Any recommendations for Dobson setting circles

[spaceboy]

Hi all

I am a beginner to the dobo scene and have seen some threads about setting circles and wondered if they are any good? From what I can make out there are print out and tape on sort and the make your life so much more easier digital type.

Would one of those GPS handhelds be any good (that ramblers use) for RA and the digital angle finder for DEC

Am I right in saying either method requires a PDA or laptop to get up to the minute bearings. If so are there recommended PDA's for such a perpose. I'm no banker so I wouldn't need the old filofax type PDA just one that I can drop Stellerium on.

Any and all advice would be of help as I have no idea

HAS ANYONE GOT PICTURES TO SEE HOW THE SETTING CIRCLES WORK ON DOBS AS I'M SURE IT WILL BE A GREAT HELP TO OTHER BEGINNERS TOO!

[Doc]

I use a lap top for alt az positions. A degree circle handmade for the base and a wixey for altitude.

Mines pretty accurate, dead quick and places object in FOV in my 28 Uwan.

Quicker then most go-to's.

[spaceboy]

Just found a good link detailing improvements to Sky-watcher Dobs http://www.jim-easterbrook.me.uk/astro/scope/dob/

Again I take it some form of up to date positions are required.

[watchmakerjohn]

I agree with the wixey

[Mark Porter]

Just found a good link detailing improvements to Sky-watcher Dobs Sky-Watcher SkyLiner 200 Dobsonian Telescope

Again I take it some form of up to date positions are required.

Thanks for posting the link, very useful - Currently I have a Silva compass on my base & a Wixley on my OTA, I can see myself spending the weekend of modding my Skyliner!

[spaceboy]

Has anyone used a digital compass with a wixey???

Seen this on eBay and has a level bubble aswell which could be used to get the mount level Omnisat Digital Satellite Compass on eBay (end time 24-Oct-10 12:10:39 BST)

[coffee_prince]

http://stargazerslounge.com/diy-astronomer/80995-diy-dob-setting-circles.html

I plan to do something similar, but try using glow in the dark ink as well.

I'm not sure how I will measure out the tape correctly though, seems difficult?

Measure the base circumferunce and divide by 360 and handmark it all out with accuracy, easier said than done

[spaceboy]

Just found a good link detailing improvements to Sky-watcher Dobs Sky-Watcher SkyLiner 200 Dobsonian Telescope

Well guys and girls I can vouch for the improvements made to the dobsonian pivot bolt.

Who would have thought that this is all that was needed by Skywatcher to improve begginers dobson experiance. I drove for an hr to get my dob 2nd hand and as luck would have it, it was a dark night and I was able to give it a quick try in the sellers garden my 1st impressions were not ones I wanted an hr drive home with and came close to saying no thank you. Could this be why the guy had only had it a month and wanted to sell it? It was new no doubt... and a quick check of the optics was OK so it had to be because of the nightmare jolt as the teflon pads finally let go and the view of Jupiter wizzed of out of view. Several attempts later I finally gave in but considered if worst came to worst I could always mount the OTA so handed over the cash.

MY POINT IS.... I know I love observing and I know what the sky has to offer and the options of mounts out there. What would a newbie think??? Well actually I now know, they sell the scope after a month.

Before becoming a member of SGL I had no idea that telescopes of any kind required any kind of mods. I would assume no begginers would either. All that was needed was a 6mm nylon sheet (eBay) a 70mmm M10 bolt (Hardware shop like B&Q) and a 6mm aluminum plate (scrap yard) TOTAL £10 (a little spare for if you have more than 1 dob) Plus a little bit of DIY skills and some handyman tools.

The guy states in the description that the aluminum needs to be tapped square and yes this is very correct. I unfortunetly I'm just one of those people who can't do anything right no matter how hard I try so my effort came out as psst as a sailor on leave. This said I don't think it works as smooth as it should but hey that sticky teflon pad problem has been resolved. My only problem with a wonky bolt is 1 1/4 of the turn is a little stiffer to go around which means the nudge needs a little more controlled. I figure this 1/4 will face north and should'nt be an issue while out observing.

Some fella give up on the dob I assume for sticky pads I almost didn't buy a dob for the same reason. I cannot believe how easy the issue can be resolved skywatcher need to pull their finger out!

[Moonshane]

on a similar thread but thinking laterally (as I don't think the design of my Orion Optics base allows an azimuth setting circle to be fitted) is there such a thing as a horizontal Wixey? what I am thinking is that if you could set it at 0.00 when pointing to Polaris, could you then use it to get the correct azimuth setting and then a standard wixey for declination? or am I thinking in too simple terms?

[spaceboy]

I think you are thinking of a compass my friend. I got a digital compass from China for £10 the same as the ones on ebay for £16 For Camping Outdoor Digital Compass Thermometer on eBay (end time 07-Nov-10 14:13:58 GMT). Thank goodness aswell as they are cheap *** looking things. I have yet to try it out with the wixey as the only stars I'm viewing latley are on stellarium.

[Moonshane]

ha ha

great minds think alike! I have ordered one of the similar ones off the bay myself.

I have since found this Rotary Angle Encoder and Remote Display, with a 6mm diameter shaft. which looks very promising.

[spaceboy]

I LIKE!!! good idea but how will you mount it? Will it not have to be in the center of the base to work? How do OO bases pivot?

[Moonshane]

that's the main thing I have to work out. there's M8 bolt up from the floor and a nyloc nut holds the feet and the base together. there's a teflon collar around the m8 bolt which is what turns, the bolt and nut (and feet) remain stationary. fitting the spindle to the bolt/nut is easy enough (maybe with a rod connector, glued to the spindle and bolted to the end of bolt) and I'd just need to create a raised ali plate to fix the encoder to the base so the encoder turns and the spindle remains fixed. I might need to add weight to the tube to allow me to raise it a little though.

[spaceboy]

I think I know what you mean

What I think would work is... A longer bolt through the middle. Center drill the bolt for the spindle on the wixey thing to fit into. Side drill the bolt and key it so it holds the spindle tight. Have an alloy plate with an 8mm hole drilled in the center and fix the wixey through this to keep it solid and then fix to the base with stilts.

Picture may explain better.. forgive the crudeness it is rushed

[spaceboy]

Dam you got me thinking now Shane. I do like the idea of this and it zeros to so adjustments can be made nice and easy. I have a little alloy left over from fixing the center bolt Hmmm Wonder how long the batteries last in these things? Wonder if I could wire it up to me power pack

Go to resist the temptation need a low power ep

Have you seen the same thing cheaper £41 is a little steep maybe

[spaceboy]

Any further progress Moonshane. Thanks to some members helpful advice I think the low power EP I was after should no longer be necessary so I have some spare funds and I am hooked on your idea They even advertise this product that it can be used with telescopes so someone somewhere must of successfully made a rig to work with their base.

I assume the battery will last as long as a wixey angle finder (looks like the same kind of thing) so has anyone got a rough idea how long the CR2032 lasts in them??

[Moonshane]

not so far mate - I have no dosh at the minute - something always crops up when I have a bit saved! 10mm Radian this time.

you could almost certainly use the Rigel Battery 'converter' which has a 'dead' battery attached which goes into the body and links via red/black wires to a 2xaa battery carrier - lasts a lot longer and you can recharge. Finders - Rigel QuikFinder Compact Reflex Sight

maybe FLO would sell one separately?

I am definitely going to do this though and like the accuracy of the spindle rather than trying to bodge it with a compass. I think it will be a standard issue item for any future dobs I build - next project is an 8.5" f8 dob with a 35mm secondary for planetary - got the mirror cheap and good practise for my larger version in the future when I can afford a 16" mirror set. they will both have one.

[Moonshane]

ps from other posts re wixeys I have seen the time is impacted in a major way by turning off each time and it recalls the zeroing level apparently.

[irishbloke]

Have you seen the same thing cheaper £41 is a little steep maybe

Spaceboy,

I think this is the same as the other one. Buy GemRed Rotary Angle Encoder with Remote Sensor from Axminster, fast delivery for the UK £35.70

I think this looks like a great modification.

I'm following both this thread and John R's thread http://stargazerslounge.com/diy-astronomer/118838-dobs-direction-finder.html#post1576268 to see how it all works out.

Thanks

Brian

[spaceboy]

Cheers Brian Couldn't be doing £41+VAT+postage

Thats my mind made up then. 4 weeks and counting. I'd better get down that scrap yard again

[ponytale]

just a thought, could one of those flexible driver shafts for drills be used to connect the units to the central bolt allowing the digital readout to be located in amore convenient place on the dob, i am sure i have seen one in focus or homebase or suchlike ?

i am thinking of using one of these units with my homebuilt dob so i will follow your posts with interest, tony

[Moonshane]

don't see why not Tony - good thinking. that said, if you can get that in, I bet you have enough room for the encoder? there's a 1m or so cable from the encoder to the reader.