth adjustment. The LX200 attached to the wedge with the inch center bolt and a 3/8 inch bolt at the front of the scope base.

Once the 10 LX200 was in place I was disappointed with the apparent flex in the wedge. Over time and whilst in use I realised this was not really a problem. Although rapping the scope does cause a visible vibration in the wedge, under normal imaging conditions you tend not to start jumping up and down and knocking the scope!

The latitude adjustment works fine, however I have been to lazy to fit a azimuth adjustment and this relies on nudging the scope into position. As polar alignment is reasonably well maintained these adjustment shortcomings are just an occasional inconvenience.

Im still on the look out for a second hand Meade Superwedge, however I believe my DIY wedge is doing an equivalent job in the meantime.

Modifications

I have recently added an adjustable base plate between the wedge and the pier to ensure the pier top is accurately level. I have thought about the necessity of this for a long time and has posted questions to the various newsgroups for other peoples thoughts. In the end, although Im not convinced of its necessity, I fitted the adjustable plate as it was simply accomplished with an additional 13mm steel plate and four adjustable bolts located at each corner.

 

Construction Pictures