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Author Topic: Dome Motorisation  (Read 1382 times)

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Offline petevasey

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Re: Dome Motorisation
« Reply #60 on: 21:56:21, 27 April, 2017 »
A final tweak coming up!

My daytime test yesterday kept the telescope nicely on the slot for 3 hours with plenty in hand  :D  But for more predictable control I'm going to fit an extra potentiometer to set the slow speed.  It will be preset (inside the handbox) and I can fine tune using the on-off timer.  I will of course wire the toggle switch (it is double pole double throw) so that I can go back to the manual speed control for initial positioning and close down etc. 

So I should have everything working nicely just in time for twilight  :embarrass:

Cheers,

Peter
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

Offline petevasey

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Re: Dome Motorisation
« Reply #61 on: 16:23:14, 02 May, 2017 »
That 'tweak' works nicely  :yes:  With the interval at 590 seconds and the run time at 3 seconds the telescope slowly gains on the dome, - in an hour or so it only gains by a couple of inches of the aperture when crossing the meridian, so no worries about the dome catching up with the 'scope!  Very promising.  So that's that, apart from further remedial action over the Summer to the part of the rim damaged by rot - fibreglass will probably be the solution! Here's a pic of the complete installation.

Cheers,

Peter.
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

Offline petevasey

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Re: Dome Motorisation
« Reply #62 on: 23:32:00, 14 May, 2017 »
Just a final note.  I've now repaired the rim damage with liberal application of fibreglass, and although the wood of the main body of the rim is in poor condition, it should now last provided it doesn't get wet again!  Major attention needed to the outside paintwork - gloss paint tends to pull away from the fine cracks when applied, so I have to find something which will properly seal the cracks yet be flexible.  But I'm happy with the internal repair which works fine.  I won't post all the boring stuff here, but if anyone's interested, I've put a page on my website covering the complete installation and repair.

http://www.madpc.co.uk/~peterv/astroplover/equipnbits/ObservatoryDrive.htm

Cheers,

Peter.
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

Online chris.bailey

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Re: Dome Motorisation
« Reply #63 on: 07:52:00, 15 May, 2017 »
Looks like the internal repairs should give you a couple of years service. Could you not Fibreglass the outside too?

Chris
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Offline petevasey

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Re: Dome Motorisation
« Reply #64 on: 09:26:13, 15 May, 2017 »
Looks like the internal repairs should give you a couple of years service. Could you not Fibreglass the outside too?

Chris

Hi, Chris,

That thought has crossed my mind, and using fibreglass cloth (thinner and lighter than mat and much cleaner to handle) it wouldn't add too much weight.  But the total area to cover - I would do the whole dome - is approximately 8 square metres.  An awful lot of work to strip all the paint down to the bare wood, or at least strip some of it and sand really sound paint to give the resin a grip. So I'd need weather set fair and dry for several days.  But probably worth it in the long run - if it keeps my Obsy going until I'm too decrepit to continue, that would be great  ;)  It would be nice to have a new observatory, probably the 9 ft. Pulsar, but that would be a lot of work as well!  And a lot more money than a few Kg of resin and a few litres of paint!

Cheers,

Peter
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

Online chris.bailey

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Re: Dome Motorisation
« Reply #65 on: 09:32:22, 15 May, 2017 »
Peter

I would imaging it would be enough just to sand off any flaking paint. Fibreglass resin always seems to me to stick to anything (at least anything you don't want it to stick to).

Good point about needing fair weather for a few days, that is probably the biggest issue!

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo

Offline petevasey

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Re: Dome Motorisation
« Reply #66 on: 10:29:31, 15 May, 2017 »
Hi, Chris,

I've just done some browsing, and came across a major supplier just 30 miles away in South Shields: https://www.ecfibreglasssupplies.co.uk/  The guy I spoke to has a caravan on a site just 1/2 mile away from me, so he's going to call in some time and advise on the best product to use  ;)  Probably twill weave cloth and epoxy resin (twill weave is softer and more flexible for awkward corners etc.)  But he is of the opinion that I should strip all the paint.  We shall see.  If it works, that would be a great solution long term.  Probable cost with materials (and paint) around £120.  Definitely a Summer project, needing a few days of continuous warm dry weather.  Live in hope!

Cheers,

Peter.
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

Offline petevasey

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Re: Dome Motorisation
« Reply #67 on: 15:35:14, 11 June, 2017 »
Hi, Chris et al,

Maybe .....

My system works ok when imaging in the South, but as you know the dome slot position and required movement is very different when imaging in the North, particularly if near the Pole (this for northern hemisphere of course).  So I'm toying with going further.  I've been looking at 'Lesvedome' which looks like a very reasonably priced solution, using the inexpensive Velleman board and a couple of relays and IR sensors.  I'd make my own sensor wheel, and don't intend to motorise the shutter.  But I'm a bit confused as to how to enter the GEM axis offset into POTH - does anybody know if you have to change the sign depending on which side of the mount the telescope is lying when starting a session, or is this automatically allowed for by the interface of POTH with the telescope control system?  My mount uses LX200/Autostar standard, and can start imaging on the 'wrong' side of the meridian without doing a meridian flip.

Cheers,

Peter.
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

Online chris.bailey

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Re: Dome Motorisation
« Reply #68 on: 16:08:22, 11 June, 2017 »
Peter

No need to change the sign, it is just an offset. I found I had to fiddle a bit with the settings from those measured to optimise the scope lining up with the dome slit.

Lesvedome is a pretty good DIY approach, I have an 85% built version of it before deciding to go a different route (my motor is on the rotating part so issues with wiring).

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo

Offline petevasey

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Re: Dome Motorisation
« Reply #69 on: 16:30:47, 11 June, 2017 »
Thanks, Chris, that's good to know.

I recently visited a guy who lives in Newcastle (just 26 miles away).  He has a Lesvedome/Velleman system, but only uses it to position his dome.  But it seems to integrate ok with Maxim DL via Ascom POTH.  I think I might give it a try.  I'll enjoy building the Velleman K8055N board from a kit (less than £25), assuming of course it tests ok at the end of the build!  And the trial version of Lesvedome is free for 60 days - should be more than long enough for getting everything running smoothly.

It's interesting that Velleman provide examples in Delphi including all the commands.  If I was MUCH better acquainted with Delphi and Ascom, I'd have been tempted to write my own interface just for dome control.  But for me that's firmly in the realms of fantasy, particularly as Lesvedome is so reasonably priced ;-)

Just a thought.  I must check to see how much current the on-off-reverse switch on the motor speed control takes - I might not need a relay interface if the Velleman board can switch it directly.  There again when I look at the schematics, perhaps not - the systems aren't compatible.

Cheers,

Peter.
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

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Re: Dome Motorisation
« Reply #70 on: 12:33:24, 12 June, 2017 »
Peter

I think the 8055 will only switch logic level currents so you will need relays or interface to a motor control board. The encoder does not need to be anything that special, I hooked mine up to the motor drive spindle rather than having another friction drive and used a plastic disc with holes drilled in ii and a couple of led/sensor pairs. I then used a magnetic reed switch for homing.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo

Offline petevasey

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Re: Dome Motorisation
« Reply #71 on: 14:01:46, 12 June, 2017 »
Hi, Chris,

Yes, you're absolutely right about the 8055.  I wouldn't be switching the actual motor currents, just the control inputs from the existing forward/off/reverse switch.  But better to play safe, and relays useful for manual operation if I don't have the computer on.  I've already drawn up a template for a sensor wheel - there is plenty room to fit one between the acorn wheel and the frame, just need some mods to fit it and the sensors.  I've got a reed switch lying around from a burglar alarm - that should do the trick  ;)

Off on holiday for a couple of weeks, so will delay ordering the 8055 and relays 'til I get back - the packages might not go through our letterbox.  But then the fun starts all over again!

Cheers,

Peter.
GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50, Daystar Quark Chromosphere 'eyepiece' filter, Canon 15x50 IS Binos, various camera lenses.   Gemini G41 mount with Pulsar controller. EQ6 Pro mount, EQ3-2 mount with DS Autostar. Star Adventurer mount, QSI 683wsg, SX AO, Art285 (beta), Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (monochrome), LE Vesta Pro, Toucam.

Offline tomhow

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Re: Dome Motorisation
« Reply #72 on: 11:24:09, 18 June, 2017 »
If I may offer a few hard-won remarks....

Regards the GEM offset, you just put in a static absolute value. POTH works out the dome azimuth using the telescope mount  driver's  SideOfPier property. So you are reliant on the telescope mount provider having implemented this correctly. It isn't simply which side of the meridian you are pointing otherwise the moment you track beyond the meridian it all goes wrong.

POTH also uses the telescope mount DestinationSideOfPier property. When you do a big GOTO, POTH will tell the dome to go to the right place for the end of the GOTO, and not chase the slew. As the author of telescope ASCOM drivers, I know this one is a sod to get right.

Assuming you have a commercial telescope mount, you can't do much about these things, but it is useful to understand what's going on.

There is (or certainly was, and nobody seemed keen to fix it) a bug in POTH regards the EWNS settings - when your mount RA/DEC intersection isn't centred in the dome, and whose is? Aside from Chris, obviously.

The box labelled "Scope Position +E/-W" is actually ass backwards. It should say +W/-E

https://groups.yahoo.com/neo/groups/ASCOM-Talk/conversations/messages/35981

One game to play is get the scope running normally, and then attach POTH to the simulator dome. Put in what you think are the right parameters and see what azimuth pops out. Try tracking beyond the M and also pointing in a few odd places - pointing up near the zenith produces some surprisingly non-intuitive azimuth solutions.


Hope that helps :)

Tom


Hi, Chris et al,

Maybe .....

My system works ok when imaging in the South, but as you know the dome slot position and required movement is very different when imaging in the North, particularly if near the Pole (this for northern hemisphere of course).  So I'm toying with going further.  I've been looking at 'Lesvedome' which looks like a very reasonably priced solution, using the inexpensive Velleman board and a couple of relays and IR sensors.  I'd make my own sensor wheel, and don't intend to motorise the shutter.  But I'm a bit confused as to how to enter the GEM axis offset into POTH - does anybody know if you have to change the sign depending on which side of the mount the telescope is lying when starting a session, or is this automatically allowed for by the interface of POTH with the telescope control system?  My mount uses LX200/Autostar standard, and can start imaging on the 'wrong' side of the meridian without doing a meridian flip.

Cheers,

Peter.
Tak Sky 90, Atik 490, Homemade Mount, OAG, Lodestar

The Curdridge Observatory

 

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