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Installation of a FeatherTouch SC Microfocuser. Hard to turn focuser knob..fix?

 

Original focuser was normal and easy to turn.? The FeatherTouch is very difficult to turn.? The threads on the focuser shaft were untouched throughout the installation and the feathertouch nut turned easily during installation.??


Any ideas?
 

that is not right. ?

1) remove?Feather Touch
2)?check the action of the scope focus
3) check the action of the Feather Touch
4) re-install

?Good luck!

Stan
 

P.S. Make sure the mirror locks are unlocked!
Gary Jarrette
 

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The surface that that is machined in the rear casting of the scope is not perpendicular to the mirror threaded shaft. That is why Feather Touch supplies an ¡®O¡¯ Ring to put between the Feather Touch and the machined surface that it rests against. You are not supposed to synch the screws all the way down that hold the Feather Touch to the rear cell, if you do you will put a bind on the screw. That is what is causing the tightness. With the ¡®O¡¯ Ring you can pivot the flange to the proper alignment.

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What you need to do is back off on the three hold down screws and as you turn the focus knob screw in each screw in its turn. I am assuming of course that you installed the ¡®O¡¯ Ring which is necessary. If you detect a bind then tighten one of the other screws.? When you feel you have gone as far as you can stop. Three points determine a plane and so it is with the three screws. Your job is to find the sweet spot by adjusting the screws until the Feather Touch is in line with the threaded shaft.

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I went one further because I did not like the ¡®O¡¯ Ring deal I got rid of it. What I did is I drilled and tapped three 6-32 screw holes between the three hold down holes already in the Feather Touch flange. I then installed three set screws that I used in conjunction with the three hold down screws to establish a plane which is perpendicular to the screw shaft. Working the hold down screws against the set screws provided me a very tight positive attitude adjustment for the flange.

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Mine is perfectly in line with the 3/8-24 mirror shaft, no bind at all.

?

Gary

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Carpe Noctem

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From: C14_EdgeHD@... [mailto:C14_EdgeHD@...]
Sent: Wednesday, August 2, 2017 7:28 AM
To: C14_EdgeHD@...
Subject: [C14_EdgeHD] Installation of a FeatherTouch SC Microfocuser. Hard to turn focuser knob..fix?

?

?

Original focuser was normal and easy to turn.? The FeatherTouch is very difficult to turn.? The threads on the focuser shaft were untouched throughout the installation and the feathertouch nut turned easily during installation.??

?

Any ideas?
 

Thank you....I believe that is the problem.? I think I will remove the focuser and establish a perpendicular with a square and see if I can find a parallel.? I'll post the results.?

I was kinda wondering the function of the o ring. ?
 

Worked with the focuser this afternoon.? I isolated a single problem.? The brass nut that turns on the mirror focus rod was binding at the outer edge of the thread.? Visual inspection under magnification shows not burs or cross threading.? It may be that it is engineered to have a tight end. ? I would like to put it on a tap but in the mean time I smoothed and polished the threads.? I put it back together and found that it turns a bit easier.? My final step of screwing in the 3 screws.? I did find that no matter how I tightened them, the focuser became bound.? I ended up tightening just to take out "slack".? Seems OK.? I am anticipating that there may be problems when the mirror is at a bottom position.? I will not really know if the problem is solved until I have a star to focus on.?
Thanks for the heads up on the mounting plate screw issue...it is a very sensitive and requires great care to get right.? I am not sure it should be like this and plan on contacting StarLight instruments and talk about my installation.
Gary Jarrette
 

When you attach the focuser just pull the mirror back and forth. It should slide very smoothly. If you cannot pull the mirror through its entire range and do so very smoothly, you have other issues.

When you have the focuser in hand and turn it, it should be very smooth. If both of these tests work then it is your alignment of the focuser. Perhaps your observations have turned up another flaw but the alignment is critical.

Gary
Carpe Noctem

Sent From My LG-V10 Phone




On Wed, Aug 2, 2017 at 4:10 PM -0700, "gdunham@... [C14_EdgeHD]" <C14_EdgeHD@...> wrote:

?

Worked with the focuser this afternoon.? I isolated a single problem.? The brass nut that turns on the mirror focus rod was binding at the outer edge of the thread.? Visual inspection under magnification shows not burs or cross threading.? It may be that it is engineered to have a tight end. ? I would like to put it on a tap but in the mean time I smoothed and polished the threads.? I put it back together and found that it turns a bit easier.? My final step of screwing in the 3 screws.? I did find that no matter how I tightened them, the focuser became bound.? I ended up tightening just to take out "slack".? Seems OK.? I am anticipating that there may be problems when the mirror is at a bottom position.? I will not really know if the problem is solved until I have a star to focus on.?
Thanks for the heads up on the mounting plate screw issue...it is a very sensitive and requires great care to get right.? I am not sure it should be like this and plan on contacting StarLight instruments and talk about my installation.
 

Not to say it doesn't happens but I've never seen this non-orthogonal issue and I've installed several Feather Touches and have friends who've done likewise. ?If I were to identify such a problem I would be inclined to investigate why (i.e. a defect in the mirror mount?) but if it can be "fixed" by tilting the FT then that is probably adequate.

Your description of the "tight nut" seems to imply that the problem is solely within the FT unit? ?They are expensive so I would not mess with it and return it as a defective unit. ?But if that issue is within the SCT itself it is not so easy to return and the warranty may have expired, in which case you are on your own.

BTW, every FT I've used is silky smooth.

Stan
 

This will be hard to describe but I will try.? Ultimately I found one issue that made the turning of the focuser difficult.? I found that there is an issue with the threads of the brass stop (as described in the installation sheet).? It seems that the brass stop binds and becomes difficult to turn, when the focuser shaft reaches the end of the threads in the brass stop.? I visually inspected the threads under magnification, and found no issues such as burs or cross threading marks.? I threaded the brass stop in the opposite direction and found that issue is with the end threads on the focuser side of the brass stop. ? I used some steal wool to smooth the threads and then polished the threads.? The focuser was then re-assembled and the focusing is definitely improved.? The force needed to turn the focuser increases as the scope turns towards zenith though.?

A second issue ... the fine focus seems to fail when the force increases past a certain point.? This renders the quicklync motor focuser useless.? This seems to be a "broken" part problem.

I now have concluded that I just need to keep the focuser base screwed to snug and no more.? The alignment arbitrarily takes care of itself.

I have found that everything else is good.? The mirror glides smoothly and evenly, in and out.

I don't know if these problems are a result of initial problems of installation or if they came with the product from the manufacture.? I put in a message to starinstruments but Wayne is out of the office for a week ...uggg.
 

Talked to StarLight instruments.? The brass stop tolerance vs the Celestron focuser shaft tolerances have recently been an issue and have resulted in difficulty with turning the focuser.

Will be a warranty repair.?
 

Follow up on feathertouch focuser for C14EdgeHD in Hyperstar mode.? StarLight Instruments repaired under warranty and returned in less than a week...outstanding.? I installed the feathertouch focuser and tested.? Very smooth and easy travel.? Great!??

Issue: The brass stop thread size did not match specs on Celestron focus rod by a minute amount.? StarLight Instruments is aware and has resized brass stops for this problem.?

Installed the Optech Quicklynx motor and tested with TSXPro @focus2 and @focus3.? I need to work on settings for the @focus2 but @focus 3 achieved perfect focus first time and then on 2 more repeats.? OTA was at about 80degrees.? No "mirror flop" encountered.?

I couldn't be happier!? My HyperStar setup is fully remote capable!

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