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Many people like to set new year resolutions for themselves. A challenge, usually involving a difficult change of behaviour or breaking an unhealthy or unwanted habit. It occurred to me that I might have some unique insights into making resolutions regarding amateur astronomy.
The best telescope is the one which gets used. Many amateurs must aspire to a larger instrument. Only to be defeated by the mental and physical hurdles of actually setting it up outside.
The best telescope is the one which gets used. Many amateurs must aspire to a larger instrument. Only to be defeated by the mental and physical hurdles of actually setting it up outside.
For over 50 years I have been building white elephants in the name of ATM [amateur telescope making.] Often my ambitions exceeded all common sense where my absence of clairvoyance really mattered.
I once made a 16" mirror for a large, classical Dobsonian shortly after discovering this class of instrument in American publications. I even went so far as to buy a 20" diameter PVC tube for it. Which weighed at least as much as the full thickness mirror blank! The problem then proved to be a lack of storage height for an F5 colossus of such an aperture! Having perfected the plate glass mirror at F5 I was then forced to regrind and deepen it to F4. A far more difficult and demanding surface.
This also coincided with the arrival of summer and extreme heat in in my concrete roofed, optical workshop. My pitch laps were literally flowing off the tools overnight. I eventually cured the heat problem with a layer of recycled aluminium sheeting. Fixed on top of the cast concrete roof it was highly effective but far too late by then. I never finished that plate glass mirror surface at F4 to my satisfaction.
I found a 24" cast iron lathe faceplate in a scrap yard and dragged it home somehow. This became a disk type, equatorial mounting. A solid steel TV stand acted as the PA axis with 4" steel rollers supporting the rim. Despite ball bearings all round, the whole thing weighed a ton and the friction and momentum was far too high for manual slewing.
I made a 5" F/15 achromatic lens from Schott BK7 and F2. Being so long is was quite a struggle to mount and far too heavy in a 6" PVC drainpipe. So I built a scaffolding pipe tripod and offset and cantilevered, Dobsonian/Berry fork mounting for it. It was never very successful but showed me the planets, Moon and a bright comet. Later I made a rolled aircraft ply tube for it and that transformed its weight. But I was experimenting with plywood, equatorial mountings with Dobsonian PTFE/Teflon bearings at the time. Probably trying to be too clever [again!]
The friction was far too high and the steel pier impossibly heavy to lift out of the ground once filled with concrete. So it stayed put and rocked no matter how I rammed huge stones around the base.
Later on I tried to make an all brass refractor using huge, artillery, shell casings and my home made 5" achromat. These casings quickly proved to be so heavy I could never have lifted the complete OTA. I finally found a 6" steel, spiral ventilation tube for the lens. This was arguably the best tube option at the time but the MkIV mounting still struggled with backlash. Nor was the spiral tube very pretty. I later discovered straight seamed, industrial extractor tubing and have used that on my 7" and 10" telescopes. Provided the seam goes into the gaps for the hinges the plywood packed rings will fit snugly.
The friction was far too high and the steel pier impossibly heavy to lift out of the ground once filled with concrete. So it stayed put and rocked no matter how I rammed huge stones around the base.
Later on I tried to make an all brass refractor using huge, artillery, shell casings and my home made 5" achromat. These casings quickly proved to be so heavy I could never have lifted the complete OTA. I finally found a 6" steel, spiral ventilation tube for the lens. This was arguably the best tube option at the time but the MkIV mounting still struggled with backlash. Nor was the spiral tube very pretty. I later discovered straight seamed, industrial extractor tubing and have used that on my 7" and 10" telescopes. Provided the seam goes into the gaps for the hinges the plywood packed rings will fit snugly.
I made a 7" f/12 refractor with an iStar achromat lens. This proved to be so long and heavy that my Fullerscopes MkIV mounting could not possibly cope. I had welded up a massive steel pier for the MkIV years earlier but it did not help. Moving the whole thing around on a sloping, undulating and often soggy lawn was an exhausting nightmare! The risk of tipping was very real regardless of which wheels I applied to the radiating legs!
I tried a folded 7" refractor based on an aluminium tubing, shelf building system. That was hardly lighter than the straight tube and only 3/4 as long. Still the MkIV complained.
So then I started on a huge equatorial mounting which would support the refractor and quite possibly my 10" F/8 reflector simultaneously. The latter had proved another white elephant thanks to beam torsional flexure!
This quickly lead to the realization that I had no clear sky views. Just moving the telescope down the rutted, gravel drive to clear southerly skies was nearly impossible. So I decided to build a platform for the mounting to go on top of a raised pier. The pyramidal pier is massive and built from full lengths of 4"x4" x 15' tall!
And so it goes on. A 6" f/12 would have fitted into 2.7m commercial dome. My 7" f/12 is a foot longer than a 6" and has no chance of fitting inside. So I am having to build a 10' plywood dome, from scratch, to go up on the platform. I even looked at a 14' GRP dome intended for rearing calves. But each of the three fiberglass segments weighed 160lbs! I would still go that way if I had clear skies at ground level... but I haven't.
If you find a chain hoist essential to your amateur astronomical pursuits you may well have crossed an important line. My ambition always far exceeds common sense by a considerable margin. Let my example be a warning to those who would imitate me! Though I should admit it has been a fascinating, if occasionally frustrating journey. Almost always done on a shoestring from scrap materials. Success was always going to be dependent on my ability to convert the rather limited raw materials available.
So then I started on a huge equatorial mounting which would support the refractor and quite possibly my 10" F/8 reflector simultaneously. The latter had proved another white elephant thanks to beam torsional flexure!
This quickly lead to the realization that I had no clear sky views. Just moving the telescope down the rutted, gravel drive to clear southerly skies was nearly impossible. So I decided to build a platform for the mounting to go on top of a raised pier. The pyramidal pier is massive and built from full lengths of 4"x4" x 15' tall!
And so it goes on. A 6" f/12 would have fitted into 2.7m commercial dome. My 7" f/12 is a foot longer than a 6" and has no chance of fitting inside. So I am having to build a 10' plywood dome, from scratch, to go up on the platform. I even looked at a 14' GRP dome intended for rearing calves. But each of the three fiberglass segments weighed 160lbs! I would still go that way if I had clear skies at ground level... but I haven't.
If you find a chain hoist essential to your amateur astronomical pursuits you may well have crossed an important line. My ambition always far exceeds common sense by a considerable margin. Let my example be a warning to those who would imitate me! Though I should admit it has been a fascinating, if occasionally frustrating journey. Almost always done on a shoestring from scrap materials. Success was always going to be dependent on my ability to convert the rather limited raw materials available.
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