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First Light On My 20" f/3 Lockwood/JP Astrocraft

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#51 Bob S.

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Posted 02 December 2012 - 02:25 PM

This is a mockup of the control panel. I will have to create a checklist not unlike an aircraft to get my procedures down so that I can control the scope via the ultrabook's planetarium software that will interface with the ArgoNavis and also the Mallincam astrovideo camera. We have tried to think of everything and a friend mentioned that the glass screens were prone to dewing up. We will be building a metal hood surrounding the instrument panel that will be cork-lined and also have a heating element for the glass screen on the computer monitor so that it will not dew up. The hood will also screen any light from the telescope so that my astrovideo or visual activities will not be disturbed by ambient light. I can put a cloth shield over the hood opening to block any stray light from entering an observing site if I am at a dark site. The control panel was purposely placed on the opposite side from the focuser because this will be a total sit down scope and I did not want any podium/control panel to be anywhere near where I was sitting/observing. I will have the wireless remote control around my neck or somewhere so that I can manually move the scope with the controller without have to get off my chair.

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#52 tezster

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Posted 02 December 2012 - 07:54 PM

What I like about this scope is that, despite all the 'stuff' attached, everything has its place and is neatly connected. I was about the ask about the wireless control, but you already mentioned the wireless control (although I was kind of thinking more about a wireless DSC connection i.e. to a tablet PC. I'm always a fan of seated observing (with feet on the ground), and this looks like the ultimate sit-down scope.

Something else I wanted to ask is, is a field-derotator needed with alt-az tracking, considering the short exposure times of a Mallincam?

#53 astrocrafter

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Posted 02 December 2012 - 08:37 PM

The nice base for the holster is a 3.5" focuser end cap from Starlight. I removed 3 set screws in the base, drilled out the threads, and put a flat spotface on the holes as the base has a slight taper there, and presto! A slick looking 2" holster. Holds an extra eyepiece for visual observing too.
John

#54 Bob S.

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Posted 02 December 2012 - 10:11 PM

Terence, The Mallincam exposures will generally be no more than about 30-45 second integrations. In that short of an accumulation time of the image, in most directions, the stars will not show much if any field rotation. I am glad that John, the scope designer/builder, jumped in on the fabrication of the 3.5" holster. About the only thing I can create is a wish list. He fortunately has the skills to operationalize the dreams<g>. Bob

#55 FrankG

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Posted 03 December 2012 - 05:54 AM

Thanks, Bob!

#56 fnowat

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Posted 05 December 2012 - 01:05 AM

Impressive!! I can imagine the b/w classic film of Frankenstein and you wearing your white over-coat (smock)rubbing your hands together and as lighting strikes your lab above you, you chuckle in an evil way..."it's alive...IT'S ALIVE!!!" in the near future.

Nice story in the making. Impressive ingenuity in your build!

#57 Bob S.

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Posted 05 December 2012 - 06:56 PM

We are getting to the shorter strokes on this build. John Pratte just sent me a picture of the mirror box cover that will install with or without the front fan installed. You will notice two sets of tabs in the two corners of the mirror box. The lower set of tabs dimensionally holds the front fan frame down securely. The second set of tabs holds the mirror cover in place over the installed front fan. If I choose to not have the fan there, the cover is secured by what ordinarily will hold the fan frame. The reason for the trimmed corner edges on the mirror cover is that you have to do this to be able to get the cover out when you have the trusses installed. John advised me that we have gone to a heavier gauge wire and getting the tension correct is like collimating a piano, uh, I mean telescope<g>. In the upper right hand corner is the female RCA power outlet for the front fan that you simply plug into when utilizing the front fan. To say that I am getting excited would be a very gross understatement of how I am feeling :jump:

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#58 Bob S.

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Posted 06 December 2012 - 05:10 PM

As many of you know, when you are dealing with large/thin mirrors such as I am with the 20" f/3 being only 1.25" thick, you need a superlative mirror cell to prevent cell-induced abberations. Below is a picture of John Pratte with the mirror cell that he fabricated for the scope. The pads are riding on spherical bearings and the lower edge supports have rotating bearing surfaces to insure that there is no induced astigmatism from the cell. The cell was tested with the partially completed mirror at Lockwood's shop to check for any stig and there was no appreciable stig to be seen. You will also notice behind John is a 42" cell that is nearing completion. John can build them up to 60" (kind of makes my 20" look puny). For those of you contemplating custom scopes, I highly recommend that you insure that your mirror cell is up to the job that you are asking of it. Especially when the scope is approaching the horizontal position. Just about any mirror cell works when the scope is vertical. It is when there are tortional forces at play that the cell can either work for you or against you.

You can also see the rear sucking fan of the CBLMS (Comprehensive Boundary Layer Mitigation System) that has the Maglev fan suspended in sorbothane and sandwiched between support substructure that John used rivets to hold everything tight without inducing vibrations. BTW, the cell has built-in contact points that when installed in the scope transfer power from the ground board up to the rest of the scope. Bob

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#59 Bob S.

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Posted 06 December 2012 - 05:19 PM

Here is a close up pic of this beautiful mirror cell. As many will tell you, it is all in the details.

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#60 Bob S.

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Posted 06 December 2012 - 05:33 PM

This was a second-light picture of the scope back in the shop. The cast of characters from left to right is: John Pratte (Owner of JP Astrocraft), Bob Schilling (the bald/short scope developer), Bob From Illinois, Mike Lockwood (Owner of Lockwood Optics). You can see the early detail of the control table on the non-focuser side of the scope. This has a shield being built for it to house the ultrabook and keep it warm while preventing stray light. You can also see that beautiful 5" Lockwood secondary that as you know, is half of the optical train. My advice is, don't cheap out on the secondary ;)

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#61 tezster

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Posted 07 December 2012 - 09:21 AM

Typically, large aperture reflectors tend to look bigger in photos where people are standing beside it and you're able to get a better sense of scale.

I think this is the first time I've seen a picture of a 20" where it actually appears SMALLER with people standing beside it. That is one short dob - I love short dobs :)

#62 audioaficionado

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Posted 07 December 2012 - 02:43 PM

I'm really enjoying this build. It's pushing the state of the art and making future builds ever better. If I live long enough and keep my health, I'd sure like to get one like it. Ladders and darkness don't go well together.

#63 fnowat

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Posted 07 December 2012 - 11:55 PM

Hey, you listed John, Bob, Bob, and Mike...but who is the other un-named in the photo trying to get some attention?

#64 Mike Lockwood

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Posted 08 December 2012 - 01:26 AM

Hey, you listed John, Bob, Bob, and Mike...but who is the other un-named in the photo trying to get some attention?

That would be Lucky, the attention-seeking dog.

#65 Bob S.

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Posted 08 December 2012 - 01:05 PM

John P. completed the removable front fan with controller as part of the CBLMS (Comprehensive Boundary Layer Mitigation System). Doesn't the CBLMS just roll off your tongue<g>. Anyway, he went to a higher strength wire than originally spec'd and routed the power cables for the fan in the inside diameter of the ring and then out to the attach point on the top of the mirror box. The speed controller was placed in the corner where the power supply is. The fan is designed to be lifted up when collimating the scope and then resides in the shadow of the secondary during periods of operation. As mentioned earlier, the "strings" for the fan are coincident with the secondary spider vanes and will not add additional diffraction spikes.

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#66 Bob S.

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Posted 08 December 2012 - 01:08 PM

The fan speed controller is conventiently located on the top of the mirror box for easy access. There is no doubt that the regulation of the front and back fans will require a learning curve to coordinate the scope needs with the varying temperature conditions that the scope will be operating in. This is a picture of the variable fan speed controller which is the same kind that is controlling the rear fan and that controller is accessible from the back of the mirror box. You can see the detail of the capture clips that are designed to hold the fan unit in place and the mirror cover above the fan when installed.

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#67 Bob S.

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Posted 09 December 2012 - 07:02 PM

Typically, large aperture reflectors tend to look bigger in photos where people are standing beside it and you're able to get a better sense of scale.

I think this is the first time I've seen a picture of a 20" where it actually appears SMALLER with people standing beside it. That is one short dob - I love short dobs :)


Terence, When John Pratte was in the early stages of testing the scope, he had it out and his wife took a picture of him next to the scope in the daylight. This will give you a better perspective of how a 20" f/3 can look with an ep height at zenith of 62". It will definetly be primarily a sit-down scope.

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#68 Bob S.

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Posted 11 December 2012 - 04:23 PM

Well, We continue to get closer and closer to completion. The control center cover has been constructed out of .040 aluminum and only weighs a couple of pounds. John temporarily used sheet metal screws to prove the final concept and after painting the shield inside/out it will be ready for final pop rivets. The inside of the control center shield will be lined with cork to prevent any sweating inside of the aluminum housing. John made the shield such that any water/dew accumulating on the outside of the shield will drip free of the internal components housed in the shield as well as the telescope innards.

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#69 Bob S.

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Posted 17 December 2012 - 11:18 AM

John Pratte at JP Astrocraft in Illinois and I gave birth to a strapping 20" f/3 baby boy this weekend. At least that is how it felt after the telescope completed its Autocal sequences of the ServoCat system. This is a shout out for the principal figures in the build in the following order: God, creator of everything; John Pratte, owner of JP Astrocraft; Mike Lockwood, owner of Lockwood Custom Optics, Gary Myers, owner of StellarCat/ServoCat; and my wife for putting up with my dreams (this one is out of the order). Here is a picture of the completed scope in the shop prior to taking it home.

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#70 Bob S.

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Posted 17 December 2012 - 11:21 AM

Here is a picture of the control panel/hood. The laptop has a warming pad from Kendrick that gently keeps the screen from dewing up. The control panel is cork-lined with a controller for the dew heater, wired and wireless handcontrollers and an Argo Navis tilted to get the best ergonomics. The orange dew heater actually is placed behind the laptop screen to keep it warm and not underneath the computer as is depicted.

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#71 Bob S.

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Posted 17 December 2012 - 11:24 AM

Here is a picture of the successful computer control of the Mallincam Extreme through the telescope's internal wiring to the Mallincam.

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#72 Bob S.

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Posted 17 December 2012 - 11:26 AM

Here is a another shop picture of the scope with me at the controls of this rocket ship.

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#73 Bob S.

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Posted 17 December 2012 - 11:28 AM

And lastly, this is an overall picture of the scope including the control center, etc. The only design features we did not incorporate were a weather station positioned on top of the hood and a piston-actuated servo-controlled viewing chair that would move in unison with the telescope's eyepiece position. Those features will have to wait for the next iteration from the JP Astrocraft/Schilling skunkworks :lol:

The telescope has three seperate wiring systems incorporated into the build that include: the ServoCat/Argo Navis/computer; the Mallicam control isolated to reduce/prevent radio frequency interference with/and from the dew control systems. The only batteries on the scope are in the Telrad. Everything else is powered by only one 12v power cable coming into one of the two powered-groundboard recepticles. No dangling wires to trip on and a very clean design.

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#74 jwheel

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Posted 17 December 2012 - 11:52 AM

Nice looking telescope Bob!

Joe Wheelock :waytogo:

#75 Mike Lockwood

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Posted 17 December 2012 - 11:54 AM

The only design features we did not incorporate were a weather station positioned on top of the hood and a piston-actuated servo-controlled viewing chair that would move in unison with the telescope's eyepiece position. Those features will have to wait for the next iteration from the JP Astrocraft/Schilling skunkworks :lol:

I hear those features will be incorporated into the 40" version..... :grin:






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