Altitude & azimuth calibrations, free to good homes.

[richardda1st]

Attention moderators, is this OK. Any suggestions?

If anyone is looking for or trying to make altitude & azimuth calibrations, I'm more than happy to draw them up for you using your design/details/size.

As a draftsman I can draw them up to scale using a cad program (licensed software). I will save them as a pdf file and attach them to this post for you and anyone else to download as you/they please.

Can you state the brand name of your dob as others may like to use it as well.

You can take this pdf file to a printing firm and have it printed full size and laminated.


Mine works well, see attachment. Although I use a Wixey digital angle gauge for the altitude.

Richard

ps
Can you please indicate with a post if you use any of these files.:thumbsup:

[[1ponders]]

Beautiful work Richard.

[richardda1st]

Well thank you Paul.:thanx:

I think that maybe the crowd is more into the electronic digital versions.:P

[Rod]

Hi Richard,

Yes that does look great! I would love to take you up on your offer as I am making a travelscope to take away with me to the NT in 3 weeks - nearly finished but this is one detail I would love to add. I have a wixey too for altitude but could use an azimuth circle like yours that was 340mm in diameter. Is that something you could do?

Thanks,

Rod.

[mercedes_sl1970]

Very nicely done.

Andrew

[richardda1st]

Hi Rod, it's my pleasure. Please find your file attached to the first post.
Have a close look at it and let me know if you need to change anything.
Let us know how it goes.:thumbsup:

Thanks Andrew, but it's the cad software that does a good job.:D

Cheers
Richard

[DavidU]

That's beautiful work Richard ! I really like the font.
I must measure up my 12" Dob and see what's required.
:thumbsup:

[richardda1st]

Hi Dave, I'll be looking out for it.

Can you state the brand name of your 12"dob as others may like to use it as well.:)

[Rod]

Thank you very much Richard,

I've been wanting to get one of these for a while. I'll get it laminated and let you know how it goes.

Rod.

[JethroB76]

These work really well, I had a wixey for my alt too, although it wasnt a great fan of the cold.

[richardda1st]

Hi Jethro

Yes the wixey is good, I don't have any trouble with it in the cold.
I would like the digits to be twice as big with a back light.

I have read and heard that you don't have to level the dob base when using the wixey as it will read the actual angle so long as it's zeroed correctly. I still level the base, otherwise the azimuth will not be spot on. The scope will be at the right altitude but will be tilted away in the azimuth, the worst case is when the scope is at right angles to the slope. I Suppose it all depends on how close you want to get. I like testing my self by trying to get my target in view with my 11mm plossl. Very satisfying when it happens. My 26mm wide angle is often used to rescue me when I miss.

I see that you have made it easy for yourself by using an Argo Navis.
If my interest doesn't wain I may consider one myself but it would have to follow an upgrade to my scopes mirrors.

Cheers
Richard

[JethroB76]

Yes, I never bothered about levelling the base (it was reasonably level where I always used it but I never once checked it), all I did was zero the Wixey with a spirit level and got very acurate results.
The AN came along as a B'day/Xmas gift but also through my desire for a more self contained unit so I didnt need a laptop out in the field.

[Visionoz]

Richard

I noticed that the readouts (degrees) are in a clockwise manner; my query is if there is any reason why it should not be anti-clockwise instead? Just a noob with a 12" SW FlexDob tussling with the idea of using the az scale ;) - and where can you purchase the Wixey (the USA mob doesn't want to ship international as they say they are too busy!!:shrug:)

TIA
Cheers
Bill

[JethroB76]

You should be able to get the Wixey gauge off Ebay - probably out of the UK, for about $50

[richardda1st]

Hi Bill

Not sure if I'm understanding you query correctly.
North is zero and east is to the right at 90degrees and so on.
Looking down at the calibrations this is clockwise.

As Jethro said, try eBay I did and found a supplier in England.

[mental4astro]

Please excuse my ignorance, but is there some program to convert sky co-ordinates to alt/az? Would prove most useful then.

I've got my alt. bearings with an 800mm diameter! Nothing subtle here! The azimuth bearing will need to have the ground board extended to expose it. No big deal, but doable.

[Rod]

Hi Alex,

Most planetarium programs I know of give object positions in both RA and Dec as well as alt and az coordinates. There are planetariums to suit PDAs, computers and phones.

You don't need a bigger ground board- just cut out a notch in the rocker so the numbers are visible like shown here:

http://www.homebuiltastronomy.com/ManualDobSettingCircles.htm

Rod.

[JethroB76]

RTGUI is also a good option for realtime altaz

[mental4astro]

:thumbsup::thanks:

[richardda1st]

Hi Alex,

I'm using starmappro on an iPod, works really well. An 800mm altitude scale, that would give very accurate readings. How about some pics?

Richard

[mental4astro]

Here are a few pics of the completed scope.

The width of the bearing's profile is 40mm if I remember correctly. Could be 50mm. Will have to double check.

Mental.

[richardda1st]

Mental it is.

Mental, I'm not sure if you are requesting any calibrations.:question:
Nice scope anyway. :thumbsup:

[Visionoz]

Thanks Richard - knew there was good reason of course for the Az to read clockwise - how silly of me :question:!
Ok will google for Wixey

Cheers
Bill

[Paddy]

Hi Richard,

What a generous offer. And timely. I'm planning to make one of these

http://www.iceinspace.com.au/forum/showthread.php?t=50647&highlight=spacegate

to convert RA-Dec to Alt-Az, and I've ordered a digital compass and inclinometer for setting circles. I've been wondering how to make the calibrations for the astrolabe. Hmmm...

[mental4astro]

Hi Richard,

I am keen on a set of scales, yes!

Probably best if I PM you my thoughts and stuff, and see what we come up with. OK with you? Or we can make it a project of this thread?

[richardda1st]

No problem Paddy, looks interesting. Just sort out what you need and get it to me.:)

Hey Mental, looks like Paddy is on the same band wagon as you are.;)

It's your project so I'll leave it to you, maybe the initial details can be via a PM, then back on this thread.:thumbsup:

[richardda1st]

Hi Mental

As per my PM please find your 3 PDF files.

Richard:thumbsup:

[mental4astro]

WOW!

Many thanks Richard, :thumbsup:!

Mental.

[richardda1st]

My pleasure mental, if you need/want to change anything it's no problem.
If you end up using them it would be good to see some pics.

Richard

[ColHut]

Hi Richard,
Per my PM, I will get you the specs for my 10" GSO. I am pretty sure that the the viewable area is 25 to 27 cm radius of an overall radius of 28.25cm. I will check. The depth is 19mm. (I am using a 51mm desk grommet)

regards


regards

[richardda1st]

Hi Colin,

Have a look at this attached (preliminary) pdf. Depending on your availability to a printer, maybe you can print a small section (to scale) on A4 and see if it will work. If it doesn't work just let me know, we can sort it out.:thumbsup:

Cheers
Richard

[ColHut]

Richard,
many thanks. I am testing it this evening to check fit.

This is much appreciated.

regards

[richardda1st]

Colin, I suspect the numbers may be to big, or may not line up properly with your 50mm cutout.
Are you going to fit a magnifying glass over this cutout, if so we can make the numbers smaller. Can you post a pic of the base.

Richard

[ColHut]

Richard,

I have decided to leave out the partial hole cover and thus the numbers and scale now fit very well. (You were right). Final checking will take a little longer as unfortunately when I printed it on my plotter it came out for some bizarre reason at 95% scale (The 100mm true line was 95mm long!) So I will need to check the settings before printing again.


regards and many thanks:thumbsup:

[ColHut]

Richard,
It seems that 98% of scale is perfect so I will reprint it at that. Thanks for everything. I will post a pic when done.

regards

[richardda1st]

My pleasure Colin, don't hesitate to ask if you need to tweak it for any reason. ;)
These things have to be perfect, don,t they?:D
I will be looking out for your pic.:thumbsup:

Cheers
Richard

[Greenswale]

A big thanks to Richard for providing me with a template to suit my 12" Lightbridge. Marvellous things happen at Snake Valley camps!

Richard has offered this for others to use, so the file is attached.

Now maybe my vague pointing at things will become a little less vague??!!

[alistairsam]

Hi Richard,

Attached are some pics of a quick dob mount that I built for my Imaging scope. as PM'd, the radius of the azimuth board is 23cm, and the diameter of the altitude semicircle is 11.8cm.

I built this mount over a few days, thanks to ideas from Alex (mental4astro).

I've used a lazy susan bearing in the azimuth, and for braking, I placed three slide eazy pads from bunnings, and stuck some felt over it. the combined height was 1mm more than the gap of the two boards with the bearing, so the felt was pressing on the upper board. I tightened the pivot bolt a bit (M12 with a nyloc nut and washers), and its now very smooth with no overshoot and stays in one place. have attached castors as well.

I have to get some teflon for the altitude, and reduce the size of the ota cradle, apply some varnish.

thanks.

[richardda1st]

Hi Alistair, here's your calibrations.
As I have said to the others, please don't hesitate to ask for any modifications.


Cheers :)
Richard

[alistairsam]

Excellent, thanks Richard, one minor change, can you please separate them into two pdf's, one for alt, and one for the az axis.
will then take them to the local print store.

Thanks

[bojan]

Hi Richard,
Those setting circles look really cool :thumbsup:

May I suggest one little thing: to improve the visibility (by reducing the number of lines) and still keep the same resolution, perhaps you could design the suitable vernier for each scale? This may be a bit fiddly to do (scale of the printout for each vernier must be reduced by appropriate factor, 9/10 or 5/6), but this may be be useful..
Such verniers were/are used on old-fashioned sextants and callipers (sometimes they have also magnifier for more accurate reading, not necessary here of course).
http://en.wikipedia.org/wiki/Vernier_scale

[richardda1st]

Alistair, will do, but take the A1 size as well, you may find it cheaper to print and laminate than 2 smaller ones.





Hi Bojan, I will look into doing that, sounds like a good idea. :thumbsup: thanks.

On my azimuth I do have a magnifying glass and find that using the 0.25 gradations is very easy.
But there's nothing wrong with more accuracy :)

Cheers
Richard

[richardda1st]

Hi Alistair

Make sure that the calibrations will suit the situation especially the azimuth to suit the window/cutout in the upper board. May need to compress the design.

Is the azimuth going to be free to rotate independently to line up without having to move the whole dob base? With mine it fits neatly around the lazy susan (not sandwiched in-between) so I'm able to easily adjust the azimuth with a known star then lock in place with a drawing board clip. Makes it real easy.

I will be checking out Bojan's suggestion shortly.

Cheers
Richard

[alistairsam]

Thanks for that Richard,

yes, the Azimuth circle will rotate around the lazy susan, i'll use a drawing board clip as well.

Will post some pics once installed.
Will be interesting to see the vernier idea as well.

Thanks again.

[richardda1st]

Alistair, if you can wait till tonight I'll draw up a set with the vernier. Drawing them up is no trouble, but fitting the vernier to your pivot will be slightly more involved than just fitting a pointer. But as Bojan pointed out it will be easier to read and more accurate :thumbsup:

By the way, You might remember that I use one of those electronic inclonometers (Wixey) for my altitude, simpler still.

Cheers
Richard

[alistairsam]

Thanks Richard,
yes, fitting the vernier might be a bit tricky as it'll need to maintain proper alignment and stay rigid. but worth a try.

one possibility is to stick it to the underside of a transparent plastic piece and sticking or fixing that to the underside of the top azimuth board. so the vernier scale will be outside the azimuth scale printout when viewed vertically and will rotate with the Dob mount.

yes, i do have an inclinometer as well, will try it out. do you manage to get objects in the FOV with its 1/10th degree resolution and do you have to calibrate it often?

[richardda1st]

Hi Alistair,

Here are the pdf files for the new calibrations with verniers.

As we are trying something different, I think it may be easier to sort out the fine details over the phone. The actual size and layout may need a lot more sorting. I think the altitude is going to be to small, we can extend the radius past your actual radius but this will need a very rigid setup.

As for the inclinometer, it's simple and perfect. I set mine up by locating a main star or planet using my 6mm or 11mm plossl, set the inclinometer to zero, lower the scope till the inclinometer reads the targets actual altitude then zero it again, no need to redo unless you think you need more accuracy. I generally find my targets using my 20mm plossl, sometimes fluke it with my 11mm.

Cheers
Richard

[bojan]

Richard,
this looks good, and it's much easier to read even from some distance.... :thumbsup:

The cutting should be done such that the black printed edges of the scales are not included - so the lines of both scales and verniers are in direct contact.

[alistairsam]

Hi Richard,

Not sure if I've understood it correctly, but wouldn't degrees need to be divided into 60 units for minutes?, so 10,20,30 .. 60?
how do we use the vernier scale from 0 to 9 to read as minutes?

[bojan]

Currently division is 1° , so resolution with vernier is 1/10° or 6'...

For resolution of say 10', the vernier should have 6 stripes, stretched over 9/10° on the main scale.
But, I think this is not a big issue at all.

[alistairsam]

its not an issue, but will be easier to read if the numbers were in minutes. that way you won't have to convert div 4 to 4x6' = 24mins.

or there could be 12 divisions of 5 minutes whatever's practically usable.
what do you think Richard?

[richardda1st]

Alistair, I always use decimal degrees, I find it a lot easier and more natural for my simple brain. Note that I have been using 0.25d on my original azimuth scale with a fixed magnifying glass and I have absolutely no trouble finding my targets. My only problem is recognizing a faint object.

Using the vernier as I have drawn it your are able to read 0.1d much easier even without magnification.:thumbsup:

Have you looked at the link on Bojan's post http://en.wikipedia.org/wiki/Vernier_scale very informative.

Anyway, let us know if you need to change anything, I am more than happy to draw up to your needs. It's up to you to tell me the actual size/radius and which side you need the vernier.

Cheers
Richard

ps Just saw that you added a new post before I posted this one, I'm very slow at this :P

Sent you a PM

[alistairsam]

Hi Richard,

I prefer decimals as well for measurements, but for astronomy, this concept of minutes and seconds is a bit harder since its in a scale of 0 to 60.

so when you look at the alt/az co-ordinates say in stellarium, that gives it to you in deg, min, sec.

not sure how you look for 21d 9m in decimals - is it 21.15deg?
my problem is converting the 1/10 vernier scale back to minutes or vice versa.

so 21deg 0.5 on the vernier scale would need to be converted to minutes, 0.5 * 60 = 30mins or 5 * 6 = 30mins if i'm not mistaken.

but if the scale was 1/12 and 0 to 60, that makes it very easy as each division is 5 minutes.
then you'd just need to watch the vernier scale till 30 lines up.

sorry if it looks like I'm asking for too much, but just my thoughts.
if its difficult, pls don't worry about it. this is ample.

i'll build a jig for the vernier anyway.

[richardda1st]

Hi Alistair, I wasn't aware that Stellarium only used d,m,s. I have been using Skysafari and Starmap Pro which allow you to use either.

I don't understand your numbers but I have made a vernier with minutes for the azimuth, have a good look and advise me as required. You may want to move the vernier to the inside, or whatever.

After that we can sort out how you want the altitude laid out, if you still want it.

Don't concern yourself about asking to much or to difficult. It's not costing me any money and I enjoy the exercise, so long as we get a perfect result.:thumbsup:

Cheers
Richard

[richardda1st]

Had another play around with the vernier, now I've got the hang of it.

I think this is what you are after Alistair, or maybe just 30min instead of 60min. This will be very easy to use, and very accurate.

Thanks Bojan, I wish you had mentioned it earlier.:thumbsup:

Cheers
Richard

ps To those of you who have the earlier versions v.1 :P:P:P

If you like to upgrade to v.2 just let me know.:lol:

[bojan]

Wow, this is Super-Vernier :thumbsup::thumbsup:
I was quite happy with first versions, but this one is really high resolution one.

[alistairsam]

Thanks Richard,
it does look much better. I will print it out and give it a shot.

A suggestion, is it possible to make it half the arc size with 60 minutes?
the current vernier is from 0 to 60 degrees (main scale) and may be too wide to get a quick reading, if the vernier is from 0 to 30 degrees (am referring to the arc length) it might be quicker as number of gradations would be half.

it might be a good idea to practically try out both the sizes in the field.
if you could draw up the smaller scale, i'll print both and bring it to snake valley and we could try it out.

we may not need to fix the vernier scale under the top baseboard. I plan to make an adaptor fixed to the upper face of the top baseboard with a double L bracket. so just need to print out the vernier scale.
I will attach some pics.

[alistairsam]

Hi Richard,
I presume we'll have to zero the vernier scale once the azimuth scale is rotated during star alignment or align the scale to the objects minutes value?

we'll have to think up an adjustable holder for the vernier as well that can be locked when zeroed.

[bojan]

Hi Alistair,
If you want the same resolution 1arc min), the number of graduations will be the same, only the distance between them will be halved, meaning you may compromise the readability somewhat (in the dark... it may be tricky for some).

[alistairsam]

Hi,

I meant half the gradations with half the resolution as 1 arc minute resolution may not be required to locate visual targets if the TFOV is around 1degree.

so if the resolution of the vernier is 2 arc mins, the line spacing would be similar to the current one but half the number of lines to visually align.

moreover, in the 10 secs or so that it might take to move the mount to the co-ordinate, the object would have moved by 1 to 3 arc mins in Az anyway.

I'm happy both ways, but a practical field test for ease of use would be the best way to determine optimum vernier scale.

Richard, thoughts?

[richardda1st]

The vernier will have to be fixed to the top board otherwise you won't be able to make your setting, I can't see the need for any adjustment.

The main azimuth scale will rotate freely on the bottom base (as previously mentioned) until you align your scope to a chosen target. Same as my setup, but replacing my pointer with the vernier. Actually simpler than I originally thought. You will have to fit the vernier by locating the 12mm hole to your M12 pivot bolt, simple.

As I mentioned earlier I will make a set with the vernier located on the inside of the main azimuth scale. The main thing will be to make the main azimuth scale with enough thickness to rub up against the lazy susan without sliding underneath. Also you will need to make your circular cutout around the lazy susan as close as possible and of course concentric with the calibrations and the M12 pivot. I will include a 12mm circle at the centre of the azimuth scale to locate it on the pivot. With the lazy susan fitted on top of the azimuth, use a new sharp blade (surgical blade) you should be able to stab the azimuth scale right up tight against the lazy susan. With the blade held at a slight angle secured into the bottom board and by rotating the free azimuth scale achieve a very accurate fit, this is how I did mine.

A lot of this depends on what type of lazy susan you are using. The one on the lightbridge has two identical round plates located simply with a centre hole. I have seen some lazy susan bearings which are rings not plates, not to sure how easy this type are to fit accurately.

I will post this new set shortly.:thumbsup:

Cheers
Richard

[richardda1st]

Hi Alistair

A new azimuth scale with internal vernier, let me know what you think. An old fashioned phone call will be better.:lol:

Cheers
Richard

ps As we discussed, added 60' vernier.

Will post pics ASAP

[alistairsam]

Richard,

Thanks a lot. Apologies for not calling, been a bit caught up at work.
Will call you.

Thanks

[alistairsam]

Thanks Richard, I will print out the 60min internal vernier and let you know if any of the measurements need adjusting, but otherwise looks perfect.
I understand why 60 mins can't be accommodated in a 30deg arc without increasing the main scale gradations, so will just stick to the 60min vernier.

should be able to fix it to my dob in a few days. will post pics once done.
thanks

[Battery519IDA]

Hi Richard,

My name is Dan and I have a odd request about the azimuth ring (circle) template you create (your talents are desired by more than the amateur astronomy groups).

Is it possible to make a azimuth template like the ones you have in this forum, but have it fit a 60-inch radius?

I have been searching for a program or anyone who could make a 120-inch round azimuth ring (template) and found your posts here. I have tried; Word, PowerPoint, Google SketchUp, GcmWin316BeGreat_Circle_Map.exe, RACIRC.EXE, SETCIRC.EXE, and Shadows.exe. None of which I could figure out or have it correctly create azimuth scale with a 60-inch radius (they may do it, I just couldn't).

What is the purpose of the 60-inch azimuth ring? During WWII the seacoast artillery battery's used a plotting board to track the location of targets (ships) to fire at. The actual board is listed in the WWII manual as having a 58-1/3 plotting radius (there are several different board sizes).

I am attempting to reconstruct a seacoast artillery plotting board for Battery 519 (Fort Miles) located in Lewis, Delaware (USA) with a diameter of around 120-inches (60-in plotting radius). It's a little larger due to the construction materials used (wood). The board will be used for student educational purposes and to show the basic operation of a seacoast artillery plotting board.

Attached is a picture of the board I am constructing (here also):
https://skydrive.live.com/?cid=7B47FB4AD80A1BD1#cid=7B47FB4AD 80A1BD1&id=7B47FB4AD80A1BD1!168 (https://skydrive.live.com/?cid=7B47FB4AD80A1BD1#cid=7B47FB4AD 80A1BD1&id=7B47FB4AD80A1BD1%21168)

The outer most ring in the picture is the azimuth ring/circle.

What type of azimuth circle template is needed?
* Fits a radius of 60-inches (120-inch dia)
* "0" as true south (180 north) ** The centerline (directrix) for this battery was: 278.86, East
* scale width of 1-1/2 inch (sections length as fits on standard paper)
* regular font (no italics for the numbers)

And if possible could it be made as "reverse printing" also? This would allow printing the sheets on plastic so they wouldn't be rubbed off.

If making a full circle template is not feasible then could one or two scales be made which when copied/printed they would fit a 60-inch radius (I could edit in the numbers)?

General text from the seacoast artillery manual:
"The circle is engrayed and numbered at 1 deg intervals, and the mean azimuth of the gun is indicated by the graduation on the center line of the board."
"The verniers on fixed gun azimuth circles were installed to read azimuths from true south."

I don't fully understand why they used true south as their base (0/360 orientation).

FYI: the astronomy websites are the only places I have found who deal with making their own azimuth rings/circles (and great pictures also)! So I thank you all for looking to the stars; what a lovely gaze you have!

For some good reading about the seacoast artillery battery's see:
Coastal defenses of Australia during World War II:
http://en.wikipedia.org/wiki/Coastal_defences_of_Australia_durin g_World_War_II

Thank you very much if you consider doing this,

Dan

[richardda1st]

Hello Dan

I will need some more details regarding your project before we can proceed. :shrug:

As this project is not related to astronomy I think it's best to use Private Messaging or emails. I suspect that there will be a fair bit of corresponding.
Maybe if it all works out okay we can add some details here later, just in case there is any interest from other members.:thumbsup:

Dan, I will send you a PM shortly (a day or 2)

I have just perused your Home Page http://www.fortmiles.org/ which has caused me to re-write all of the above, I had some unpleasant thoughts :rofl:

Cheers :cheers:
Richard