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RVing Here and There

Thoughts, news and information about the world as seen through RV windows
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  • Printing Flex on Kodama Trinus 3D Printer

    Posted on April 13th, 2020 admin No comments

    Although I’ve had my Kodama Trinus 3D printer for a long time (I was one of the first Kickstarter backers back in 2016), I had never had occasion to use flexible filament

    Early reports said this was difficult on the Trinus; I had printed a filament guide (thing #2041586) that was to make flex possible, then for some reason never got around to using one of the two samples of flexible filament that I had on hand.

    When the strap retainer on my watch broke, I decided it was time.

    Left, the original broken part; center, a draft in PLA; right, the final part in flexible filament

    I had the broken part, and used it as the basis for a design in Fusion 360. The design was sliced in Simplify3D. I did a quick draft in black AMZ3D PLA to check dimensions, and made some minor revisions to the design.

    The flex filament I used was from RepRap Warehouse, a local printing supplier. It was a sample of flexible blue TPU that they gave me with another order. It printed well enough at the manufacturer’s recommended settings, though there were some bridging issues. Since this is for a decade-old work watch that is falling apart and due for replacement soon, I didn’t worry about that and kept the first print.

    Far from my best print, but good enough for a worn-out watch

    We’ll see if this little blue replacement lasts the rest of the life of the watch.

    At any rate, the Trinus did a good enough job with the TPU, and would probably do better with some slicer tweaks. For now, I’m satisfied.

    But I still have a couple of metres of the blue TPU. What shall I print next?

  • Philippines to Shoot Coronavirus Victims Who Violate Lockdown Laws

    Posted on April 2nd, 2020 admin No comments

    Philippines President Rodrigo Duterte is allowing for the use of deadly force against those found violating lockdown standards implemented in an effort curtail the spread of the coronavirus, according to a report by NYDailyNews.com.

    The country of 107 million has had a whopping total of 2084 cases with 88 deaths, the report states. That’s an infection rate of .000019 and a relatively high death rate of 4.3 %. Other areas report a death rate of 2.3 to 3.9%

    National police chief Gen. Archie Gamboa on Thursday clarified the president’s remarks, noting authorities understood he “just overemphasized” the law and that lethal force would only be used when absolutely necessary, Bloomberg News reported.

    Man, I think we’re really going overboard on this. The thing isn’t THAT deadly, even in the Philippines.

    Compare it to the related viruses MERS-CoV (30-40% death rate) and SARS (9.6% ); or to other viruses such as Ebola (up to 71%), Influenza (Spanish Flu, up to 40%) or Hantavirus (12 – 36%). This one is a pussycat by comparison. Source: Deadliest Viruses on Earth.

    Perhaps one reason we’re scared is that most of those other more deadly killers were largely “over there” foreign diseases–the same psychology that had Trump at first calling it “the Chinese virus”. This one is making itself at home in a lot of countries.

  • Coronavirus Survival vs Temperature

    Posted on March 30th, 2020 admin No comments

    Given that it’s -14C outside, I started to wonder about survival rates of the coronavirus vs temperature and relative humidity, particularly at sub-freezing temperatures. Because the virus is new, almost all the studies I would find were looking at “cousins” of the one that causes covid-19.

    Viruses can be transmitted via either airborne particles (close personal contact), or fomites (surfaces such as clothing, doorknobs, counters and the like)

    Survival as Airborne Particles

    • Survival characteristics of airborne human coronavirus 229E” showed that survival was lowest at room temp and high relative humidity (about 3 hours), yet greatest at refrigerator temp and high humidity (about 3.6 days). Oddly enough, the long-term survival of airborne virus was greatest at 50% RH for both temperatures. (https://www.ncbi.nlm.nih.gov/pubmed/2999318)

    Survival on Surfaces

    • Effects of air temperature and relative humidity on coronavirus survival on surfaces” used two non-covid-19 coronaviruses, again at room temperature (20C) and refrigerator temperature (4C) but also at high temperature (40C). The results showed that “At 4 degrees C, infectious virus persisted for as long as 28 days, and the lowest level of inactivation occurred at 20% RH. Inactivation was more rapid at 20 degrees C than at 4 degrees C at all humidity levels; the viruses persisted for 5 to 28 days, and the slowest inactivation occurred at low RH. Both viruses were inactivated more rapidly at 40 degrees C than at 20 degrees C.” In other words, the virus thrives best on surfaces inside your fridge and can last from a week to a month. Isn’t that nice to know. Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2863430/
    A coronavirus, with anatomy
    • The Effects of Temperature and Relative Humidity on the Viability of the SARS Coronavirus” from 2010 looked at survival of the virus on smooth surfaces. The study found that “The dried virus on smooth surfaces retained its viability for over 5 days at temperatures of 22–25°C and relative humidity of 40–50%, that is, typical air-conditioned environments. However, virus viability was rapidly lost…at higher temperatures and higher relative humidity (e.g., 38°C, and relative humidity of >95%). Source: https://www.hindawi.com/journals/av/2011/734690/
    • Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents” reviewed 22 studies on this topic. The authors conclude that, depending on the material and the conditions, “Human coronaviruses can remain infectious on inanimate surfaces at room temperature for up to 9 days. At a temperature of 30°C [86°F] or more, the duration of persistence is shorter. Veterinary coronaviruses have been shown to persist even longer for 28 d[ays].” When the scientists delved into the literature on the persistence of coronaviruses on different surfaces, the results were variable. For instance, the MERS virus persisted for 48 hours on a steel surface at 20°C (68°F). However, on a similar surface and at the same temperature, TGEV survived for up to 28 days. Similarly, two studies investigated the survival of two strains of SARS coronavirus on a paper surface. One survived 4–5 days, the other for just 3 hours. Source: https://www.journalofhospitalinfection.com/article/S0195-6701(20)30046-3/fulltext
    • An oft-quoted recent study, “Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1” found that the viruses were “more stable on plastic and stainless steel than on copper and cardboard, and viable virus was detected up to 72 hours after application.” The viruses lasted two or three days on plastic and steel, less than eight hours on copper and less than 24 hours on cardboard, all presumably at room temperature. Source: https://www.nejm.org/doi/full/10.1056/NEJMc2004973

    Survival Below Freezing

    None of these studies have looked at below-freezing temperatures. I was able to find at least some additional information.

    • Dr. Mohamad Mooty, Department Chair, Infectious Diseases, Medical Subspecialty Institute, at Cleveland Clinic Abu Dhabi, has reported that “Research…has shown that, in general, coronaviruses are stable in freezing temperatures and have been shown to survive for up to two years at -20 degrees Celsius.” However, I was unable to obtain that research online. Source: https://english.alarabiya.net/en/features/2020/03/19/How-long-can-coronaviruses-survive-in-a-freezer-Up-to-two-years-warns-expert
    • Survival of human parainfluenza viruses in the South Polar environment” dealt with a different type of virus. The study found that three strains lasted between four and twelve days at room temp and seven to 17 days outside at -22C to -33C. From this it appears that those strains can last longer in frigid temps, but hardly the two years reported above by Dr. Mooty for coronavirus. Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC239486/
    • “Can deadly virus and microbes survive in the ice?” answers its own question and says, yes, “viruses and bacteria can survive in permafrost and in very old ice.” These viruses, up to 30,000 years old, are in some cases viable and capable of causing infections. Source: https://secretsoftheice.com/news/2017/03/09/virus-microbes-ice/

    Conclusions

    What research I was able to find suggested that viruses can actually survive slightly longer in colder temperatures, even well below freezing, than at room temperature. Cold weather gives us no protection.

    The most disturbing fact is that coronavirus can survive far longer in your refrigerator than in your living room. Ugh.

  • Rotating 3d Printer Tool Holder

    Posted on March 22nd, 2020 admin No comments

    Although a lot of folks use their 3d printer to print a tool holder, I found this handy gadget at my local Staples store: a rotating desk organizer for only $13 CAD plus tax. The various bins hold all the tools I usually use, for ready access.

    It fits perfectly on top of an empty filament spool fitted with drawers (you can find a wide variety of designs on Thingiverse). I expect to add more drawer layers as time goes on.

    Perhaps some day I will print something else, but this has served my needs well for the past few years. So maybe not.

  • Inexpensive 3D Printer Table

    Posted on March 22nd, 2020 admin No comments

    Making a 3d Printer Table for Under $30

    My CR-10s Pro 3d printer was too big for the table I used with my Kodama Trinus. Time to build something bigger!

    At the recommendation of a couple of other printer users, I bought a couple of side tables (Ikea LACK for only $12 CAD each). They’re sturdy and inexpensive and big enough to support the printer. One table formed the bottom or base, the second table became the printer support.

    Inexpensive 3d printer table for Creality CR-10s Pro

    To the base table, I added a quick and easy shelf, using a piece of scrap 1/2″ plywood that I had on hand. I cut rough notches to fit around the legs and supported/attached the shelf with a 2″ angle bracket (flat brace, less than $1 each) on each leg.

    For the top table, I cut each leg off at 10″. This leaves the bottom of each leg hollow. To locate the top onto the bottom, I cut four scrap pieces to fit inside the leg, and used 1″ deck screws to fasten these onto the top of the base table. The top table sits on these; they hold it solidly without slipping, but the top can still be easily removed.

    A hollow leg after the bottom was cut of
    An angled block cut from scrap to fit into the hollow leg

    It took only an hour to make the whole setup and it works well, especially considering that it cost under $30! There is a little vibration when the printer is moving and I might add some diagonal aluminum struts across the sides and back.

    The shelves are handy for storing boxed filaments in front with other equipment in behind (accessible from the sides, or by removing the boxes)

  • Why I’m not afraid of GMOs

    Posted on May 18th, 2019 admin No comments

    People don’t seem to realize that almost everything we eat has been genetically modified for greater yield, better flavor, etc. through centuries of selective breeding. Somebody spots a trait in a plant or animal that seems useful — say, higher milk production in dairy cattle — and that trait is given preference when the organism is reproduced. This is called artificial selection (as opposed to “natural” selection). The history of maize is a good example.

    Genetic editing is a relatively new method of doing the same thing, and it’s human nature to resist change and to fear the new and relatively unknown.

    There is always ignorance, as well, about new products or processes, such as those people who somehow think that GE involves “pumping chemicals into the plants” or that GE is somehow another form of “chemical additive”.

    Gene editing is a natural process done by bacteria as a way of protecting themselves from viruses. We’ve figured out how they do it, and are applying the technique (called Crispr) to replace one gene with another .

    I’m not talking about “frankenfoods” or “frankencritters” where DNA from one species is spliced into that of another. I’m talking about gene editing, where a modified gene from the same species is inserted in place of the original gene. One example is the gene that makes cut apples turn brown. While another few hundred generations of selective breeding might produce a non-browning apple, the GE variant is here already, created by silencing the gene that causes discoloration.

    The aim is to produce plants with higher yield, better insect/disease resistance, better nutrition and taste. It can be done in a thousand years with selective breeding, or it can be done in a generation or two with gene editing.

  • Parts of an Axe

    Posted on April 12th, 2019 admin No comments

    Basic Parts

    Asked to name the parts of an axe, the average person will say, “Uh… the head…and the handle… and, uh…” And that’s a pretty good start, since the head and the haft or handle are in fact the two basic parts.

    Basic Parts of an Axe

    The Head

    The head is the working end of the axe, the entire V-shaped metal (usually steel) cutting portion. There is a wide variety of head styles developed in various locales and for various purposes, and the names of the parts may vary as well.

    • Bit or blade – the tip of the “V”, that cuts into the wood (the sharp part is sometimes called the cutting edge)
    • Toe and Heel – being the top and bottom portions of the blade
    • Cheeks – the two sides of the head between bit and the hole where the handle goes. Each side may also be called a Face.
    • Eye – the hole through the head where the handle passes (or the portion at the top of the head where the handle sticks through or can be seen)
    • Wedge – a smaller V of wood, metal, or plastic driven into the top of the handle to secure it firmly in the eye
    • Butt or poll — the flat end opposite the V of the blade
    • Beard – oddly named, the underside of the blade immediately forward of the haft on the blade side
    • Shoulder – the underside of the blade immediately behind the handle on the butt side.

    The Handle

    Variously called handle, haft, or helve, depending on region, this is the user end of the axe. Traditionally made of wood but today of fibreglass, composite, or steel, the handle can be curved or straight and in various shapes and lengths.

    From axebyp.com
    • Back and Belly refer to the rear and front surfaces of the handle
    • Knob is a swelling on the “bottom” of the handle, furthest from the head, designed to keep the handle from slipping out of the user’s hands
    • Some types of handle have other parts, such as Toe, Heel, and Grip, as shown in the diagrams.
    • Throat – shown in the top diagram as being the highest part of the Back, but sometimes (by comparison with human anatomy), the part of the Belly just below the head.

    Axes come in a wide variety of shapes and sizes, designed at various times and places for a range of users and purposes. Although the names of the parts may differ from place to place, those shown here are fairly common.

    Further Reading

  • Selecting an Axe by Size

    Posted on April 12th, 2019 admin No comments

    Select an Axe by Size

    It is important to have a tool that’s not to big or too small for the intended user. An axe that has too heavy or too light a head, with a handle that is too long or too short, is an axe that poses a potential danger to the user and to bystanders.

    Weight of the Axe Head

    A light hatchet head might be one to two lbs (0.5 to 1 kg). A typical forest axe is 2-1/2 to 3-1/2 lbs (1 kg to 1.5 kg). A splitting axe is in the same range. A splitting maul might be 4-1/2 to 8 lbs (2 kg to 3.5 kg). An axe that is too light or too heavy will be more work to use, the first because it is uncomfortably heavy and the second because more swing effort will be required to drive the light head.

    A stronger person may be more comfortable with a heavier axe head.

    A variety of sizes of axe (note that the three to the right have identically designed heads)

    Length of the Axe Handle

    Axes come in a range of lengths for each type.

    • A hatchet may range from 8″ (200 mm) to 14″ (400 mm),
    • A forest axe might range from 28″ to 36″ (700 mm to 900 mm)
    • A camp axe will be 20″ to 24″ (500 to 600 mm).
    A variety of head weights and handle lengths

    Generally the shorter handles also have lighter heads. Because an axe is a lever, the force of the head is magnified by the handle. A handle that is too long takes excessive effort to wield and will be dangerous in the hands of a small or unskilled user with insufficient strength (who will choke up on the handle, compounding the danger), while a handle that is too short cannot apply sufficient force and may strike at an awkward angle.  Generally speaking, a taller user might be more comfortable with a longer handle. A smaller user or a youth will find both a lighter head and a shorter handle to be convenient.

    There may also be carrying considerations – backpacking or canoeing may dictate a shorter, lighter axe, for example.

    For efficiency and safety, choose the right axe

    For most efficient cutting and greatest safety, choose an axe that is right for the job, with a head weight and handle length that suits the strength, frame, and skill of the user.

  • A Terrible Teacher

    Posted on April 12th, 2019 admin No comments

    I once had a terrible university prof. Instead of teaching the course, he just listed study after study that we had to memorize. There seemed to be no order; just random studies. Many of his students were failing the course and considering lodging a complaint to the dean. I actually loathed the man.

    A few students were managing passing grades. I approached them and asked what they were doing. Their answer was that they carefully noted the order in which the studies were presented and on exams carefully regurgitated them in that precise order.

    One day, around mid-term, it occurred to me that each study either blocked off a false line of inquiry or led to another approach…which the next study either blocked or clarified. The studies were arranged with an inexorable logic like bricks building a wall.

    It was an innovative and unusual teaching method, with the students left to figure it out or not.

    The professor never explained this (would have made sense to have done so, and certainly helped his class) but once I understood what he was doing, I began to get top marks in the class. Not only could I recite the studies in the proper order, I was able to explain the logic and order and what each study contributed to the growing body of theory.

    Once I had “got it”, we got along a bit better. He turned out to be like Dr. Cooper on “Big Bang Theory”, a brilliant man with quirky social (and teaching) skills who later became my mentor for my Honors Thesis.

  • How Much Does a Good Axe Cost?

    Posted on April 12th, 2019 admin No comments

    What is the cost of a good axe?

    There are several factors that determine the cost of an axe, but the price is not always related directly to the value. Of six apparently identical axes in a rack, one may well be worth more than the others. Here are the factors to consider:

    Axe head considerations

    A well-forged head will not split or crack, but cheaper axes may not be well-forged. A head that is annealed and hard enough to maintain a good edge may also chip if mistreated.

    Most axes in hardware and camping stores are general-purpose splitting axes, with a wide bevel at the bit, and a convex shape towards the eye.

    “If you just casually camp and want to split wood at campsites where chunks are likely to be gritty – stay with a cheap axe: it will be more durable and the less acute bevel will split knotty stuff better.” – James Aston, http://www.oldjimbo.com/survival/iltis.html

    Axe handle material also affects the cost.

    • Wood is the traditional material and remains the most economical, though cheaper axes use poor wood of low strength and questionable grain hidden by paint. While some feel it is the most ecologically friendly (because of the cost and environmental impact of other materials), it does require regular maintenance and care.
    • Fiberglass – stronger and lighter by comparison to wood, but more costly. Because it is relatively impervious to moisture and abuse by porcupines, and because it damps striking vibrations, it is an increasingly popular choice in standard axes and especially on splitting mauls.
    • Steel – Unibody axes, with head and handle forged as a single unit, are high-end models. The striking force transmitted down the handle is damped with a rubber grip. One popular brand that uses steel handles is Estwing. Cheaper versions may have a tubular steel handle brazed into the eye of a standard head.
    • Composite – New plastic/fibreglass composite materials are finding their way into handles for axes and hatchets.The handle is molded around the head, eliminating the eye. Fiskars and Gerber are well-known brands using this design. Other composites include a fiberglass core, a polypropylene sleeve, and an elastomer grip.

    Watch for sales

    Of course, you’ll want to watch your local stores for specials. Sometimes top quality tools are available at discount prices. You might luck out for a good discount at a “scratch and save” event. Manufacturer’s specials also come up from time to time.

    Get the best axe you can afford

    When choosing an axe based on cost, you’ll still want to look for a tool that will be suited for its intended use and user. Your goal is to select the best axe you can get for the price you pay.

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