A Good Time To Hit The Shop

Discussion and instructions for astronomy-related projects
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Apollo XX
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A Good Time To Hit The Shop

Unread post by Apollo XX » Sat Mar 14, 2020 6:26 pm

With COVID-19 wreaking havoc on the world and 'social distancing' virtually mandatory now, I can't think of a better place to self-isolate than my workshop. I've decided to finally get down to the business of making a pier extension for my LXD75 mounts, of which I own three. I like them. They do what I need them to do very well, but when I've got a long-ish refractor mounted up, the eyepiece can get uncomfortably low. Today I started cutting up the parts to raise the mount a bit. In this picture they're just stacked up, not necessarily in their final order 😂 More on this as it progresses 👍

When you buy commercially made pier extensions they're typically constructed entirely of aluminum, but that can get expensive on a one-off basis and the equipment to work large slices of metals isn't typically found in your average backyard workshop. The large tube for example would cost about $80 to source, and the material for the discs would at least double that. So we've got two things going on here; first is that there are no commercially produced extensions on the market for this mount any more (mass production brings the price into reason on products like this), and second is that the typical materials used in mass producing a product like this aren't absolutely necessary for good functionality. In fact, the materials I'm using may be better in some senses. For example, the large tube, or 'riser' as it's called, I'm making out of PVC. It's got plenty of strength in the direction of forces that this task demands and is much lighter than an aluminum version of the same would be. For the base and top plates and centering plates I'm using furniture-grade plywood. Again, it's lighter than the equivalent aluminum counterparts, and wood has an inherent vibration damping characteristic that does not exist in the aluminum. Now to be clear, the construction technique for a riser made out of aluminum would be different than what I'm showing here and less material would be used, but ultimately my extension should still be lighter, which translates into better performance overall because the weight is above the tripod hub. So why aren't pier extensions typically constructed out of materials other than aluminum? The answer is simple; durability. With my PVC/Wood/Aluminum composite piece I'll need to be more careful in handling it, while an aluminum unit could survive one of those gorilla suitcase ads of the 1970's vintage: https://www.youtube.com/watch?v=749iU2Zv1kw


Total height rise of the final product will be ten inches. That may not sound like a lot, but it'll make a huge difference when in use. With my 5" F/9.3 refractor on the mount with no extension and pointed at zenith, I'm kneeling on the ground to look in the eyepiece.
Extension Stack.jpg
Extension Stack.jpg (816.18 KiB) Viewed 795 times

Turning the shaft that goes up the middle of the stack:
Extension Shaft.jpg
Extension Shaft.jpg (1.63 MiB) Viewed 795 times
Mike M.
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Apollo XX
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Re: A Good Time To Hit The Shop

Unread post by Apollo XX » Mon Mar 16, 2020 1:15 pm

OK, everything has been cut, turned, bored, drilled and tapped, and she's ready for a pre-assembly mockup to make sure everything is going to work together:

Parts & Pieces.jpg
Parts & Pieces.jpg (1.91 MiB) Viewed 789 times
And it does! One nice thing I like about this design is that the extension is merely sandwiched between the mount head and tripod with the clamping force of the original bolt. That way I can easily choose whether or not I want to use it, and the original functionality and portability of the mount is retained.

Pre-Assembly Mockup.jpg
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Mike M.
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Apollo XX
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Re: A Good Time To Hit The Shop

Unread post by Apollo XX » Wed Mar 18, 2020 1:50 pm

Almost there - all the parts have been mated, aligned, glued and screwed and we now have a functional assembly. Now it's off to final finishing, where we'll do some things to it to make it impervious to the weather and Sunday-best presentable. Of course in considering what color to make it, it's always good to remember that old international law of astronomy gear coloring and one that none other than Henry Ford invoked himself during the early days of assembly line automobile manufacturing - you can have any color you want, as long as it's black.


It's entirely usable as it stands, but I'll still pretty it up a bit:
PierAssembly.jpg
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Mike M.
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Apollo XX
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Re: A Good Time To Hit The Shop

Unread post by Apollo XX » Fri Mar 27, 2020 6:05 pm

Ok, it's all painted up and ready to use - which I'm hoping to this evening. On the top and bottom surfaces I used an ebony stain, because I've found that if you use rattle-can paints on mating surfaces the paint never hardens up like a commercial finish and you wind up with transfer between the surfaces - ugly! On the edges and tube I started with a specialty plastic primer to prep the PVC, then coated it with a regular primer and finally a few coats of satin black. A couple of days in a sunny window and we're ready to roll.


Law-abiding black she is:
InPaint.jpg
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Mike M.
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Apollo XX
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Re: A Good Time To Hit The Shop

Unread post by Apollo XX » Fri Mar 27, 2020 11:47 pm

Well, it works quite well if I do say so myself. There is a large improvement in the comfort factor while using a long-ish refractor on the GEM mount, and I'm quite happy with the way it worked out. Even at zenith the eyepiece can be accessed without extreme contortionism, which is much appreciated by my knees, thank you very much.


Out in the night, looking around:
20200327_194207.jpg
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Re: A Good Time To Hit The Shop

Unread post by Bruce D » Sat Mar 28, 2020 12:07 am

Well done Mike!
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Dr. Powell
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Re: A Good Time To Hit The Shop

Unread post by Dr. Powell » Mon Mar 30, 2020 8:33 am

You are always making cool stuff. Impressive.
Mike
Mark Gibsonian 6" Newtonian Scope with a Spence mount.
16 X 50 Binoculars
60mm Bushnell Refractor
Jason Comet Hunter
5 1/4" Meade Reflector
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