Re: safe way to load the OTA on the MACH2


Christopher Erickson
 

Here are some rambling musings of an equipment addict and observatory engineer. FWIW.

All of my OTA's have permanent dovetail bars on them. Additionally, all of them also have handles or bars on top of the OTA. This extra gripping spot really helps me to get OTA's on and off of mounts. Sometimes I have had to machine the handle or bar myself if a commercial solution wasn't available. I NEVER take any of my OTA's out of the rings, if it has them. My AP 130 and 92 both have handles on top and never come out of their rings. I had a custom case made to hold my 130 in its rings and handle, along with room lengthwise for a camera and such too. I am not lucky enough to have a BIG AP refractor or I might be doing it the way Roland does his. Fortunately (unfortunately?) my 130 and 92 aren't very heavy.

As for my C14, C11 (x2), C9.25, C8, M16, M10, M5, N10 and RC20, only the C14, M16, N10 and RC20 offer much challenge. The others are pretty-easy and don't require much strength.

I tried the Rayox "automatic engaging" saddle bracket with my C14 and found it even more difficult to use than a regular AP D-style dovetail bracket. I just couldn't hold the entire weight of a C14 steady enough (video method one) to carefully line it up with the darn bracket. I tried both Park2 and Park 3 and it was just as impossible either way. The Rayox dovetail bracket now lives in my spare parts piles. What helps the most is having that long, grippable bar on top of the C14.

The N10 (10" f3.8 RFT Newt in a fiberglass tube with custom, permanent rotating rings on a long D-bar) also benefits from a long bar (handle) on top.

I really, really don't like the old-style Losmandy dovetail bracket that requires sliding the OTA dovetail bars in and out from the end. I have several in my spare parts piles. Free to anyone who wants them. My G11 currently has a Chinese combination D-V dovetail bracket on it. Eventually I will put an AP D-style dovetail bracket on it. I really prefer combination D-V brackets on my mounts. I am always testing or repairing different OTA's and having a combination D-V saddle bracket is very handy.

Having the bracket locks independent from each other is much better than having them combined. Example is the comparison between the ADM brackets (combined) and the AP brackets (independent). IMO, it takes a lot less human-force on the knobs to securely lock an OTA in an AP bracket than it does an ADM bracket. Whenever I have had to put an OTA onto an ADM bracket, I have always used the special ADM wrench to really-tighten the knobs. Not very convenient. The AP locks feel significantly more secure.

On my M16 (Meade LX200GPS-16), I use a hitch-crane (hitch-hoist/game-hoist from Cabella's) to assemble and disassemble the scope by myself. Required adding a dovetail bar to the top of the OTA with a threaded hole in the top bar for a stainless eye bolt. Works well and feels very secure and safe. I put a bar on the bottom too. Handy for counterweights, Polemasters, dome-cams, etc. I use the same hitch-crane on my RC20. RC20 currently under re-construction and being moved to a custom Alt-Az mount with optical rotator. Will probably still need the hitch-crane when I am done. Unless I install it in an observatory.

I am 62 and My C14 is getting heavier every year. Currently I am using video-method-1 but eventually will probably have to move to video-method-2. Or extend the height of my hitch-crane. I have tried video-method-2 in the past and it was a real PITA to handle. Everything depends on the quality, size and stability of the astro-chair involved. The bigger, probably the better and more stable. A better approach might be a Lymax electric lifting column (Pier-Tech style) with four fold-out, locking, 8" wheeled, legs on the bottom and an OTA-diameter, cup-style base on top.

In observatories, adding an eyebolt to a strong point in a roll-off roof is handy for a lifting point, if your structure can handle the weight of your various scope parts. Ash domes are super-strong and I often drill a hole into the center tab on the bottom of the upper shutter and put a stainless-steel clevis through the drilled hole for a lifting point. Rotating the dome and running the upper shutter up and down allows me to get the lifting point just about anywhere over the scope and the observatory floor. Sometimes I use an electric winch and other times a simple come-along. Instant, one-person observatory crane!

I hope this helps.

"My advice is always free and worth every penny!"

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii


On Thu, Dec 31, 2020 at 7:17 AM Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
I always put the rings on the mount, open them and then place the scope into the rings. This is done in Park2 position. I can load my 155 and 160EDF refractors that way by myself, and I'm not a strong man weight lifter.

I would NEVER load any refractor with the dovetail and rings attached to the scope. It's asking for disaster.

Roland



-----Original Message-----
From: Andrea Lucchetti <andlucchett@...>
To: main@ap-gto.groups.io
Sent: Thu, Dec 31, 2020 10:04 am
Subject: [ap-gto] safe way to load the OTA on the MACH2

Hello,
I am not new to the hobby but my current OTA makes the set up phase not easy at all.

the diameter is 270mm and weight around 19 kg, and I don't feel confident in loading the telescope by myself on the mount.
I wonder if someone has perfectioned a style for the move. :-)
I use the AP DoveDV10 saddle plate, open the lockers, put the bar flat and on the left, close the lockers.
I load the scope in PARK3 position.
previously I used to slide the telescope from behind ( a TEC 140) but now this seems impossible.

I know it sounds like a joke but I don't like to be dependent on other people for the task.
if you know a trick , please share it.
Thank you
Andrea

--
Roland Christen
Astro-Physics

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