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Thursday, August 8, 2013

Preparing for astro season: mounting stuff to a telescope

The Perseids aside, these months are poor for astro (as I've complained a bit about here). But it does give you an excellent opportunity to get your gear together for the winter. A mate of mine has a nice telescope with an equatorial mount, but no camera that can be triggered remotely in a practical way. I have a rather decent camera but no scope or mount that is able to decently track the night sky (no, the O-GPS1 doesn't even come close to using a real mount).

We figured it'd be stupid no to put the two together.

As we are on a budget, a bit of DIY is needed to make this happen. First up is a way of mounting the camera's to the scope.

From the depths of the ultra secret Nugigeruli Labs™: a DIY scope mounted base plate!

This is a plate mounted to the side of the main scope tube on which we can mount all kinds of equipment, such as a camera, spectrometer or optical guidance scope (more on the guidance scope in a later post).

Of course you can buy these kind of plates off-the-shelf, but even a simple side-by-side mount (for mounting a scope and a camera) will cost you at least 100 euros (here's an example). If you want more devices on your scope, prepare to spend even more.

So we're building it ourselves. The assembly we've made will be clamped between the screws of the main scope tube rings.


Schematic and shopping list


Here's a very crude schematic of what we came up with shown on a common Meade tube. Corner profile is denoted in red, plates in blue and bolts in green.

Crude schematic of the scope mounted baseplate

So what do we need?
  • 35 cm of aluminium corner profile.
  • Some sort of metal reinforcement or connection plate (shown in picture below)
  • Stainless bolts and nuts M6
  • (optional) Some spraypaint
Total cost: about 22 euros. If you want to go cheaper, get regular bolts and nuts.

Components needed (excl. the corner profile): there aren't many!

You'll find all this stuff at the local hardware store or DIY-empirium.

Please note the three plates, each 60mmx180mm (the blue ones in the sketch). They will form the mounting plate, which will be 180mmx180mm in total. I've chosen these because they are sufficiently rigid without being too heavy. The fact  that they are full of holes is a big bonus as we don't need to drill those ourselves.

Teaser: the pipe clamps  and little l-shaped metal pieces are part of another build, which I will discuss in the next blog post.

I'm assuming that the tools are already bought of course. You will need:
  • A powerdrill (with drills for metal)
  • Iron saw (hand or powered)
  • Wrenches
  • Pencil
  • Measuring tape or rulers
  • Machinist square
  • Center
  • Hammer 

The build


Making the mounting plate is pretty straightforward, hence there are no pictures of the build process. You can probably build it without these instruction by just looking at the pictures of the finished product below.

But for those who like directions, here they are:
  1. Measure the profile to extent just a little beyond the tube rings on both sides. Also measure the distance between the screw.
  2. Cut the profile to size and drill the holes for the tube ring screws. I recommend you drill these holes a little bigger than the actual screw size so you'll have a little leeway.
  3. Find the center of the profile and use that to mark the holes for the connection plates. we've used two adjacent holes per plate as they are almost centered. If they are not centered (like mine), you'll want to have the long side extending towards the mount of the scope. This means the weight will be closer to the center of the mount and the tracking motors have less work to do.
  4. Drill holes for the plates and mount the plates using the M6 bolts. We've mounted them with the head on top, which makes for a nice low appearance.
  5. Spray paint if you want. We recommend a matte black finish.
  6. Put some rubber or foam on the plate where you expect to mount your stuff.
  7. ???
  8. PROFIT!
This is what it will look like (which is to say: better than the schematic).

Unpainted
Painted

Notice that I haven't put any rubber or foam on the plate, but you may want to do so as it will protect the base of your camera.

Mounting stuff on this plate is as simple as putting a screw through one of the holes and into, for example, the tripod mount of a camera. As I've just teased, the rings you see on top of the plate are DIY mounts for the optical guidance cam, so they are not part of this little tutorial. They will be part of the next tutorial on how to make such a cam though.

And that's basically it. Simple solution, not?

You can of course adapt this design to fit your own scope; make it longer, wider, shorter, thicker etc. This is just an idea to show that it's really easy to piggyback (a lot of) stuff on a telescope and that you really shouldn't spend all that money on fancy pieces of metal.

Stay tuned for more Astro-DIY goodness!

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