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Bought a Tectron Scope from CL-Needs Truss Rods

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#1 withoutreason2

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Posted 23 May 2019 - 05:04 PM

A local ad popped up for a 18" Tectron scope so I went and looked (and bought).  The mirror is marked 17.5 (Reineke).  It all looks like its in great shape especially for being 25+ years old.  However, the truss rods are not available.  Does anyone have suggestions on locating or fabricating replacements rods?  I'm not sure of the focal length of this mirror.  Guessing its F5.

 

Here are some picturesIMG_3984 (1).jpg IMG_3985 (1).jpg IMG_3986 (1).jpg IMG_3987 (1).jpg IMG_3988 (1).jpg IMG_3989 (1).jpg

 

Thanks for your feedback

Dave


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#2 clusterbuster

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Posted 23 May 2019 - 05:11 PM

That looks like a beauty, can't wait to look through it !

 Mark 


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#3 Augustus

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Posted 23 May 2019 - 05:12 PM

DX Engineering sells really nice-looking aluminum tubing at great prices, I'd recommend ordering from them. 

 

Looks like you'll need upper hardware from Aurora, though.


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#4 Vic Menard

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Posted 23 May 2019 - 05:38 PM

If I recall correctly, the optics are from Tom Clark's Coulter Odyssey II, circa 1984 (focal ratio 4.5). The scope was eventually purchased by Bill Reineke, who ultimately had Tom build the new structure to make the scope more user "friendly". If it's the scope I remember, the optics were quite good. The first light story of that Odyssey II is a good one!

 

FWIW, the Tectron tubes were cut to length and one end was crimped flat with a vise--the corners of the flattened end were then rounded with a grinder, and the resulting tab was drilled to match the studs on the UTA. I suppose you could turn an insert and make a tab if you have access to a small lathe, but Tom's simple solution has passed the test of time with flying colors. The bottom of the tube fits flush in the compression fitting on the top of the mirror box.


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#5 CHASLX200

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Posted 23 May 2019 - 05:53 PM

Hope it is better than the one i had with a Nova mirror. I saw it for sale, but was scared to take a chance.


Edited by CHASLX200, 23 May 2019 - 05:54 PM.


#6 apfever

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Posted 23 May 2019 - 08:05 PM

Hi Dave,

 

Most of us will try to be pertinent and constructive. I have one of Tom Clarks Tectrons. It is very much the same construction of yours. I'll get pictures of the tubes, the ends, the fittings etc. but not today, too late now.

First, the truss tubes on mine are definitely too small a diameter. To try and be constructive with some follow through, I suggest you look into some design specs for dob truss tubes. Your smaller scope may have the correct size tubes.  Is your mirror box completely enclosed by modern standards, with some small vent holes in the back?  You can open the back some, being careful of what is structural. Ventilation is critical in these boxes.

 

On the bright side, my mirror is a good one. A lot of Tom's mirrors came from Vaughn Parsons, Inter Mountain Optics (IMO, not OMI).  Just about every make and model of scopes will have some hit and miss mirrors. There was some recent discussion about the 42" mirror not being so good that is Tom's personal scope. It was refigured. Tom has retired Tectron some time ago so you might as well look into parts and modifications from any and all sources. I don't think there is an intrinsic value for originality here.  Back to my mirror:  It's a 36" F4.65, Tom's second largest production scope. The largest was a 36" F5. The focal lengths are another whole story.  I took my mirror to Swayze who I know as a good acquaintance. I've been to his shop in Portland a few times. The first thing he said on the bench was "I don't know about the other mirrors but this is a good one".  Swayze also stated "...more than diffraction limited..".  Not perfect, none are. With some discussion time it was determined that the expense of stripping, figuring, and recoating wasn't going to be worth what may not even be a respectable difference in a side by side view test if a 'before and after' could be done.  

First and foremost, use your experience to see it the images are what you like. Move to testing AFTER that if you desire, it's a wise order. 

 

Note on big glass, as a rule Swayze no longer does 36" work. 


Edited by apfever, 23 May 2019 - 08:07 PM.

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#7 withoutreason2

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Posted 23 May 2019 - 08:54 PM

Yes, the mirror box might be an issue for getting the mirror to equilibirum.  I'll look at better ventilation options.  Thanks for the offer to take pictures of your struts, as that will give me a guide to fabricate them.  The tube diameter for this scope looks to be just over 0.8".  I'm not sure if that is under or right sized.    thanks for the guidance


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#8 withoutreason2

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Posted 23 May 2019 - 09:02 PM

If I recall correctly, the optics are from Tom Clark's Coulter Odyssey II, circa 1984 (focal ratio 4.5). The scope was eventually purchased by Bill Reineke, who ultimately had Tom build the new structure to make the scope more user "friendly". If it's the scope I remember, the optics were quite good. The first light story of that Odyssey II is a good one!

 

FWIW, the Tectron tubes were cut to length and one end was crimped flat with a vise--the corners of the flattened end were then rounded with a grinder, and the resulting tab was drilled to match the studs on the UTA. I suppose you could turn an insert and make a tab if you have access to a small lathe, but Tom's simple solution has passed the test of time with flying colors. The bottom of the tube fits flush in the compression fitting on the top of the mirror box.

It great to learn the history of the scope.  Just looked up Bill Reineke who passed in 2015 and taught  at a local college and the Bishop Planetarium.  Seems like he really embraced astronomy.    Its encouraging to hear that the mirror performed well.  Also thanks for the construction guidance on the tubes, I think I can perform that technique.  I look forward to getting this scope back under the stars.


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#9 clusterbuster

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Posted 24 May 2019 - 12:40 AM

Dave, 

 I would be willing to bet that you have a fine mirror there. My Meade 16 mirror is not as PRISTINE as a brand new mirror, but you have seen through my Meade 16 and I am sure that you would agree, it shows some fine images !.. I am very happy with mine, and I am sure that you will be very happy with yours !

 Mark


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#10 bremms

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Posted 24 May 2019 - 11:40 AM

Wow.. Nice find. Sure beats another 60mm refractor.


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#11 withoutreason2

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Posted 24 May 2019 - 11:54 AM

Dave, 

 I would be willing to bet that you have a fine mirror there. My Meade 16 mirror is not as PRISTINE as a brand new mirror, but you have seen through my Meade 16 and I am sure that you would agree, it shows some fine images !.. I am very happy with mine, and I am sure that you will be very happy with yours !

 Mark

Your Meade does indeed show some great views. I enjoyed viewing through it at the last meet.   It was an awesome find.


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#12 CHASLX200

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Posted 24 May 2019 - 05:41 PM

I loved the scope itself. It was a 18" F/5 that would fit thru my door all setup.  Scope worked great, but the Nova mirror was a total dud.


Edited by CHASLX200, 24 May 2019 - 05:41 PM.


#13 Vic Menard

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Posted 24 May 2019 - 06:26 PM

I loved the scope itself. It was a 18" F/5 that would fit thru my door all setup.  Scope worked great, but the Nova mirror was a total dud.

Just to be clear--Dave's 17.5-inch mirror is NOT a Nova mirror.

If this mirror set is the one I think it is, Dave is going to be pretty happy with his purchase.

If I'm right on the provenance, it was these optics that infected Tom Clark with a serious case of aperture fever

 

Edit (Attached a picture of the scope in its original "Big Blue" Coulter structure--note the 5-inch f/5 Jaegers RFT mounted as a finder scope. In the background, another 5-inch Jaeger is mounted atop my old C8, set up to capture Halley's Comet.)

 

 

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  • TC12.5.jpg

Edited by Vic Menard, 24 May 2019 - 06:36 PM.

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#14 CHASLX200

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Posted 24 May 2019 - 06:37 PM

Just to be clear--Dave's 17.5-inch mirror is NOT a Nova mirror.

If this mirror set is the one I think it is, Dave is going to be pretty happy with his purchase.

If I'm right on the provenance, it was these optics that infected Tom Clark with a serious case of aperture fever

I think the mirror you have is good if i remember right.  I sure  wanted to keep my 18" Tectron.  I paid around 2500 for it, but the mirror never would come into focus, like a half a turn was needed as the planets at higher powers would just mush around focus. Low power for deep sky it did ok, and i sold it to a guy that has loved it since for his deep sky viewing. I gave it away about on the price.  To refigure the mirror would have cost too much for my taste.  But the motions and colllimation were great.



#15 Vic Menard

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Posted 24 May 2019 - 06:47 PM

Also, I'm pretty sure that Tom only made one 17.5-inch Tectron Dob, and It's the one we're talking about. He made a bunch of 15, 18, 20, 24, and 25-inch Dobs, and a handful of 10, 12.5, 30, 32, 36 and (one) 42-inch Dobs (not to mention a few lightweight composite fork mounted 16 and 20-inch equatorial scopes)!

 

If I recall correctly, the first optical supplier for Tectron was Galaxy--Nova came later...



#16 CHASLX200

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Posted 24 May 2019 - 06:53 PM

Also, I'm pretty sure that Tom only made one 17.5-inch Tectron Dob, and It's the one we're talking about. He made a bunch of 15, 18, 20, 24, and 25-inch Dobs, and a handful of 10, 12.5, 30, 32, 36 and (one) 42-inch Dobs (not to mention a few lightweight composite fork mounted 16 and 20-inch equatorial scopes)!

 

If I recall correctly, the first optical supplier for Tectron was Galaxy--Nova came later...

Nova seemed to be very good, so it was a shock mine was not that good.  I wonder if someone could have refigured it later down the road?  I remember Tectron being the first real Dobs to come around in the mid and later 80's as Tom would show up at the Hill or Chiefland.  This was before Obsession got going. I remember looking thru his 18 to 26" Dobs before he was selling the Tectrons around 1986 to 87.



#17 apfever

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Posted 24 May 2019 - 06:56 PM

When did IMO make Tectron mirrors?  Mine is the Yard Scope II, the Yard Scope 1 came first but was too long at F5 it was supposed to be F4.5.   

My scope at F4.65 was supposed to be F4.5 but no complaints from me, I like it this way. 

I thought Tom's personal scope is 42", so would it be the same as the only one he made?  I heard that 42" mirror was IMO.

 

I'm still planning on getting the truss tube pictures and dimensions. 



#18 Vic Menard

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Posted 24 May 2019 - 06:57 PM

It great to learn the history of the scope.  Just looked up Bill Reineke who passed in 2015 and taught  at a local college and the Bishop Planetarium.  Seems like he really embraced astronomy.    Its encouraging to hear that the mirror performed well.  Also thanks for the construction guidance on the tubes, I think I can perform that technique.  I look forward to getting this scope back under the stars.

Bill Reineke was one of the first people to join The Local Group (around 1983), an amateur astronomy club (still) based out of Bradenton, FL. He was active in the Group until he passed away. He taught mathematics at the local community college (now State College of Florida). He would regularly bring the 17.5-inch out to the college for Al Varn's astronomy class. He also volunteered at the Bishop Planetarium and could always be found at the Bishop Observatory on public observing nights. And he always had a dog!

 

I miss him...


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#19 Vic Menard

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Posted 24 May 2019 - 07:15 PM

When did IMO make Tectron mirrors?  Mine is the Yard Scope II, the Yard Scope 1 came first but was too long at F5 it was supposed to be F4.5.   

My scope at F4.65 was supposed to be F4.5 but no complaints from me, I like it this way. 

I thought Tom's personal scope is 42", so would it be the same as the only one he made?  I heard that 42" mirror was IMO.

 

I'm still planning on getting the truss tube pictures and dimensions. 

You're right, Vaughn Parsons did most (if not all) of the largest Tectron mirrors. I remember first light on the Yard Scope 1 (June 1992). It was (as you noted) ordered at f/4.5, but arrived f/5, a bit of a problem as the Dob structure was already built! Tom got it reconfigured in a hurry and we observed Mars (near opposition) through the shop roll up door. I think we were somewhere around 400 to 500X, and the surface detail was amazing. I told Tom right then that "The Yard Scope" was a keeper! (And he kept it quite a long time.)

 

Back in the day, Tom called his persistent search for more aperture "brute-force astronomy". When you think about it, 500X on a 36-inch is only 14X per inch of aperture, about half what you would need to "see" a diffraction ring around a star. The optics didn't need to be perfect when the magnification was kept so low... And all that aperture really brightened the image--you would lose your dark adaptation looking at the Orion Nebula.


Edited by Vic Menard, 24 May 2019 - 07:16 PM.


#20 apfever

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Posted 24 May 2019 - 10:49 PM

Wow Vic,

 

You viewed through the Yard Scope I, that is so cool. Did you get a view through the Yard Scope II, my scope now?  Word is that Vaughn stopped a little short of goal on the focal lengths to simplify the figure. 

Apparently Tom asked Vaughn to get the second one at the focal ratio ordered - F4.5,  it's close enough. 



#21 withoutreason2

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Posted 25 May 2019 - 08:46 AM

DX Engineering sells really nice-looking aluminum tubing at great prices, I'd recommend ordering from them. 

 

Looks like you'll need upper hardware from Aurora, though.

Great tip, I just placed an order with DX engineering.  Thanks


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#22 Vic Menard

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Posted 26 May 2019 - 09:27 AM

You viewed through the Yard Scope I, that is so cool. Did you get a view through the Yard Scope II, my scope now?  Word is that Vaughn stopped a little short of goal on the focal lengths to simplify the figure. 

Apparently Tom asked Vaughn to get the second one at the focal ratio ordered - F4.5,  it's close enough. 

 

I was usually available when Tom called for pretty much all the scopes that were built in Sarasota/Bradenton, FL, as well as many of the scopes that ended up in Chiefland, FL. I remember getting some observing time on the YardScope II in Chiefland, and "The Beast" (Tom's 42-inch--2002) showed up about four years after he moved to Chiefland. The 42 optics were recently refigured by Mike Lockwood, and the mirror support upgraded as well, but I haven't been to New Mexico (where Tom currently resides) to view through the 42 since the upgrades...

 

(And to correct my earlier post, the original YardScope saw first light in 1993 (not 1992). I'm not sure how I messed up that date...)


Edited by Vic Menard, 26 May 2019 - 09:39 AM.

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#23 bobhen

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Posted 26 May 2019 - 09:43 AM

I owned a 15-inch Tectron back in the day. It had a Galaxy F5 mirror that was killer. I mean one of the best I have seen – perfect star test and fine details on Jupiter, etc.

 

The mechanics and design of the Tectron were “just okay” and were at times frustrating.

 

Since then, Dobsonian designs have evolved and been refined by later Dob designers.

 

Killer mirror though.

 

Tom published a book awhile back ( Starry Starry Nights) about Tectron, scope makeing, etc. It was a fun read. 

 

Bob


Edited by bobhen, 26 May 2019 - 09:49 AM.

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#24 apfever

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Posted 26 May 2019 - 10:48 AM

Here's the ends. These tubes are only 1-1/8" O.D. 

I neglected to get the wall, but way too narrow for this scope anyway.

These are about 12" long. The other end is square. One has a power cord the length.

The cord looks like maybe for a classic C5 to piggy the upper cage.  It's a about 6lb. tail heavy empty. 

 

Careful on your alloy. Do not get 7075 aluminum alloy, it is too brittle. 6061-T6 is common and malleable enough to do this if you're careful, I wouldn't go any stiffer. Some of the ends are split at the crease but no big deal, like a double tang bolt up. I will eventually rebuild this one with tubes in the 2" range and different end fittings. I have all the aircraft tubing from old airframes already so pick and choose.  I have some that are made to sleeve and thought of collapsing trusses. I'd put a ring at the junction which would also support the shroud mid way or so. Such a system would be rock solid.

Attached Thumbnails

  • P5250002.JPG

Edited by apfever, 26 May 2019 - 10:59 AM.

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#25 withoutreason2

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Posted 31 May 2019 - 11:03 PM

Here is the 1st rough truss fitting.  The truss length should be long. Will need to verify later.   Modified some boat canopy connectors to attach the upper secondary assembly to the trusses.  Fits pretty well.  Primary and secondary are in decent alignment for a 1st fit.  More work to go, but its coming togther.

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  • scope pic1.jpg
  • scope pic2.jpg

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