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FSQ106EDXIII - Micro Touch adaptation

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#1 bilgebay

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Posted 05 January 2013 - 10:52 AM

Details will follow, hopefully tomorrow, but here is the video:

http://www.youtube.c...h?v=fEVCGtBBR4A

1 count is equal to 5 microns. The total free travel is 29.58mm (5916 counts).

I discovered that my FSQ's focuser had 45 microns backlash (9 counts) :(

By manufacturing a bushing for the gear to fit the FSQ's fine focus shaft and an adaptor to fit the MSM30 motor to the FSQ's focuser body, I was able to use the existing motor and Micro Touch controller to drive the stock FSQ focuser.

Clear skies

#2 Denimsky

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Posted 05 January 2013 - 12:02 PM

Wow very nice clean setup!
Thank you for sharing.

#3 bilgebay

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Posted 07 January 2013 - 04:37 AM

Thank you Donghun. Yes, it is a very neat setup indeed. I haven't seen a better motorization to date :)

Here are the detailed photos for those who are interested:

This is how the Tak focuser looks after removing the fine and course focus knobs.

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The pinion gear is approx 1mm larger than the focuser shaft. I fixed it onto the shaft with the help of the set screw just to take the necessary measurements.

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The motor will be approx at this position after the adaptation

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Measuring the critical diameters

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#4 bilgebay

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Posted 07 January 2013 - 08:35 AM

A week later...

Before installing the adaptor and the modified gear

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I could have fit the gear with the help of a sleeve. Due to a misunderstanding I have a modified hub that fits the Tak shaft :(


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The sleeve technique is used by Starizona

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Here is the slit adaptor I produced to fit the MSM30 motor to the Tak focuser.

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Motor goes in

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Et voila!

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http://astrofotograf...zation _19_.JPG

The motor extends out 4-5 centimeters more compared to the knobs. Don't think this will be a problem though

http://astrofotograf...zation _20_.JPG

I have also removed the manual focus knob on the left/port side of the scope. This is necessary to avoid the risk of damaging the motorized focusing system. Using a piece of Gorilla Band, I have sealed the cavity lest dust and other stuff should penetrate the focuser bearings

http://astrofotograf...zation _21_.JPG

Bottom view

http://astrofotograf...zation _22_.JPG

#5 bilgebay

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Posted 07 January 2013 - 12:03 PM

Oh! One last thing before I forget: I have fixed the lock lever in the open position with some Gorilla band until I find a better solution. To keep the lock lever disengaged is very important. Locking it can be a very costly mistake.

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#6 dflipp

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Posted 07 January 2013 - 03:31 PM

Very nice!

I'd love to see the details of how you did this, but the photos aren't displaying.

-Dan

#7 bilgebay

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Posted 07 January 2013 - 03:55 PM

Thank you Dan.

According to me, the only missing information here is the drawing of the adaptor and the pinion sleeve. I hope to add those tomorrow.

The pinion gear, the MSM30 stepper motor assy and the Micro Touch Controller are sold by Starizona and Starlight Instruments.

If there is anything else you want know, please be more specific and I'll do my best to explain.

Cheers

#8 dflipp

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Posted 07 January 2013 - 04:14 PM

I see the photos now.

I already have the Micro Touch controller and MSM30 motor. I will need to get the Tak micro focuser. My scope is the older FSQ-106N, but hopefully the dimensions will be the same. I should be able to get a local machine shop to make the adaptor and pinion collar.

Thanks for posting this!

-Dan

#9 Logan Tudor

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Posted 07 January 2013 - 05:01 PM

Is it just me and my cpu, or are the pictures not visible? I only see a red 'X' in their place. Cheers, Logan.

P.S. bilgebay, if possible, could you upload high res versions to say Dropbox? Very intersted in this modification.

#10 bilgebay

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Posted 07 January 2013 - 05:29 PM

Hope this link works for you. If not, pls let me know and i will load the photos to dropbox tomorrow morning.

Cheers

#11 Mike Clemens

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Posted 07 January 2013 - 05:53 PM

Super nice. 5 micron steps. How big is the critical focus zone for blue light on the FSQ?

#12 Logan Tudor

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Posted 07 January 2013 - 08:31 PM

Thanks bilgebay, pics are now visible. Great post, thanks for sharing.

I wonder if the entire range of FT focus motors would work, namely: MSM20, MSM30 and MSM35? Anyone know?

I have a TOA-150 with the older focuser (not the 'B' version as also used on FSQ) and a new Microtouch hand controller (just like yours) sitting around unused. Would this be possible? Fingers crossed!

#13 hytham

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Posted 07 January 2013 - 10:55 PM

Very clean and very nice!

#14 bilgebay

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Posted 08 January 2013 - 02:31 AM

Super nice. 5 micron steps. How big is the critical focus zone for blue light on the FSQ?


Hi Mike, thank you.

In the case of FSQ, 5 micron steps are a bit coarse. The CFZ @ f/5 is 58 microns and @ f/3.6 it is 30 microns for blue light.

Attached is a spread sheet I put together for calculating CFZ for all scopes and here is a thread with some discussion on the subject based on a previous thread Jerry Lodriguss posted where he refers to his article on Focus Change Due to Temperature Variation.

If you follow the calculations in Don Goldman's article on New Critical Focus Zone you need to reduce the figure you find in my spread sheet by almost 60%.

Attached Files



#15 bilgebay

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Posted 08 January 2013 - 02:37 AM

Hi Logan,

I guess the motor selection depends on the load you are going to apply. In my case even the MSM20 would be sufficient but MSM30 was a better fit for an easier adaptation.

Hope you find the best solution for your case.

Clear skies.

Sedat

#16 schling

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Posted 08 January 2013 - 05:28 PM

Hi Sedat,

Great job. Funny, I am thinking about getting a FSQ106 and was tinkering with the idea of then doing exactly what you did, as I already have the Microtouch driving a StarlightInstruments focuser. Much neater setup like this.

I'll drop you a line if I get in trouble with my project when the time comes...

Clear skies

Robert

#17 schling

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Posted 09 January 2013 - 11:36 AM

Hi Sedat,

One more thing...

You mention that you discovered that the focuser has a backlash of 9 counts (45 microns). Do you think that this is due to the planetary reduction gear, or is it linked to loose tolerancing of the rack & pinion set?

Thanks

Robert

#18 bilgebay

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Posted 09 January 2013 - 12:25 PM

Hi Robert,

I will be glad to be of any help.

Hope to post the drawing with dimensions as well but it is in my other computer which is 500 miles away from me now :)

Regarding the backlash, I can say at least 7 out of 9 counts are coming from the Tak's rack and pinion. There should be a way to reduce this but then some other problems may/will occur.

As long as I know the backlash in terms of counts or microns, it is not that important in fact. Since the load will apply a force that will push the draw tube away from the scope, I will always reach focus from the opposite direction, i.e. by moving the draw tube inwards. The software I will be using (Sequence Generator Pro) takes care of that. When adjusting the focus, if the new focus position is further out from its current position, it moves out some further distance (which I am determining, say 50 counts) then comes to the new focus point. If, on the other hand, the new focus position is further inward compared to the current position, it just moves the draw tube in by the necessary distance.

#19 schling

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Posted 09 January 2013 - 02:38 PM

Thanks!

If you could get around to posting the drawings and dimensions that would be great.

With respect to backlash, I actually never bothered to try to measure it on my FeatherTouch. Just like you mention, when autofocusing I always move from out to in on the final move, making sure the any backlash has been "eaten up". The question was just technical curiosity on my part.

Regards,

Robert

#20 Denimsky

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Posted 09 January 2013 - 04:12 PM

In the case of FSQ, 5 micron steps are a bit coarse.


Hi Sedat,

Why do you say 5 micron steps are coarse even though it is way below the CFZ :question:?

#21 Quarkroscoe

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Posted 09 January 2013 - 06:54 PM

What an elegant solution. I have just started my search for a remote focusing solution for my TOA-130. My TOA was built in 2004 and the 4" focuser is a bit different from what I see in your pics (see attached). I have looked at JMI and RoboFocus and your solution is by far the best. It also uses the fine focus shaft and the JMI does not. I have heard about a lot of slipage issues with the RoboFocus. By the looks of the attached pic, do you think your solution would work on my TOA?

Cheers,
Dennis
www.RoscoeSkies.com

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#22 bilgebay

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Posted 10 January 2013 - 12:52 AM

Thank you Dennis. My answer will be "yes" to your question :)

#23 bilgebay

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Posted 10 January 2013 - 01:43 AM

In the case of FSQ, 5 micron steps are a bit coarse.


Hi Sedat,

Why do you say 5 micron steps are coarse even though it is way below the CFZ :question:?


Maybe it was a bit early to utter my judgement on this. However, we have a very limited CFZ to start with. Let's say the temperature has dropped 1 degree and this means that your tube will contract by 13 microns. With this setup you have the ability to move either 10 or 15 microns, not 13. This may look unimportant at first look but if you consider all you have is 30 microns only, it is a bit tight to fit in.

Additionally, I have heard from other users that there is a hysteresis problem with the Micro Touch system. So, more steps could help me to land in this tiny CFZ slot with better precision.

I need to do some testing on the accuracy of the system. I hope to find the time for this before the end of this month.

Clear skies.

#24 Quarkroscoe

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Posted 10 January 2013 - 01:25 PM

Hi Sadat,

Looks like I am going forward with your solution. In reviewing your pics, I see two different gears with respect to what is mounted on the fine focus shaft (see your attached photos). The brass gear looks more like the one shown in the Micro Touch Manual (see attached). What am I missing here?

Cheers,
Dennis

Attached Files



#25 bilgebay

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Posted 10 January 2013 - 01:59 PM

Dennis, the brass gear and the bushing/sleeve is just there to show the original Starizona delivery for the MSM20 motor. Has nothing to do with this mod other than to demonstrate the sleeve technique is used by Starizona in this kind of application. Sorry for the confusion.

Hope it is clear now.

Sedat






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