Setting Circle mod for dob bases.

[Daz Type-R]

Just like my lazy susan bearing mod guide I did, I thought I would also knock together a guide for any dob user who wants to fit a setting circle to their dob base, just to aid in finding those faint fuzzes.

 

So first off a list of the things you will need.

 

1.  While not actually part of the setting circle, if you intend to find those faint fuzzes then you need something to give you the ALT co-ordinates, for this you need a Wixey or similar angle gauge, these retail for approx £20 and can be picked up from Amazon, E-Bay etc.  Just do a search fir wixey digital angle gauge.

 

2.  This is a list of things you will need for the actual setting circle itself.....

 

A sheet of 3mm Ply wood or MDF.

 

A cable tidy (Approx 2" in diameter)

 

Some black wood paint (I suggest Matt black, as gloss could reflect some shine) and a paint brush

 

Sand paper

 

A drill

 

A drill bit the width of a paper clip

 

A hole cutter (2")

 

A paper clip (red or white)

 

Strong glue

 

A squirty bottle with a fine spray nozzle with some water and a tiny bit of washing up liquid in it

 

The actual setting circle itself which can be purchased from our very own member Mike (Perkil8r) by dropping him a PM.  (for non-members reading this his website should be up and running soon, I will insert the web address here when he is ready).

 

Jigsaw or hand saw

 

Credit or debit card (not just to buy everything)

 

Now there are a number of ways in which you can attach the setting circle and it also depends on what other mods you have done (lazy susan bearing for example) and how much time and effort you want to spend.

 

The simple option would be to just stick the setting circle to the ground board and cut a hole in your top board but this means you would have to keep lifting your whole dob base and OTA just to get Polaris in the centre of your FOV and the setting circle to be at zero degrees.

 

I went for the more difficult option but also the option which gave greatest flexibility come set-up time.

 

So the picture below is my ground board with the lazy susan bearing and slide guides all ready attached.

 

 

Now, I need to fit my movable setting circle around the bearing and the slide guides, so to do this I have had to cut my setting circle with a hole in the middle (for the bearing) and holes just out side this to cater for the slide guides.  To cut the hole in the centre I just removed the bearing and drew around it onto the setting circle then cut it out.  To cater for the slide guides, I just measured how far they were from the centre hole and then decide how wide the hole needed to be, see picture below...

 

 

The width of the gap equates to 30 degrees on the setting circle, so come set-up time, I can get Polaris in the centre of the EP, then adjust the setting circle so it reads zero, with out having to keep lifting the dob base and OTA up.

 

Now the setting circle by itself is only thin vinyl so is very weak and flexible, so to give it some strength I am going to stick it to some 3mm ply wood.  This wooden base will also have a handle, this is required as when the setting circle is sandwiched between the ground board and the top board, it will be very difficult to turn the setting circle.

 

The wooden base for my setting circle also needs to be the exact shape and size as the vinyl setting circle, so this was simple to achieve as you just place the vinyl setting circle onto the 3mm ply wood and draw round it and cut it out, see picture below (note the extra "lump" on the base, this is the handle, you can make this as large or as small as you like).

 

 

Next I just sanded it smooth, wiped it down with a damp cloth and then once dried, set about painting it.

 

 

And the finished look..

 

 

While this was drying, I set about measuring how wide the actual degrees were on the setting circle and where the viewing window on my top board would need to be (by "how wide", I mean how wide is the black boarder with numbers on, see below....)

 

 

I have not provided any measurements in this guide as the size of the ground board, setting circle and top board will all vary depending on the size of your OTA ( a 6" OTA will have a smaller dob base than a 16" OTA).

 

Now my setting circles degrees are 2" wide, hence why I have listed a 2" hole cutter on the list of requirements.

 

Once measured where the setting circle viewing window would need to be, I cut it out.

 

 

Now you need to stick the vinyl setting circle to the 3mm ply wooden base, to make this a lot easier, I peeled the backing sheet off the setting circle and then using the squirty bottle with water and a small amount of washing up liquid in, I sprayed the back (the side that is sticky) with the soapy water and then placed the vinyl onto the ply wood matching all the spaces etc.  Sqirting the soapy water onto the vinyl makes it a lot easier to move into place, without the soapy water, the vinyl would just stick to the wood and you would end up in a mess.  The vinyl may have air bubbles in it, so using a credit/debit card, gently push the air bubbles and any creases out.

 

It should now look something like this...

 

 

and placed on the ground board...

 

 

Now I advise that you leave this overnight somewhere warm and with a heavy ish weight on it.  This will make sure it dries flat.

 

While that is drying, I set about making the marker that will fit into the viewing window and makes reading the Azimuth degrees a lot simpler.

 

So taking your cable tidy, draw a straight line on the top of both sides of the cable tidy and then extend the lines down the side, now on these lines and at equal height, drill a small hole so that the paper clip (once completely straightened out) will fit through, so that you have something like this....

 

 

I used a red paper clip but you could use white.

 

You could glue the paper clip in place but I held it in place by bending it and leaving it like this....

 

 

It is held in place once you insert it into your top board but before you do, place some strong glue on the lip of the cable tidy and then press firmly into place, wiping up any excess glue immediately.  It should now look like this...

 

 

By now your setting circle should be flat, dry and ready to be put back in between your ground board and top board and bolted back together.

 

If you have measured everything correctly, it should now look like this.....

 

 

Hope this guide has been useful, if you have any questions or comments,  please post them below.

 

 

Edited June 22, 2018 by Daz Type-R
Trying to sort out the photos thanks to rubbish Photobucket

[BAZ]

That is an excellent guide Daz, thanks for sharing, Iam sure it will be very useful.

It must work, as your Messier count has climbed rapidly recently.

[Doc]

fantastic tutorial Daz.

 

it's easy to read and the photo's work very well.

 

Does the white on black show well at night?  Also are you going to add a light to the peephole.

[Daz Type-R]

Thanks guys.

Yes Mick, there was some substantial testing done by myself and the person who made me the vinyl setting circle, which involved me, a red light torch, the under stairs cupboard and a section of the setting circle with white numbers on black and vice a versa.

What we decided was the best is the above.

Not sure on the red light as I have a red light strapped to my head most observing sessions anyway so it would just be something else to power but I have not ruled it out.

[T A WOW]

Brilliant guide Daz

[+RonC]

Thanks Daz, did you find the website for the setting circle please??

 

Cheers

Ron

[Tibbz2]

Awesome guide! 

 

I would love to do this but I don't think I have all the money or tools for it at the moment!  Looks great though

[Daz Type-R]

Thanks Daz, did you find the website for the setting circle please??

Cheers

Ron

Hi Ron, just waiting for the chap to get back to me.

[Daz Type-R]

Awesome guide!

I would love to do this but I don't think I have all the money or tools for it at the moment! Looks great though

Thanks!

As for the cost, it's not that bad, granted what one person thinks is cheap, another person may well think it is expensive, I will try and give an estimate below, this is of course assuming you have drills, drill bits etc, I'm just giving you a parts cost....

Wixey £20

3mm ply board, a big sheet enough to make 2 setting circle boards, £6 from Wicks.

Black paint £5 from local DIY shop

Box of paper clips, £2-3 (guess)

Super glue, £3-4

Cable tidy, pack of 4 from Amazon/E-Bay, £2-3

Sand paper, £1

Setting circle, depends on your size of dob, not sure of price as I got mine "cheap" as mine was the prototype, £25-£40????

So approximately £72 for the lot and it can all be made in 24 hrs if you have the time (and no 3 year old!!)

[Daz Type-R]

Ron, heard back from my chap and he is.......

Our very own Mike! (Perkil8r)

If you want one, can you drop him a PM.

Edited January 18, 2019 by tuckstar

[Perkil8r]

Ron, heard back from my chap and he is.......

Our very own Mike! (Perkil8r)

If you want one, can you drop him a PM.

 

It is me yes   If anybody wants one PM me and I'll sort you out. I have most scopes done but can do them to almost any size.

[Guest devil74]

Excellent tutorial there Daz and was good to see it in the making round yours, certainly helped me understand it better.

 

Might give this a go myself if i can work out how to fix it to the base (mine isn't the skywatcher).

[Guest devil74]

Right I have a bit of a dilemma...I want to fit a setting circle but cant decide on which way to go.

 

Mine is an Orion with the square metal base (well aluminum) so makes it a bit more awkward. The base itself is approx 12.5" square, 18" across its diagonal. So my two dilemmas are;

 

1) A setting circle that would fit nicely under the footprint of the base...about 18" diameter. This would not stick out as i rotate around. Also, as the base is aluminum it could easily be drilled for a viewing/pointer hole as Daz and Ron have done - I like this idea because the footprint of the base is not increased.

 

2) A setting circle whereby the degree markings are 'outside' of the footprint of the base, i.e the degree markings start at 18". I'm guessing the whole circle itself would then be a few inches bigger..maybe 22"-24". Now the problem here is this would increase the footprint quite a bit (and its circular) and some form of pointer would have to be fitted to a corner of the base so that it sits over degree markings, however this may be prone to damage with feet.

 

Any thoughts on this you astro freaks  .

[Daz Type-R]

Can you stick a photo up of your base, might help us visualise a solution.

[Guest devil74]

Here you go Daz;

 

http://www.orionoptics.co.uk/MOUNTS/dobsonianmount.html

[+RonC]

That looks interesting?

[Guest devil74]

Daz looking at your pics it looked like you allowed 15 degrees either side of each slide bearing... has this worked ok for you in terms of being able to 'polar align'?

 

I only have three feet thus three nylon runners to contend with 

[Guest devil74]

That looks interesting?

 

What do you think Ron?

[+RonC]

I would suggest a square board under the base, similar size with a round setting circle and an aperture cut through to read it?

Mine is fixed and takes a bit of setting up using 2-3 known star positions.But is very accurate for the rest of the session!

[Perkil8r]

I would suggest a setting circle that falls inside the confines of the base so there is less to trip over etc. 18" is no problem size wise.

 

As for mounting, I would be tempted to go Ron's route with it being a square base.

Edited August 25, 2013 by Perkil8r

[Daz Type-R]

Daz looking at your pics it looked like you allowed 15 degrees either side of each slide bearing... has this worked ok for you in terms of being able to 'polar align'?

 

I only have three feet thus three nylon runners to contend with 

More than enough, no issues at all.

[Guest devil74]

Ok thanks guys.

Mike if I had an 18" setting circle is there a standard blank edge around it?

[Perkil8r]

Ok thanks guys.

Mike if I had an 18" setting circle is there a standard blank edge around it?

 

they come square to cut out to the dotted line. There is approx 10mm between the dotted line and the edge of the scale, and 5mm outside of that for the square if that makes sense? I can get them printed any which way you want though. Any size etc. I have done the files for most common sizes, yours may have to be done from scratch so it can be however you need it Of course there's nothing to say you have to have one of mine

[Guest devil74]

they come square to cut out to the dotted line. There is approx 10mm between the dotted line and the edge of the scale, and 5mm outside of that for the square if that makes sense? I can get them printed any which way you want though. Any size etc. I have done the files for most common sizes, yours may have to be done from scratch so it can be however you need it Of course there's nothing to say you have to have one of mine

Understood Mike. I defo want one of yours because I know they are good quality. I'll start measuring/getting head around it etc tomorrow and I can then do you a drawing with measurements on or something. PM me the price if you wouldn't mind Mr Perkil8r!

Damian

[Osborne]

Hello,

I'm a new member trying to find my way around the site. I came across your setting circles for dobs I have a ten inch meade and wish to set it up with a setting circle. I have not been able to find where I could buy the setting circle. You say go to a member Perkil8r, how can I contact him please? I want to get on with this project, I already have an Inclinometer.

Yours Osborne.