Lunt LS60 / BF 1200 Mod. - Help

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chriskosmos
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Lunt LS60 / BF 1200 Mod. - Help

Post by chriskosmos »

Hi Guys,
I have a Lunt LS60 / BF 1200 solar scope.
I have read a lot about the modification of a LS 50 but nothing about a LS60 mod.
The problem is the connection to the pressure tuner. The external thread has a diameter of approx. 86 mm.
My favorite Scope is the Svbony SV503 ED (102 mm)

- Achromatic
- f/7 and 714 mm
The details are the same like the Lunt LS100.

Is the modification possible with the LS60 and what concrete designation has the thread from the Lunt. I have a 3D printer and maybe I could print something. But maybe there are adapters to buy?
I hope anybody can help me.

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Bye
Chris


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by marktownley »

Hi Chris.

Not sure what the thread sizes are both ends you want to mate together, best just to measure with calipers. Someone like precise parts will be able to make a custom adapter.

You will need to work out how much to cut off the donor scope tube to be able to reach focus.

Mark


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by _RA_ »

Chris,

Are you able to ascertain the thread size of the SVbony tube? I assume the aim is to unscrew the focuser from the donor scope to mate with the Lunt60PT?

~ Ross


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by chriskosmos »

Thanks Guys! At the moment I do not have SVbony Scope. A basic question: Is my LS60 Bf1200 Scope suitable for the modification?
I think the connection and correct distance is possible but maybe there are other problems?
I have not seen modifications with the LS60 it was always mods. with the LS50.

Chris


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by rsfoto »

Is the modification possible with the LS60 and what concrete designation has the thread from the Lunt.
Hi,

If you measured a diameter of something like 85.35 mm then it is a M86x1.0 ¿? male thread. Measure the distance from peak to peak of the thread. I do not think it is a M86x0.75 as that would be very fine and unnecessary.

You can also ask Lunt what thread it is and explain why you need it and perhaps they even help you with the correct length of the scope ¿?

You mentioned you have a 3D printer. I was doing a different project (camera rotator for Takahashi telescope) and trying to make a M78x1.0 male and female thread and it will require a lot of test printings due to tolerances of the shrinking plastic and a thread with that pitch needs at least a layer of 0.12mm when printing.


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by marktownley »

chriskosmos wrote: Thu Jan 06, 2022 4:33 pm A basic question: Is my LS60 Bf1200 Scope suitable for the modification?

I have not seen modifications with the LS60 it was always mods. with the LS50.
Hi Chris

It is possible, but you will have to cut the tube down on the donor scope. Then you will lose any threads on the end of the OTA which will hinder your ability to connect squarely to the etalon module.

Maybe there's a reason you don't see LS60 mods?

Genuinely, if you don't know how to do it you should probably avoid it as it will just create a load more headaches down the line as you encounter more things you haven't considered...

Mark


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by Rusted »

With respect, you can save the end of tube, screw threads, by cutting out a short section at a suitable mid-point.
This cut out section is calculated to shorten the tube without damaging the threaded end.
It would require some manual skill but would not be too difficult.
Use the paper roll, wrapping method and a fine toothed hacksaw for cutting.
You would have to take careful account of any internal baffles or other components before you start sawing the main tube.

Smooth the cut ends and square them using abrasive paper. Glued onto a flat plate like thick glass or marble?
Or even glued or pinned onto smooth, flat plywood.
The tube held upright and moved gently in circles. Change to finer sandpaper as you progress.
Glue and sleeve the cut joint with a suitable material using Epoxy.

I have done this in sizes up to 18" Ø 1/4" wall PVC tube. [50cm Ø x 6mm wall thickness]
Even managed to achieve a perfectly matched miter joint at 53° degrees.
Using more abrasive paper wrapped around a length of 18" Ø tube. Some patience was required. ;)

Or, use a lathe to square the cut ends if you have access to machine tools. Use plugs and tapered centers to hold the tube safely.

I believe AOK Swiss [of PST etalon adapter fame] make adapters to order. As do Telescopes-Express in Germany.


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H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by chriskosmos »

Thanks a lot for your informations! I will report to you. :)
Have a nice werekend!

Chris


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by _RA_ »

Rusted wrote: Fri Jan 07, 2022 3:50 pm With respect, you can save the end of tube, screw threads, by cutting out a short section at a suitable mid-point.
[\]
Interesting. What about all the baffling?


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by Rusted »

_RA_ wrote: Fri Jan 07, 2022 7:37 pm
Rusted wrote: Fri Jan 07, 2022 3:50 pm With respect, you can save the end of tube, screw threads, by cutting out a short section at a suitable mid-point.
[\]
Interesting. What about all the baffling?
I did mention baffling. Shortening any refractor will inevitably involve baffles or internal components.
As Mark suggests: If the modder isn't fully competent then the risks of failure are much higher.

We can help with advice, given enough information, but most modding is carried out by more experienced users/abusers.
The high cost, per aperture, of complete H-alpha solar telescopes suggests that modification be carried out with great care.
Resale of modded solar telescopes is fraught with problems. People expect cosmetic perfection at this level of retail pricing.
The different thread sizes are also a problem. Which may be tackled and later reproduced by competent 3D printer operators.

Then there is the serious matter of safety. A non-approved mod could project more harmful [blinding] rays into the modder's eyes/cameras.
Most of the individual components in solar telescopes are complete unknowns. There are airy claims from manufacturers, or literally, none at all.
Not all components or telescopes perform precisely as claimed, or often hyped.
The final commercial product may be safe but swapping things around still needs great care.

Mods inevitably involve larger apertures. With greatly increased light and heat passing through highly sensitive components.
When in doubt don't. Let somebody else take the risk and report back to the benefit, or otherwise, of all.


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H-alpha: Baader 160mm D-ERF, iStar 150/10 H-alpha objective, 2" Baader 35nm H-a, 2" Beloptik KG3,
Lunt 60MT etalon, Lunt B1200S2 BF, Assorted T-S GPCs or 2x "Shorty" Barlow, ZWO ASI174.
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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by marktownley »

_RA_ wrote: Fri Jan 07, 2022 7:37 pm
Rusted wrote: Fri Jan 07, 2022 3:50 pm With respect, you can save the end of tube, screw threads, by cutting out a short section at a suitable mid-point.
[\]
Interesting. What about all the baffling?
Any baffling in the lower section of ota (focuser end) will not be in their ideal place and will need repositioning.


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by _RA_ »

marktownley wrote: Sat Jan 08, 2022 7:53 am
_RA_ wrote: Fri Jan 07, 2022 7:37 pm
Rusted wrote: Fri Jan 07, 2022 3:50 pm With respect, you can save the end of tube, screw threads, by cutting out a short section at a suitable mid-point.
[\]
Interesting. What about all the baffling?
Any baffling in the lower section of ota (focuser end) will not be in their ideal place and will need repositioning.
That makes sense. But @Rusted was talking about removing a section from the middle to preserve threads, which has merit. But that seems like it would just completely mess up any baffling.

It seems like at some point, shortening the tube may not be much less labor intensive than just getting a new tube custom cut and threaded, and building the baffle system to match.

Mind you, I have yet to undertake any of this myself, so I'm just thinking aloud in advance of doing so.


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by chriskosmos »

For information:
Lunt told me the details

It's a M86 x 1.0 thread


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by marktownley »

chriskosmos wrote: Sat Jan 15, 2022 9:23 pm For information:
Lunt told me the details

It's a M86 x 1.0 thread
That's a good metric to know thanks, and a fairly standard thread in the world of astro so you should be able to pick up a range of suitable adapters to mate the parts.


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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by rsfoto »

chriskosmos wrote: Sat Jan 15, 2022 9:23 pm For information:
Lunt told me the details

It's a M86 x 1.0 thread
So I was quite on the right track :lol:


regards Rainer

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Re: Lunt LS60 / BF 1200 Mod. - Help

Post by Ivan »

What lens does the LS60Tha PT have? Is it a singlet or a doublet?

I know that the modular Lunt60 has an apochromatic doublet, Marty built his mod based on it, and described everything in great detail: viewtopic.php?f=9&t=34331

I also know that the very first Lunt 60 THa were singlets and the etalon was tilt-tuned. I heard that they were almost impossible to mod, because. were singles.

Let more experienced participants correct me if I wrote something wrong.

Ivan


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