Re: Mount recommendation for TEC 180FL with FLI 16803 + FW #Mach2GTO


Roland Christen
 

I am guiding and doing unguided imaging with an AP160 scope (27lb tube) which has 1200mm focal length. The scope is quite robust with a heavy 4" focuser. Overall system length with extended dewcap and camera is 58", weight I'm guessing at around 48 lb (which includes the camera and dovetail system). The scope is balanced with 64lb worth of counterweight and counterweight bar. The mount is on a very light weight Losmandy tripod, which is definitely not recommended for serious imaging, but it works for me in the observatory. I have measured damping times of between 1.5 to 2 seconds, depending on where the scope is pointed. Most of that is because of the tripod which torques and twists pretty easily. The mount guides this setup quite easily and doesn't really tax anything. The weak link is of course my tripod. If this setup were mounted on a concrete pillar, the damping times would most likely be less than a second.

I have not seen a TEC 180, don't know the dimensions and weighs involved. I suppose if it is used with a robust tripod or pier, the mount would have no problem slewing it around. The bearings are heavy enough to hold any kind of weight, and normal tracking doesn't really stress the gear teeth. I would lower the max slew speed to 1000x, down from 1800x. If the mount doesn't catch a lot of wind, it would most likely guide very accurately. I've imaged in gusty wind conditions with the 160 and had no problem guiding.

Just make sure there are no dangling wires off the back of the scope because that represents quite a bit of force at the gearwheel. Every ounce of cable drag is multiplied 10x at the gear teeth. A disturbance of 1 arc sec at the gears is only 0.4 microns of  gear wheel motion at the teeth.

Rolando



-----Original Message-----
From: Terri Zittritsch <theresamarie11@...>
To: main@ap-gto.groups.io
Sent: Tue, May 19, 2020 2:24 pm
Subject: Re: [ap-gto] Mount recommendation for TEC 180FL with FLI 16803 + FW #Mach2GTO

Unless I'm reading it wrong, the OP is suggesting 50" and 52 pounds.  The A-P literature says the Mach2 is fine for 60 pounds at 50" of length, and assume the A-P literature isn't defining a point of failure or a point we can't use it for AP.    And granted, if I was buying a new mount specifically for a telescope, I might not pick a mount within 10-15% of its limit.   But since I own a Mach2, are you suggesting I shouldn't use it with a TEC180?  I measured 11 pounds of guidescope+camera plus filter wheel and imaging camera for my own setup.    But I'm sure with the cables, focuser controller, usb hub, etc.. it will hit 15 pounds, but much of this is at the balance point, not at the ends,  except camera and filter wheel, which should lessen the moment load.
It will be disappointing to think that the mount I've purchased is basically maxed out now.    I have been looking at a 180 size scope, in fact maybe the exact same scope as the OP.


Terri

On Fri, May 8, 2020 at 05:30 PM, uncarollo2 <chris1011@...> wrote:
I do not recommend that size scope on the Mach2. The 160 is fine, the 180 is pushing things.
 
Rolando

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