Gym weights as counter weights

[tomato]

I’m sure I am not the first one to do this, but I needed at least another 5 kg to balance my dual rig, and balked a bit at around £100 for a Geoptik item to match those already supplied with the mount. Had a look on Amazon and found these, £23 for 4 x 2.5 kg.

 

So, first step was to bore out the 1” centres to 40 mm, drill and tap some holes to bolt them together with their centres aligned, and then drill and tap one of them for a clamp bolt. The OD  of the weights is a bit bigger than the Geoptiks,  but they don’t look too out of place on the shaft along side the existing weights.

I know you will be saying, “all very well if you have access to machine tools”, but based on experience, the next thing an astronomer should purchase after a telescope and mount, is a second hand hobbyist lathe, it will save you £££ in the long run.

Edited January 9, 2020 by tomato
Typo correction

[michael8554]

I went for the rubber coated ones from Decathlon, about the same price.

Michael

[skybadger]

I used a drill press to do this, with a large hole boring bit. I ran out of energy eventually as the iron work hardened with just 2mm to go..

[Paul M]

I'm surprised they aren't more popular as counterweights. My old Fullerscope Mk3 mount was supplied with 1 x 5kg and I bought another when I was doing some experimenting. Luckily the shaft was sized to suit the existing hole. 

I know they are a bit ugly but, well, we use them in the dark. I doubt the neighbours would be gasping and tutting with indignation for lowering the tone of the neighbourhood.

Those on my Fullerscope are so old they must be old imperial kilos not the new metric type...

 

 

[tomato]

2 hours ago, skybadger said:

I used a drill press to do this, with a large hole boring bit. I ran out of energy eventually as the iron work hardened with just 2mm to go..

Yes, machining cast iron can be a bit of a lottery wrt encountering hard spots, fortunately these Chinese items seem to be made from nice and consistent material and bored out with no trouble at all.

[Rusted]

I've been using barbel weights for years on my old Fullerscopes mountings.
Aldi did a nice set in a box with loads of smaller weights up to 1.5kg. Very handy!

I used the cheapest and smallest diameter 5kg weights I could find online on my big mounting.
At 9" Ø they only just fitted in my lathe to smooth the rim on the rather rough castings.

These weights were sold as "Olympic standard" bore but were rather loose on my 50mm stainless steel shafts.
I eventually painted them white to avoid them attacking me in the dark.
It didn't work. They weren't properly "house trained" before I got them.