Tension springs vs counterweights for Dobs
Posted 20 January 2004 - 01:16 AM
Posted 20 January 2004 - 01:40 AM
Nice design! It looks like a nice, light rig.
Tension springs are not normally used to achieve balance, but rather to increase tension on the altitude bearings.
I don't understnad why the balance on your scope changes between indoors and outdoors?
Posted 20 January 2004 - 02:40 AM
Otherwise, if you have a tight tension, it will be stiff and will overshoot the objects you are viewing.
Posted 20 January 2004 - 03:34 AM
Posted 20 January 2004 - 09:48 AM
I'm thinking that the cold makes the teflon and velcro less sticky.
Posted 20 January 2004 - 09:57 AM
of light, buttery smooth movement by increasing the
Try Tom Kracji's virtual counterweight scheme in which a
spring on the rocker box is rigged through a pulley to a
fixed mounting point on the altitude bearing. The beauty
of this idea is that it works at all tube elvations from
0 to 90 degrees.
This is due to the fact that the pulley changes the tension
developed by the spring from linear to sinusoidal which
exactly mimics the dynamics of the shift in balance as the
scope swings from a vertical to a horizontal position.
I have used this construction principle on a paralellogram
bino mount and am adapting it for my 8" Dob.
It works like a charm.
a link which I hope is still valid. Otherwise check on
Mel Bartels ATM site.
Posted 21 January 2004 - 02:01 AM
After using the telescope again tonight I think that the sliding counterweight Idea is the most feasable. It would be infinitely adjustable and very simple to make. Thanks to everyone for their ideas!
Posted 21 January 2004 - 11:12 AM
After using the telescope again tonight I think that the sliding counterweight Idea is the most feasable.
Good luck with your project, and let us know how it turns out.
I'm sure you're already aware of this... a virtual counterweight 'moves' the center of gravity, which could introduce some instability - especially if you are using an equatorial platform.
Posted 21 January 2004 - 06:45 PM
If nose heavy, see above. But it does appear that you can move the bearings to change your balance point and avoid all that rigarmarole.
Posted 22 January 2004 - 12:18 AM
Posted 22 January 2004 - 08:17 PM
Posted 22 January 2004 - 11:31 PM
Posted 22 January 2004 - 11:44 PM
I think the counterweight should be red as well..
Posted 23 January 2004 - 10:27 AM
Posted 23 January 2004 - 01:42 PM
Posted 23 January 2004 - 02:00 PM
Posted 25 January 2004 - 09:34 PM