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Old 10-10-2019, 06:20 AM
mura_gadi (Steve)
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Improving my first newtonian telescope

Hello,

I am after advice and tips on how to cheaply improve my night time viewing, the funds are driven by the left over gold coins, so my budget is minimal.

Firstly, my scope - SW 8" collapsible(goto). 2nd hand and somewhere along the way encountered a car at low speeds, (I think the car was moving not the dob...) the impact was great enough to crack the 18mm chipboard base.

I have since copied over the pieces to pine and have a fairly usable scope, however, there is a little "stickyiness" over 30 degrees or so on the azimuth. Its easy enough to work around, but I think the bolt on the base may have a slight lean in it from the impact.

Tips for helping set the tension on my alt would be great, the sliding magnet helps a lot, but I seem to be for ever adjusting the alt bolt between nights. I do use both 1.25" and 2" ep's, with and without a 2" barlow (with 1.25" adaptor). Also tips on how to refine collimation off a star in the dark solo would be great.



Here's what I've done so far trying to get the last few .% gains for urban viewing, easy of use etc. (ty to all those that post these tips)

Oil stone on the focuser plate to grind to a flatter finish, which was a great improvement for me.

Black board paint -
the end of the focuser tube that protrudes into the scope,
the 2 runners and flat focus plate were taped over to gap the paint edge.
and any chromed screw heads inside the tube assembly painted black.

Home made shroud (yoga mat, stiff cardboard for a few spines and covered in black velvet)

Dew cover ( read -more light protection against the neighbors patio lights though)

Dew control - got lucky and the dog won't use the $30 heated mat we got him, so I had been using that very effectively over winter with a couple of bungee straps. (His budget is a lot better than mine.)

A door stop (thanks Mike Salway) makes a lot of sense and hadn't seen that one anywhere else

Adjustable plastic legs for the base which allow for 150mm of travel and gives me a good gap away from the ground and is easy to level.

Setting circle of a sort - phone (with compass app and red light screen) against the base for Az and an digital inclinometer with a magnetic base on the tube. I have a 2" 80 degree 30mm ep, this setup gets the object in view and I change ep's as needed from there. I would prefer a printed setting circle over the phone though, but I'm having trouble finding something that will print at 510mm and not lose resolution or accuracy.

Butchered the $10 stereo from a garage sale for a heap of nice magnets and cut the pockets out of an old shirt to protect the tube. Very handy after getting some cheap 2" eps and barlow to blow my balance out yet again.

Collimation - Collimated within the laser window, however on a star test I do bloat out slightly over a small part of the arc.

Storage - Two option in-house, spare room seldom used but soon the water evaporate will be in use, or the garage, get very hot and its dusty but seldom used as well. Throw a blanket over the unit when not in use. (happy to setup and wait before use, more interested in best practices for storage)

Tips on a do-it-yourself bob's nobs setup from a supplier like bunnings for the SW 8" collapsible tube? I was thinking of butterfly heads bolts, but I would prefer not to have to re-assemble the telescope when I bring it in and its easier to move around if I can rest on end for setting up.


---------------------------------
Added from comments:
Adjustable barstool - (Get a back rest if you're in the colder climates, helps a lot with trapping heat around your lower back)
Right angle finder scope - Why this is is not standard is crazy.
Cooler Unit: Removable and padded against vibration
---------------------------------


So, what else can I do, what are hints and tips for newbies I've missed?


Thanks for reading this far,
Steve.

Ps. “Mura Gardi” means a pathway for searching in the local Ngunnawal language, the language of the first Australians around the Canberra area.

Last edited by mura_gadi; 16-10-2019 at 09:10 AM. Reason: descriptor on the title
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Old 10-10-2019, 02:56 PM
brian nordstrom (As avatar)
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Photos mate , these would help a lot.

Brian
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Old 11-10-2019, 06:57 AM
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Allan_L (Allan)
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Hi Steve,
Congratulations on buying a great scope.
And it sounds like you already have done most of the worthwhile modifications.

I've completed many of those myself.
The focuser mod I found to be a big improvement, like you. It shows your serious. Well done.

If its GoTo, I am wondering why you want setting circles?
I found a post years ago with a bunch of setting circle print files. Including one for a 10" SW, which I took to a Print Shop to have printed and laminated.
I'll see if I can find the link.
http://www.iceinspace.com.au/forum/s...etting+circles

I used a little magnetic inclinometer for the altitude settings.
But again, GoTo should make this unnecessary.

A valuable addition to my setups has been a red dot finder. I use it first to get in the right area, then use the finder scope to line up precisely.

Speaking of finder scope, I have swapped the straight through for a 90 degree finder. Saves a lot of wear and tear on my old back.

Speaking of back savers, I totally recommend an adjustable observing chair. They are expensive, but I wouldn't be without it nowadays. I have seen some home made ones if you need to minimize the spend, but truly they are worth it.

I also have a removable cooling fan for the primary.
Cut into a base cover made from that yoga mat stuff.
Attach with Velcro, and switchable (as vibration can cause observing distortion).

Portable battery? Jaycar sell a small light bunch of batteries (home alarm backup batteries). I think a 7Ah is around $49 and sits nicely on the dob base. It can power the fan and some dew heaters.

Some other mods I've done aren't really suitable for GoTo.

BTW, I haven't heard of the Mike Salway door stop? Whats that do?

Any further questions, fire away.
Good luck with it all.
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Old 11-10-2019, 10:35 AM
mura_gadi (Steve)
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Hello,

Thanks for the responses, I have taken photos and I'm trying to upload them now.

The goto part of the telescope was just an extra, and tbh, I am yet to run through the setup procedures.

I'm a very happy little camper wherever I point my scope normally. The goto is great for keeping the planets in the ep though. I micro-adjust rather than pass the object across the eyepiece as I have edge-of field issues with some ep's.

I got the what I will call "Knightowl" 2" eyepieces, there are certainly enough reviews around to put ppl off these eyepieces. I bought the 15mm and 30mm used for $50, on my f/6 dob setup, they have been great upgrades from the provided super-plossls. Paired with the 1.5 barlow for the extra 10mm/20mm, the views are really good.

(General Tip for viewing, if you normally get contrails from overhead aircraft, you can use them to judge good viewing nights, the shorter and sooner the contrails go, the better the nights viewing)

The chair I couldn't agree more with, got mine for $20 at the trash&treasure. Adjustable from 53cm to 79cm and I'm 6 foot or so, that gives me 35-90 degree from the chair. The back rest I also recommend if you suffer from chills on your lower back, tucks in the jumpers and jackets nicely in winter.

Thanks for the tip on vibration padding, at the moment I am leaning towards getting a petrol generator for power. I use mains at home and camping with power will make "tele-camping?" a little easier. The units on ebay are well priced atm and the generator will get more all round use.

Also should mention, by a complete fluke I managed to get a "tap" test down under 2 seconds. So the change over in material hasn't reduced the weight by much.

I ran into "admin" problems attaching pictures, think I was too slow and got my login timed out. So, I'll try and post the main pictures again.


Thanks all
Steve
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Old 11-10-2019, 10:45 AM
brian nordstrom (As avatar)
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Got the photo .

They are easier to download and easier for us to see at our end if you use Windows ' Paint ' , open the photo in 'Paint' and resize in 'Pixel' size , I use about 900 pixel's on the longest side and save ( it will ask if you want to save a copy when you X out of Paint ) and they come out well , not to large when downloaded here .

On eyepieces , jump on the 15mm Superview in the classifieds , it's among a set being sold now . Awesome 68* eyepieces.

Disregard , the 15mm superview just sold , you have to be quick on these .

Brian.

Last edited by brian nordstrom; 11-10-2019 at 10:50 AM. Reason: Superview sold
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  #6  
Old 11-10-2019, 11:00 AM
mura_gadi (Steve)
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Hello,

Thanks, resized and worked fine, better than the camera man did I'd guess.

After scrimping on most buys, I have already spent my Christmas present money on new Starguider 8mm and 12mm eyepieces. They are in the post as we speak, as with the digital inclinometer ($20 - .2 degree accuracy stated.).
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Old 11-10-2019, 02:13 PM
brian nordstrom (As avatar)
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Steve that looks really good mate , on the stickyness you are felling there are 100's of google pages on fine tuning the motions into what suites you , take your time and enjoy .

You have a scope for a life time there mate .

Brian.
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Old 12-10-2019, 07:40 AM
gaseous (Patrick)
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I made a set of DIY bob's knobs from bunnings with some M4 threaded screws. Cut the head off, then attach the cut end to the knob of your choice - again, I chose a small door pull from the bunnings furniture hardware aisle. They need to be slim enough that they can be installed and still have room to put your fingers around. There is a thread glue for fixing the door pull to the threaded bolt so it doesn't unscrew. This was for my 20" scope, so you may need quite small knobs for an 8".
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Old 12-10-2019, 01:19 PM
mura_gadi (Steve)
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Hello,

Thanks for the advice on redoing the bolt heads, looking at the base the gap for the heads looks like an issue.

To get the tool free collimation bolt setup and fans fitted, any reason against putting a hard wooden biscuit in;
-pad the biscuit for vibration
-fan with a few extra breather holes/channels
-run the new bolts through, with larger tool free heads
-set a circle of dowel bits protruding away from the board over the height of the new bolt heads and fix a resting/storage plate to those.

There are three 3mm threaded holes not in use on the telescopes base plate I think I can fix into. If I gap the holes around the new longer collimation bolts, I shouldn't stress the collimation bolts when resting the telescope on its end.

Unless the biscuit get a few no's, I think I have a new project underway.


thanks
Steve
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Old 13-10-2019, 07:33 AM
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Allan_L (Allan)
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You can also replace the original springs on the collimation screws with stronger ones. There are some available from Bunnings. I saw this in a thread here somewhere. can't recall the spring number, try a search.
You may need to trim a little off the length.
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Old 15-10-2019, 04:11 AM
mura_gadi (Steve)
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Hello,

I may have bitten off more than i can chew. I was hoping that I could simply replace the bolts one at a time and cycle around the collimation bolts. If I need access to the springs will I need to drop the mirror off the back?

Downloaded the SW manual for the primary mirror assembly, the spring appears to rest in a well. If I removed the screws with the telescope up-ended, can I get away with replacing the collimation bolts individually without removing the mirror assembly?


Thanks
Steve
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Old 15-10-2019, 09:11 AM
GeoffreyBarnes (Geoff)
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[QUOTE=mura_gadi;1449814]Hello,

I may have bitten off more than i can chew. I was hoping that I could simply replace the bolts one at a time and cycle around the collimation bolts. If I need access to the springs will I need to drop the mirror off the back?

Downloaded the SW manual for the primary mirror assembly, the spring appears to rest in a well. If I removed the screws with the telescope up-ended, can I get away with replacing the collimation bolts individually without removing the mirror assembly?
-------------------------------------------------------------------------

Yes you can, that's exactly how I did mine.
Had the Dob tilted up at about 45 degrees and replaced the springs one at a time so the mirror stayed intact.
Took one of the original springs to Bunnings and got the closest match, but stronger guage steel.
I did have to take a few mm's off them with an angle grinder, but that was all. Worked well.
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Old 15-10-2019, 09:32 AM
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Allan_L (Allan)
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some earlier posts I found with basic search might help.
From memory, you don't have to remove the mirror cell.
Just loosen off the adjustment screws and remove and replace one by one.

http://www.iceinspace.com.au/forum/s...ht=springs+Dob

http://www.iceinspace.com.au/forum/s...hlight=springs

http://www.iceinspace.com.au/forum/s...hlight=springs
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Old 16-10-2019, 06:27 AM
mura_gadi (Steve)
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Hello,

Thanks for the links and the advice, I will keep hacking away.

Got the two biscuits taking shape, and will work on the lengths of the uprights once I have the bolts and button heads.

Think this part of the build may be better in the projects area now. I will start a post there when I have some bad pictures to post. Hopefully have something ready to fit and fit for purpose by the new moon.


Steve
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Old 16-10-2019, 07:05 AM
mura_gadi (Steve)
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How do I get the title of this discussion changed to "Improving my 1st newtonian telescope" btw?
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Old 16-10-2019, 08:51 AM
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You should be able to go to the first post, click on the edit box then click on the go advanced box,
The Title can normally be changed then.
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Old 16-10-2019, 09:01 AM
mura_gadi (Steve)
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Quote:
Originally Posted by Allan_L View Post
You should be able to go to the first post, click on the edit box then click on the go advanced box,
The Title can normally be changed then.

Done and tyvm
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