perfrej

Details? Motor, 18V DC, gearbox, total torque on 18V is 900 N, i.e. can lift around 90 kg. At 12V it is just right for roofs. Clutch, simple to operate, bicycle chain sprocket as final drive.

The garage door opener as a complete product is called the Sommer Marathon 1100. I simply bought the motor carriage as a spare part. The part was SEK 1862 and the freight to Olly's was SEK 280. If you buy from them you may need to pay VAT, but we can probably fix that for you. The price given is as per May 8th this year.

http://www.sommer.eu/en/marathon-sl.html

As you see on that page, the unit is available in three different "strengths". With our four pier, 4 x 5 m observatory, I figured the biggest. You can get the medium one. Check it out.

/per

I still say get the garage door motor with chain sprocket and clutch. It moves very slowly and works very well, and it is quite cheap. Also, no need to run the chain in a loop - one way will suffice. I'll ask Olly to shoot some images of our's when the weather clears.

/per

2000 lbs of pull? DON'T do it!

/p

Yes, they are 1.47 m each. So four of them would cost you in the neighborhood of £12-15. Are you sure you can live with that cost?

/per

They last a long time when greased properly, that's for sure. I recall paying about £3.50 for the chains and we bought 3 or 4 of them. Maybe I should just source it for you... 116 links, standard 1/2" by 1/8" bicycle chain, SEK 39 according to the web site...

/per

I'm in a bar right now, but I'll get you the motor details tomorrow morning [emoji12]

The drive I use has a clutch. Chain is standard bicycle chain available on every corner for close to nothing... Our's runs partly outside - no issies.

Gina, spooling is a difficult thing to tame! I strongly recommend a chain instead. If you stick with the winch, in whatever configuration, add a big low ohm resistor in series as a shunt so that you can measure the current and abort if it gets too high. A winch will rip the roof and everything off if left alone to do its thing...

If you want I can help you get a 800 N 12V chain drive motor from a garage door opener as a spare part. I bought one here in Sweden and had the supplier direct ship it to Olly's. I think it was about £150 including UPS freight.

/per

Exactly! I would use at least a five minute sliding average (and will in my own focuser design) - in the driver, naturally (hehe).

/per

Good thinking [emoji4]

I an not sure that temp comp should be in the imaging app. It is better to have it in the driver as temperatures can change quite rapidly during a long sub. The amounts of change are small - in the microns - and a good focuser doesn't shift the image during focusing.

/per

OK, I got the rowan and installed in an hour and a half - which I think is pretty good! 

Frank, which mod are you talking about? Rowan?

Quick one: Having never seen the mount in question, does it not need counter-weights?

/per

I don't know if the COM+ extensions to DCOM are used, but I guess they are not. I am simply going to have to test this one day

/per

The ASCOM Initiative is a loosely-knit group of developers and astronomical instrument makers that work together to bring vendor-independent and language-independent plug-and play compatibility between astronomy software and astronomical instruments on Windows computers. ASCOM stands for the Astronomy Common Object Model.

I think the fact that ASCOM is not OS independant or at least able to work over a network "out of the box" a fairly fundamental architectural flaw. 

But it is. It is based on a communications framework called COM (Compound Object Model, if I remember correctly). If take a COM application and just change the attributes of it in the COM control panel you can make the object you are creating (for instance a telescope) be created on another computer. Neither the applications nor ASCOM drivers see any difference. If you do this you have entered the world of DCOM, or Distributed COM.

As for being a nightmare to set up, well, I have given tons of talks on this and find it very straightforward; that is if you fully understand the advanced concepts of windows security, such as impersonation.

I have not had any real need to run ASCOM distributed myself, but maybe I should just for the heck of it. There may be issues, for example if the developers haven't observed all the norms you have to comply with...

/per

Theoretically ASCOM should work between computers. It is all COM-based communication so with some configuration DCOM (which is networked COM) should work. The drivers or applications wouldn't see the difference, it is all handled at the communications layer.

/per

I find it hard to picture what is wrong when a worm gear has uneven "tightness".  The only thing that comes to mind is that the worm wheel is not centered, as Olly suggests. How the heck do you fix that???

/per

Olly, that thing has low resolution absolute encoders! What happened to your principles? It is even suitable for automation! (sorry, shouldn't use that word)

/per

Yes, that is the cost of "real" bearings. I would go for sealed as they keep the lubricationproperly in place.

/per

One important thing with astro stuff, regardless of operating system, is USB. It is a very tricky thing to get stable, and the fact that the connectors are Rubbish also adds to the bonfire. I solved this with a hardware device that has an on-board 4-port USB hub with three of the ports switchable, both 5V and data leads. With that I can "physically unplug/replug" any USB device without doing anything to the computer. I have incorporated device drivers for ASCOM, but the protocol to talk to the thing is so simple that it would be a close to no-brainer to write Linuxdrivers for it.

General specs:

5 switchable 12V supply outputs

3 switchable 12V supply outputs that are switched together with...

3 switchable USB-ports

2 PWM 12V outputs for roof motors

4 digital inputs for roof sensors (opto isolated)

4 general inputs (opto isolated)

1 analog input for voltage check on batteries

4 general digital outputs (opto isolated)

1 sky quality sensor input (sensor is $5, same as in the commercial SQMs)

1 stepper motor driver for focuser

ATMEGA 328P processor with all "firmware" in Arduino code

As you can see, it is an entire observatory bar the astro stuff. You could easily run it from Linux via a serial port and get focuser, roof control and what have you. The focus driver, by the way, is a hardware stepper driver that can do unipolar and bipolar, and that micro-steps up to x8 if you want to run the motor without gear-box. There is software controlled hold/no hold also - good if you run naked steppers.

The coolest feature is the switchable USB ports. They use analog switches specific for USB switching use.

Great DYI project, indeed! Prototype (1 of 6) is running on my desk and will be integrated into the balcony setup this weekend. Since it has an Arduino boot-loader in the processor, you can write your own firmware with free tools on Windows (that is how it is spelled), Linux and OSX.

/per

Hmmm... I booted my obsy computer in early August when I put the stuff back on the balcony. Hasn't been off or rebooted since, hasn't lost a session or part thereof, hasn't shown any hickups of any kind. I never did understand the "windows needs constant reboots" doctrine. The days of blue screens and reboots are over and have been since the introduction of Windows 7.

Apart from that, it would be interesting to put something resembling ACP together with the help of Qt. Crappy IDE but good thinking, cross-platform (if you chose compiler wisely).

Problem is device drivers...

/per

I have performed some tests. It is easy to write software that connects to MaximDL and "subscribes" to event notifications. My test included a small application that got notification of the "start exposure" event from Maxim and then sent a signal to Nebulosity to shoot an image. It worked OK and did the job.

Now, as for full automation... ACP doesn't really have any support for multi-rig setup. It would, however, not be difficult to modify a few ACP scripts to fire off five other cameras at the same time as the one it is controlling. The problem is focusing. I can envision this as such:

• A PC runs ACP and controls mount, scope, dome, weather and one camera/focuser
  
• A virtual machine in the same physical PC runs MaximDL and FocusMax and handles one scope/camera/focuser
  
• Add one virtual machine per additional scope/camera/focuser
  
• In each of the virtual machines, a small application that receives commands over the virtual network controls MaximDL and Focusmax in that VM
  

Should work...

/p

Off the top of my head; yes.

On another note, I hope the milling that has to be done is in the mount and not the center hole in the wheel!

/p

Corpze!

Here is my list of bearings that I got for mine two years ago. I bought from Spekuma and I believe they substituted one of them. SKF numbers are as follows:

4st SKF 608-2RSH

6st SKF 6008-2RS1

1st SKF 30206-J2/Q

1st SKF 32208-J2/Q

At that time I had had my EQ6 for less than a year and not used it much. Still, two of the main bearings were corroded. I suggest you replace them all.

/p