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Star-tracker

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Chris Smale:
Busy building me a star-tracker. That's why I needed that worm/wormwheel-set I posted earlier.
The geared stepper has 1:100 ratio, the (self-made)worm/wheel another 1:157. That should be enough to slow things down.
Worm and wheel are pushed against each other with a controlled spring.
There's an adjustable green laser on board serving as 'Polaris pointer'.
There are 3 large and 2 smaller ball-bearings.
The unit measures 160x75x55mm(about 6x3x2 inches)
At the top of the smooth rod (on the right side) comes a small platform.
There are 3 large and 2 smaller printed parts.

A DC-version of this star-tracker will also be made.

The electronics for this tracker will be designed and made by Guy, our electronics guru.
PCB not yet in the drawing



salonpeli:
I like the spring loaded worm idea.

Don

grateganir:
Hi,
This is what I'v got so far.
Works perfectly, not tested under stars yet. Still, one weak point has to be removed.

In the last pictures there's a 'dummy cover' on top, just to look inside while it's running. The real cover is on the right.









colzefuli:
Chris,
I really like the work you are doing and all the attention to details. Congradulations.

However, there is one thing I don't understand: what is the purpose of the shaft that sticks out right next to the motor? Would a camera not normaly be attached to the worm gear driven shaft only?

Paul Woodrow:
Pierre,

The wormwheel's axis is supported by two ball bearings. One ball-bearing sits at the bottom of the box and the other is pressed into the cover. On top of that axis(outside the unit) rests a large ball-head to support a camera or whatever small device.

Thanks for the comment.

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