CDK 14 on a Mach 2? #Mach2GTO


skester@...
 

Xentex, the similarity in weight and length between the 12.5 and 14 was one of the reasons I posted my question. 

I will also admit to some confusion on my part in how the Mach 2 capacity chart indicates how to measure the OTA diameter/height.  The top two drawings seem to indicate the measurement is of the OTA tube only, and does not include the height of the mounting rings or dovetail, while the piggyback setup measures from the bottom of the dovetail to the top of the upper scope.  Which is the correct way to measure for the CDK?


Terri Zittritsch
 

So I'll provide a counterpoint here, but I would still listen to Roland's feedback.

I was thinking exactly the same thing as you, and that is, if it fits within the green zone of use conditions then it should be fair game.    I guess when looking at lesser built mounts that are built for a price rather than performance point, I'd be skeptical and maybe apply judgement to their specifications, but this is Astro-Physics, and I'd expect that if they spec and sell the mount to meet a performance window, than we can all take that to the bank so to speak.    Now maybe what we're seeing is that because of all of the experience here, these users know that you're not actually going to achieve a green-zone build with that scope and therefore will ultimately fall outside of the specification box, then it's good and helpful feedback.    Otherwise I'd like to know that I can use the mach2 within the specification window advertised.  That was a factor for purchasing the mount in the first place and I'd like not to be accused of under mounting a scope that fits in the A-P spec window.    I have the mach2, and the biggest scope I've used on it is an 11" edge and it works well.     


Wayne Hixson
 

I had a 12.5” AGO iDK on my Mach 2 for a few months and it handled it well. 


On Dec 20, 2020, at 4:51 PM, Xentex <michael@...> wrote:

I think it's reasonable to ask the same question regarding the CDK 12.5.  It weighs the same as the CDK 14 and comes in at 17.26" diameter (vs 18.95 for the 14") and 35" length before adding the imaging train (vs 35.7" for the 14").  Not a huge difference between them.

I've asked myself this exact same question about maybe someday putting a CDK on the Mach 2.


Xentex
 

I think it's reasonable to ask the same question regarding the CDK 12.5.  It weighs the same as the CDK 14 and comes in at 17.26" diameter (vs 18.95 for the 14") and 35" length before adding the imaging train (vs 35.7" for the 14").  Not a huge difference between them.

I've asked myself this exact same question about maybe someday putting a CDK on the Mach 2.


Al Luken
 

The 14CDK does quite well on our 1100 mount

University of Oregon
Pine Mountain Observatory


dvjbaja
 

Over-mounting reasons are obvious.  I have typically run my Tak FSQ with 16803 camera, filter wheel, atlas focuser, guidescope on my AP 1200.  Not over-mounted by any means.  I can also carry my 155 edf and RHA 305 on the 1200 with no problem.  NO JELLO vibrations and damping time is zero.   A 1600 and Planewave 12.5 would be a great combination, and will support your 14 when you decide to upgrade.  In fact, the 1600 could probably carry the Planewave 17.5" as well and many do.  Over-mounting allows you flexibility like that.   But don't take my word for it.  Do a little research as to what the top imagers use.   

-j

On Sun, Dec 20, 2020 at 12:30 PM <skester@...> wrote:
I knew the CDK 14 on the Mach 2 was probably a stretch, which is why I asked the question here. On the other hand why would I 'over mount' a scope and have capacity I will never use?   I was already planning to go with a CDK 12.5 rather than the 14, so the question was a theoretical one.


skester@...
 

I knew the CDK 14 on the Mach 2 was probably a stretch, which is why I asked the question here. On the other hand why would I 'over mount' a scope and have capacity I will never use?   I was already planning to go with a CDK 12.5 rather than the 14, so the question was a theoretical one.


dvjbaja
 

I'm always amazed that folks buy really big, expensive telescopes, then want to undermount them.  So it has always been in this hobby, so it shall always be.  

j


Christopher Erickson
 

Personally I would put a 1600 or 1200 under that scope.


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Sun, Dec 20, 2020, 7:28 AM <skester@...> wrote:
Sounds like the answer is no then.  Thanks.


skester@...
 

Sounds like the answer is no then.  Thanks.


KHursh
 

The Planewave version of the CDK 14 is 19" in diameter according to this http://pw-ecommerce.com/wp-content/uploads/2019/02/140101A-OVERALL-DIMENSIONS.pdf.
I do think this OTA is too much for the Mach2 if you are following the guidelines on the A-P site. I also think keeping the overall length within 50" would be a challenge.


Roland Christen
 

Weight is not the issue, it's moment arm. I think you're stretching it with that size.

Rolando



-----Original Message-----
From: skester@...
To: main@ap-gto.groups.io
Sent: Sat, Dec 19, 2020 9:49 pm
Subject: [ap-gto] CDK 14 on a Mach 2? #Mach2GTO

Based on the weight of the OTA + focuser/OAG/guider/FW of 55 lbs, outer diameter of 16" and a total length of 50", a CDK 14 would be well within the "Green" of the Mach 2 capacity chart in both RA and Dec.  However the recommendations I have seen on this forum often seem to be more conservative than the chart would suggest, so I thought I would as the experts directly.  Would a CDK14 be too much scope for a Mach 2?  I know most would recommend an 1100, but if the Mach 2 can handle it that would be my preference.

--
Roland Christen
Astro-Physics


skester@...
 

Based on the weight of the OTA + focuser/OAG/guider/FW of 55 lbs, outer diameter of 16" and a total length of 50", a CDK 14 would be well within the "Green" of the Mach 2 capacity chart in both RA and Dec.  However the recommendations I have seen on this forum often seem to be more conservative than the chart would suggest, so I thought I would as the experts directly.  Would a CDK14 be too much scope for a Mach 2?  I know most would recommend an 1100, but if the Mach 2 can handle it that would be my preference.