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Dob base build begins!


Daz69

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What glue have people used to stick the LP to the underside of the box? I've got some Evo-Stik contact adhesive but not sure if it will stick to the vinyl of the disc???

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Just catching up with this build - it's looking good ! :icon_biggrin:

Shane built me a dob base to fit my 12" optical tube but that was an F/5.3 so it's definitely a standing scope. I like standing when observing and Shane managed to design the base so the eyepiece was at a good height for me :icon_biggrin:

It's a robust piece of work as well - still going strong and more or less unmarked after 2 years of ownership and quite a few star party trips:

 

oo12dob01.JPG

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1 hour ago, John said:

Just catching up with this build - it's looking good ! :icon_biggrin:

Shane built me a dob base to fit my 12" optical tube but that was an F/5.3 so it's definitely a standing scope. I like standing when observing and Shane managed to design the base so the eyepiece was at a good height for me :icon_biggrin:

It's a robust piece of work as well - still going strong and more or less unmarked after 2 years of ownership and quite a few star party trips:

 

oo12dob01.JPG

That's a good looking tube. I actually found your set up when searching on Google for images of a dob base, didn't realise it was yours, and seeing how tall yours was, decided to add the extra 5". Mine is f/5 and meant to be on a tripod, but I bought it S/H without a tripod (£120). I'd like an HEQ5 but funds do not permit, and with a load of 3/4" ply in the workshop, and a workshop full of woodwork machines, thought I'd build a dob base so at least I can use it until I get a tripod or a pier. 

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The 200mm F/5's are good optical tubes. Excellent performance per £ spent when you can get them for £120 !.

Years ago I picked up one with the older "Helios" branding and made a dob mount for it. Not as nice a job as yours though :rolleyes2:

 

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3 hours ago, John said:

The 200mm F/5's are good optical tubes. Excellent performance per £ spent when you can get them for £120 !.

Years ago I picked up one with the older "Helios" branding and made a dob mount for it. Not as nice a job as yours though :rolleyes2:

 

Thanks for your kind words. 

There was no way I was going to let that go at that price, so I jumped on it. 

I've got to sand down the filler which I put over the joints (not that they were bad joints as it was all cut on my tablesaw) to cover the tear-outs as the ply wasn't the best, and my blade needs sharpening. I also put filler over the end cuts that are visible. I got my T nuts today so I'm all ready to go once it's painted. I'll get some photos once it's all done.

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10 minutes ago, faulksy said:

looks great mate, are you painting it black

Hi Mike. I'm painting it white because that's what I have got in the workshop and it can be used for exterior wood. Any specific reason why it should be black? 

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20 minutes ago, Daz69 said:

Hi Mike. I'm painting it white because that's what I have got in the workshop and it can be used for exterior wood. Any specific reason why it should be black? 

no daz, not at all. look nice and it will match your tube :grin:

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1 minute ago, faulksy said:

no daz, not at all. look nice and it will match your tube :grin:

:D  Haha, I was sat here thinking, "Why does it need to be black? What am I missing?" :D  If I had some then yes it would've been black, but I've got a half 2.5L tin of exterior white gloss which won't be used as we have no need for it. i suppose it could've gone to the dump a long time ago, but I'm a hoarder of "Oh that'll be useful one day" bits n' pieces. 

What I plan to do, is use the round base board as an azimuth circle and have a fixed illuminated pointer on the box section, so I'll be engraving 360 marks around the edge (I must be mad!) to aid alignment, and will use black enamel model paint in the marks so they don't rub off and will be more visible in red light. I thought about laminating an azimuth template on top of the base board using Doculam. This is quite thin but very strong as I've used it to cover a balsa RC plane, and I've got around 50 metres of it, but I cannot get my computer to enlarge and tile such a template. I might try another laptop to see if that one will do it, otherwise I could try and find a print company perhaps. I suppose it would save me a few hours using an arm protractor. 

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Got my first undercoat on today.

dob%20base%207_zpso85vf8ks.jpg

dob%20base%208_zpsxduhb4be.jpg

dob%20base%209_zps1yre6tv8.jpg

Tomorrow I will give it a light rub over with 240, get another coat on, another sand with 600, then start with the top coat. I thin my paint down 60/40 with white spirit so it goes on smoother and dries quicker. Good sanding in between each coat of finish paint and tack ragged off, top coat after will get a wet rub over with 1200 wet and dry, should get a nice shiny finish once buffed. 

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On 06/03/2017 at 17:35, Daz69 said:

What glue have people used to stick the LP to the underside of the box? I've got some Evo-Stik contact adhesive but not sure if it will stick to the vinyl of the disc???

And that was me thinking the LP was for listening to?

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7 hours ago, gtis said:

And that was me thinking the LP was for listening to?

It's Shirley Bassey, I'll burn you a copy if you like? No one on the forum will know............ much :) 

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This paint is taking ages to dry between coats, probably still on the cold side for it I guess. Still, it's looking good so far. 

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I got my azimuth compass printed today at my local printers today. I've done a video, but I'm yet to upload it, showing how I've protected it. 

Now uploaded 

 

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On Tue Mar 07 2017 at 22:43, Daz69 said:

Hi Mike. I'm painting it white because that's what I have got in the workshop and it can be used for exterior wood. Any specific reason why it should be black? 

Cos blacks cool man :thumbright:

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A bit more done. I mounted the azimuth compass on the base board 

dob%20base%2010_zpswxeh08ln.jpg

and then used Evo-stik contact adhesive to stick my Shirley Bassey LP to the base box. Whilst the adhesive was drying, I mounted the 3 teflon pads to the base board. The glue was drying off nicely so I applied said LP to the underside of the base box, using the centre bolt to line it up correctly. I used a press roller to squeeze out any trapped air bubbles, and then fitted the base box to the board, and gave it a spin :) A slight adjustment to the centre bolt gets me enough stiction without it binding but also enough sliption without it being like Torvil and Dean on ice. 

I was going to do a final 1200 wet and dry sand before using a buffing wheel to really flatten out the paint, but I couldn't be bothered with the hassle of buffing compound being flung everywhere. However, I'm quite happy with the finish and the current shine. 

dob%20base%2011_zpsvs1odqxh.jpg

dob%20base%2012_zpseersgagt.jpg

Thanks for looking 

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Just now, estwing said:

Very nice well done sir

Thank you kindly. I'm still some ways off completion, need to work out how to illuminate a pointer or project a line onto the compass. Been looking at laser lines, but cannot find anyone who supplies just the laser and at a reasonable (cheap) cost. I could use a 99p laser pointer I suppose????

I've got a few ideas in my head using a red LED through the edge of a small piece of 2mm perspex, but I need to work out the angles that I need to cut the perspex in order to see the illuminated edge from the above position. I trialled a few different angles but not quite there yet. 

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