23 replies to this topic

[Tom Graham]

Who can help document —in this one message post, the correct focuser draw tube threads (i.e., the threading of the “bare” draw tube) for Takahashi refractor focusers (at least those < 3”) and including whether the draw tube threads are pos (male) or neg (female)?

 

I’ve had difficulty identifying the focuser draw tube threads for the FOA-60Q. (I measure it as 47mm OD). Some resources say that the focuser is identical to the older 2 inch draw tubes used on the FC50/FC60 but I can’t locate those thread measurements (and my FC-60NZ has the larger focuser.)

 

I think that it would be very helpful to have one source for each of Takahashi’s refractor focusers (that Tak has used over time.)

 

Lately, we most commonly see references to the Tak 2.5” and Tak 2.7” focusers, but let’s include any other variations such as Tak 2” focuser and the Sky 90.

For example:
​Takahashi 2.7" Focuser: 72mm x 1.0mm (neg)

Takahashi 2.5” Focuser: ?

Takahashi Sky 90: 55.9mm x 0.75mm (pos/neg?)

Takahashi 2" Focuser: ??

 

 

[Lentini]

I have an FC-100DC, which has a male M56x0.75 focuser drawtube end, listed as a 2.2" rack and pinion focuser.

 

It accepts various focuser adapters including the Baader Click-Lock CLTAK-2i 2956255, and the Takahashi Coupling TKP20006B (Male M56 to Female M56), which is also listed as compatible with the FS-60CB.

 

So I assume the FS-60CB is also male M56x0.75 2.2" rack and pinion.

 

 

Looking at the FOA-60 and FOA-60Q system chart, it is shown with a Takahashi TKP28001 on the end of the focuser tube, which gives it an M56x0.75 as well. But what's on the scope side of the TKP28001 isn't readily given in my quick google search.

[Lentini]

I believe my 1.25" TS-80 has a female M36.4x1.0 end, fwiw.

[nic35]

Tom

 

Here's a listing of all (most?) Tak adapters with specs on their diameters and thread sizes.

 

If you have a system diagram and can find the first item that attaches to the drawtube, you can figure out the spec.

 

FWIW, my FS-60CB has  a 56x0.75 male end to the draw tube, as does my old FC-76.

 

john

 

 Takahashi-Adapter-Specifications.pdf   135.23KB   204 downloads

Edited by nic35, 29 April 2024 - 12:38 PM.

[Lentini]

Nice. Thanks for uploading that. But of course it's missing the one adapter for the FOA-60/60Q.   No TKP28001!

[nic35]

Yes.  I added the parenthetical (most) once I realized that.

 

A question best asked on the takitis! thread.

 

j

[Tom Graham]

Thanks to you both for these replies and especially for the Takahashi Adapter Specifications resource. That is exactly what I had been looking for. I had seen it before and searched for it for two days and couldn’t find it.

 

That should help me answer the question for those models that I do own — except the FOA-60Q and not for the older FC50 & FC60’s…

[Tom Graham]

RE: TKP28001
I think but have not yet confirmed that the FOA-60/60Q Part (10) TKP28001 would be: 

 

“M56x0.75 male to M47x0.75 female thread adapter (56mm to 47mm step-down ring)”

https://rafcamera.co...5m-to-m47x0-75f
(tvg…in this case, a ‘step-up”) this would be consistent with my 47mm OD measurement of the FOA-60Q draw tube thread. 

 

I have emailed Takahashi America this evening and will post update when response is received. 

 

[Tom Graham]

I discovered in another post that Matt (Kunama) had confirmed the thread dimensions for the FOA-60/60Q Part (10) TKP28001 and worked with (!) RAF Camera to create a couple of options. That confirms that the focuser drawtube threads for FOA-60(Q) are M47x0.75 male/positive.

 

I hope to learn what focuser drawtube threads the “Tiny Taks” (e.g., FC-50 & FC-60) use and have posed that question on their Fan Thread. 
 

In the interim, this is the most complete list that I could prepare based upon those Takahashi refractors that I own and as augmented by the numerous system charts that I could find online. 

 

I have been very surprised to find so many variations. I would have expected some, but far more standardization. 
 

Please review the “Focuser DrawTube Thread (Male/Female)” column in this chart below very closely and advise if you see any mistakes or if you have additions to make:

 

 

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[edif300]

Hi Tom,

 

FS-128F -> TKP27001 has M92P1 / ⌀89

                    TKP27113 has ⌀89 / M72P1 Female

[Weisswurst Josef]

Hi Tom,

 

have measured the FOA-60Q and confirm the M 47 x 0.75 mm male.

 

TS-65P and FC-50 end in M 43 x 0,75 mm female.

 

Measured the FC-65 to M 55.7 x 0.75 mm male.

Think it`s just M 56 x 0.75 mm.

 

My TS-80 is stored away, will measure it in some weeks.

Will also de-store the FC-100N for measuring.

 

Regards,

Andreas

[Tom Graham]

FOA-60Q …M 47 x 0.75 mm male.

TS-65P…[M 43 x 0,75 mm female]

FC-50 …M 43 x 0,75 mm female...

FC-65 … M 56 x 0.75 mm.

 

…

TS-80…will measure it in some weeks [& the]

…FC-100N…

@Andreas, Wow! Thanks for this many additions! (After I have someone confirm whether the FS-128F drawtube is male or female, I’ll use all these and update the chart.)

[Weisswurst Josef]

Tom,

 

the FS-128F should have the same big drawtube as the FS-152.

A FS-152 with this big drawtube will arrive in some weeks/months. So I can measure it.

Note: There were FS-152 with the same "small" 2.7" drawtube as the normal FS-128.

 

Will also measure the FS-78 to confirm the list.

Can measure the FS-128, but it`s also stored away.

 

Little zoo of Takahashi fracs here.

 

Note: The leading "M" stands for "metric". Think it`s not necessary. I´m just used to write it ...

 

Regards

Andreas

[Weisswurst Josef]

Two further measurements:

 

 FS-78:   56 x 0.75 male

 FC-100N:   56 x 0.75 male

 

The FC-100N has 100/100 and was built in the 90s.

 

 

Now I`ve to digg out the FS-128 and the TS-80.

Will take some years.

Edited by Weisswurst Josef, 03 May 2024 - 07:12 PM.

[Tom Graham]

I’ve added several more (and corrected a couple) Takahashi focuser draw tube thread measurements, but we still lack a few that I know are owned by some of our CN members.

 

I appreciate those that have taken time to check your inventory and pull out your caliper and pitch gauge. There are at least 1/4 of these models that don’t appear to have a system chart with part numbers (with thread measurements) like the newer/current models.

 

My original purpose in compiling this list was to identify which of my refractors had a 2” vs 2.5” vs 2.7” focuser — so that I could know which FeatherTouch MPA to order. But then I realized that Takahashi had made many different focusers over time -  that were similar in size, but not identical to one another.

 

So, then my goal of the list was to identify the drawtube threads for each - to serve as a resource to those that complain about the cost and/or complexity of Takahashi adapters.

 

If you know the drawtube threads for each focuser, then you can order only one (the first) adapter to convert to whatever threads you happen to prefer (whether competitive, custom or after-market adapters.)

 

 

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[Lentini]

Post #3 has the TS-80 info, and the TS-65D was the same. 

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[Tom Graham]

I believe my 1.25" TS-80 has a female M36.4x1.0 end, fwiw.

Post #3 has the TS-80 info, and the TS-65D was the same. 

Thank you, Lentini. I’ll post these two additions as highlighted edits to the table as we next have another model to add. 

[Lentini]

This TKP28001 link implies the FOA-60 and FOA-60Q have M56x0.75.

 

https://www.deepspac...-ad-ring-foa-60

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[Tom Graham]

This TKP28001 link implies the FOA-60 and FOA-60Q have M56x0.75.

 

https://www.deepspac...-ad-ring-foa-60

Does anyone have any other Takahashi refractor models that we can add? 
 

 

Rob,

You’ve already been a great help in this project and thank you for double-checking me. I’ve remained focused on the threads of the drawtube itself … before any attachments. The observer side of the TKP28001 is indeed M56x0,75(pos)* however the objective side of that attachment mates to the focuser drawtube which I’ve since reconfirmed (by measuring my own FOA-60Q) to be 47mm x 0.75mm M. Image now attached. 

*both specifically stated here: https://teleskop-aus...aptor-to-M56-Nr and as measured by me. 

 

 

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[Tom Graham]

mizumo has recently posted a link to this outstanding reference from Starbase.jp in his post on the Takitis! thread. Using the translation feature from most web browsers, I see that they have listed the focuser draw tube thread in the last column on the far right side of the table. There is no reason for us to re-create or further maintain a database while they are sharing an even more complete record here:

 

https://www.starbase...entries/23.html

 

[cengell]

On my Tak FC60 looks 100% correct... Thank you!!!

 

Christopher

[BYoesle]

The Starbase link translation lists the focuser tube as the "Drain Tube." For the FC-60 the thread is correctly listed as M47 x 0.75.

[nic35]

The Starbase link translation lists the focuser tube as the "Drain Tube." For the FC-60 the thread is correctly listed as M47 x 0.75.

As in "drain your bank account" ?

[BYoesle]

  Exactly!

 

And to paraphrase a famous physicist "if I wanted to have to memorize and configure all these adapter sizes, I would have become a botanist."