PST Tuning Ring

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
Post Reply
User avatar
MapleRidge
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 10199
Joined: Fri Jan 13, 2012 11:58 pm
Location: Cambray, ON Canada
Has thanked: 64 times
Been thanked: 4340 times
Contact:

PST Tuning Ring

Post by MapleRidge »

Hi All...

My clumsy fingers dropped the little bolt that threads in to lock the tuning ring on the PST etalon and despite searching for over an hour I can't find the little thing in the grass :oops:

Can anyone tell me what the thread size is so I can hunt down a replacement? The smallest machine bolt I have is a 4-40 and it doesn't seem to want to thread in and I don't want to force it.

Thanks for any guidance :bow
Brian


Brian Colville

Maple Ridge Observatory
Cambray, ON Canada

Photos: https://www.flickr.com/photos/185395281@N08/albums

10'x15 Roll-off Roof Observatory
Takahashi EM400 Mount carrying:
C14 + Lunt 80ED
Deep Sky Work - ASI294MM Pro+EFW 7x36/Canon 60D (Ha mod), ONAG
Planetary Work - SBIG CFW10, ASI462MM

2.2m Diameter Dome
iOptron CEM70G Mount carrying:
Orion EON 130ED, f7 OTA for Day & Night Use
Ha Setup: Lunt LS80PT/LS75FHa/B1200Ha + Home Brew Lunt Double Stack/B1800Ha on the Orion OTA + Daystar Quantum
WL, G-Band & CaK Setup: Lunt Wedge & Lunt B1800CaK, Baader K-Line and Altair 2nm G-Band filter
ASI1600MM, ASI432MM, ASI294MM Pro, ASI174MM, ASI462MM
thesmiths
Almost There...
Almost There...
Posts: 1054
Joined: Mon Jun 04, 2012 8:13 pm
Location: London, England
Has thanked: 42 times
Been thanked: 1487 times

Re: PST Tuning Ring

Post by thesmiths »

I'm assuming that the etalon is being used in a PST mod?


User avatar
MapleRidge
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 10199
Joined: Fri Jan 13, 2012 11:58 pm
Location: Cambray, ON Canada
Has thanked: 64 times
Been thanked: 4340 times
Contact:

Re: PST Tuning Ring

Post by MapleRidge »

I have used it on a mod, but in this case I had re-assembled the PST to its original form and found I had to change the tuning more than the ring would allow. I was just careless and dropped the little bolt that locks the tuning ring in place, and can't find it in the grass. I heard it hit the tripod as it fell and did not see which way it was deflected.

Brian


Brian Colville

Maple Ridge Observatory
Cambray, ON Canada

Photos: https://www.flickr.com/photos/185395281@N08/albums

10'x15 Roll-off Roof Observatory
Takahashi EM400 Mount carrying:
C14 + Lunt 80ED
Deep Sky Work - ASI294MM Pro+EFW 7x36/Canon 60D (Ha mod), ONAG
Planetary Work - SBIG CFW10, ASI462MM

2.2m Diameter Dome
iOptron CEM70G Mount carrying:
Orion EON 130ED, f7 OTA for Day & Night Use
Ha Setup: Lunt LS80PT/LS75FHa/B1200Ha + Home Brew Lunt Double Stack/B1800Ha on the Orion OTA + Daystar Quantum
WL, G-Band & CaK Setup: Lunt Wedge & Lunt B1800CaK, Baader K-Line and Altair 2nm G-Band filter
ASI1600MM, ASI432MM, ASI294MM Pro, ASI174MM, ASI462MM
Fabio_Imm
Ohhhhhh My!
Ohhhhhh My!
Posts: 91
Joined: Sun Oct 18, 2020 2:33 pm
Location: Emilia Romagna [Italy]
Has thanked: 214 times
Been thanked: 146 times

Re: PST Tuning Ring

Post by Fabio_Imm »

Hello Brian,
As a last resort, you might consider "fishing" the area with a strong magnet.

Fabio


User avatar
MapleRidge
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 10199
Joined: Fri Jan 13, 2012 11:58 pm
Location: Cambray, ON Canada
Has thanked: 64 times
Been thanked: 4340 times
Contact:

Re: PST Tuning Ring

Post by MapleRidge »

Hi Fabio...

The magnet was my first try after I couldn't find it in the grass when it first fell. It bounced off the tripod leg and I have no idea which direction it went or distance which makes it more difficult to pin down a search. I am going to look again today and see fi I get lucky!

Thanks,
Brian


Brian Colville

Maple Ridge Observatory
Cambray, ON Canada

Photos: https://www.flickr.com/photos/185395281@N08/albums

10'x15 Roll-off Roof Observatory
Takahashi EM400 Mount carrying:
C14 + Lunt 80ED
Deep Sky Work - ASI294MM Pro+EFW 7x36/Canon 60D (Ha mod), ONAG
Planetary Work - SBIG CFW10, ASI462MM

2.2m Diameter Dome
iOptron CEM70G Mount carrying:
Orion EON 130ED, f7 OTA for Day & Night Use
Ha Setup: Lunt LS80PT/LS75FHa/B1200Ha + Home Brew Lunt Double Stack/B1800Ha on the Orion OTA + Daystar Quantum
WL, G-Band & CaK Setup: Lunt Wedge & Lunt B1800CaK, Baader K-Line and Altair 2nm G-Band filter
ASI1600MM, ASI432MM, ASI294MM Pro, ASI174MM, ASI462MM
User avatar
Merlin66
Librarian
Librarian
Posts: 3970
Joined: Tue Dec 13, 2011 1:23 pm
Location: Junortoun, Australia
Has thanked: 173 times
Been thanked: 615 times
Contact:

Re: PST Tuning Ring

Post by Merlin66 »

Brian,

EDIT: correction. It's obviously a M2.5 screw!!!!


"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before
https://groups.io/g/astronomicalspectroscopy  
http://astronomicalspectroscopy.com
"Astronomical Spectroscopy for Amateurs" and
"Imaging Sunlight - using a digital spectroheliograph" - Springer
thesmiths
Almost There...
Almost There...
Posts: 1054
Joined: Mon Jun 04, 2012 8:13 pm
Location: London, England
Has thanked: 42 times
Been thanked: 1487 times

Re: PST Tuning Ring

Post by thesmiths »

I assume it is this screw that you dropped:
pst screw
pst screw
1043.jpg (72.73 KiB) Viewed 2669 times
I tested to see if it is even magnetic. With a very strong N42 magnet, it is just barely able to be picked up. I suspect that if it were embeded in grass, a magnet would not be able to catch it.

Here are some measurements. Maybe it's a M2.5 screw?
screw diameter
screw diameter
1040.jpg (137.83 KiB) Viewed 2669 times
screw thread
screw thread
1042.jpg (71.39 KiB) Viewed 2669 times
The screw just threads into the outside ring. The etalon itself has no threads. In theory, you could drill and tap any size hole. I actually removed the ring entirely and just use a match stick as it allows access to all the little holes and you can have a wider tuning range (since the tuning changes with time due to compression of the spacers inside).
pst match stick mod
pst match stick mod
1044.jpg (139.79 KiB) Viewed 2669 times


User avatar
MapleRidge
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 10199
Joined: Fri Jan 13, 2012 11:58 pm
Location: Cambray, ON Canada
Has thanked: 64 times
Been thanked: 4340 times
Contact:

Re: PST Tuning Ring

Post by MapleRidge »

Hi Ken...

Yes, that's the one!

I tried with the magnet and found nothing...similar sized bolts I had were not overly attracted to the magnet and the grass would tend to bush it off if it did catch it. I'll take a look for a replacement int he size you suggest, and can keep it working for the time being.

Thanks,
Brian


Brian Colville

Maple Ridge Observatory
Cambray, ON Canada

Photos: https://www.flickr.com/photos/185395281@N08/albums

10'x15 Roll-off Roof Observatory
Takahashi EM400 Mount carrying:
C14 + Lunt 80ED
Deep Sky Work - ASI294MM Pro+EFW 7x36/Canon 60D (Ha mod), ONAG
Planetary Work - SBIG CFW10, ASI462MM

2.2m Diameter Dome
iOptron CEM70G Mount carrying:
Orion EON 130ED, f7 OTA for Day & Night Use
Ha Setup: Lunt LS80PT/LS75FHa/B1200Ha + Home Brew Lunt Double Stack/B1800Ha on the Orion OTA + Daystar Quantum
WL, G-Band & CaK Setup: Lunt Wedge & Lunt B1800CaK, Baader K-Line and Altair 2nm G-Band filter
ASI1600MM, ASI432MM, ASI294MM Pro, ASI174MM, ASI462MM
thesmiths
Almost There...
Almost There...
Posts: 1054
Joined: Mon Jun 04, 2012 8:13 pm
Location: London, England
Has thanked: 42 times
Been thanked: 1487 times

Re: PST Tuning Ring

Post by thesmiths »

To Brian: actually, the photos of the screw came from me, your fellow Canadian (not Ken). I took a look at the specs for M2.5 and the thread seems to approximately match the photo I took (around 0.5/mm). So M2.5 x 10mm Philips flathead countersunk appears to be the likely replacement. Doug


User avatar
MapleRidge
Way More Fun to Share It!!
Way More Fun to Share It!!
Posts: 10199
Joined: Fri Jan 13, 2012 11:58 pm
Location: Cambray, ON Canada
Has thanked: 64 times
Been thanked: 4340 times
Contact:

Re: PST Tuning Ring

Post by MapleRidge »

Sorry about that mix up...what I get for looking on the phone and small screens cut off the full post.

What part of Canada do you call home?

Brian


Brian Colville

Maple Ridge Observatory
Cambray, ON Canada

Photos: https://www.flickr.com/photos/185395281@N08/albums

10'x15 Roll-off Roof Observatory
Takahashi EM400 Mount carrying:
C14 + Lunt 80ED
Deep Sky Work - ASI294MM Pro+EFW 7x36/Canon 60D (Ha mod), ONAG
Planetary Work - SBIG CFW10, ASI462MM

2.2m Diameter Dome
iOptron CEM70G Mount carrying:
Orion EON 130ED, f7 OTA for Day & Night Use
Ha Setup: Lunt LS80PT/LS75FHa/B1200Ha + Home Brew Lunt Double Stack/B1800Ha on the Orion OTA + Daystar Quantum
WL, G-Band & CaK Setup: Lunt Wedge & Lunt B1800CaK, Baader K-Line and Altair 2nm G-Band filter
ASI1600MM, ASI432MM, ASI294MM Pro, ASI174MM, ASI462MM
thesmiths
Almost There...
Almost There...
Posts: 1054
Joined: Mon Jun 04, 2012 8:13 pm
Location: London, England
Has thanked: 42 times
Been thanked: 1487 times

Re: PST Tuning Ring

Post by thesmiths »

To Brian: Montrealer living in London (not the one in Ontario). Doug


Post Reply