Magnets as counterweights

[wavelandscott (Scott)]

Anyone have any ideas where I might be able to source (in the Sydney area) some magnets to be used as metal tube dob counterweights?

I am not interested in going to e-bay so a retail store suggesstion would be valued.

Thanks!

[rogerg (Roger)]

Wouldn't magnets be a little risky, considering they can adversley affect so many objects? (credit cards, computer components, compases, data cables, etc)

[mill (Martin)]

You can get magnets out of old speakers some friends might have?

[gbeal]

Originally Posted by mill

You can get magnets out of old speakers some friends might have?

That was the way I went, old speaker bits, went to a car audio place, and rummaged their rubbish bin, got a few old sandwiches as well, LOL, just kidding.
Fit a metal strip to the underside of the tube, opposite the focuser/finder, and plonk the magnet on.

[ballaratdragons (Ken)]

Speaker Magnets is all I ever use. They come in so many different sizes (weights). You can slide then anywhere along the OTA.

Most Speaker Magnets are only held on to the Speaker with soft aluminium rivets, which file off, or break off, easily. Then I glued bicycle tube rubber to one side so it didn't scratch the paint on the tube, Felt would work too.

Here is a pic of my Magnets, with one tipped upside down so you can see the rubber glued to it.

[circumpolar (Matt)]

Originally Posted by rogerg

Wouldn't magnets be a little risky, considering they can adversley affect so many objects? (credit cards, computer components, compases, data cables, etc)

Does anyone know if they do effect Data Cables like encoders cables?

[monoxide]

if your worried about magnets try using a length of chain, as you go up in altitude the chain rests on the ground/dob base reducing the weight, same deal in reverse.
if you work out the right size chain then theres no need for swapping weights around as it does it by itself.

[wavelandscott (Scott)]

Thanks all for the comments...I had not thought of "speakers" as a source of potential magnets (I'm not sure why but I had not)...

[Starkler (Geoff)]

Originally Posted by circumpolar

Does anyone know if they do effect Data Cables like encoders cables?

Wont affect it at all.
Magnets could effect the magnetic encoders as fitted on the orion intelliscopes if they were close to them. Most everyone else uses optical encoders
(Im an electronics tech).

[erick (Eric)]

As I've added more weight at the front end - dew shield on finder - illumination of the finder, electric focusser - and as I reduced the altitude bearing friction with new teflon and ebonystar laminate wrapped on the bearing, counterweights have become essential for balance. I wrapped my speaker magnets in felt to avoid scratching the scope. Screwed a piece of steelplate on the side of the base (opposite to the eyepiece racks) to hold them in place when not in use. The felt is also useful when (!) you drop them in the dirt and they pick up small magnetiseable particles. If all else fails, the felt can be taken off and particles shaken off.

The only problem - when the scope gets moist (which is does frequently as the dew settles!), the magnets/felt may well slip as you raise your altitude without thinking. I've learnt the habit of reaching for the magnet (whether it is there or not) if I'm going to significantly alter the altitude. I've also moved the magnet to the top of the scope at high altitude (either against the Finderscope doveplate, or against a small stop I've fitted to the underside of the top end. Currently nothing else on the scope (eg. encoders) to interfere with - but I wouldn't want to drop the big magnet onto the eyepiece rack!