Tube Rings for GS12" Dobbie *FINISHED!!!!!!!!!!*

[ballaratdragons]

If you are like me and want to mount your GS 12" Dobbie up on an EQ mount, you are going to need some pretty Heavy Duty tube rings!

I had a local engineer make me a set which work reasonably well, but who wants reasonable???

I found that the weight of the 12" tends to pull on the rings as soon as it is tilted off centre. This is why rings need to be very strong! The rings I had made are not quite strong enough and are prone to twist.

A simple solution (but it took me a lot of time investigating alternatives) is to go to an Automotive LPG installer and purchase a set of LPG mounts to hold a 14-15" LPG bottle (a standard size).
These are perfect, as the GS 12" OTA is 14" diameter.

All that is needed (in my case anyway) is to weld on some hinges and some locking devices, then line the inside of the rings with rubber. Hey Presto!

Here is a pic of the LPG bottle rings I purchased today for $55, and they are VERY VERY VERY strong!!!!

The rings are 40mm wide & 5mm thick steel!

I will post more pics as the construction moves along.

Good luck tranforming your 12" Dobbie to an EQ :thumbsup:

[acropolite]

Typical Ozzie ingenuity Ken I'll be curious to see how they perform.:cool2:

[h0ughy]

nice one ken, they look a bit more industrial, hinges will be interesting to see later.

[astro_nutt]

Good idea Ken!!...BTW what type of rubber would you use to line the rings?

[robinsm]

BRILLIANT!!!!!! I have been racking my brains about a more solid replacement for my home made rings. My GSO 12" is mounted on a pier on top of an EQ6 (original type). The rings I made work but are not really solid enough. Thanks for the idea!!!

Cheers
Maynard

[ballaratdragons]

Dunno yet until I go to Clark Rubber and check out the densities, and grippiness. (I just made that word up, you can tell can't you :lol: )


That's why I stuck it in here Maynard, so others can use ite idea :thumbsup:

[ballaratdragons]

Here is the next phase of my new 'Heavy Duty' 12" tube rings.

Below is a pic of the parts ready for welding tomorrow.

On the left are the hinges. I searched Ballarat for the right hinges but had no luck finding 40mm wide 'Heavy' hinges, so I used the one I had at home and cut it in half!

On the right are the bolts and wing nuts for the locking system.

At bottom is the mounting brackets for the locking system. It is a car exhaust U clamp base cut in half. These will be welded under the flanges with the bolts drilled and pinned into them so the bolts can pivot up into place.

Keep watching this space for updates :thumbsup:

Hmmm, they look smaller in the pic than they actually are!

[ving]

very cool mr ken :)
you have quite a resourceful brain on top of those shoulders of yours :)

[gbeal]

Don't post too many tips, we don't want all those dobbers using a GEM as well.
I too use mine (only a 10" though) in a dob base as well as a GEM, brilliant.

[ving]

seems to be a few of us Eq dobbers :)

[ballaratdragons]

Gotta give people the option of EQ'ing the Dobbie ;)

Here it is after welding today.

All that's left now it to fit the locking bolts and the ED80 dovetail plate.

Oh, and paint it!

Oh yeah, forgot to mention, LPG gas bottle rings come in all sorts of sizes. Might be some to fit the 10" & 8" dobbies too. Get the rings that are 5mm thick steel though, the others are a bit thin.

Pic 1: The hinges welded on
Pic 2: Lock brackets welded on
Pic 3: Rings welded to cradle

[wavelandscott]

As your Scope is signed by John Dobson, I reckon that your work on these rings would make him proud!!!

Using "unusual" pieces to make a usable telescope I think is something he would find appealing.

Cool Idea!

[Starkler]

Ken, I reckon you are better off lining the inside with felt instead of rubber so you are able to rotate the ota in the rings.

[xelasnave]

That is real handy to know (have a 12 myself).
Now that is a fine first act but I want to see how you can turn out an EQ mount (suitable for fine astrophograpy) for under $200.
I am slowly building one using ford wheel bearings in an English Equatorial configaration but am apprehensive of a result for photos.
Do you have the eq mount?
alex

[ving]

thats what i thought... :)

[ballaratdragons]

Geoff and Vingo,

I thought about using felt, but it ain't for optical usage, it's for imaging, so it doesn't matter which way up the scope is. Plus (as I have already discovered) the OTA is so heavy that it slides down thru the rings even when done up tight!!! So the rubber will help grip it into place and hopefully stop the dreaded slide. (can be fixed if need be).

If it becomes a nuisance and I do want to turn it in the rings, I have some proper stick-on Tube rings felt which I can attach to the rubber.

For optical use it will be plopped into the Dob mount anyway.



Alex, where have you been for the last 6 months? You have never seen the threads about my EQ??? in here or SCP or Cloudy Nights?

Shame Shame! Guess who doesn't read the site properly :lol:

Alex, try here: http://www.iceinspace.com.au/forum/showthread.php?t=5657&highlight=restoration
and here: http://www.iceinspace.com.au/forum/showthread.php?t=10687&highlight=mount
and there are more in IIS.

Then try here: http://www.cloudynights.com/ubbthreads/showflat.php?Cat=&Board=atm&Number=858808&Forum=All_Forums&Words=EQ%20restoration&Searchpage=0&Limit=25&Main=858808&Search=true&where=bodysub&Name=15563&daterange=1&newerval=1&newertype=y&olderval=1&oldertype=m&bodyprev=#Post858808

So as you can see Alex, Yes I do have a mount :lol:

[xelasnave]

Well I must give the impression all I do is read stuff on the net and that is more or less true... however even I find that there is stuff I dont know about...I know I know you find that hard to believe but assure you that is the truth.
Missing an eq article particularly on a 12 inch such as we are both privelledged to enjoy clearly points to the need for some helpers in the Lab. I am already working 7 nights a week.
Top marks for your project I feel encouraged to keep at my project..well almost..I think I will watch for a while longer.
alex

[Sausageman]

Ken,

What a great bit of innovation,
Just a thought on the hinges though.
Hinge pins are usually riveted at each end, now you have cut through it, be careful that the pins don't work thier way out. Either replace the pins with longer ones and bend the ends or a tiny weld on the cut end should hold them in position.
Don't wanna see a 12" hit the ground.

Mike

[ballaratdragons]

Very good point to mention Mike.

Fortunately I forsaw the problem and how I solved it was to remove the hinge pins from both halves, countersunk the cut ends, and re-inserted the pins. Then I hammered (riveted) them into the countersink.

Alex, sit back and read as I make all my mistakes. Then you will be able to get it all right when you do yours. Good luck when you attempt it and keep us up to date with yours too :thumbsup:

[ballaratdragons]

UPDATE

Today was spent making the Dovetail Base Plate or Saddle or whatever it's correct name is.

It is constructed in the simplest way by using 2.5" x 3mm flat and 2 lengths of 1/2" steel rod.

The rods are welded along each edge off the flat creating a tapered channel for the dovetail to sit in. Then two holes are drilled and tapped for the locking screws to lock the dovetail in place.

It is heavy, but weight doesn't bother me. I'll just add another counterweight!

Here are the pics.

Pic 1: the Dovetail Saddle runs from one ring to the other giving plenty of sliding adjustment.
Pic 2: See the negative dovetail shape created by the round bars.
Pic 3: Dovetail plate and rings in place in the Saddle.

[xelasnave]

I am happy to see all the weight you are going to ask that mount to manage. I just thought of something you can put a gas tank in there rather than the scope to get things sortted with suitable weight... it would look strange but how convenient.
I have build one large mount (fork configuration) out of an old bed frame and wheel bearings and I should know not to try again really but as you know a mount to carry our little darlings capable of astrophotos is not cheap...I want to carry the 12 inch and 2 six inch scopes so a commercial mount would be over $20,000 I expect.
I will try and post the plans at some stage but in terms of real work its a pile of steel and bearings at the moment
alex

[Harpspitfire]

great job!-i have a nephew that works in a machine shop and sometimes makes me accessories i need- i like the heavy duty quality of home made stuff

[ballaratdragons]

Alex,

Most of the good home-made stuff begins as a pile of bits and pieces and junk. It's up to us to turn it into Astro Art.

You will usually find that the majority of home-made items are made with overkill in mind, so if you make a home made mount to carry a 12", it will probably carry a 14 - 16".

I think Darren (wombat) was looking at making a home made fork mount for his 12" as well.

If you want some very solid heavy duty axis bearing use car hubs. If they can carry the weight of a car they can carry a telescope!!!

Mine has Holden hubs and bearings on both axis and they glide so smooooothly.

I look forward to seeing your plans and watch it develop.



Also gives a sense of pride - and it's cheaper too!

[ballaratdragons]

HOORAY!

Here is the finished product.

I couldn't take a pic of it all set up on the mount coz it's raining.

The rubber lining inside the rings is from Clark Rubber. I tried several densities at the shop until I found the right one.

I am very happy with the finished product and it ended up cheaper than I expected.


THE COST:

LPG Bottle rings - $55
Base Cradle & all welding - $40
Etch Primer & Black Paint - $20
Hinge (1 cut in half) - $4
Lock bolts & wingnuts - $2
Rubber - $22
2 Dovetail lock screws - 50c

TOTAL - $143.50

[ving]

now show us her mounted :)

[h0ughy]

VING:eyepop: :D

[ving]

come on houghy, back outta the gutter with you!!! :rolleyes:
:)

[ballaratdragons]

I'm waiting for the rain to stop. I wanna see it on the EQ mount too!!!!

[ballaratdragons]

Correction,

I wanna USE it on the EQ mount!!!

[Astroman]

Looks great Ken, well done. We are an inventive lot arnt we :)

[ballaratdragons]

We sure are Astrew!

For those that want to make their own set-up like this, here is a close-up of the ring locks.

I used 1/2" bolts with the heads cut off, positioned in the brackets I made using the car exhaust clamp cut in halves, then drilled with a 5mm drill and pinned with 5mm Split-Pins. It is plenty strong enough!

[h0ughy]

no not me, its already nounted, just needs to be placed on the mount:D ;) :rofl:

[ballaratdragons]

Drum Roll Please ................................... .........



Presenting the finished Product, complete and assembled and scope inserted!!!

Finally the rain stopped long enough for me to test out the new tube rings.
I had to add lot's of counterweight.

Pic 1: The rings on top of the Mount
Pic 2: Scope mounted in rings

[ballaratdragons]

and one more pic: Harry Modelling with the finished set-up :thumbsup:

[avandonk]

Ok Ken why is the dob mount on the same axis as the EQ mount? All the the jokes aside, looks very fantastic and shmickkk.

Bert

[xelasnave]

That looks great. I presume we can expect some astro photos sooon?
You young fellas sure can get things done.
alex

[ballaratdragons]

Thanks Bert.

Answer to your question: Symmetry ;)

Hope you are happy with the finished product :thumbsup:
Bit different to what it used to look like. Thanks for giving me the opportunity of restoring such a fine mount.


As soon as the sky permits me to, Alex. :)

Young fella? Cool, haven't been called that in a long loooong time. :lol:

[h0ughy]

:2thumbs: :jawdrop: :nerd: :prey2: :clap: :clap: :clap: :clap: :party: :thumbsup: