BTW, could you let me know where did you find those clamps?
I was looking for something like this for quite a while.... I would like to use it like on bw image of my OTA.
Hi Bojan,
I bought them from Mitre10 and Bunnings. there are a few types but this one suited the best.
Thanks for the plans Justin.
I've just bought 18mm ply.
While balancing, i noticed that without any load, it had a tendency to swing more on one section than the other. not a sideways bias, but a sectional bias.
on measurement, i found that the central 50mm hole is actually off centre by about 2mm. hence the bias and errors in tracking.
not too difficult to fix.
so I'm redoing the fork, this time with a different approach, but maintaining focus on stiffness and lightness.
will email some plans through.
If I get the chance, I'm going to try out some truss designs as well similar to these. a lot more difficult but should be a lot lighter and stiffer if i get the truss calculations and joints correct.
cheers.
Finally got the ST4 autoguiding working with Phd, an St80 guide scope and a QHY5.
A control picaxe monitors the state of the 4 ST4 pins from the QHY5 optocoupler outputs and sends appropriate RA corrections to the picaxe controlling the stepper via I2C.
Since the picaxes run at 64Mhz, corrections are instant.
I added LED's as well so I can visually see when guide pulses are sent.
Each correction pulse changes the tracking speed by 0.5x for the duration of the pulse to reduce or increase the tracking speed.
I was only able to test it for a minute before the clouds rolled in but the Phd RA graph was within one division of the centre line and I got perfectly round stars. So its looking promising.
I mounted the ST80 on the opposite side of the QHY8 and focuser, so it acts like a counterweight.
Just waiting for the skies to clear and will try it again.
Yes, I have 6 cables coming off the scope and have to route them properly along the fork arms so they don't snag.
Skies aren't looking too good this month. weatherzone shows a high probability of rain almost the whole of this month.
