18 replies to this topic

[Trader_Vix]

There have been a number of postings in regarding to potential guiding issues affecting image quality. Although wire and cable management could be considered a beginning imager's issue, I have seen this discussed recently in this forum and have seen classic problem areas in some of the setups and would like to give a little back here in the way of a few tips learned many years ago with regards to wire/cable management performing long term exposures while doing film work, and as I integrated those lesson into my own recent imaging setup. Although this may not have been a direct cause of someone’s guiding issues that have been reported, we can still take simple steps to make sure this is not a problem with our setup and take it off the potential or future issues list. Everyone has a different setup and what works for me may be a little different depending on your own setup, but some of this is basic good practice whether you go portable often or in an observatory. My own setup is a hybrid, I just move it from garage to driveway for an imaging session. Some of this is just my own experience based on years in aerospace practices.

 

1. Consider that there are 2 distinct areas for cable management, the Upper or moveable section, and the Lower part of the mount, this will drive how you approach the best practices/integration techniques.
2. Minimize what moves (I am not against using an upper mounted power center or controllers, just make sure they are really needed and not just nice to have) especially when it comes to cables.
3.  Minimize cable lengths to only slightly longer then needed, combine and use cable sheathing.
4. Cables should never run directly from any device on the Upper (OTA/guidescope/focuser, camera, controller, etc) to the ground. All upper (cables should be sheathed, secured at several places at the upper (Dovetail Areas etc.). Even lower mount cables should be secured along the (pier/tripod) etc, not draped to the ground.
5. Cable running from Upper moveable to Lower of Mount should be combined and well secured along length.
6. Use securing clamps wherever possible. Leaving any excess slack in any cable is bad, a very slight breeze just loves to screw around with excess cable lengths.
7. Make cable disconnects accessible but don’t sacrifice cable security.
8. Test as you integrate your wiring through all possible OTA movement geometries to make sure there are not areas of flopping or binding cables. I have it a little easier since I can only image east of meridian.

 

I have included some example pics to show how I address the above tips. I hope they may help. When I have any guiding anomalies I always review my setup, but usually it is atmosphere related more times than not.

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[ryanha]

Very nice setup!

 

One thing I also do it secure the cables to the camera body (just a long velcro strap around the body of the camera securing the sheathed cable bundle) to reduce strain on the connectors in the camera.  That way the weight of the cables is held by the velcro strap on the camera, not on the connectors.

 

--Ryan

[dghent]

Don't recommend letting the 12V and USB connectors on the camera carry the weight and strain of the bundle. If that wrapped bundle catches on something, it's going to possibly damage the USB connector on the camera. On QHYs, the 12V coaxial power plug is at least screwed to the rear plate of the camera, but the USB port is soldered to the pcboard and can be more easily broken.

 

Take one or two velcro cinch straps, the kind with the plastic buckle, and secure the bundle to the body of the camera so that strap takes the weight and much of any strain instead of the connectors.

[rgsalinger]

+1 for securing the "bundle" to the camera. 

 

Rgrds-Roiss

[Trader_Vix]

Edited and deleted previous response....re-added the velcro I had on the camera previously....will see how it goes with the auto-focus routine.....

 

When I had this on previously my auto focus was glitchy.....that went away without the extra strap...that camera cable section with the upper clamp has most of its load on that upper clamp...that is why I added it....the sheathing is the key to the rigidity...not a lot of loading on the connectors, what is there is shared and good strain relief...we shall see how it goes when (if) the skies clear.

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Edited by Trader_Vix, 20 September 2022 - 06:40 AM.

[Birddogoby]

With my rig, I need two power sources - one each for my new 10Micron mount and Pegasus UPBV2 on top of the scope that powers everything else. The power for the mount is on my pier but the power for the Pegasus runs from a ground based battery or AC source. Any suggestions about avoiding a cable from the ground to the Pegasus PB?

[Trader_Vix]

With my rig, I need two power sources - one each for my new 10Micron mount and Pegasus UPBV2 on top of the scope that powers everything else. The power for the mount is on my pier but the power for the Pegasus runs from a ground based battery or AC source. Any suggestions about avoiding a cable from the ground to the Pegasus PB?

My posting was about how to configure what you have to work with in regards to securing and integrating. If you have to run (any) cables, just make sure they are secured all the way up from the ground source to the device(s). Others may have a good suggestion based on your particular mount and power box configuration.
 

[Birddogoby]

My posting was about how to configure what you have to work with in regards to securing and integrating. If you have to run (any) cables, just make sure they are secured all the way up from the ground source to the device(s). Others may have a good suggestion based on your particular mount and power box configuration.
 

I may have misunderstood your earlier statement that “Cables should never run directly from any device on the Upper (OTA/guidescope/focuser, camera, controller, etc) to the ground”, which is the case in my situation.   I don’t think I can avoid the power cable feeding the Pegasus PB from dangling to the ground unless I’m missing something (very possible).  Sometimes, it just takes another person to see it with fresh eyes.

[psandelle]

I may have misunderstood your earlier statement that “Cables should never run directly from any device on the Upper (OTA/guidescope/focuser, camera, controller, etc) to the ground”, which is the case in my situation.   I don’t think I can avoid the power cable feeding the Pegasus PB from dangling to the ground unless I’m missing something (very possible).  Sometimes, it just takes another person to see it with fresh eyes.

I think he means to anchor the cable that goes from the Pegasus PB (I have the Pegasus UPBv2, and I run one power and one USB to it, then everything else comes off the box) to two points before the ground (don't let it fall directly to the ground, which can cause snags and the ripping of ports). I have the cables in a weave. They come off the Pegasus and anchor to my dovetail plate (there are other anchor points, but this is about the basics). From there, I have a "loop" (that's big enough to allow for the Dec axis to rotate 180 degrees in each direction from North to South) that then attaches to my counterweight bar (with velcro), then a second "loop" (that's big enough to allow for the RA axis to rotate 180 degrees E/W) that anchors (with velcro) to the top of the tripod/base of mount. Then the rest of the cable goes on its merry way to my computer and my power box.

Paul

 

[RamStrocsop]

Neat setup. Thanks for the tips.

[badgie]

One tip is to set your mount points as close to rotational axes as possible.  For example, if you mount your lower -> upper cable bundle next to the RA axis, then you minimize the extra distance required as RA rotates.  I tie my cables down with my setup with the axes in the "longest possible" configuration and then check to make sure I have fully free rotation.

[Birddogoby]

I think he means to anchor the cable that goes from the Pegasus PB (I have the Pegasus UPBv2, and I run one power and one USB to it, then everything else comes off the box) to two points before the ground (don't let it fall directly to the ground, which can cause snags and the ripping of ports). I have the cables in a weave. They come off the Pegasus and anchor to my dovetail plate (there are other anchor points, but this is about the basics). From there, I have a "loop" (that's big enough to allow for the Dec axis to rotate 180 degrees in each direction from North to South) that then attaches to my counterweight bar (with velcro), then a second "loop" (that's big enough to allow for the RA axis to rotate 180 degrees E/W) that anchors (with velcro) to the top of the tripod/base of mount. Then the rest of the cable goes on its merry way to my computer and my power box.

Thanks for your feedback.  I’ll have to see if I can do something similar although to be honest, I’m not real crazy about attaching anything to the CW bar.  I need to stand back and take a good look at my options.

 

Paul

[psandelle]

Thanks for your feedback.  I’ll have to see if I can do something similar although to be honest, I’m not real crazy about attaching anything to the CW bar.  I need to stand back and take a good look at my options.

 

Paul

Many do it elsewhere on the RA axis. For me, at the very point where the bar screws in works well for me.

 

Paul

[Birddogoby]

Ahh.  Makes sense now - I thought you meant on the CW bar itself.  

 

Paul

Edited by Birddogoby, 20 September 2022 - 01:41 PM.

[Trader_Vix]

Agree on bringing everything as close to center of rotation as possible before heading down to the lower (fixed) part of the mount, as you can see I have brought the two sheathed bundles together, tie wrapped and then down as one cable to the lower section. The only other wire is the Losmandy Dec motor cable I leave as a standalone since Scott already had that all figured out. The Dec and RA motor cables are the only ones I leave as is. Regarding the question of the cables run to the ground, Paul answered that, as I described in #4, they all should be secured several places on the upper and then smartly run to the lower parts of the mount, secured again....and then even velcrod to the tripod leg or secured to the pier before going into a power box, power strip, or to other places...computers, hubs etc. I have actually seen pics here of setups with some cables drapped direclty from the upper section to the ground. Even when in setup testing mode, bad cable routing, even temporary, can contaminate testing results. CGEM setups will be a little different, but cable security still applies. Testing everything with power off and loosened clutches, if possible, thru all travel range, should always be done when you make a change...don't forget to have your focuser out in the imaging position when testing for clearances and balance (don't ask why I added this)  .

[Sparks-M16]

That's about as tidy as it gets, very nice! 

 

The picture might be deceiving a little, but when your rig slews full west to the meridian, it looks like the main bundle may get tight.  You have enough slack there?  I'm sure you've tested it, so perhaps never mind.

[choward94002]

One thing I would add would be a short cable going from the camera to the wire bundle cable, with the short cable looped and zip tied/ glued to the camera.  Why?  If for some reason the main cable gets caught on something (tripod, passing leg, errant dog, etc.) and gets a hefty tug, you don't want the "weakest link" to be the USB connector on your camera.  The connection between the main cable and the short cable would instead part, which can be easily reconnected ... here's a good site for those kinds of short cables [https://www.usbfirew.../default.aspx?]

[Trader_Vix]

That's about as tidy as it gets, very nice! 

 

The picture might be deceiving a little, but when your rig slews full west to the meridian, it looks like the main bundle may get tight.  You have enough slack there?  I'm sure you've tested it, so perhaps never mind.

I could slew west of meridian, I have tested it on both sides, plenty of slack and no tangle or binding, but I only have a very narrow sky with house and trees in that direction so all my imaging takes place east. That makes it easier. However, I still made sure it has full clearance in both directions when I do clearance testing since the scope could, and in fact has, slewed to the west on a mistaken Goto an object that was west and not east....due to operator brain freeze.
 

[Trader_Vix]

Update - After re-adding that additional harness strap at the Camera, no glitches with auto-focusing last night so I will just keep the strap on for now to further minimize stray cabling per the subject of my own thread. Guiding was excellent, driven by excellent seeing, very stable...low FWHM and Eccentricity numbers....however lousy transparency (lowering star count and SNR) due to high level clouds moving in...oh well, kept 6 out of 25 subs...system working well...atmosphere cooperation - not so much.