Lunt L60 thread dimensions

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_Zakalwe
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Lunt L60 thread dimensions

Post by _Zakalwe » Wed Apr 23, 2014 7:54 am

Hello guys,

Do any off you know the thread specifications for the thread that the white barrel on a Lunt L60 has? The one that screws to the Etalon?

:bow2 :bow2

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Re: Lunt L60 thread dimensions

Post by marktownley » Wed Apr 23, 2014 8:32 am

I think its 92mm, but may be wrong there. I'm sure someone else will chirp in.
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Re: Lunt L60 thread dimensions

Post by swisswalter » Wed Apr 23, 2014 3:35 pm

Hi Stephen

a year ago I could have measured it. No more LUNT 60 here. Sorry
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: Lunt L60 thread dimensions

Post by thesmiths » Wed Apr 23, 2014 11:25 pm

On my Lunt60 PT, the white tube has outside diameter of just under 90mm. The inside front thread, into which the front lens is attached, appears to have diameter of 86mm. I would assume the rear threads, into which the PT etalon is attached, would be the same. But please don't take my measurements as at all exact.

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Re: Lunt L60 thread dimensions

Post by Sunwatcher » Thu Apr 24, 2014 1:21 am

Would this info help? (See photos below.)

Measured across the top of the threads = 89mm plus just under 14 thousandths of an inch.
Measured across the bottom of the threads = 89mm plus 3 thousandths of an inch.
The serial number plate on the module.

Please don't consider these to be the most accurate measurments for use to cut threads on a lathe.
top.jpg
top.jpg (113.57 KiB) Viewed 2400 times
bottom.jpg
bottom.jpg (110.57 KiB) Viewed 2400 times
dblstackmodule.jpg
dblstackmodule.jpg (114.97 KiB) Viewed 2400 times
Downtown Fort Worth.

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Re: Lunt L60 thread dimensions

Post by Merlin66 » Thu Apr 24, 2014 1:58 am

Hmmm
I think he's looking for the external thread dimensions where the white tube screws into the internal etalon assembly on the Lunt 60...
I'm sure when we looked at the Lunt 60 etalon "mod" we noted these sizes....I'll need to check the drawings...
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Re: Lunt L60 thread dimensions

Post by Merlin66 » Thu Apr 24, 2014 2:02 am

Looks like 86.5 x1....
Lunt60_sketch_own.gif
measurements of the Lunt60 (Viljo)
Lunt60_sketch_own.gif (108.46 KiB) Viewed 2398 times
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Re: Lunt L60 thread dimensions

Post by _Zakalwe » Thu Apr 24, 2014 5:37 am

Perfect, thanks Ken. So its a metric thread, not some daft Imperial thing Good.

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Re: Lunt L60 thread dimensions

Post by marktownley » Thu Apr 24, 2014 10:18 am

Good job you didn't listen to me :roll:

Now I know though too... ;)
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Re: Lunt L60 thread dimensions

Post by _Zakalwe » Thu Apr 24, 2014 10:43 am

I did some measurements over the weekend to see what sort of adapter I'd need to mount the Lunt L60 onto a Helios 120mm 'frac. I measured the diameter of the light cone that the Lunt objective produces at the front of the Etalon assembly. I then found the position in the Helios lightcone that gives me the same diameter.
The next step is to mock up an adapter, probably using the method that Viljo used- 2 pieces of hardwood to hold the Lunt OTA (obviously with the Lunt objective removed) inside the Helios OTA.
If that works then I can get an adapter made up in ally, hence the need to know the thread details.

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Re: Lunt L60 thread dimensions

Post by _Zakalwe » Thu Apr 24, 2014 10:58 am

One question. I don't yet have an ERF (will probably mount a sub-aperture ERF inside the OTA).

is it safe to do some quick test without an ERF? Or would the Lunt ERF be damaged?

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Re: Lunt L60 thread dimensions

Post by swisswalter » Thu Apr 24, 2014 3:50 pm

_Zakalwe wrote:One question. I don't yet have an ERF (will probably mount a sub-aperture ERF inside the OTA).

is it safe to do some quick test without an ERF? Or would the Lunt ERF be damaged?
Hi Stephen


I guess you mean the LUNT Etalon being damaged , aren't you ?
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: Lunt L60 thread dimensions

Post by _Zakalwe » Thu Apr 24, 2014 4:13 pm

swisswalter wrote:
_Zakalwe wrote:One question. I don't yet have an ERF (will probably mount a sub-aperture ERF inside the OTA).

is it safe to do some quick test without an ERF? Or would the Lunt ERF be damaged?
Hi Stephen
I guess you mean the LUNT Etalon being damaged , aren't you ?
Hi Walter,
The Lunt has the ERF mounted directly in front of the Etalon. I'm concerned that a 120mm objective would be pumping a LOT more energy into it than the native 60mm objective. I'm guessing that it would be OK for short periods of time? Enough to test focus?

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Re: Lunt L60 thread dimensions

Post by swisswalter » Thu Apr 24, 2014 5:40 pm

Hi Stephen


yes you are so right. I have forgotten it. I think for a very short time that should work without doing damage to the ERF nor the etalon
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)

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Re: Lunt L60 thread dimensions

Post by _Zakalwe » Thu Apr 24, 2014 9:38 pm

The Frankescope..
ImageUntitled by Stephen Jennette, on Flickr

ImageUntitled by Stephen Jennette, on Flickr

ImageUntitled by Stephen Jennette, on Flickr

Hopefully, I'll get a chance to test it to the weekend.

If it works, then the next step is a sub-aperture ERF and a machined ally sleeve to replace the white Lunt barrel.

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Re: Lunt L60 thread dimensions

Post by marktownley » Thu Apr 24, 2014 10:13 pm

Cool fish! I look forward to seeing how you get on :)
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Re: Lunt L60 thread dimensions

Post by swisswalter » Fri Apr 25, 2014 4:18 am

Hi Stephen

that looks great. Wish you CS for the weekend
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: Lunt L60 thread dimensions

Post by _Zakalwe » Sun Apr 27, 2014 11:08 am

Well..I had a quick bash in very poor conditions and I cannot report success. I couldn't get the image to come to focus. I'm thinking that I perhaps need to recalculate my positions. Either that or something is not lined up, though I did use a laser collimator to get the solarscope on the optical axis.

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Re: Lunt L60 thread dimensions

Post by swisswalter » Sun Apr 27, 2014 11:29 am

Hi Stephen

good luck on the second try
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)

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Re: Lunt L60 thread dimensions

Post by solarmax2016 » Mon Nov 07, 2016 5:07 am

Its a 1 mm micro - hard to cut

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