Home Made "Flip" Mirror for £12

[smudgeball]

Hi all

Just thought I would share a project that I've been working on for a little while.

I fancied purchasing a flip mirror star diagonal for my SCT to help with webcam alignment.

But as these are around £70 I wondered if I could make one for a bit less.

You be the judge, but I think I have?

I purchased two budget star diagonals from astroboot @ £3.50 each, a plastic project box with lid off ebay @ £1.99 a hinge from my local hardware store @ 99p and then rumaged through drawers to see what I could find.

The build steps are shown below:

I removed the diagonal side of each star diagonal and removed this and the mirror within. I then butted the two diagonals together and held with some gaffer tape.

A diagonal back was put back and held with a piece of insulating tape (as a hinge) and an unfolded paperclip stuck to the back to act as a lever.

As the principal idea looked ok, I measured the shape and looked for a box to hold everything. Most were either too big or just a bit too small. So I looked again at the design and decided to loose the second diagonal, but keep the black eyepiece holder part.

This now meant I could get a cheap plastic box for £1.99 off ebay.

While I was waiting for the box to be delivered, I removed the temporary pvc tape hinge and replaced with a brass hinge. I also found a picture hook to add to the back to act as a securing point for the operating lever. In my case the lever was an old allen key that I found.

All parts were "Araldited" in place and you'll see that a piece of plastic straw is placed on the end of the allen key to stop it coming out of the picture hook.

The palstic box arrived and I lined up the diagonal inside (which fitted really snugly)

I then cut out a hole to allow the eyepiece holder to fit at the far end of the box as shown below.

Again the eyepiece holder was held in place with araldite.

I cut a small slot in the base of the box to allow the allen key to move up and down.

I used super glue to fix the star diagonal to the plastic box and then re-inforced this with a weld of more araldite.

All that was left was to cut a part of the plastic lid to cover up the gap between the box end and the end of the star diagonal.

I was going to paint the finished box, but had an old reel of pvc tape so covered it in this instead.

Initial test are very promising, but will need to get a proper first light on this project.

So total cost inc. delivery £12 ( a bit more if you don't have araldite or the "spare parts" mentioned),........but a lot chaper than buying one !

If anyone fancies trying this I can always be PM'd for advice.

Cheers

Neil

[Gina]

Brilliant I see another astro project coming up Lining up the relatively tiny sensor in a webcam has always been a problem. The finder-scope isn't really accurate enough for lining up planets when using a Barlow.

[smudgeball]

Thanks,

I've got a 4 x imagemate and so far alignment has been an issue with that much power .

A scope at F40 is a real challenge to line up so any assistance (especially on a budget) is worth a try ?

[Gina]

One question... Was there a reason for having the box parallel to the diagonal rather than parallel to the straight through light path?

[smudgeball]

Yep !

Size of the box

When it arrived I had to give up on the idea of just putting the parts in straight.

But because the mirror was the same size as the internal dimensions of the box I decided to try it rather than order a new box.

But yeah putting it all into a bigger box may well have been easier?

Cutting out the hole for the eyepiece holder was a bit tricky and you have to be careful ligning it up before the araldite sets !!

A plus point though is a much more compact model, so your webcam is nearer to the scope?

[Gina]

Fair enough

[JamesF]

Nicely done. I now use a £36 illuminated reticle 12mm EP for lining up the scope to use with a webcam. Makes live so much easier. I wish I'd done it ages ago. This is far more inventive though.

James

[Gina]

I've got to do something like this. Getting a planet's image on the webcam sensor is far too fiddly and time consuming. By the time I've done it the clouds are back!

[JamesF]

I used to run up and down my eyepieces getting the object centred as best I could tell each time, then swapping to the camera. It's a nightmare when you can't find it in the camera and swap back to a short focal length EP only to discover it's gone missing there, too. I'd not thought of a flip mirror, I have to admit. Perhaps subconsciously I just knew how expensive it would be to buy one

James

[Gina]

I've just ordered one of those star diagonals from AstroBoot - good value for a fiver I reckon I have a box that I think will do the job. I could probably mount the modified webcam in the box if it turns out suitable.

[smudgeball]

Mind you need two eyepiece holders (the bit with the locking screw)

So three parts in total (unless you've another bit spare ?)

Neil

Sorry I think you're putting the web cam into the box at the back directly, so ignore my reply

[Gina]

Yes, I'm hoping to fit the webcam inside but later had a thought that I might want to swap webcams if I want to image smaller DSOs with the LX modified SPC900NC. For planetary I expect to use my MS LifeCam Cinema with it's higher resolution. I should have bought two diagonals while I was at it. They're a good source of bits as well.

On second thoughts, DSOs may be too faint to see in an eyepiece. Hmm...

[smudgeball]

I should have bought two diagonals while I was at it. ...

Yep, I think it's free P&P if you spend £10 ?

[jnp]

Nice improvisation, well done.

I am looking at build a flip solution too, but I am tempted to shorten the mirror to make it more compact so I don't loose quite as much back focus.

[Gina]

The star diagonal came today. A rather cheap looking plastic job (apart from the mirror) but quite adequate I think and still good value for money. The mirror diverted view doesn't need to be all that accurate as I'll only be using it for finding the planet and putting it roughly in the middle then the webcam image can take over for focussing and more exact positioning. Or I can use a star and Bahtimov filter to focus before slewing onto the planet.

[Gina]

Here's more detailed diagrams of my flip mirror and a photo. I used a slightly different mod to the star diagonal. The diagonal part of the plastic case clips in with ridges on the long edges - I cut these off with a Stanley knife and pared the edges down slightly so that this piece was a loose fit in the rest of the case. This piece holds the mirror in, otherwise the mirror was loose. So I glued the mirror to this plastic piece. Rather than use a hinge, I used a pivot axle made from a cotton bud with the cotton removed leaving a small plastic tube. This was glued to the plastic piece with hot melt glue. Holes were made in the diagonal casing to take this little tube providing crude bearings for the cotton bud axle.

It now remains to cut holes in the box I shall be using and fix the diagonal in together with the webcam and a mechanism to raise and lower the mirror. I'll post photos when it's done.

[smudgeball]

I think I need to get these plans off to the patent office before Gina does any more work !!

[Gina]

I've been thinking I should start my own thread instead of gatecrashing yours - sorry. Yes, I'm likely to pick up on any good ideas and modify them to suit me Thank you for posting - very useful No, more than that a godsend!