16" f4 Orion Optics UK Dobsonian Project

[Astrokev]

Looking great Shane.

[Moonshane]

cheers Glen. hmmmm.....stars and stripes livery........

yeah I agree stainless is a nightmare. in truth I asked for mild steel and could only collect from next door to the supplier as they closed on the afternoon I collected it. could not be bothered going back and just buckled down. not easy to cut and shape by hand at all. I found out after I have done them that my father in law has a plasma cutter - doh!

drilling however, is not problem as long as you buy cobalt drill bits. dead cheap on ebay and work superbly well even with no lubricant.

looking forward to first light!

[Moonshane]

incidentally, if anyone wants to know what the collimation bolts are for the primary, I got these Adjustable feet (Large Diameter M6 & M8 Thread) | eBay UK

one will be used as a dob knob and the other three in the cell as shown.

this was a tip from Kriege and Berry with the advantage that as they are designed to hold heavy loads you can take the scope off the mount and stand it on the collimation bolts.

won't be doing that for long though.

[Moonshane]

Looking great Shane.

cheers Kev

starting to feel like progress now.

a mate is also lending me a spray gun for when it comes to painting the woodwork. sweet!

[spaceboy]

cheers mate. I considered powder coating but trying to keep costs down so will probably do a smooth satin black hammerite. not sure whether to spray or brush though. any tips?

TBH I'm not a big fan of painting metal. When possible I get stuff powder coated but as it adds to the dimensions it's not always possible. If I have no choice but to paint I have found red oxide offers the best rust protection and adheres reasonably well but to do a proper job can take forever having to wait between coats. Once this is done I sand it down as best I can and spray paint a top coat as a finish as this is often the cleanest look. One thing I will say is they don't make them like they used to and spray painting ain't like it used to. I know it wasn't environmentally friendly but cellulose used to stick like poo to a shovel. Todays spray paints have less adhesion than womens nail varnish IMO.

[Moonshane]

I may look into power coating then in that case as I bet the hammerite will be a few quid. do you have any idea of the cost of powder coating these days? I really have no idea.

[spaceboy]

I may look into power coating then in that case as I bet the hammerite will be a few quid. do you have any idea of the cost of powder coating these days? I really have no idea.

TBH I don't as daft as it sounds. Where I take stuff to be powder coated I often only have to buy a box of tea bags or top up the petty cash tin with a couple of Jacks. They often deal with £100,000 orders and just run what I need doing through with that. Powder coat really dose make a difference to the size so you have to take this into account and any threaded holes will require re-tapping but the finish is more durable than paint and can be in and out a coater in a day

[Moonshane]

cheers matey. I'll probably just end up hammeriting it.

seems likely to be a lot cheaper and once I get into a better financial position, I can always whip the mirror out of the cell and powder coat it in the future. maybe see how well the finish lasts and then do it the summer after it starts looking tatty.

[Moonshane]

hi all. the previous owner decided to paint a large matt black square on the tube around the focuser - see the first pic below. this was to reduce the reflectivity of the white paint when observing. the theory sounds ok and I originally planned to leave it as it was. however, you know those things that bug you every time you look at them? well this was one.

so I set about using wet and dry, P400 first and then P1000 to remove the paint. two hours later and it's gone. unfortunately in a couple of places I went a bit far and took the white paint back a bit (see second pic below). however, I can possibly repaint the tube or this section in due course if I want to. for now it looks a million times better and I am pretty happy with it. just needs a T-cut or buffing and will be OK.

you'll note the original owner also put in additional spider holes as he felt the originals were somehow wrong. not sure why, but anyway, one will be used for a dob knob and the other covered by a telrad base so only the two on the bottom side will be visible and underneath while observing and will have 10mm plastic hole bungs in.

[Astrokev]

Crikey, the size difference in the first image is astounding!

[Moonshane]

indeed and that's a 10" ota!

[Moonshane]

only kidding - it's a 6" f5

[johninderby]

Looks better already with that black sqaure around the focuser gone. I thought it didn't look right when you showed me the tube after you'd collected it.

Powder coating isn't that expensive, particularly if you want the same colour that they're working with so that they can do it along with another job. It's when you want them to change colours that they charge extra.

John

[Moonshane]

cheers John

I totally agree, miles better.

I think I will leave it as it is for now and see how it goes. I can always mask off and paint it in due course if it bugs me.

for now I really want to get it to a usable scope in time for the end of summer.

Powder coating will be good I think but I went out and bought some hammerite (and special metals primer) and will be hand painting it for now. It is, after all, up the wrong end of a telescope so not really a big issue. As long as I prep it properly it should be good as hammerite is a half decent finish when done well.

[Peter Drew]

The black square might look unsightly but it can add nearly 1/2 a magnitude on faint fuzzies if you keep both eyes open when observing, the non eyepiece eye then sees a black background rather than a white one, the brain automatically combines both signals. .

[Moonshane]

very interesting Peter. I may in that case rig up something to test if this works for me (although I tend to observe with one eye closed).

[Glen]

only kidding - it's a 6" f5

You got me with that one, had to have another look at the pic

Good to see things moving on Shane, your a glutton for punishment eh..

Be interested to know what you think the difference makes with/without the black square with this beast.

[spaceboy]

I observe with a patch. Call me captain Jack Sparrow ARRR...

[Peter Drew]

Moonshane. I used to observe with one eye closed but since spending a lot of time using binoviewers I,m now in the habit of keeping them both open even when using a single eyepiece. On a trip to Tenerife recently I noticed that when using my C8 SE, the fork base has a bright circular section, Saturns fainter moons did not appear until the superimposed image, as seen by my non obseving eye, moved on to the black surrounding part of the base. You can try this out by placing anything black in front of the non use eye. For some reason, for me at least, an eyepatch doesn't seem to have quite the same benefit.

[Glen]

I observe with a patch. Call me captain Jack Sparrow ARRR...

Got to say, that did make me chuckle ...

[Moonshane]

Moonshane. I used to observe with one eye closed but since spending a lot of time using binoviewers I,m now in the habit of keeping them both open even when using a single eyepiece. On a trip to Tenerife recently I noticed that when using my C8 SE, the fork base has a bright circular section, Saturns fainter moons did not appear until the superimposed image, as seen by my non obseving eye, moved on to the black surrounding part of the base. You can try this out by placing anything black in front of the non use eye. For some reason, for me at least, an eyepatch doesn't seem to have quite the same benefit.

Thanks Peter

I may try this but screwing up my face has now become second nature!

I much prefer the look of the straight white tube although may try and rig something up to test the theory you suggest above. you never know if may work for me too!

[spaceboy]

What I fancy is one of those cloaks that go over you head at the EP. I did see a commercial one some time ago but I guess they are easy enough to make. What I like is not only do you get to keep both eyes open and so reducing eye strain you also reduce any stray light distracting the eye doing all the work. I'm assuming these also help stop stray light entering the focuser ????? Not to mention it would also save me looking a total plonka with me eye patch.

[Moonshane]

good idea Cap'n! now, what do I have to do to get a seat at your table?

I sometimes use a black T shirt with the shirt going up instead of down. I do get a bit sweaty though so I might do this and cut out a face shaped hole in one side and this will allow me to actually breathe!

[spaceboy]

You after bring ye yer rum arrrrr

[Moonshane]

and really bad eggs......