PDA

View Full Version here: : The best laid plans of mice and men


Leo.G
19-04-2025, 01:40 PM
I obtained a new head for my tripod with 25Kg capacity, a Cambo SCH. I decided a Vixen dovetail was the best way to mount my Astro Trac on the head, that's where the fun started.
In saying the fun if I weld up a stand and fold up and weld a tray for a milling machine this job would have taken NO TIME, instead it took hours including finding something I could grind to do the job. I could machine my own Vixen plate if the milling machine was set up, custom made for the purposes (mounting it for machining the centre hole was fun), I have the tooling for it.
Yes, the machining is VERY rough, I learnt machining at TAFE 27 years ago and hardly did anything since, giving my old lathe away and 20+ years without access to one.
I don't have a boring bar and ground an old tool I found laying around that had nothing to do with what I was doing, slid my arm down it grabbing something else after grinding it (it was razor sharp as I found out) and butchered my Vixen dovetail plate but it works. I'm yet to cut the Vixen plate down. I first had to drill and tap the Losmandy clamp to 3/8 to mount it on the head and wanted 3/8 to the plate as well. The Astro Trac has provision for 3/8 both sides, 15Kg capacity and I plan on using my full frame Nikon and small Megrez travel scope on it (and should have done so last night).


Now I have to figure out the camera focus with the Nikon and Rokinon lenses attached, I've spent ages and still can't get the focal point right.
The camera mount was made out of some scrap aluminium C channel and some other scrap which puts a reasonable amount of alloy on the rear of the camera to maybe (hopefully) keep it a little cooler. I'm prepared to drip refrigerant gas onto the alloy plate to see if it makes a difference (canned air is refrigerant gas if turned upside down and dripped out).



Today is overcast and rain expected today or tomorrow, last night was perfect but I failed.....

Crater101
20-04-2025, 10:13 AM
Mate, I'd say you were making progress. I think it was Alexander Bell in the USA who said that successful ideas are the result of slow growth and you can't get to perfection in a day.
(Sounds a bit like my own astrophotography, but anyway...)
Looking forward to see how it all ends up mate.

Leo.G
20-04-2025, 11:22 AM
Thanks Warren!
My focus problem may be more a ID-10-T error (yes, it spells idiot).
I don't understand Sharpcap and therein lies the problem. I got perfect focus on the moon last night but had trouble with star fields so it's my miscomprehension of the software or how to use it. The moon was after attempting focus on stars and with a different lens (80-200 f2.8ED Nikon) I had been using a 35mm f 1.4 Rokinon on star fields. I had however checked focus during daylight and having no problem. However once I pointed my 200mm already infinity focused lens at stars I got nothing on the screen. I really have to read up on how to use the software.

This after years of using SLR and DSLR cameras for astronomy, the little dedicated unit requires software I just don't seem to be able to get settings right in.


In saying that you may have noticed the Polemaster mounted on the Astro-Trac, I got to try it out with my sons help. The screen came up and said "Rotate the RA around 30 degrees in the direction of the arrow". It's not a proper astronomy mount (obviously) and I started rotating the Dec axis instead while watching the screen expecting the software to give me an alert when I was close.

Well that never happened and now I'm going to RTFM and get my axis correct (I do know the difference, I'd had a stressful day).
I completely messed everything up and just packed up (I was crook and really shouldn't have been out playing).
Plus I'd levelled the head not the tripod in a sloping yard and that was a major mistake once the head was rotated. Now I'm determined to get my pier in within the week, I'll order the aggregate tomorrow from the local landscape supplier and buy cement at Bunnings. I have 5 bags here, probably old but I'll break one or two up in my pit with gravel in it and tamp it down with the crowbar (today) because of the clay, it absorbs water out of the concrete mix and destroys the final result. My gravel and cement mix should theoretically prevent that.

Crater101
21-04-2025, 08:32 AM
Ha! mate, we've all been through the trial-and-error, why-didn't-that-work process, and it can be frustrating. Even if you set up everything right, for some reason once in a while the software throws you a wrong 'un. Usually when you've got clear skies and good seeing..


I had to put in a new clothesline for the wife recently, and one thing I found was that you always seem to need one extra bag more of concrete than you have. Just a thought. Keep us posted on how the pier goes mate.

Leo.G
21-04-2025, 12:03 PM
I compacted a lot of gravel and 2 bags of dry cement into the clay yesterday and reduced my hole by 300mm depth. I may have put too much gravel in but my gear isn't overly heavy, the pier is though.. The crowbar took it's toll. I'll still have around 400mm depth and 600x600.

Weather permitting I'll be ordering the aggregate tomorrow and picking up 15 bags of cement at Bunnings, maybe.....
Then it's a wheelbarrow and a hoe to mix.
I better go do another 100 push ups today, double my daily target.

Leo.G
23-04-2025, 10:18 AM
As expected it's now raining and that is forecast to remain for the next 2 weeks......
I guess you're getting the same Warren?

Crater101
23-04-2025, 10:21 AM
Yep. :cloudy::rain:
Everything is tuned in and ready to go, so of course there had to be cloud cover! :shrug: