Benach
member
Reged: 01/24/08
Posts: 28
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Preston: ok, my bad, got wrong information years ago.
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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Mike Jones has already posted, so perhaps he will post a link to his program...
Mike....are you here????????
Regards,
Preston
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A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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That's Ok...
Thanks for admitting the faultly info...
Best Regards,
Preston
Just trying to keep everything on an even playing field...
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A few I enjoy,
and a few more in the works ;<)
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Mike I. Jones
Pooh-Bah
Reged: 07/02/06
Posts: 1103
Loc: Fort Worth TX
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Yes, I'm here NOW finally. Been working a proposal at work till late every night for days. My turn in the barrel I guess, but fun future work if we win.
Attached is a zipped file for CassDesign. Let me know how you like it. I have a Version 2 of it in work, but it ain't ready yet.
Mike
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56 mirrors, lenses, 16" f/6 Newt, 6" f/10 refractor, TOA-130S, Tinsley 5" f/15 Mak, 6" f/4 RFT, Coronado PST. Still to build: 24" f/10 Modified Dall-Kirkham, 10" f/26 Mak, 8" f/12 apo, spectrohelioscope, Herrig, Schupmann, and a new design you'll like.
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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Burning the midnight oil by posting at 11:51pm...
Thanks Mike, but Please get some rest...
I'm sure others will enjoy you CassDesign program, as I found it very useful.
Best Regards,
Preston 
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A few I enjoy,
and a few more in the works ;<)
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Strgazr27
Scope Junkie
Reged: 10/04/04
Posts: 6026
Loc: StonyHill Observatory
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Quote:
Yes Jason,
Focusing is not an easy question nor is it without some compromise. I am also going to put my existing ST8XME/CFW10 behind the scope and would like to add a motorised rotator - so room for a conventional rear low profile crayford focuser is not easy. Might even try an A0-8 as well? I have to wait until the primary cell assembly is completed. Although the VSI secondary spider/focus assembly I'm using is super strong, weight balanced and able to easily carry/move its payload within tiny tolerances, I'd expect it has quite a bit of thermal intertia. Local seeing effects may well swamp such heat effects however. When I have an OTA completed I might experiment with the A-P 0.75x reducer in the rear assembly. Star Instruments indicated that a custom reducer for the f6.6 optics may become available - not sure when.
I recently converted a Vixen VC200L optical set into a truss tube OTA. This VC rig peforms very well and gave me the confidence to home-build this 12" RC. Plus I built a successful 20" Obsession-clone dob a few years ago using local commercial optics. Just need the local weather to improve now.
thanks
Guy
I don't mean to hijack this thread but Guy, Please if you have any pictures of the VC200L I would love to see it. That has been an idea of mine for quite awhile.
I can't wait for more pics of this project 
CS's
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Bobby
StonyHill Observatory
Atlas w EQMOD
Vixen R200SS
Orion ED-80
AT-111
AT66-ED
QHY-8
SSAG
YAHOO TMB 130SS Group
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jasonharris
super member
Reged: 09/16/06
Posts: 137
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Been away for a couple of days and the thread has nearly doubled..
Preston, I needed a filter wheel for my current set up. Its a one shot colour but I didn't want to change my Ha in and out.
Knowing I would use it on the RC I wanted something low profile. When I saw the FLI wheel and more importantly their PDF focuser I placed an order. I couldn't find much about them on the net good or bad but I think I am safe with the purchase.
I also like the fact that they are both USB because I have managed to keep only one cable going to the pier - A USBcable feeding a hub to connect the two cameras, mount, filter wheel, focuser and guiding through directguide.
Jason
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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Hi Jason,
I think you will really like the setup...I have the FLI Dream Machine CCD now likely 4-5 years old, but a heck of a camera...
Thier support and accessories seem to be the way to go...
We have our order in for the same...looking at the 8 place filter wheel if I remember correctly...but the thin line focuser for sure...and even with this we are down to about 1-1.5 inches of back space behind the primary back plate...after getting to the filter wheel and focuser..
I'm in the middle of a possible business turn around deal..and thus will not have a lot of time to post either here or start a new thread on the 20 inch RC group build that Mike Jones has helped so much with thus far...
I'm glad to be of help, and will try further in the furture.
Best Regards,
Preston 
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A few I enjoy,
and a few more in the works ;<)
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fetoma
professor emeritus
Reged: 09/26/06
Posts: 608
Loc: NW Ohio
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Guys,
I am a machinist and would love to build one of these using the Star Instrument optics. Any instructions, drawings, blueprints, or material lists floating around?
Frank
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Frank in NW Ohio
Vixen VC200L
Vixen R200SS
Celestron 9.25 SCT
TMB 80/480 LOMO Triplet (FOR SALE)
Orion ED80 w/Moonlite focuser (FOR SALE)
Astro-Tech 66ED
Orion Atlas EQ-G/EQMOD
Canon 40D Un-Modded
Canon 350XT Modded
QHY8
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GuyFleming
member
Reged: 01/21/08
Posts: 23
Loc: Newcastle, Australia
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Hi Strgazr
I've attached a pic of the Vixen truss 'first pass' prototype - I plan to re-do it more precisely and with carbon trusses next time 'round. This was intended merely to replace the old steel tube in the most basic fashion, making the truss conversion very simple. The Vixen primary/focuser assembly is secured snugly in the rear of a carefully routed plywood box - a number of internal screws hold the rear casting in place. The Vixen secondary spider assembly is secured in a routed plywood ring as per the primary. Simple trusses join it together. It looks quite impressive on the Paramount. Not in the class of the 12" in prep here by Jason, but a very economical poor cousin.
thanks
guy
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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Hi Frank,
When we finish the design of the 20 inch RC I may be willing to offer plans for a price...
You have no idea of the time involved, nor did I upon starting this venture...hundreds and hundreds of hours
Or the stumbling blocks that came next...
Like a purchased 12K CNC mill dumped on its face by the shipping company that we are still trying to make functional...after about a year....
The scope would be very close to being finished...but that's all the more reason for me to start the 20 inch RC building thread...
Soon that will occur...
Best Regards,
Preston  
--------------------
A few I enjoy,
and a few more in the works ;<)
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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Hi Guy,
That's still an amazying scope on the Paramount...just change things out as they appear to improve the images...
Just a Thought...
Preston
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A few I enjoy,
and a few more in the works ;<)
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jasonharris
super member
Reged: 09/16/06
Posts: 137
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Hi all, this thread is alive again.
Our baby is settled in so I am back on the project with a bit more time on my hands..
I am now working on the mirror cell. I have emailed with Jim Sapp and decided to replicate what he has been doing for his scopes. I talked to a local foundry who will cast the mirror cell. This is the most economical way to do it as it would cost a fortune to do it from a solid piece of alloy.
I will try to get the pattern to them this week and have it early next week to finish on the lathe. They use a good grade which is heat treated afterwards so machines very nicely, better then your average cast alloy.
One thing holding me up is finding out where the three triangles for the mirror support will sit. You can see from the picture below that I will have segments removed from the cell for weight and air circulation. The trouble is I need the spokes to be in the right place to support the triangles.
I have played around with PLOP but I can't get it to give me any good results. It worked when I was doing my newt but I cant figure it out for the cass with a central obstruction. If there is a PLOP guru who could spend five minutes feeding in my mirror data it would be *much* appreciated!
Once I have that I can cut the segments from the pattern and send it on for casting.
When I have machined the cast cell it will have a wall 5mm thick, just under 1/4" and the wall diameter will be a couple thou larger then the mirror diameter. Just enough to put some tape around the mirror if needed and stop any lateral movement outside of collimation tolerances .
pics so far.. hopefully soon more finished pics
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jasonharris
super member
Reged: 09/16/06
Posts: 137
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Route lots a rings, make pattern still a little bit of work to finish it like the drawing above..
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jasonharris
super member
Reged: 09/16/06
Posts: 137
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Scrap the plop thing. I have got it working from another thread I started a while back. It didn't seem to work for me in the past but some wine had it working this time
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jasonharris
super member
Reged: 09/16/06
Posts: 137
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Hi all, while I am on a roll with plop I thought I would post two runs for comment.
One is a 9 point and the other is a 6 point. To be honest, I dont know what the difference between the two would amount to.
Any comments appreciated. I have no trouble going to the extra effort to do the nine point but just want confirmation on what plop is telling me.
This is the 6 point, 9 point in next post.
Thanks,
Jason
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jasonharris
super member
Reged: 09/16/06
Posts: 137
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And the 9 point.
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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Hi Jason..
Nice to have you back...
I like the 9 point mount...
Best Regards,,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
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jasonharris
super member
Reged: 09/16/06
Posts: 137
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I dont yet have the cell in my hands but I saw it after it was cast. It still has to get heat treated before I machine it. The quality of the casting looks fine, I don't think I will have any troubles machining it.
In fact it has made me decide that I am going to get the three other major parts cast and then machine them to final dimensions. It is going to make the project a lot cheaper then I first though.
Without the cell to machine I finally started to do the spider. It has been sitting on the mill since mid February as I didnt have the time.
So I started and then when I was getting ready to use the slitting saw to create the space for the vanes I found I had lost a collet. Only one lost collet of course and only the very collet I needed.
I went for a 25 minute drive to get one and out of all the collets, which one were they out of stock? Yep, only the one I needed. I guess it will sit there for a little bit longer
I will do some drilling and tapping on it thenput it in the lather to bore out the centre and part it off.. Hopefully the finished product will be done shortly after I get a new collet..
Jason
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PrestonE
scholastic sledgehammer
Reged: 04/29/05
Posts: 840
Loc: Houston,Texas
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Hi Jason, Looking good so far.
How are you going to adjust the secondary to primary spacing? Something on the secondary holder?
Also, on you primary cell or holder. How close to the sides of the mirror is that edge that is next to the mirrors outer edge?
Can you show us a CAD drawing with the mirror in the cell?
Regards,
Preston
--------------------
A few I enjoy,
and a few more in the works ;<)
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