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In praise of the paint kettle...

Mak One

By Mak One
in DIY Astronomer

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Mak One

Mak One

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OK, so it's not a patch on some of the projects on here, but you've gotta start somewhere...

A while ago I threatened to make a solar filter for the Mak on the basis that it should double my chances of using the scope, given the weather since the turn of the year. Well, I finally got around to it.

After much thought and consideration, I decided that I didn’t want sticky tape or Velcro all over the outside of the OTA, nor did I want soggy cardboard held together in the same way. £70+ from the dealers for something substantial? Must be able to better. But how to secure the filter and hold it in place on the ‘scope?

The grey matter whirred louder than a CG5-GT on fast slew. Now, it just so happens that a £2.50 5 litre paint kettle from the local Dulux decorator centre is just the right diameter for the outside of the OTA. Cut the bottom off, cut a hole in it. A ready-made filter “cap”. Two sheets of thin plastic from the local model shop (1 black, 1 white) cut to shape. Sandwich the Baader film in between and stick the lot inside the cap. Then form some folded cut outs at 120 deg intervals on the walls of the cap that, when bent in, catch on the rim of the scope and stop the cap sliding off. Pics below (together with the Bhatinov mask I slaved over - if only I'd known about the "Y" shaped strips thread first. Never mind. It works).

With the film, plastic and kettle I got exactly what I wanted for less than £25. Robust, no sticky tape and I can remove the filter cell and put it in a larger paint kettle base if I ever go up in aperture - I'll still have a 150mm dia solar filter. Marvellous.

I’ve just got to wait for the Sun to come out now...

Ta for looking.

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Mak One

Mak One

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Tools for the job:

1 set compasses to scribe the circles for the plastic sheet to sandwich the film and also to scribe the bottom of the paint kettle.

1 CD marker pen to draw the cut line around the outside of the kettle using a finger guide on the base - same way you might draw a margin down the side of a page.

1 pair large scissors to cut around the outside of the plastic circles

1 pair curved nail scissors (short blades) to cut the inside circles and the kettle (works but tough on the fingers - a junior hacksaw blade might be better (dust?) or if you trust yourself not to lop things off with it, a craft knife or scalpel).

1 roll double sided tape...

...and a steady hand and patience.

All the cuts to the kettle can be started using the blade/scalpel. No need for drills or power tools.

Took about a hour all in. Well worth it. Measurements etc will vary depending on the size of you OTA and the size of any 'scope rim to latch it on to.

There are many different diameters of plastic kettle available - just get the one that suits your scope. If it's too big you could always pack it out with spare foam sections from the equipment cases we tend to collect. I went for the kettle because it has pretty straight walls - not flared greatly from the base, it's lightweight plastic and it's cheap!

Good luck if you give it a go. Post up some pics if you do.

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  • 2 weeks later...
Mak One

Mak One

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Pale Blue...

That's the one. Just check to make sure the dia is suitable to be as snug a fit around the outside of your OTA as possible and bingo! The 5 litre suits the 150 Mak OK (192mm external dia.) and to be fair you'd struggle to get much more from an A4 sheet of Baader film.

Having given the filter a proper airing last week in Snowdonia I have used 3 thin foam strips in addition to the cut outs just to make it extra snug. One other improvement - having used strong double sided tape to hold the cell sandwich together, the clear outer layer of the film de-laminated, leaving the silverised surface exposed. A bit more judicious taping was required to re-laminate the film layers. May be me, may be some iffy film?

At the same time I realised the next DIY will be a shroud for the laptop so I can see the image from the webcam when solar imaging. If only bright ideas came in pairs...:(

Thanks all for the positive responses. :)

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Mak One

Mak One

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Geoff

Painting? You mean, (gulp) "proper" DIY... :)

Funnily enough - the idea started with home thermo-forming a sheet of plastic. Disaster, so thought about using something "pre-fabricated" - First, I was going for the end of a 50p builders bucket from B&Q (not a classy solution, visually), so then moved on to the bottom of a used :( emulsion pot, before the brainstorm of the nice, clean, available in various sizes, paint kettle.

If it had required doing some painting to get a pot, it would still be waiting to be made. What did someone say about invention, inspiration and perspiration..?

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Eclectic_Mixer

Eclectic_Mixer

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Ash,

I must admit I always enjoy looking at the DIY section in SGL as the ingenuity of the members is amazing.:) I' m currently atrying to adapt a EQ2 to fit on my GOTO tripod to mount the DSLR for driven widefield shots. I wish I'd kept all the bits and pieces I've been forced to throw out by SWMBO, ("what are you keeping that for").

Geoff

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Mak One

Mak One

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Ah! I see the magpie tendency is strong in you too. Is hoarding "it might come in handy one day and save me a few bob" stuff a bloke thing? If you're like me, you'll have a bloke's pile of timber offcuts in the corner of the shed/garage and have trouble resisting "salvaging" bits and bolts from stuff due for the tip...

There are some seriously ingenious bods on here though - way out of my league...

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yesyes

yesyes

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Ah! I see the magpie tendency is strong in you too. Is hoarding "it might come in handy one day and save me a few bob" stuff a bloke thing? If you're like me, you'll have a bloke's pile of timber offcuts in the corner of the shed/garage and have trouble resisting "salvaging" bits and bolts from stuff due for the tip...

Hmmmmm, now why does that sound soooo familiar... :)

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Gina

Gina

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I'm not a bloke but I am a hoarder! I do card craft (Christmas, birthday cards etc.) with our local WI and hoarding is the keyword there too :) No, hoarding is not confined to blokes.

As for the Baader sun filter, I more or less followed the "Blue Peter" instructions with thick cardboard (from packing carton) but used spray-on glue instead of double sided sticky tape - less fiddly. Oh, and the ring to fit the OTA came from a very large postal tube, so I didn't need to bend cardboard and build it up in layers - it was already done. I used blobs of hot melt glue to attach the filter to the cardboard tube - again quick and easy. (Avoid getting hot glue on your fingers - painful!)

I love recycling things for construction - most satisfying :eek:

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