Tak FC-100 - a few questions :)

[GavStar]

3 minutes ago, Piero said:

@BGazing Well, we are not the first ones getting the MEF-3. Actually, the majority of members upgrade the standard focuser with this microfocuser, rather than replacing it completely with a FT one. Over time, it will be more and more clear how effective to us this works.

 

@Stu Out of curiosity, which models of Tak focusers have you experienced issues with? Do you reckon the problem was due to the MEF-3 or the focuser itself (e.g. rotation movements, backslash along the travel, etc) ?

My issues with the mef-3 and Tak focuser were due to the mef-3 screws gradually working loose rather than anything with the Tak focuser itself. Also I did find the metal plate flexed a bit when using heavy eyepieces which made it lose a bit of the feel imo

[Piero]

1 hour ago, GavStar said:

My issues with the mef-3 and Tak focuser were due to the mef-3 screws gradually working loose rather than anything with the Tak focuser itself. Also I did find the metal plate flexed a bit when using heavy eyepieces which made it lose a bit of the feel imo

[Piero]

Oh well, I'll see how it goes and if it works badly, I'll replace the whole thing with a feathertouch one. 

[25585]

Are the FT focusers rotatable? 

[GavStar]

8 minutes ago, Piero said:

Oh well, I'll see how it goes and if it works badly, I'll replace the whole thing with a feathertouch one. 

I think there’s a very good chance you will be happy. I used my mef-3 for a couple of years fine. However I then made the mistake (?) of buying a scope with a feathertouch and it spoilt me a bit I think. As I think I mentioned earlier in this thread, one dark night the mef-3 screws worked loose for a second time ever in 2 years. However I didn’t have the little Allen key with me to tighten them up again in the dark so was reduced to the 1x focuser for the rest of the night - this was the straw that broke the camels back for me. I’ve now had the feathertouch on my Tak for a year and it has always done a perfect job for me with my heavy eyepieces and long NV attachments.

Edited May 17, 2018 by GavStar

[Piero]

1 hour ago, GavStar said:

I think there’s a very good chance you will be happy. I used my mef-3 for a couple of years fine. However I then made the mistake (?) of buying a scope with a feathertouch and it spoilt me a bit I think. As I think I mentioned earlier in this thread, one dark night the mef-3 screws worked loose for a second time ever in 2 years. However I didn’t have the little Allen key with me to tighten them up again in the dark so was reduced to the 1x focuser for the rest of the night - this was the straw that broke the camels back for me. I’ve now had the feathertouch on my Tak for a year and it has always done a perfect job for me with my heavy eyepieces and long NV attachments.

Thank you for your support!

Which heavy eyepieces did you use with your original Tak DF?

[GavStar]

19 minutes ago, Piero said:

Thank you for your support!

Which heavy eyepieces did you use with your original Tak DF?

17 Ethos and Es 92 so definitely at the upper end re weight ?

[Highburymark]

19 hours ago, Piero said:

Thanks Mark. That's what I thought too. I believe the washer and additional screw are meant as a replacement of the large screw with the two micro-holes, which now holds the metal bar. 

Stu is right on the money about the weakness of that bar though. If the two screws loosen a bit, there should be some backslash. Maybe, Takahashi should have attached that metal bar to the microfocuser permanently without those screws. 

I think I described the MEF as a bit Heath Robinson (ie flimsy) on SGL when I first fixed it to the scope Piero. That was 18 months ago, and it has worked very well ever since. Haven't even tightened or adjusted the screws. Perfect tension for tiny changes in focus. But it is still a bit rudimentary for such a lovely telescope. And if it did cause problems I would get an FT without hesitation.

[Piero]

6 minutes ago, GavStar said:

17 Ethos and Es 92 so definitely at the upper end re weight ?

Thank you.  ... 17E weighs 700g... that's about the weight of my heavy eyepieces..    

[Piero]

1 minute ago, Highburymark said:

I think I described the MEF as a bit Heath Robinson (ie flimsy) on SGL when I first fixed it to the scope Piero. That was 18 months ago, and it has worked very well ever since. Haven't even tightened or adjusted the screws. Perfect tension for tiny changes in focus. But it is still a bit rudimentary for such a lovely telescope. And if it did cause problems I would get an FT without hesitation.

I have to say that ..... I AGREE !! 

[25585]

Moonlite 2.5 inch focuser is what I may choose. 

Using 41mm Panoptic or ES 40mm Maxview requires no less. Cheaper than a FT, and more options. 

[Stu]

48 minutes ago, 25585 said:

Moonlite 2.5 inch focuser is what I may choose. 

Using 41mm Panoptic or ES 40mm Maxview requires no less. Cheaper than a FT, and more options. 

To me that misses the point. Why take a lightweight scope and add a heavy weight focuser to it? The 2” Feathertouch is totally capable of handling heavy 2” eyepieces and to me is much more in keeping with the scope. Non rotatable, but easy enough to rotate the scope in the rings, although having to loosen off four of them each time may change that.....

[Piero]

@Stu  

In the above thread, you disclosed that you attached your FT to the Tak using the A20-302 adaptor. I did not expect that that adapter would work with the FC100 as it is meant to work with the FS60 and FC76. Searching on the SI website (http://starlightinstruments.com/store/index.php?route=product/product&path=38_60&product_id=405), the adapter for the FC100 should be A20-304. The difference is in the OTA thread side: M77.5 (A20-302) vs M95 (A20-304). 

Do you think that the A20-304 replace the aluminium circle which in your photo is between the ring and the focuser? And why did you choose the A20-302 over the A20-304?

[Stu]

12 hours ago, Piero said:

@Stu  

In the above thread, you disclosed that you attached your FT to the Tak using the A20-302 adaptor. I did not expect that that adapter would work with the FC100 as it is meant to work with the FS60 and FC76. Searching on the SI website (http://starlightinstruments.com/store/index.php?route=product/product&path=38_60&product_id=405), the adapter for the FC100 should be A20-304. The difference is in the OTA thread side: M77.5 (A20-302) vs M95 (A20-304). 

Do you think that the A20-304 replace the aluminium circle which in your photo is between the ring and the focuser? And why did you choose the A20-302 over the A20-304?

You are quite right, the ‘correct’ adapter is the 304. I started down the Tak/Feathertouch route with an FS-60C and FC-76DC and these used the 302, which just so happens to fit the FC-100 too.

Personally I prefer the look of the 302, it just seems smaller and less dominating, and leaves the silver ring at the back exposed, whereas the 304 covers this up. They basically do the same job, although I think the 304 may be ever so slightly shorter. There is a thread somewhere which I will try to dig out. 

DOH, it is in the thread above after all.

[Ricochet]

21 hours ago, Piero said:

If the screws often loosen, one could glue the screws, metal plate, and microfocuser together, so that those three components stay permanently in place. A metal-to-metal glue should do the work just fine;

I would try locktite 243 on the screw threads. It should prevent the screws loosening but allow you to undo the screws if required in future. 

[Piero]

32 minutes ago, Ricochet said:

I would try locktite 243 on the screw threads. It should prevent the screws loosening but allow you to undo the screws if required in future. 

Interesting! Thank you! I must admit that I know nothing about these things! 

Edited May 17, 2018 by Piero

[AndyH]

Agreed. Blue or even purple loctite will do the job. Handy stuff, esp for spectacle micro screws etc. i've had a bottle of purple for what seems like forever. Still seems to work.

http://www.loctite.com.au/aue/content_data/133403_LT_4985_Threadlocking_Users_Guide.pdf

 

Andy

 

[Piero]

1 hour ago, Ricochet said:

I would try locktite 243 on the screw threads. It should prevent the screws loosening but allow you to undo the screws if required in future. 

 

17 minutes ago, AndyH said:

Agreed. Blue or even purple loctite will do the job. Handy stuff, esp for spectacle micro screws etc. i've had a bottle of purple for what seems like forever. Still seems to work.

http://www.loctite.com.au/aue/content_data/133403_LT_4985_Threadlocking_Users_Guide.pdf

 

Thank you, both of you! That seems exactly what is needed here. The purple loctite (Loctite 222) should be more than enough. These screws are very small, certainly smaller than M6. 

[mikeDnight]

My MEF focuser has been on for a couple of years or more and its worked flawlessly. I've never had a screw loose! 

[Stu]

9 minutes ago, mikeDnight said:

I've never had a screw loose! 

I think we should have a vote on that Mike  

[25585]

Periodic checks on all nuts, bolts, screws is part of running maintenance. For all things.

[Piero]

7 hours ago, 25585 said:

Periodic checks on all nuts, bolts, screws is part of running maintenance. For all things.

Whilst I accept the fact that there is a small chance that it can happen, my opinion is that if one can be certain that it will happen, then the design has some fault... 

If I buy a car, I do not expect to have to regularly check the bolts and nuts of each door to make sure not to lose (!!) one while driving! Can you imagine a similar scenario on a motorway?? 

[BGazing]

7 hours ago, 25585 said:

Periodic checks on all nuts, bolts, screws is part of running maintenance. For all things.

True that. I had the 2in clicklock part of the Baader dielectric diagonal come loose in the dark, those tiny screws were not gripping as they should anymore. I never leave without the appropriate allen key anymore.

FT is great. When pondering options, I could not justify cost, but now it looks like 6 or half a dozen dilemma...with a small trade-off in functionality vs aesthetics. 

But I do not need FT, I need more nights of good seeing and Jupiter just a couple of degrees higher (I know I cannot get the second wish fulfilled at present).

[25585]

29 minutes ago, Piero said:

Whilst I accept the fact that there is a small chance that it can happen, my opinion is that if one can be certain that it will happen, then the design has some fault... 

If I buy a car, I do not expect to have to regularly check the bolts and nuts of each door to make sure not to lose (!!) one while driving! Can you imagine a similar scenario on a motorway?? 

But you do for wheels & tyres I hope!

[Piero]

I have tried the MEF-3 for a while now. 

Pros: it does job, meaning that it allows you to reach a better focus smoothly, even when a moderately heavy combo like the ZZ+VIP is used.

Cons: when the rotation begins (both inward or outward), I can feel that there is no "grip". It is not backlash, but the fact that the rotation of the microfocuser drives a shift of the aluminium plate along the rotation. The feeling is like a "rubbery behaviour", when I start rotating the micro-focuser. To me, it is quite weird. Note that this is not due to screws loosening. Those are in place.

I believe the rotation should improve if that aluminium plate were replaced with one made of steel. It'd be interesting to try this.