Simple low cost counter weight for AzGti

[vlaiv]

I've got craving to do some light weight wide field imaging - just a simple DSLR on a tracker from my back yard (not the best location but I'll take it ).

Since I still have not ordered wedge and counter weight for AzGti to go in EQ mode - for this little exercise I decided to go with what I have on hand. At first I thought to just go without counter weight, but then I realized that I have L bracket and camera (Eos 750d) and 55-250 Canon IS STM lens and I'll be shooting stuff near zenith right past meridian - all that weight will be hanging at almost 90 degrees - almost horizontal - like the worst place to hang weight without having counter weights.

Wedge will be simple Ball head for photography, and hopefully I'll manage polar alignment with simple finder scope (I'll aim for Polaris itself - that will give me just enough error to have sub pixel trailing at 55mm FL for one minute exposure).

I had everything sorted except for counter weight. Where could I get it on a short notice at a reasonable price? It turns out that it was less expensive than I even hoped.

Here is the unit "assembled"

I purchased threaded rod - M12 - one meter long - ~ 1.3 euro (you can even save some money if you can get 20-25cm M12 screw threaded full length and you are happy with that length of CW shaft).

Three M12 hex nuts - two regular ones and one with rubber thingy that I used as nice end cap ~ 0.7 euro total

15 pieces of slightly oversized washers - larger than M12 but small enough so they can still be held in place with M12 nut  ~0.75 euro total

Assembly - well, one just needs to cut off a piece of threaded rod - long enough to be decent counter weight shaft - I used hand saw and it took me something like 5 minutes to do it? Then assemble as per image above.

Balancing is achieved by loosening and moving nuts and washers and then tightening them back up.

It would perhaps be better idea to use one nut with counter screw as above can become loose on rotation - like when screwing everything into mount head.

Btw, each washer is about 40g so 15 of them will be roughly 600g - enough to balance DSLR and lens but probably not scope + camera. Either more washers would be needed for that or something else for counter weight.

Total cost ~2.75 euro. I don't see it being cheaper than that

 

[Robindonne]

Whats nice of all these diy solutions, you dont have to be embarrassed at all.  Its always used at night and in the dark🙂

[AstroMuni]

2 hours ago, vlaiv said:

I purchased threaded rod - M12 - one meter long - ~ 1.3 euro

I love it....and only wish I could get things so cheap in the UK 😞

Edited August 19, 2020 by AstroMuni

[vlaiv]

1 hour ago, AstroMuni said:

I love it....and only wish I could get things so cheap in the UK 😞

Indeed, I guess wholesale prices can't be that different. I just saw pack of M12 hex nuts - 100 pcs for £7.59 online.

Rest is just price of running the business and wages in UK are a bit higher than over here

[szymon]

Hah.  I have just gotten an AZGTi from FLO (delivered today to the dark site we are visiting in Exmoor from tomorrow, thanks Steve) and I realised that I don’t have a counterweight bar.  So the plan was to pop into B&Q on the way tomorrow morning and get an M12 threaded bar and do exactly this 🙂.  I have a small rechargeable usb-powered dremel with me (usually used for tidying up 3D printed items but I am hoping it will cut through metal, albeit maybe slowly) and with luck will have a working counterweight bar for imaging tomorrow 😄 

[szymon]

Ok, I am working on a CB solution 😉.  However, a question — should the R.A. axis be so stiff?  Even when the clutch is completely undone it’s not loose enough to “balance”...

[szymon]

This is the initial CB solution 😉.  B&Q were sold out of M12 washers!  

[vlaiv]

11 minutes ago, szymon said:

should the R.A. axis be so stiff?

My RA was rather stiff but with time I've got the feeling that its becoming better / more fluent - it is almost at the point where one could balance

12 minutes ago, szymon said:

This is the initial CB solution

That is probably not the best solution - water is going to shift around and cause shake issues.

Smaller bottle filled with sand might be better option - sand is also not the best solution as it is "runny" as well, but at least won't be sloshing around in breeze.

[szymon]

Yeah it’s only a temp solution as I don’t have enough weight for the bar.  I got an m12 threaded rod and nuts but there were only five washers in the shop!  Will see tomorrow elsewhere if they have some.  I can try multiple nuts or something 😉

[SthBohemia]

In the making....

Ingredients-

1 large can of fruit salad with contents removed, either eaten or tipped out the nearest window.

a length of copper water pipe slightly longer than the can. 3/4" internal diameter for a SW mount.

a pile of rusty nails, screws and any other heavy metal objects that will fit into the can.

100mls of bondcrete or similar cement hardener.

a couple of kilos of cement.

Method-

Cut central hole in can to accommodate the copper tube, place tube inside can fitted into the hole.

mix cement thoroughly with some water and the bondcrete, add cement mix to the can slowly 15-25mm then introduce metal objects and more cement 🙂

Stir well with a wooden spoon 🙂  Fill can with metal junk and cement to the top leaving say, 25-35mm of pipe exposed!

Bake within a moderate oven set at reglo 50C for a day or 3.

Remove from oven (do not attempt to eat) and drill/tap to accommodate a 4BA screw (must be 4BA) to hold the weight to the axis!

Paint finished article with a Mickey Mouse face 🙂 

Voila....

[Peter-uk]

Metal junk would rust prefer my solution

[david_taurus83]

I used a custard tin.

 

[Ags]

On 20/08/2020 at 20:07, vlaiv said:

That is probably not the best solution - water is going to shift around and cause shake issues.

No issues when temperatures are below 0°C 😀