CG-5 mount

[Louwai]

Hello all,
Is anyone able to give me the exact specs for the standard counterweight bar on a CG-5 mount?? I need to know the definate thread sizes for the large male thread where it screws into the mount & also the small female thread which accepts the small end safety cap.
I have it laying here in front of me but don't have the suitable tools to measure these accurately. Would also like to know the exact diameter of the shaft. It looks to be 20mm when measured with a ruler but could well be 19.5mm or similar. Possibly 3/4".
Any info would be appreciated.

Cheers, Bryan

[sheeny]

Bryan,

My rod measures 19.9mm +/- 0.05mm measured with verniers - 3/4" is 19.05mm so it's 20mm rod.

I don't have any thread gauges or thread tables at home so I can't be definite about the thread other than to say it is not metric - 20 pitches measures 40 and a bit mm... 16mm metric coarse thread would be a neat 40mm. I would be 90% sure its a 5/8" UNC thread.

The keeper thread measures 5.7mmOD. A standard 1/4" camera mount thread (which I think is the same as 1/4" W:thumbsup:) does not fit. I would expect it to be a 1/4" UNC but I can't be sure...

Al.

[sheeny]

OK, Bryan.

The keeper thread in the end of the rod is an M6 coarse thread:thumbsup:. I just tried some different screws I had in the shed.;)

BTW a 1/4" camera mount thread is the same as 1/4" UNC which is the same as 1/4" W.

If ever there was evidence that is was an american design made in asia it's the mixing of units and thread systems!:rolleyes::screwy:

Al.

[Louwai]

Greatly appreciated Al.
It's certainly a step closer than where I was 2hrs ago.:)

Cheers, Bryan

[Louwai]

Just to explain my reasons.
I need a slightly longer c/weight bar. About an extra 100mm.
Just so happens that my retired father who lives at Bribie Island just north of Brisbane has a nice lathe in the shed that he loves to play with.
Mum's coming to visit us in Melb in September so I thought I'd get Dad to whip up a longer bar & Mum can stick it in her suitcase when she comes.

I could send the original to him for a definate sizing, but I don't want to be without the use of the scope for that long. So, dimensions will have to do.

Again, thanks for the help.

Bryan

[g__day]

A longer bar will increase vibrations by the cube of the length according to physics, sure you can't just add more weight and keep everything really well balanced?

[Louwai]

Yes I certainly could add more weight, but as usual I'm looking at my cheapest option. As described below would cost me virtually nothing. (family's good to me) ;)

I could ask Dad to make extra weights, but they'd be to heavy for poor old Mum in the luggage. And they are far to expensive to buy considering what they are.
Most frustrating thing is that being a boilermaker I could whip up a weight in an hr or so but having recently moved to Melbourne I don't have any of my gear. It's all still in Bris.:mad2:

So the next best thing was to extend the shaft.
If anyone has access to a boilermaking workshop in Melbourne that I could "borrow" for a couple of hrs I'd be set.

Bryan

[Terry B]

I agree that the counterweights are ridiculously expensive. Normal barbell weights are vastly cheaper but have the wrong size hole. A clever person could machine an adaptor for the hole but you still would need that lathe as you suggested. It would be much lighter though to just pack a small adaptor rather than a big weight. Then a small clamp to hold the weight against the counterweight you already have.

[mill]

I just used dumbell weights on my cg5 by first fitting an original weight, than the dumbell and then another original weight.
This keeps the dumbell weight locked inbetween the two other weights.
Dumbell weights here are $1.00 a kilo.

[Louwai]

Looks like this might be the way to go.
An adapter will be no problem. Have made several in the past to enable power saw blades with different hub / hole sizes to be used on my power saw.
If I reacll, the hole in lifting weights is around 25 to 30mm. Should be no problem making a sleeve & also making some sort of locking mechanism.

I'm thinking of a externally threaded shaft 30mm longer than the thickness of the weight. A flange on 1 end to stop it pulling all the way through. A locking nut which will screw onto it & lock the shaft / spacer into the weight. Then a grub locking screw through the protruding section onto the original bar to keep the weight in place.

[g__day]

I use one dumbell weight sandwiched between two Celestron counterweights. I simply made a very snug plug out of wood, so the dumbell weight was very snug on the bar and then sandwiched it very snugly and spray paints it black.

Ultra economical, totally fit for purpose, looks fine!

[spearo]

Hi
I agree, longer shaft might cause more problems than it solves.
I too decided to move to adding weight plates from a local Gym equipment store (very cheap).
I needed to make the hole a snugger fit and discovered that a section of tube that holds the little solar powered garden lights fits perfectly (I'd kept the tube after a light got broken...I KNEW it would come in handy...It was worth it just to be able to show my better half there was a point in me keeping things...:D).

I simply refuse to pay the outrageous price of commercial weights.

I added a thin layer of rubber (2 mm wetsuit type stuff) between the sandwiched weights just to be sure there would be no movements.

cheers
frank

[Louwai]

Well gents you've certainly made a good case. Have put a bid on a couple of weights on Ebay. I still need to look into a locking device as I only have the 1 standard weight with a locking screw, & therefore can't lock the Gym weight between. (I've currently got a couple of diving weights attached)

[Terry B]

I bought a locking ring that is designed to go on a barbell. It is larger in diameter than the counterweight bar but still works as a lock.

[ballaratdragons]

Barbell weights work well :thumbsup:

And if need be, you can easily just add more . . and more . . and more

Here's mine :eyepop:

[g__day]

Brilliant!

[erick]

and More and MORE AND MORE!!!

You sound just like my trainer at the gym!!

[Louwai]

Well.... I've acquired a set of dumb bell weights from ebay for $5. Total of all weights is about 25kg so should be able to do what I need to with that.
I just have to go pick them up.
We'll see how I end up.

B

[wasyoungonce]

This thread is exactly the info I've been seeking.....Thanks Gents:thumbsup:

[Louwai]

OK guys, here it is. I only used 2 x 5kg weights + the original. Still have spares if I need them.;)

[g__day]

Bryan - excellent - but now you've really caught my interest! Could you please take a few shots of you saddle plate and brackets - in particular have you attached the Celestron by a CGE bar to the dovetail bracket? I really want to do that! Is that a Losmandy bar you used or one of the incredible Robyn Casady saddles?

A few close up shots of the saddle and brackets would be really helpful - especially if you put a ruler into the picture. Could you tell me where you got the connectors and what kind of dollars they cost.

Many thanks,

Matthew

[Louwai]

Mathew,
I bought the side-by-side mount from Ken Duzat. (Ken's Rings)http://www.kendauzat.net/

I bought the mount X bracket, the slide & rings for the AT80 & I also bought the AT80 from him 2nd H.
The X bracket suits the CG-5 mount & the dove-tail which accepts the tube bar is removable. So you could choose one to suit a tube with a CG-5 or a CGE. This is also in a fixed position on the end of the main X bar.
The dove tail on the other end of the main X bar which my AT80 is in, is attached via a slot in the main X bar & so the AT80 could (if needed) be adjusted to suit cross balance.

You can see I've also mounted the ctrl box for my Feather Touch focuser on the bar as well.

Ken seems a nice enough guy, but I don't think I'd buy from him again.
I wasn't overly impressed with the quality & finish of the bits for the money.
In the pic showing the underside of the AT80 you can clearly see that the rings are miss-aligned. Also, he has used very cheap paint on the aluminium which scratches at the lightest touch.

I recently saw similar mounts & brackets at http://starstuff.com.au/page15.html or http://www.robincasady.com/Astro/index.html
These seem to be a little better made.


With regard to your offer of a cable YES PLEASE.

Please send me a PM with your email add & I'll send all the pics & details for cable.

[g__day]

Thanks - yes Ken's rings seem function but low end finish and milling.

Robin Casady's appear to be the other end of the spectrum.

I might go local - I hear a neighbour within 100 metres is a top machinist!