westmarch
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Posts posted by westmarch
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On a desert island, with no light pollution, who needs a telescope?
John
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Hi there,
Missed this thread first time around. I have used these adjustable furniture feet. You can either drill holes in the base of the dob and mount them directly or attach them to a plywood platform.
This is where I got them:
John
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And scorpions! We regularly had people brought in to the local hospitals with scorpion stings. Watch out, especially at dusk.
John
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Just as well you picked seafarers then. Cowboys would have been useless at geometry!
John
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Its coming on nicely! 👍
John
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I recently took advantage of the ‘good’ weather and arranged to meet a mate at a dark sky site. He had his new goto Mak and I had the dob. We each took about 30 mins to set up but that is where the similarities ended.
I was slightly frustrated by the poor transparency with haze extending to about 40 degrees but concentrated on deep sky targets overhead, despite a dob’s known problems with manoeuvring around vertical targets. I had six hours of enjoyment, star hopping, locating and viewing deep sky targets, albeit not the ones I had intended.
Sadly my friend could not get his scope to align. He then spent the next three hours troubleshooting - eliminating the Starsense, power tank, bluetooth dongle, SkySafari controls and then hand controller setup as the cause of the problem. To add to his frustration he was obviously trying to do this in the dark to avoid us both loosing dark adaptation. He failed and left deeply frustrated with the session, having had no opportunity to look up and, frankly, having lost all inclination to do so.
I saw something similar while on holiday - two anglers with a radio controlled bait dinghy, fishing rod rests that alerted their smart phones when there was a bite......
Sometimes technology seems to become a hobby in itself.
John
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Hi Michael,
You might be falling into the trap of thinking too deeply about this. The whole centre of gravity thing and building a motor from scratch put me off initially. Sometimes, like Frank, you just give it a go and are pleasantly surprised or improvise.
It’s important to keep the top board parallel with the bottom, the south pívot works as a bolt in a depression in the underside of the top board. For visual observation, this works.
Good luck with the build.
John
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Hi Michael,
It is confusing 🙄 As far as I can make out, Skywatcher branded their lightest German Equatorial Mount as EQ1: it has a payload capacity of 3.2kg. The EQ2 has a heavier payload of 4.1kg. The motor drive for both is identical and it is only Skywatcher who term their motor drives as EQ2.(with variable speed or without).
Having looked at a number of them, the only thing that differentiates them is the writing on the box, sometimes the orientation of the motor/ attachment bracket and of course the cost. I think they all use the same components and may even come from the same factory.
John
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Hi Michael,
The design posted requires a basic EQ1 motor. This is has been tested by many of us and found perfectly adequate for a 10 inch dob platform. Somewhat confusingly, EQ2 mounts can be driven by an EQ1 motor. Skywatcher also markets another motor called an EQ2 motor with multi speed capabilities - you don’t need this for the equatorial platform.
BW
John
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I admire your fortitude. I lasted until from 8pm until 11pm before packing it in when I couldn’t make out the plough anymore.
John
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3 hours ago, Carbon Brush said:
Now fishing is something different.
Is it?
https://www.bbc.co.uk/news/av/uk-scotland-highlands-islands-60646570
Western Isles angler catches fireball meteor in video
John
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26 minutes ago, skyhog said:
its probably fair to say this hobby is extremely niche, more so than we appreciate. I always find that a little difficult to understand given the ease with which it can be undertaken.
You are not talking about AP then? 😁
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Frank, I think you are in motor bike engine territory with your scope. 😄
John
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Hi there,
Sorry, I could have been clearer. The EQ1 motor is specifically designed to turn the RA part of an EQ mount at equatorial speeds. It does turn faster but it is designed to work with a standard geared arrangement on an equatorial mount. It just so happens that, with the variable resistor knob, this is within the rpm range that adequately drives a standard platform.
@FrankRyanJr is the man to talk to if you want to get into the details. He has a thread on cloudy nights relating to this:
https://www.cloudynights.com/topic/778667-celestron-eq-motor-drive-speed-question/
Hope that helps
John
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Hi there,
the EQ1 motor is specifically designed to turn your telescope on the RA axis once every sidereal day (23hr 56min 4sec) that equates to 1/4 degree per minute, you can adjust it slightly with a variable resistor knob on the motor and this is sufficient to compensate for any lag. There is no modification to the motor required.
John
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A lovely piece of work. I wish you dark skies to enjoy it.
John
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Congrats on seeing the project through to its conclusion. I love how you have adapted it to your own circumstances - isn’t that the joy of a self build?
Good luck with imaging - if you recheck the platform with a spirit level, you may find it helps reduce the target drift.
John
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Hi Adrian,
the Dummies part of the title refers principally to me so I am the wrong person to ask about trigonometry. I always ended up drawing out maths problems to find a solution so my suggestion is:
1. Reduce all the platform plan dimensions by the same percentage on both the x and y axes to get an A frame that fits your scope base. e.g. if you only need a platform 50% as big, multiply all the plan dimensions by 0.5.
2. Using your printer software, reduce Reiner Vogel's 46 degree segment by the same percentage on both the x and y axes. Print it off and you should have a segment that fits your base. (You will, of course, have to reset the platform more often because you have reduced the circumference of your ellipse segment and therefore reduced its travel time).
This is my common sense theorem - not sure what Pythagoras would make of it. 🤨
Good Luck
John
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Hi Adrian,
Not sure about Perspex - suspect it may crack for a normal dob but it may work with a table top dob - good luck. I should point out that the equatorial base dimensions are probably going to be a bit large for a table top scope, so you may have to adjust them.
The 46 degree template will be fine on Reiner Vogel’s instructions.
http://www.reinervogel.net/Plattform/Vorlage Plattform 14 hoch.pdf
Most Dob users are using the scope as a light bucket so the low mag EPs have a decent field of view and cope nicely with a little target drift.
John
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Most of the clutches I have seen are either electromechanical and expensive or overly complicated dual axis drives with some sort of gearing connecting the two drives.
I think a mini drill bit might do it. The shaft of the drill bit would clamp in the EQ1 flexible collar and the end of the roller shaft would go into the drill bit. The drill bit could then be loosened to allow the roller shaft to run free within the bit. The platform arcs would then run free over the rollers to reset their position.
This sort of drill chuck would do it:
John
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Awesome technological and engineering achievement. The accompanying NASA video on the hurdles to be overcome really brings it home.
John
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Like @Davesellars I use Sky Safari Pro on an ipad mounted on a music stand. Up to date, easy to invert and/or mirror the map and no worse for your dark adapted vision than shining a red torch on a white page.
I have a copy of the Pocket Sky Atlas from Sky and Telescope that I don’t use. If you pm me, you can have it. I probably don’t live all that far from you.
John
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15 hours ago, Time Traveler said:
Changed the little peg to a micro switch to shut down motor, in I walk away for some reason during end of travel.
Hi Terry,
Great piece of innovation. I need to get round to fitting a clutch to disengage the motor and allow me to reset the platform by rolling it back on the rollers. Currently I have to get down on my knees and lift/slide it to the starting position and my back is not all it once was.
Maybe that is my winter project.
BW
John
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54 minutes ago, John said:
While there were some clear patches low down towards the west from here earlier, there was a long thin bank of cloud right along the horizon in that direction which I suspect provided a hiding place for Comet Leonard. So still no sighting of it for me
Same in N Yorks!
John
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Tell us about your astronomy glasses
in Discussions - Eyepieces
Posted
Hi there,
I also have astigmatism but find that it is easier to view deep sky objects without spectacles - gives a larger field of view with more contrast. Unfortunately this means that I am constantly having to put them back on to consult star charts. My solution was to remove one of the lenses from an old pair of glasses and cut away the lower part of the corresponding frame - I can read with the spectacled eye and view through the EP with the unspectacled one.
John