8 Inch F6 Newt

[nebulosity.]

G'day guys,

I've been asked to build an 8 inch f6 newt and to get EP's and mount so suit.

I hope to be able to have some advice on whats best.

I'm only 16 but am a bit of an ATM and the fella saw some of my scopes and must have liked them becuse he wants one off me :thumbsup:

I don't really know what I'm doing, just working it out as I go along, I thought I'd post some pictures as I progress and would love to have your opinion and any tips :thumbsup:


So, here it go's...

The tube I've made from 18 strips of Hoop pine and 9 strips of Meranti, each is 8/29/1300mm and has 6.6 degree angled edges.

These were then taped together, and I ran a bead of glue down each gap and then rolled it up and let to set.

I've then done lots of planing and sanding and reckon I got a pretty good tube. It weighs about 4 kilos and is super strong, I'm planing on giving it a few coats of clear epoxy resin after I've cut out the focuser hole and stuff.

do you think it'll be alright?

Cheers
Jo

[Astroman]

Looks good... for someone that claims he doesn't know what he is doing, you have created a one of a kind telescope, and the guy who is getting the scope should be very proud. If the mount is of equal quality it should be a very awesome scope. I think if you keep going and iron out the little problems that may arise, you should have one hell of a scope. btw 8" f6 scope good choice.

[FlashDrive]

only 16years old.....you have a talent there mate.
That tube is a fine piece of work....keep going....I will follow this thread.

Flash.....:D

[nebulosity.]

WOW! Thanks for the nice comments guys, really appreciate it :thumbsup: Heres my attempt at a secondary holder and mirror cell. The design for the secondary mirror holder was sort of copied form Steven Lee, I'm hoping it should be nice and stable.

The mirror cell design is what I used on my last telesope and it worked well, it uses three pushing bolts and one pulling bolting in the centre.

Both were made from aluminium.

Thanks for looking
Jo

[nebulosity.]

Was out testing my 6 inch f8 newt out last night, couldn't resist taking some pictures :) all I have left to do on it is make some tube straps :lol:
Im hoping the 8 inch will turn out a bit like this, except better now that I've had a bit of practice.

Cheers
Jo

[FlashDrive]

Looking over that Scope it looks like everything is ' home made '....even the focuser and the way it's fitted to the tube via a ' tapered wooden ' sleeve.
You should be a design engineer...you obviously have a decent ' workshop ' to turn out your parts.....the main mirror mount is very well made and the finish is very good indeed......secondary mount is excellent to.

Well done......Flash.....:thumbsup:

[Rod]

Hi Jo

Just showed my teenage kids the pictures of your scope. They were amazed! You have some serious skills there. Look forward to seeing the final product.

Rod

[nebulosity.]

Thanks Col, yeah I got more time than money so I have to make it if I want it. Between my dad and four brothers I got most of the tools I need.

The aluminium I cut out using a jig saw, followed by lots of filing and sanding with 1200 grit sandpaper.
Jo

[multiweb]

Beautiful craftsmanship. :thumbsup:

[Shark Bait]

I am looking forward to seeing the finished product as well. It must be satisfying constructing the OTA from scratch.

Do you intend to grind your own mirrors in the future?

[nebulosity.]

Thanks a lot Rod :thumbsup:



Cheers :thumbsup:



Yeah Stu, it is fun to build, I hope to be able to learn how to grind my own mirrors some time soon.

Jo

[LewisM]

Kudos Jo, a true craftsman.

Most kids these days don't know how to fold a paper aeroplane let alone make a telescope from scratch.

Fantastic.

[mercedes_sl1970]

Impressive work - obviously well made and very aesthetically pleasing.

Andrew

[DaveGee]

Sorry. This statement is incorrect. ;)

You know exactly what you are doing and you are doing beautiful, exacting and functional work. I'm VERY impressed!

[nebulosity.]

I have finished sanding the tube and have given it two coats of epoxy resin, I'll wait until I'm nearly done before I do the final coat and polish. I've also finished the spider and it's really rigid and strong, next job is to mount the focuser (I splurged and got one :D)

I'm planing on having two sets of attachments where the mirror cell holder attaches to the tube, one set for visual and one set for imaging. Does anyone know how much further in the imaging attachments need to be?

It's good to get back on the newt again after working on cooling my camera for the last few weeks, I have ordered the EP's and mount, an Ioptron i45, hopefully I'll have it all finished before Christmas.

Thanks for all the encouraging comments everyone, :thumbsup: it's blown me away reading them, I'll have some more pics for you soon.

Cheers
Jo

[omegacrux]

That is pretty cool
Good work

David

[FlashDrive]

Jo.....keep going....you are producing a fine Telescope that even I would be proud of....:thumbsup:

Col.....

[TimberLand]

Great work Jo, you have far better wood work skills than me and a lot more patients to go with it.

Go the ATM Newtonian's. Diffraction spikes and all.

[Lee]

Work out where the prime focus point of the mirror is, this is where the CCD plane needs to sit regardless of all else.... (depending on the back focus requirements of your camera) - in terms of secondary placement and field illumination, you'll have to wait until someone more informed pipes in....

Excellent work by the way....

[nebulosity.]

The mirror is an 8 inch f6 so does that mean the sensor needs to be exactly 1200mm from the surface of the mirror to focus? And the EP's need to be further out?
The EP's that I've ordered are ES 82's ranging from four point seven mm, to twenty four mm. It will probably be a few weeks until I see them and I don't really feel like waiting until the arrive before putting the mirror in.

So as a start, for the imaging brackets, if I put the focal point 25mm above the racked in focuser would about right for most cameras?

As far as I understand, the longer FL EP's require more infocus than the short FL ones, I have a twenty four mm Hyperion EP, would that be similar to the twenty four mm ES?
My idea was, for the visual mirror attachments, I would position them so that Hyperion would focus with the focuser racked out about 10mm (the focuser has 35mm of travel) this way I hoped the others would focus without trouble, what do you reckon?

Sorry it's so confusing, the four key has died on my keyboard :lol:

Cheers
Jo

[Lee]

1200mm - pretty sure, or close to this.... What's an eyepiece?? :)
If you point the scope at the moon, and move a piece of white paper in and out from the focuser barrel, you'll see the prime focus point, when a focused image of the moon appears on your paper.... this is the plane where the sensor needs to be....

[nebulosity.]

A bunch of lenses used by people who want to observe the universe with there own eyes, quite unnecessary. :screwy: ;)

[Meru]

Wow Jo that's really good work, love the finish on the wood. You must be quite handy for the DIY jobs at your place :P I'm curious to know how the wooden tube will hold up to the moisture (aka dew) issues and if it'll warp over time? Maybe you should try adding some nichrome wire to the scope to keep the water off?

[nebulosity.]

Thanks Meru



The tube has had two (will have three) FULL coats of fiberglass resin and is fully sealed, so should be OK. Don't think warping will be a problem, on my 6 inch tube I've had it out in the sun quite a bit and it's perfectly fine :thumbsup:

Cheers
Jo

[TimberLand]

Jo from my understanding the focus plain of an eyepiece is where the field stop is which is the ring inside the eyepiece looking from underneath. So cameras usually need a bit more distance to get focused than an eyepiece.

Also if you go for different rigs for imaging and eyepieces then you might be able to look at different secondary mirrors. With my 16 I use a 70 mm for imaging and an 88mm for visual (don't do that often though) as my camera has a smaller field of view.

You just need to figure out where your even illumination field needs to get to.

Justin.

[nebulosity.]

Is that because the camera sensor is generally further in from the top of the nose piece than the eyepiece field stop is? That makes sense I guess.



I hadn't thought about that, I will be using APS-C size sensors mainly (probably something like a QHY8) The secondary I have at the moment it a 50mm one.

Cheers
Jo

[nebulosity.]

Here is what I did yesterday, primed and painted the secondary holder and spider. And made a saddle for the scope from some leftover Hoop pine, today I hope to get the aluminium straps made that go over the tube.

It's quite exiting now that it's all coming together, sitting on the table it looks pretty big :thumbsup: can't wait to try it out.

The next thing to build is the guide scope, I have a nice 80mm F5 acro lens from Surplus shed that I plan to use. Do you reckon I should make a wooden tube for it as well?

I am thinking of splurging again and getting a focuser for it, where do you reckon I could get one? Just a 1.25 inch, preferably not plastic, rack and pinion would be alright if it has a good locking screw.

Oh, and any ideas on what would be best for mounting option for the guide scope? I'm not massively liking the thought of tube rings :shrug: any other options?

Cheers
Jo

[alistairsam]

That's truly impressive Jo.
Amazing worksmanship. What mount will you be using it on.

I'd suggest a slim OAG rather than a guidescope. saves so much hassle with having a separate guide scope and differential flexure and is not expensive either. but then you do need a sensitive guidecam.

check out the Long perng focuser from andrews. its low profile and is pretty good.
the lower the profile of the focuser, the better it is for imaging as you then get sufficient back focus, you can keep the secondary small, and less vingetting although with an F6, that shouldn't be as much an issue as with an F4.

Have you thought of re-inforcing the focuser area? I know the wood would be strong enough but its a thought.

Cheers
Alistair

[nebulosity.]

Thanks Alistair, it will be on a Ioptron I45.



As this scope will probably not be used for any serious AP I'll be going the guide scope (easier for me to make)



Yes they look nice, would it be a bit of an overkill for the guide scope though :question: (already got a 2" 10:1 Crayford for the newt)



No I haven't thought of that, it's a good idea, on the next coat of resin I'll stick some fiberglass on the inside of the tube in that area.

Thanks again
Jo

[alistairsam]

Hi,

How did you manage to cut the 6.6 degree angle on the wooden strips and wasn't there any possibility of the cylinder being slightly distorted? did you have to use an inner cylinder to ensure its not pinched anywhere?

Cheers
Alistair

[nebulosity.]

I borrowed the neighbours saw bench to cut the strips on, it allowed the blade to be tilted a little so I ran them through again to cut the edges, it would have been possible to just cut a 13.3 degree angle on one side and leave the other side at 90.

When the tube was rolled up it was tight and rigid, I didn't use any form of support, just measured across the ends as it was setting to make sure it was nice and round.

Cheers
Jo

[Meru]

Ah, well that should definitely do the trick :P Very nice!

[nebulosity.]

So, I've roughly finished the tube and it has had two coats of epoxy resin, once every thing is fitted and all the holes are drilled I will give it the final coat and start on getting a nice finish to it. The secondary mirror holder and spider has been finished and painted a flat black, and the primary mirror cell is finished as well. Both the mirrors have been mounted in. The inside of the tube is yet to be lined with black velvet. Over all, most of the big stuff is done and I just have to do all the little jobs and the finishing touches.

Here are a few pictures,

Cheers
Jo

[alistairsam]

That's just beautiful workmanship Jo. Very inspiring to see what young minds can achieve when they put their minds to it.
You might have to start taking orders and start a production line.

Look forward to the first light report.

Edit: I'd suggest using a nylock nut for the secondary centre bolt. that'll keep your tension constant and allow the secondary to be rotated during collimation.
with the 4 bolts and nuts, won't you have to hold the nut while tightening the bolt? might be easier if you glue the nut or add a thread so you just need to adjust the bolts.

Cheers
Alistair

[nebulosity.]

Thanks Alistair,

good idea about the lock nut :thumbsup: yep, the four other nuts are glued on and they seem to work well.

Jo

[FlashDrive]

Very nice work....coming on very nicely.....

Col.....

[nebulosity.]

Here are a few pics of the scope almost finished, I got an iOptron IEQ45 mount for it from OPT along with the Explore Scientific 24, 14, 8.8, and 4.7mm 82 degree eyepieces.

To finish of the tube I sanded it all down with 400 grit sand paper with lots of water and then polished it with a buff and some cutting compound.
I flocked the inside of the tube with black velvet, it make it really nice and dark, I’m thinking of making a baffle to go just in front of the primary mirror as there is a 10mm or so gap between the mirror and tube were a bit of light can come in.

The mirror cell works well, collimation is easy to adjust and holds perfectly.:thumbsup: You can see that there are two sets of holes for mounting the mirror cell the tube, well one set is for visual and one it for imaging. Moving the mirror and tweaking the collimation again takes about 2 minutes.

The mount works brilliantly, this is the first GoTo GEM I’ve ever used so it took a few nights to get used to but over all it’s very simple to use, with a rough polar align through the illuminated reticule polar scope and a one star align, GoTo’s place every object smack in the centre of the image with the 1100D. :D

The ES EP’s I’m very happy with also, certainly a lot better than my Hyperions.

I have started working on a coopered wooden 80mm F5 guide scope, it’s coming along pretty well, I hope to have everything finished in around mid February.

Cheers
Jo

[alistairsam]

Hi Jo,

That looks great. very nice work.
yes, goto mounts are very handy. does this mount have an autoguider port or support guiding?

I had two suggestions, pretty sure you've already considered these.

Looking at the pics, if you keep the focuser to one side, it'll end up in odd positions when slewing to different parts of the sky and you'll have an issue with balancing the weight.
is it balanced with the eyepiece?
if you had the find on the other side, that could even it out.
I believe this is for visual use?
its common to have the focuser facing down as that way, balancing in RA is not an issue.

second thing, do you have plans to make the two fasteners removable or adjustable? reason being you'll have to rotate the tube at some point if you use a different eyepiece that's lighter or heavier or even a camera.
so you'd need to loosen the fasteners, rotate the tube with the camera and then fasten it. I noticed both sides have bolts?
you would also need to loosen it if the OTA needs to be slid up or down again due to differing weights with cameras and eyepieces.

I like the idea of two holes for the mirror cell.
Nice work

Alistair

Edit: one other thing you could do is add a wing nut and a nyloc nut underneath it to the collimation bolts.
that way, you won't need a tool to adjust the bolts. you never know when a re-collimation is needed in the field.

Any provision for mounting a dew controller? that'll also be required to keep eyepieces and/or the finder objective dew free. else its a nightmare cause things dew up very fast.

[FlashDrive]

How good is that....great job Jo...:thumbsup:

I like the ' home made ' bike rack against the fence....awesome....;)

Col......:D

[alistairsam]

I like the tree house:)

[tilbrook@rbe.ne]

No doubt about Jo!

Your very gifted !!:thumbsup::thumbsup::thumbsup:

Look forward to your 80mm.

Cheers,

Justin.

[nebulosity.]

Yes, it's a pretty smart mount, 358,000 object data base, with GPS, permanent PEC, electronic balancing, belt drives, even got a port for dome control!




I was planing on putting the guide scope on the other side to balance it, if the focuser is not on the side were would it go :question: I could have it facing down but wouldn't that make it harder for visual? Or it that just for imaging. The scope will probably be mainly used for visual, but fully capable of imaging as well.



The camera (1100d) is pretty much exactly the same weight as the 24mm eyepiece so I've just had it balanced for them, the other eyepieces are lighter but it's hardly noticeable. I did a good nights observing with it in the same configuration as in the pictures and with a small step stool I was able to comfortable observe everywhere in the sky, this is how I generally observe anyway so it seemed OK.



Yeah, that worked out every well :thumbsup:



I'm thinking of making some fancy nobs for it, just not sure how to attach them to the bolt heads.



Have had no thoughts about dew heaters, so thanks for reminding me :thumbsup: I'll see how that can fit in.

Cheers, and thanks a lot
Jo

[nebulosity.]

Thanks Col :thumbsup:

:D
Jo

[nebulosity.]

Thanks Justin, the 80mm should be happening this week, never made a wooden refractor before so will be fun.

Jo

[cometcatcher]

It is both an engineering feat and a work of art.

You remind me of an old engineer mate I had from the 1970's also called Jo that built me my first 8 inch telescope.

[guggle]

I've only just joined this thread and loved seeing the progress on this scope. Great work Jo, you must be very proud of your work!!

How much does it weigh?

[nebulosity.]

Thank you all for your encouragement while building this setup :thumbsup:

I have now finished it and here are a few pics of the completed scope. I am sorry I haven't updated in a while.

The fist pic is of the scope and all the equipment that goes with it, then comes a few pics of the scope is self, and then a pic of me and the happy owner. (I am the guy in the purple shirt)

Cheers
Jo

[omegacrux]

Very well done
A beautiful scope
Your work bench is too tidy !

David

[nebulosity.]

Thanks David :thumbsup: the table took a long time to clean up :thumbsup:

Jo

PS, for those who have been following this thread, you will notice that the secondary holder has been changed to an improved design. Better pictures of the of the new design can be seen on my 8" truss newt thread. (http://www.iceinspace.com.au/forum/showthread.php?t=118530&page=3)

[cometcatcher]

You even made a wooden tube for the guidescope! It's so cute.

[FlashDrive]

Very Very Nice Jo ..... job well done ...enormous talent :thumbsup:

Col...........:D

[spinnaker]

That scope is truely a work of art - nice job!

[julianh72]

Congratulations - an absolute work of art! I want one - are you taking orders? ;-)

How does it perform?

When do you start the build of a hand-made wooden GEM / tripod to complement it?
http://www.cloudynights.com/ubbthreads/attachments/1131004-new%20mount%206.jpg

And what about a wooden camera for imaging?
http://www.featurepics.com/FI/Thumb300/20090728/Old-Wooden-Camera-1273207.jpg