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Orion Atlas through the mount cabling

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19 replies to this topic

#1 StarmanDan

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Posted 06 March 2018 - 12:42 PM

With the advent of plate solving polar alignment, polar scopes are likely a thing of the past.  So I'm considering removing the PA scope, removing the existing CW shaft and upgrading the CW to the 1" version, which leaves both the RA and Dec shafts hollow.  The Dec shaft has a hole bored through to allow the PA to see through which provides access to the DEC shaft.  I was thinking about utilizing the hollow shafts to feed cables through to the scope and the control board inside the mount to eliminate cables snagging, sagging and blowing in the wind.  Has anyone tried this?  Aside from providing plenty of cable slack for the DEC to turn, what other issues might I encounter?  Only thing I can think of is how to prevent the cables going to the DEC from snagging on internal components in the mount as the DEC turns.



#2 frito

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Posted 06 March 2018 - 07:15 PM

if its like the sirius thats not gonna be a good idea the hole in the dec shaft that matches with the RA hole can and will fully close and cut or at least really crimp up any cable stuck though it i bet.


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#3 StarmanDan

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Posted 09 March 2018 - 09:05 PM

So, seems like I'm in uncharted territory on this, so I decided to do a little exploratory surgery to assess the viability of my idea.  First I removed the polar scope which simply unscrews from the back of the RA shaft.

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#4 StarmanDan

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Posted 09 March 2018 - 09:08 PM

Next, I removed the panel where the power and hand box connect.  Disconnect the three cables plugged in the top for the dec and ra motors and the power switch.  Make note of what motor plugs into where, they're labeled on the circuit board but not on the motors.

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#5 StarmanDan

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Posted 09 March 2018 - 09:18 PM

The polar reticule blocks some of the RA shaft so I decided to remove it since it will no longer be required.  The dec motor is interfering with removing the led so I loosened the screws that mount the motor housing to the mount to give more room.

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#6 StarmanDan

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Posted 09 March 2018 - 09:20 PM

I used a piece of small diameter pvc pipe run up through the back of the RA shaft and used my fist as a hammer to gently remove the led without breaking it.

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#7 StarmanDan

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Posted 09 March 2018 - 09:23 PM

And the led is out!  I re-tightened the dec motor screws too.

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#8 StarmanDan

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Posted 09 March 2018 - 09:27 PM

Next I removed the dovetail clamp.  There are three recessed allen screws just above the silver flat head screws that need to be loosened.  My clamp is stock and is the dual saddle variety.

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#9 StarmanDan

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Posted 09 March 2018 - 09:28 PM

And the clamp just pulls right out.

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#10 StarmanDan

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Posted 09 March 2018 - 09:30 PM

Now to see if there is anything inside the shafts that might interfere with running cabling.  This the RA shaft.  For the exception of the dec motor protruding slightly, there's nothing in the way.

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#11 StarmanDan

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Posted 09 March 2018 - 09:34 PM

And here is the dec shaft.  I've extended the counterweight shaft and stuck a flashlight through the polar scope hole in the front of the mount to illuminate the inside of the shaft.

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#12 StarmanDan

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Posted 09 March 2018 - 09:36 PM

And here is the inside of the mount showing the hole in the dec shaft for the polar scope.

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#13 StarmanDan

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Posted 09 March 2018 - 09:37 PM

So with this little excursion into my mount, I think my idea is feasible.  Will try running some cables through it later and post my results.



#14 frito

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Posted 10 March 2018 - 09:54 AM

nice! yeah looks like it would work on the atlas, just have to be mindful to not spin the dec around too much or you'll twist up the cables in there. the heq5 has far less space inside that area unless you completely remove the front plastic cover over the main head and modify it. 



#15 elmiko

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Posted 10 March 2018 - 08:51 PM

I like your ingenuity my man!



#16 StarmanDan

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Posted 11 March 2018 - 12:48 AM

Some more progress.  Was able to easily feed a skinny USB 3 cable through the mount. 

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#17 StarmanDan

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Posted 11 March 2018 - 12:52 AM

I then rotated the Dec axis by hand clockwise for four revolutions.  Then backed off counter clockwise two revolutions to provide plenty of cable slack in the mount for the Dec axis to rotate. 

 

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#18 EFT

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Posted 11 March 2018 - 02:23 AM

It is certainly possible to do this since it is essentially what has been done with the Celestron CGX/L mounts.  There are a couple things you should watch for that Celestron has addressed in their mounts.  The first is that the edges of the hole in the DEC axis shaft are sharp.  They will easily slice the cable you use.  Celestron solved this by putting a plastic insert in there to cover the edges.  I my opinion, you would be better off removing the shaft and working to smooth out the edges so that they are smooth and will allow the cable to move easily with getting sliced or scratched.  The second thing is that you will be much better off installing some kind of hard stop on the DEC axis (and realistically on the RA as well) rather than trying to leave a bunch of loosely wrapped cable in there.  With the loosely wrapped cable I can guarantee that sooner or later you will forget which direction the wrap is in and turn the DEC axis too far and risk damaging a cable or a plug.  Using a stop will allow you to easily route one or more cables through the hole without having to worry about cable wrap at all.  The RA is fairly easy since all you would need to do is drill a hole into the large axis retaining ring and install a post that would run into a stop where the polar angle pointer currently is.  The RA will be a bit more tricky, but just remember that there is no reason for either axis to have to turn more than 360 degrees (actually more than about 220 degrees on the RA).  Your biggest challenge may actually be figuring out how to route the cable(s) out the top of the mount since there is no a lot of space around the saddle.  The stock saddle is not something that I would try to modify since you could easily reduce it integrity.  Something like an ADM saddle with hole in the middle and a channel down the center would probably be the best bet.


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#19 elmiko

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Posted 11 March 2018 - 11:17 AM

bow.gif Love this kind of stuff!


Edited by elmiko, 11 March 2018 - 11:18 AM.


#20 StarmanDan

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Posted 12 March 2018 - 10:04 PM

Worked on this some more.  I really had wanted to have all the cabling internal to the mount. I considered simply soldering wires to the control board for power, ST4, and the DB9.  But my soldering skills are very poor and I was worried about messing something up.  So I removed the circuit board drilled a 3/4" hole in the metal plate close to the position of the RA shaft and installed a grommet.  Then fed the cables through and put the circuit board back on.  I will probably use different cables for the handbox as the coiled cable was a pain to feed through the RA axis.   

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