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Plastic? Really?

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#1 Stew44

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Posted 19 February 2019 - 09:23 AM

Those that are old enough certainly remember this scene where Dustin Hoffman gets enlightened in 'The Graduate' (1967).

 

https://video.search...a6&action=click

 

Since that time 'plastic' has come to mean different things to different people.  I'm one of those that used to think the move to plastics cheapened products that were formerly made of metal or wood (or even glass).  In thinking about my Classic telescopes I realize I have come to highly prize my cast iron mounts, focusers and brass fixtures.   But in the 50+ years since 'The Graduate' was made there has been an evolution in plastic manufacturing process.  Phrases like 'breaks' easily' contrasted with 'built like a tank' have shifted to highlight benefits of these rather remarkable chemical compounds.  Words like 'composite', 'resin', and 'carbon fiber' have crept into marketing to counteract the negatives (at least here in the US) associated with the word 'plastic'.

 

The diversity of plastics today is probably best understood when making use of a 3D printer to 'print' something, say like a case for some electronic device.  Many different types of plastic feed stock are available to emphasize flexibility or stiffness, durability, temperature tolerance (both hot and cold), density, and of course color.  And we can't forget that ecologically, due to the widespread use of a myriad of various types of plastic touching every aspect of our lives, that we have created some of the worst environmental issues we presently face with burgeoning landfills full of plastic waste that will never really be anything other than what it currently is today.

 

But speaking for Classic telescopes and their kits, how do you all consider the incorporation of various plastics into telescope manufacture affecting (both positively and negatively) your perceived usability, durability and value? 

 

I consider Bakelite (polyoxybenzylmethylenglycolanhydride) the first plastic.  It is incorporated into many accys going back to its patent date (1909).  So we have lived with it for a long time.  In the 1960's things kind of took off and injection molding made huge leaps in ability to make intricate parts.  (Think about bolsa wood model planes versus twisting those little, highly detailed plastic parts off of their plastic panels and being able to have a finished model that looked truly like a miniature version of the real thing).

 

I want to contrast these trade offs with the evolution of some of my Goto telescopes as Goto-san 'innovated'.  Pretty interesting.

 

 

 


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#2 Chuck Hards

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Posted 19 February 2019 - 09:58 AM

Interesting topic, Stew.  Here's my take.

 

Unreinforced plastics should be used minimally in structural applications.  Plastics have a shorter lifetime than metals; volatile components slowly leach out over the course of decades, exposure to UV light also accellerates plastic degredation over time.   Better chemistry is constantly improving the physical properties of plastics so perhaps these shortfalls will one day be engineered-out of the material.  Some plastics are also hygroscopic, which can have an effect on dimensional stability as well as durability.  Composites can eliminate some of these concerns and have been around for three quarters of a century or more but they still show up only sporadically and lately on just the higher-end models.  I recall the days when most Newtonians used hand-laid fiberglass tubes, that application has all but died-out in recent decades, as have most labor-intensive processes and materials.  The desire now is to have the CNC crank out as many parts as possible in as little time as possible.

 

I think modern designers generally do the best they can when presented with the price point they must work towards.  Telescopes used to be much more of a niche product than they are today, when I started this hobby over a half century ago, I doubt there were more than a few tens of thousands of active amateur astronomers worldwide, even fewer who could afford a "serious" telescope.  Today they are readily available for just about any budget, and made by the hundreds of thousands.  Sporting optics are made by the millions.

 

Plastics are a product of the petroleum industry and as crude oil prices rise, so do plastics prices.  Ultimately fully synthetic formulations will be required, but perhaps by that time entirely new materials will have been engineered.  Already there are some non-petroleum-based plastics and some of them are finding uses in the market.  Looking into the crystal ball doesn't always give an accurate picture of the future, so who really knows?

 

Materials science is constantly changing and plastics play a huge role in just about every consumer product available today, for better or worse.  Telescopes probably parallel many other consumer products, as far as the adoption of plastics goes.

 

I'd rather see metal used whenever possible, but if the right plastic is chosen for the right application, it's hard to argue against.


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#3 Ishtim

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Posted 19 February 2019 - 10:02 AM

While I understand the term "plastic" can be/has been synonymous with "cheap" certainly through the 70's into the 80's and even today, as you pointed out useful plastics have been around for a while... and continue to evolve as you mentioned.  

Teflon, trade name of the highly useful plastic material polytetrafluoroethylene (PTFE) was discovered in the 1930s.  It's in our telescopes and our frying pans.

Nylon is another one of these from the 1930's.  We wear it, have brushed our teeth with it and even use it as bolts, washers, bushings and clutch plates in our telescopes. 

 

If we extend the term "plastics" to include composites (plastic epoxies & reinforcing cloth), we open up the door to some hi-tech stuff I wouldn't call cheap nowadays...

Plastics have become common place in the automotive industry.  Even the intake manifolds on some of the newer GM cars are "plastic".

 

As for telescopes, have a look at the "dreamspcopes" line of "plastic" gear.  http://www.dreamscopes.com/

 

Plastic observatories are available to us now too, but I'll stick to wood and metal grin.gif

 

I would be curious to know how far back the use of plastics occurred in amateur telescopes.  


Edited by Ishtim, 19 February 2019 - 10:03 AM.


#4 gr5org

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Posted 19 February 2019 - 10:05 AM

3d printed telescope:

https://www.cloudyni...nted-10-inch-f3


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#5 Bomber Bob

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Posted 19 February 2019 - 10:08 AM

Well, in the 1950s, Bakelite was the hot new thing:  The retaining ring in my '58 Questar.  They could've used aluminum or brass, but went with plastic -- futuristic, I guess.  And the lens cell & focusing mount on my '57 Goto Hy-Score 451.  I doubt the OTA would've been that much heavier with metal versions of those parts.

 

Honestly, I'm not crazy about plastic on vintage scopes.  Didn't stop me from buying & keeping these two, though...



#6 Stew44

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Posted 19 February 2019 - 10:36 AM

Well, in the 1950s, Bakelite was the hot new thing:  The retaining ring in my '58 Questar.  They could've used aluminum or brass, but went with plastic -- futuristic, I guess.  And the lens cell & focusing mount on my '57 Goto Hy-Score 451.  I doubt the OTA would've been that much heavier with metal versions of those parts.

 

Honestly, I'm not crazy about plastic on vintage scopes.  Didn't stop me from buying & keeping these two, though...

Prior to that the tube was a plastic called Synthane, and the screw-on lens cap was Synthane as well.  Braymer was an early adaptor as far as telescopes go.


Edited by Stew44, 19 February 2019 - 10:37 AM.


#7 darkapollo

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Posted 19 February 2019 - 10:40 AM

Mostly finished NT-5 on EQ Fork

 

You can say "cheap" but my little labor of love is a lot sturdier and less than half the weight than the steel tube it replaced. 

Sure, metal would be preferred for the gears and some of the structural supports, but the weakest link is the design of the RA, not the plastic itself. 

 

I really do not understand the dislike towards plastics when people are perfectly fine using cardboard tubes and cheap subfloor under-layment (lauan plywood). 

 


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#8 Geo31

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Posted 19 February 2019 - 10:43 AM

I don't know as I'd throw composites in with plastics.  Modern composites are pretty amazing.  Even older composites such as phenolics (BTW some people still call RV-6 tubes Backelite, but they are in fact phenolic) are pretty amazing.

 

Plastics have come a long way, and continue to develop, but I think for critical components, modern composites will win out, but at a cost.  For items made with a tight cost consideration, plastics will still win the day.


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#9 Geo31

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Posted 19 February 2019 - 10:47 AM

 

I really do not understand the dislike towards plastics when people are perfectly fine using cardboard tubes and cheap subfloor under-layment (lauan plywood). 

 

Are we really taking about cardboard and Lauan or composites?  Phenolic tubes are composites and a good value in the cost/rigidity/mass equation.  Plain Lauan plywood is pretty weak.  But many wood composites are incredibly strong.  Choice of substrate is incredibly important though.  It must be free of voids and for maximum strength should be vacuum bagged and even autoclaved.


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#10 Bomber Bob

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Posted 19 February 2019 - 10:54 AM

I get all that about synthetics.  But... there's something special about the gleam & sheen from real brass & chrome -- the Tinsley's focuser is a work of art that the Goto's is not.


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#11 Earthbound1

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Posted 19 February 2019 - 11:02 AM

One must use the right tool to get the best result for a task at hand. Similarly the right material must be used for optimal results in telescopes. My plastic Meade focuser is a perfect example of where metal would have been way better. Even soft aluminum would have been better than this chrome plated plastic. Brass or steel better still. To paraphrase Chuck, "more metal...plastic where it doesn't matter." He raised several valid points as to plastics longevity...20 years from now, lots of UV exposure, oxidation, and venting of volatile hydrocarbons can take significant tolls on it's structural integrity as evidenced by countless examples in the landfill and on the roadside...
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#12 Stew44

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Posted 19 February 2019 - 11:17 AM

Here are two Goto finder stalks and base(s).  The right is cast metal and crinkle painted.  Probably middle to late 50's.  The left is a combined stalk and base most likely injection molded.  Latest 50's to 60's.  Weight difference is pretty negligible.  Which does the job better?  Both pretty equal I think.  Which is less expensive to make?  The plastic one for sure.  Would either bother me on a Classic scope?  Not really.  I normally take care that my finder isn't hitting something to knock out of alignment or in the case of the plastic one, to break it.   More worried about optics in finder than stalk and base.  That said, the finder stalks on my '51-54 Goto Eros telescopes are nickel plated brass.  That kind of says quality to me and simply goes beyond utility.  The plastic one below is held on the focuser housing with knurled screws so convenience is somewhat maintained.  The plastic one is also used on a School telescope.  Cost had a lot to do with telescopes going into schools in the early '70s.  More than one or two could be purchased.  So for a set amount budgeted per school type, the less expensive the telescope the more that could be sold per school. 

 

P2191266.JPG


Edited by Stew44, 19 February 2019 - 06:25 PM.

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#13 Chuck Hards

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Posted 19 February 2019 - 11:33 AM

George, I think lumping composites in with plastics is OK in the sense that they are both "not metal".

 

Here are some composite (fiberglass) Dobs I made almost 30 years ago, so they qualify as "classics".  That's not me in the pic, but a friend.  He is about six feet tall, these are 10" f/5.6 scopes.  Made about a dozen.  In this case, metal was not an option due to both tooling capability as well as cost.  But the finished product works well, I believe most of these are still in use today.  I still have the molds I made for them.

 

Russamp10inchNewts_zpsbb951203.jpg

 

 


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#14 darkapollo

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Posted 19 February 2019 - 12:25 PM

Are we really taking about cardboard and Lauan or composites?  Phenolic tubes are composites and a good value in the cost/rigidity/mass equation.  Plain Lauan plywood is pretty weak.  But many wood composites are incredibly strong.  Choice of substrate is incredibly important though.  It must be free of voids and for maximum strength should be vacuum bagged and even autoclaved.

My point was, people turn up their noses when "plastic" is mentioned, but find it perfectly acceptable to use other materials of questionable rigidity, durability, or integrity. 



#15 Kasmos

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Posted 19 February 2019 - 02:09 PM

The quality of the overall build is the most important aspect of any product.

 

Plastics have there place but you see so many cheap looking and easily broken (disposable), products it reinforces the perception that plastic equals cheap. That, and too many times a otherwise decent product's point of failure is a plastic part.

 

For example. I have a three desk lamps with swivel bases. Just two days ago, the newest one, which has a plastic post that swivels in the clamp/base, the post broke. The oldest is all steel but had a plastic clamp/base that broke. I replaced it with a metal clamp from an older lamp. I also had previously repaired the third one which has a metal post, but had a clamp made of metal and plastic. In all three cases it was the plastic part that failed in an otherwise decent product. 

 

I personally like telescopes that look like fine instruments. You might also say that I'm a snob, since I generally don't like telescopes made from cardboard and underlayment. 


Edited by Kasmos, 19 February 2019 - 02:10 PM.

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#16 bremms

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Posted 19 February 2019 - 03:06 PM

Those that are old enough certainly remember this scene where Dustin Hoffman gets enlightened in 'The Graduate' (1967).

 

https://video.search...a6&action=click

 

Since that time 'plastic' has come to mean different things to different people.  I'm one of those that used to think the move to plastics cheapened products that were formerly made of metal or wood (or even glass).  In thinking about my Classic telescopes I realize I have come to highly prize my cast iron mounts, focusers and brass fixtures.   But in the 50+ years since 'The Graduate' was made there has been an evolution in plastic manufacturing process.  Phrases like 'breaks' easily' contrasted with 'built like a tank' have shifted to highlight benefits of these rather remarkable chemical compounds.  Words like 'composite', 'resin', and 'carbon fiber' have crept into marketing to counteract the negatives (at least here in the US) associated with the word 'plastic'.

 

The diversity of plastics today is probably best understood when making use of a 3D printer to 'print' something, say like a case for some electronic device.  Many different types of plastic feed stock are available to emphasize flexibility or stiffness, durability, temperature tolerance (both hot and cold), density, and of course color.  And we can't forget that ecologically, due to the widespread use of a myriad of various types of plastic touching every aspect of our lives, that we have created some of the worst environmental issues we presently face with burgeoning landfills full of plastic waste that will never really be anything other than what it currently is today.

 

But speaking for Classic telescopes and their kits, how do you all consider the incorporation of various plastics into telescope manufacture affecting (both positively and negatively) your perceived usability, durability and value? 

 

I consider Bakelite (polyoxybenzylmethylenglycolanhydride) the first plastic.  It is incorporated into many accys going back to its patent date (1909).  So we have lived with it for a long time.  In the 1960's things kind of took off and injection molding made huge leaps in ability to make intricate parts.  (Think about bolsa wood model planes versus twisting those little, highly detailed plastic parts off of their plastic panels and being able to have a finished model that looked truly like a miniature version of the real thing).

 

I want to contrast these trade offs with the evolution of some of my Goto telescopes as Goto-san 'innovated'.  Pretty interesting.

Bakelite and Phenolics were and are some very useful materials. There are so many other types and families of plastics,  Used properly they are incredible materials. But sadly a plastic part is a failure point of many products.  The lousy plastic gear on the Vixen sled focuser??  It's smooth, well engineered  but uses a plastic gear that strips if you look at it the wrong way.


Edited by bremms, 19 February 2019 - 03:09 PM.

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#17 Ishtim

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Posted 19 February 2019 - 03:10 PM

"Disposable" seems to be more and more prominent in this day and age. 

 

First it was razors, then No Deposit-No Return bottles, then the Yugo.  What's next???


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#18 Stew44

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Posted 19 February 2019 - 03:33 PM

Here's another example of the switch from metal to plastic.  Two different Goto diagonal prisms.  The square body holds a Hershel prism assembly and the triangular body a regular prism.  The earlier versions I think are brass bodies and engraved side panels.  The later appear to have metal bodies but plastic side panels with Goto logo embossed (molded in).  Heft here is certainly a factor that gives confidence of dimensional stability, but can't really assess that in the later ones.  For it's purpose it's probably just fine.  When you have both though you tend to give more value to the heftier ones.

 

P2191267.JPG

 

Certainly this evolution is not limited to Goto.  I've seen much the same changes applied to Unitron products as well.  When you are marketing telescopes, you pretty much have to stay abreast of new manufacturing methods and employ them to gain cost savings that your competition is enjoying.


Edited by Stew44, 19 February 2019 - 03:38 PM.

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#19 Earthbound1

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Posted 19 February 2019 - 03:52 PM

Here again, I have a plastic star diagonal that has two cracks in the housing running away from where the tubes thread into it...inferior, no two ways about it. Plastic is good in some areas of design and just WRONG in others.
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#20 Van Do9:3

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Posted 20 February 2019 - 01:52 AM

Stew,

 

Thanks for starting this topic. Did quality brands such as Mizar Hino and Carton make plastic OTAs? In my experiment with Zen Market, I won a Mizar Hino 60mm OTA and a Carton 40mm kit. To my dismay, both OTAs, diagonals, and mounts were plastic. Is this is a sign of poor quality from well respected manufacturers? Are the lenses of high quality even if the OTAs and some accessories are not all metal?



#21 shredder1656

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Posted 20 February 2019 - 04:37 AM

George, I think lumping composites in with plastics is OK in the sense that they are both "not metal".

 

Here are some composite (fiberglass) Dobs I made almost 30 years ago, so they qualify as "classics".  That's not me in the pic, but a friend.  He is about six feet tall, these are 10" f/5.6 scopes.  Made about a dozen.  In this case, metal was not an option due to both tooling capability as well as cost.  But the finished product works well, I believe most of these are still in use today.  I still have the molds I made for them.

 

attachicon.gif Russamp10inchNewts_zpsbb951203.jpg

 

I don't care if these are plastic, or not.  I would love to have one of these scopes.  Especially if they came with a lifetime supply of cannon balls.  lol.gif 

 

Seriously, those are awesome!



#22 Geo31

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Posted 20 February 2019 - 06:17 AM

My point was, people turn up their noses when "plastic" is mentioned, but find it perfectly acceptable to use other materials of questionable rigidity, durability, or integrity. 

Why  not?  Modern composites are stronger, stiffer, and lighter than metal if made correctly.  Formula 1 cars are mostly carbon fiber today, even things like the gearbox housings and suspension components.  Very little metal.


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#23 Stew44

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Posted 20 February 2019 - 08:53 AM

Then there is the extremely rare intact Goto eyepiece tray.  In 1955 Goto launched the Model 105 (and other school telescopes) with very nice collapsing all metal tripod spreader arms and tray.  The arms and hub were made up of 49 metal parts.  The triangular tray of 5 more parts.  It was quite elegant.

 

P2201270.JPG

P2201269.JPG

 

In the '57 Model 105 (and others) Goto simplified the spreader arms and hubs to six simple wire parts that we that have the scopes certainly recognize.

 

P2201272.JPG

 

And the Bakelite tray was formed around a brass nut, for a single unit.

 

P2201271.JPG

 

Unfortunately many of us wind up with the tray remnant on the left of this picture (or maybe a 1/4x20 nut) instead of finding the tray in the case.

 

P2201273.JPG

 

I can certainly understand the move to a lot fewer parts, and reduction in assembly labor.  But this tray has only survived in a well cared for scope.  Probably not a good adaptation for something that is used in a school environment.  Here in the US, where amateurs would use these scopes, they haven't stood up to normal amateur wear and tear for the most part.

 

 

 

 

 

 

 

 

 

 


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