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AVX Free play in RA axis

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#1 Astrohoven

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Posted 12 February 2019 - 04:50 AM

Hello,

 

After hypertuning my AVX, I've been having this lateral free play in the RA axis even when the clutch is fully tightened. My PHD guiding has huge periodic peaks every minute or so and I believe this free play is the culprit? So how can I fix that free play and could it be the reason I'm having these periodic peaks? in other words, are these the symptoms of free play?

 

Clear Skies!

 

Anthony



#2 Astrohoven

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Posted 12 February 2019 - 07:09 AM

Updates:

 

- I discovered that the motor housing was in contact with the RA axis slightly. I fixed that however I don't think that's the reason I'm having guiding peaks since it's periodic. If it was caused by the housing rubbing on RA, I guess the spikes would be random?

 

- As for the free play, I literally tensioned everything so hard the gears were barely able to move just as a test. I tensioned the thrust bearings at the back of the RA, the spacing between worm and ring gear, and the lock nut on the worm's shaft. After all that I still had some free play on the RA axis. I realize that some slop should exist but I'm worried that it's the culrpit behind the spikes in guiding. Plus I can't ever recall having any slop in the RA pre-tuning.

 

Any insights would be greatly appreciated.

 

Anthony



#3 Astrohoven

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Posted 13 February 2019 - 05:39 PM

If anyone could check this video which shows what kind of play I'm talking about.

 

Please I need any kind of insight or help. This is really frustrating :(

 

Anthony



#4 emflocater  Happy Birthday!

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Posted 14 February 2019 - 05:40 PM

Not sure this is normal but remember you are moving the axis at the farthest end of your counterweight shaft which will produce allot of torque/leverage all the way up to the mount. Try just wiggling the cone part that the shaft comes out and I am sure it will be less than when you wiggle at the end of the counterweight shaft. Hard to tell but seems minimal to me.

Cheers

Don



#5 Astrohoven

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Posted 14 February 2019 - 06:30 PM

Not sure this is normal but remember you are moving the axis at the farthest end of your counterweight shaft which will produce allot of torque/leverage all the way up to the mount. Try just wiggling the cone part that the shaft comes out and I am sure it will be less than when you wiggle at the end of the counterweight shaft. Hard to tell but seems minimal to me.

Cheers

Don

You are right, when i try to wiggle at the top of the shaft, the movement is less of course but it still looks excessive to me. I mean the slightest breeze could set this up to a wild vibration which will be impossible to guide through. 



#6 emflocater  Happy Birthday!

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Posted 14 February 2019 - 06:51 PM

Did you try to adjust the worm assembly to the worm gear via trial and error to eliminate the play? Your sure you put everything back like spacers and all in the correct order when you did the tear down? I would also re-check that all grub screws, and ring nut are tightened properly as well. Did you try adjusting ant-backlash in the hand control as well?

Cheers

Don 


Edited by emflocater, 14 February 2019 - 06:55 PM.


#7 Astrohoven

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Posted 15 February 2019 - 04:35 AM

Did you try to adjust the worm assembly to the worm gear via trial and error to eliminate the play? Your sure you put everything back like spacers and all in the correct order when you did the tear down? I would also re-check that all grub screws, and ring nut are tightened properly as well. Did you try adjusting ant-backlash in the hand control as well?

Cheers

Don 

Yes I basically tried everything;

 

1- I tried to adjust the worm spacing, I even tightened it to the point where the motor was binding and I still had the slop.

2- All bearings and spacers are back where they were. I took lots of pictures and to be honest taking it apart and reassembling it wasn't that hard or complicated. The only challenging part was getting the worm to ring spacing in the sweet spot which I believe I have yet to do that I guess.

3- I double and triple checked all screws, I was very keen on tightening them properly the last time I did this (I've done that plenty of times by now). I also tried loosening and tightening the ring nut that holds the worm shaft with no apparent improvement.

4- I don't use anti-backlash in the HC since I'm using PHD for guiding and my current issue is currently mechanical. There is actual free play in the ra axis.

 

Update: According to ED from DSP, the slop is normal after hypertuning especially after all the stickiness and grease is cleaned up. My only issue is how much free play is recommended and if that's what's affecting my guiding. I guess the only way to know is to keep adjusting and testing which is really hard to do especially with the current weather.

 

Cheers!

Anthony




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