Imperial vs. Metric

Discussion in 'The Watering Hole' started by jd2cylman, Jul 29, 2019.

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  1. Aug 3, 2019 #91

    Nytrunner

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    X kgf-m * (2.2 lb/kgf) * (3.28 ft/m)
     
  2. Aug 3, 2019 #92

    gldknght

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    My response to that always is, SO WHAT??? Why should the U.S. feel a need to follow the rest of the world?? We shouldn't do it with our health care system, we shouldn't do it with our immigration laws, why should we do it with our standards and measurements systems??

    When someone says they need a 7/16 wrench, I know without needing to think about it what that means. So the metric system is NOT easier.
     
  3. Aug 3, 2019 #93

    Alan Whitmore

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    Many decades ago, before I had ever heard of HPR, my wife Sallie and I restored and repaired antique and vintage motorcycles, mostly British, but a smattering of Italian and German bikes found there way into the shop occasionally. This was the early '70s, and so 'vintage' was early '50s and 'antique' was somewhere in the '20's. There was essentially no standardization whatsoever. We had full sets of SAE, metric, British Standard, and Whitworth wrenches, and even with that diversity were constantly scratching our heads to try to figure out how to remove or drive this or that bolt or nut. We eventually worked out a whole set of approximations and work-arounds that let us get the basic jobs done. I remember one particular nut on the Bultaco Metralla that could not be engaged by any wrench of any set that we owned. It turned out that if we glued little squares of beer-can metal to the faces of the nuts we could put a BS 1/4 wrench on it and delicately unscrew it. Just to make things interesting, BS hardware is named for the diameter of the bolt or shaft that the hex nut is designed to work with. SAE nuts, bolts and wrenches are named for the distance across the flats of the nut or bolt. Same with modern metric. All very confusing to a young scientist.
    My first motorcycle was a 1969 Norton Commando. Absolutely fabulous motorcycle, but not necessarily the best bike for a beginner. Sallie talked me into that purchase, she still laughs about it. In 1969 Norton was just beginning to export motorcycles to the US, and the earlier models like the Atlas had exclusively BS hardware and they got complaints from American shops about the difficulty. So, in 1969 the timing case, the primary chain case, and the chain adjustment nuts had SAE hardware, but when you got inside and started pulling off the cylinders or splitting the crankcase, all the hardware was BS. Lucky for me that Sallie had all the necessary tools in house. I don't know when the conversion took place, but by 1973 all the Norton export models had SAE hardware all around.
    One more difficulty that plagued us during that time was that some hardware like SAE used a 60 degree thread pitch, while Whitworth and IIRC some of the BS hardware used a 55 degree thread pitch. You could have a nut and a bolt from different jars on your shelf that looked like they would work together, and you could put your thread gauge on them and they would match up, but you could not screw one upon the other without destroying both pieces. Fun times!!

    Alan Whitmore
    Chair, TMT
     
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  4. Aug 3, 2019 #94

    OverTheTop

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    BTW, the conversion figures used were 0.4536kg=1 pound, 39.37" = 1 meter.

    Almost forgot, g=9.8 m/s/s :)
     
  5. Aug 3, 2019 #95

    KC3KNM

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    You've taken a machine shop running in inch and moved to metric? Can I ask what was changed, and what benefits you've seen?

    I run our in house machine shop, and we're still relatively small. If swapping over were to make sense, the time to do so would be now as we're growing pretty rapidly. I haven't run into issues yet working in inch, so I haven't had a reason to change anything. That said, if you're willing, I'd like to gain some insight on what was gained and what pushed you to make the change. Thanks!
     
    Last edited: Aug 3, 2019
  6. Aug 3, 2019 #96

    prfesser

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    So do I...which only means that we were born into the system. Fun fact: Imperial units are based on metric units. The inch is now defined as exactly 2.54 cm; the pound (mass) is defined in terms of the kilogram (which used to be a platinum-iridium cylinder).

    People often think the metric system is hard because of metric-imperial conversions. But if we were on the metric system there would be almost no need for conversions.

    Best -- Terry
     
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  7. Aug 3, 2019 #97

    jlabrasca

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    You don't have a drawer filled with loose Allen wrenches?

    Or, rather, you don't have one or two loose Allen wrenches lurking at the back of every drawer in your house? >smile<

    Apart from the box of Ikea wrenches, I've got one drawer in an Akro Mills parts sorter dedicated to mystery wrenches -- little cranked square drives, came-with-something Allen keys, etc. I have a matched pair (two copies) of hex wrenches that are unlike anything I have in any metric or SAE set. IIRC, something like 17/64 inch ( just about 6.75 mm) at one end and some other weird thing (like 7.25 mm -- I'd have to look) at the other. I can't throw them away because I may one day need to remove, or replace, or adjust the thing with which they were included.
     
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  8. Aug 3, 2019 #98

    dr wogz

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    Can you elaborate?
     
  9. Aug 3, 2019 #99

    dr wogz

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    No, but it might make things around the world easier.. that we all use one unit of measure.. that we can keep one set of tools in our box.. that we can fix our toys regardless of where they come from..

    yes, change will take time, and there will be frustration for a few years. But after a generation, it'll be 2nd nature.. My parents were imperial, I was schooled in metric..

    Don't forget, tourism & trade at the turn of the century had issues, as some countries kept their own standards of rail tracks (width) so trains had to stop, goods & people had to switch trains mid journey...

    I don't buy your argument that if someone asks you for a 7/16" wrench you know what that means. it's just a wrench sized to fit over a 7/16" bolt or nut (it's actually the standard for a 1/4" nut or bolt..) I could ask you for a 17mm wrench, and you just go and pull out the 17mm wrench and hand it to me.. I could also say, hand me the pink wrench, as I know that's a 9/16" wrench..
     
  10. Aug 3, 2019 #100

    mpitfield

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    Some interesting and relevant videos, that go over some facts that obviously some are unaware of.



     
  11. Aug 3, 2019 #101

    mpitfield

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    I think you misunderstood my comment.

    I have never been involved in the migration process at a business or institution level. I was speaking from my expeince as someone who was effectively "programmed" in one unit of measure then forced to learn and try to think in another. It was frustrating, and for me, it took a very long time, literally decades to be able to "natively" think in Metric. I always did the conversion in my head or on paper to visualize what I was measuring.

    I will argue that this is beyond one person or even a generation and that I take the long term view of it being the greater good for humanity. If anyone needs "proof" that there is an advantage of everyone on the planet being on a single standard unit of measure, then I don't know what to say except common sense should prevail.

    To put some perspective on this, below are some copy paste points from a quick Google. These are just random searches and in no particular order of importance or relevance. I am not standing behind the accuracy of any specific point, nor do I want to argue the validity of any of them. The point is that the list of mistakes and issues presented is long and shows no signs of going away anytime soon.
    • Consumers have difficulty in comparing prices (and hence value for money) when rival traders quote prices in different measures – for example if one trader’s prices are in $/kg and the neighbouring trader quotes in $/lb. Dual pricing (e.g. per kg and per lb) increases costs for manufacturers and causes unnecessary work for retailers – especially small shopkeepers and market traders who may have to change prices frequently by hand. These costs are ultimately borne by the consumer. Similarly, the marking of package sizes in both metric and imperial has a cost implication.
    • Misunderstandings, mistakes and disputes can occur when parties to a transaction use different units of measurement. (The 1999 failure of the Mars Climate Orbiter space probe at a cost of $125 million is the best known and most spectacular example.)
    • Much teaching of metric to schoolchildren is wasted since they have little opportunity to practise their skills outside school. When children leave school, they have to adapt to the imperial system, which they have not been formally taught. Many soon forget what they learnt at school yet have an imperfect grasp of and no ability to calculate in imperial measures. This could have serious consequences down the road.
    • The emphasis on conversions (from metric to imperial and vice versa) inhibits people from thinking easily and consistently in a single system. People who use metric at work constantly have to adjust to the imperial environment outside the workplace.
    • Standard derived measures, such as fuel consumption in miles per gallon or in litres per 100 kilometres, cannot easily be calculated when a mixture of units (litres and miles) is used.
    • Ro ad contractors have to convert metric design distances into imperial for signage with consequent costs and potential for error.
    • People purchasing properties have to do extensive conversions from metric to imperial and vice versa if they wish to estimate the costs of renovations.
    • NASA lost equipment worth millions thanks to shoddy conversion practices. SOHO, the Solar Heliospheric Observatory, a joint project between NASA and the ESA (European Space Agency), lost all communications with Earth. After about a week of trying various things, communication was restored and everyone breathed a sigh of relief. Among the problems thought to have caused the sudden blackout? There was an error in the spacecraft’s navigation measurements of nearly 100 km, which resulted in a much lower altitude than expected and led to the vehicle’s break-up in the atmosphere. The conversion factor from English to Metric units was erroneously left out of the AMD files. Interface Specification required that the impulse-bit calculations should be done using Metric Units.
    • In 1983, an Air Canada plane ran out of fuel in the middle of a flight. The cause? Not one but two mistakes in figuring how much fuel was needed. It was Air Canada’s first plane to use metric measurements, and clearly, not everyone had the hang of it yet. Luckily, no one was killed and only two people received minor injuries. That’s amazing considering the flight crew thought they had double the fuel they actually had.
    • In 1999, the Institute for Safe Medication Practices reported an instance where a patient had received 0.5 grams of Phenobarbital (a sedative) instead of 0.5 grains when the recommendation was misread. A grain is a unit of measure equal to about 0.065 grams… yikes. The Institute emphasized that only the metric system should be used for prescribing drugs.
    • An aircraft more than 30,000 pounds overweight is certainly no laughing matter. In 1994, the FAA received an anonymous tip that an American International Airways (now Kalitta Air, a cargo airline) flight had landed 15 tons heavier than it should have. The FAA investigated and discovered that the problem was in a kilogram-to-pounds conversion (or lack thereof).
    • Even Columbus had conversion problems. He miscalculated the circumference of the earth when he used Roman miles instead of nautical miles, which is part of the reason he unexpectedly ended up in the Bahamas on October 12, 1492, and assumed he had hit Asia. Whoops.
    • Power output of different appliances cannot be compared when some (e.g. central heating boilers) are expressed in “British thermal units” (BTUs) and others (such as electric heaters) are expressed in kilowatts
    • Visitors are confused by the inconsistent mixture of measures used.
     
  12. Aug 3, 2019 #102

    prfesser

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    Every measurement has to be based on some sort of standard. There are seven base units, for length, mass, time, temperature, amount of substance, electric current, and luminous intensity (metre, kilogram, second, kelvin, mole, ampere, and candela).** At one time some of these were based on a physical object; now they're all based on some sort of physical phenomenon that can be reproduced by anyone with the proper equipment and knowledge. The second is defined in terms of the vibrations of some atom, I forget which.

    In turn, Imperial/avoirdupois units are based on those base units. The definition of the inch as 2.54 cm defines the foot (12 inches), yard, and so on. Same thing with mass and temperature. The US uses the base units for time, current, and luminous intensity. So we're part-way metric already; we ought to just go whole-hog with the other units.

    BTW volume isn't a base unit; it's the cubic meter, and one liter is defined as 1/1000 of a cubic meter. I don't know which is used to define avoirdupois volume; I think the quart is defined in terms of the liter but am not sure.

    **From Hill/McCreary/Duerst/Reuter, "Hill's Chemistry for Changing Times", 15th ed. Came out in March. Yeah, I had to throw that in. ;)

    Best -- Terry (McCreary):D
     
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  13. Aug 3, 2019 #103

    KC3KNM

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    Yeah, I interpreted it as a response to my post mentioning the financial issues of swapping in a production environment. Moving from one unit personally is quite a long way from bailing on a ton of tooling. I don't understand how having to convert something is a negative over intuitively understanding it. If it's important enough to have a need to be accurately quantified, I sure as hell don't want someone doing conversions in their head. I've got a calculator and a note pad on me at work, and that seems to work out pretty well. I don't think I've ever looked at something that mattered and thought "that looks about X inches, good enough". I try to make it a point to verify things in imperial as well. What's a minute or two when you're working on equipment that's worth thousands (if not more) of dollars?

    I understand that issues can arise from conversion, but it's not as though miscalculations don't occur when working the entire project through one unit. Having one unit to be the standard isn't going to force people to have greater attention to detail. If people are losing money because they can't be bothered to pop out their smart phone and consult Google, should we feel bad?

    I suppose the same argument could be made that we agree on a language and drop the rest? I'm sure there have been just as many (if not more) problems caused by improper translation. It'd probably make sense to just use one currency while we're at it.

    I'm not arguing that standardization wouldn't be nice. It's definitely happening, though quite slowly. I understand why both are currently being used, we don't all have one foot in the grave for measuring something in inches. The best thing one could do is be proficient in both (or at least proficient with Google :p).
     
  14. Aug 3, 2019 #104

    Dave A

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    After working on bicycles and motorcycles then construction, you get used to using either wrenches. You tend to remember the cross-referencing of wrenches and sockets.
    That is until you buy an old Norton motorcycle, British Whitworth, Jesus!
     
  15. Aug 3, 2019 #105

    Dave A

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    When we build dragbikes, we tend to use Japanese motors in US built chassis. Chassis all have standard threads, the motors are metric. But we tap the motor mount holes, US 1/2"-13.
    There again, you keep both sets of tools in the trailer.
    I still have most of the metric wrenches I wanted for Christmas in 1972. My brother got me racing 10-speed bikes back then.
     
  16. Aug 3, 2019 #106

    gldknght

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    I don't really care if you buy my argument or not. When someone says an item (I don't care if its a hex nut or a popsicle stick) is 7/16" or 1/2" I know exactly what that means. When someone says 3.5 mm I have no idea how big an item that is.

    If the speed limit is 65 mph, that makes sense to me. If they say the speed limit is 104.6 kph, I say "What? Tell me what it is in MPH!!"
     
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  17. Aug 3, 2019 #107

    gldknght

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    If you want to use metric measurements instead of imperial, go right ahead. While you are at it, feel free to go live in Europe.
     
  18. Aug 4, 2019 #108

    Nytrunner

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    Change is hard. It gets harder when you find yourself left behind
     
  19. Aug 5, 2019 #109

    OverTheTop

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    We switched to metric when I was at primary school. I coexist quite happily in both units. A few basic conversion factors will get you most of what you need to survive happily dealing with the system. These are the ones I use frequently. Google does wonders for the rest.
    1m = 39.37"
    1" = 25.4mm
    degF = 9/5 x degC +32
    1kg = 2.2 (or 2.205) pound
    1 gallon (US) = 3.8 litres

    You can get most things converted with those equations or their inverse.

    Converting your height to metric and remembering it is a good thing, as when hearing descriptions of people given in metric you can compare the measurement more easily to your own.

    Note that the US has made things confusing with the gallon. Remember if you want to convert to UK gallons the factor is 4.55.

    I still think partly in inches and yards as well, but the mile is well in the past.
     
    Last edited: Aug 5, 2019
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  20. Aug 5, 2019 #110

    cwbullet

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    Metric. Learn to convert to be left behind.
     
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  21. Aug 5, 2019 #111

    OverTheTop

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    This post is a little ambiguous as to which side of the fence you are on. Personally I am on the metric side, but I can switch to imperial when necessary without much effort. FWIW I always design and work in metric except where convention has imperial, but I have a selection of metric and imperial tools (taps, dies, spanners, micrometers etc). The lathe and mill (with DROs) are metric, and I have never bothered to look where the "inch" button is.

    As for engineering or drug calculations (my wife is a nurse) I use metric only for those.
     
  22. Aug 5, 2019 #112

    cwbullet

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    I am on the metric side - convert or get left behind. Sorry, it was clear to me. Most of the medicine is metric now.
     
  23. Aug 5, 2019 #113

    Earache

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    Perhaps may of you are unaware, but the USA is a metric country. The 15 U.S. Code § 205b (which has not been repealed) declared:

    It is therefore the declared policy of the United States—
    (1) to designate the metric system of measurement as the preferred system of weights and measures for United States trade and commerce;
    (2) to require that each Federal agency, by a date certain and to the extent economically feasible by the end of the fiscal year 1992, use the metric system of measurement in its procurements, grants, and other business-related activities, except to the extent that such use is impractical or is likely to cause significant inefficiencies or loss of markets to United States firms, such as when foreign competitors are producing competing products in non-metric units;
    (3) to seek out ways to increase understanding of the metric system of measurement through educational information and guidance and in Government publications; and
    (4) to permit the continued use of traditional systems of weights and measures in non-business activities.

    The NIST defines all of the American Engineering aka US Customary Units (Used to be Imperial, but the Empire doesn't exist, and the former member don't use them) in terms of the metric equivalent. For example the inch has been defined as 0.0254 m since 1958. See https://www.nist.gov/pml/weights-and-measures/si-units-length. So whether you're using ips or mks you're using metric.
     
  24. Aug 5, 2019 #114

    OverTheTop

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    Looks like this thread is supporting point (3) nicely :).
     
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  25. Aug 5, 2019 #115

    Nytrunner

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    It's easy for me, my height is pretty much bang-on 200cm/2m

    It'd be easy to reach 100kg, but some care is needed to make sure I put on the right sort of mass lol
     
  26. Aug 5, 2019 #116

    Doug Holverson

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    When I was a early teen in the middle '70s, I sometimes tried to kludge SAE wrenches to fix a Honda ATC-90. Now, the I'm pushing 60 at the turn of the '30s, I'm sometimes trying to kludge using metric wrenches to fix old Studebakers. Then there are the Pintos with mostly metric engines and trannies and SAE everything else....
     
  27. Aug 5, 2019 #117

    Doug Holverson

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    Some of the good ol' boys of Grandpa's generation, "the day that I have to pick up a metric wrench is the day I quit being a tractor mechanic!"
     
  28. Aug 5, 2019 #118

    jlabrasca

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    I understand that you don't want to argue the validity of any of these points -- but the first one quoted seems to be claim that a conversion error dropped SOHO into the atmosphere -- which I think would be a surprise to the folks running it. I guess who ever compiled the points to which you googled used somebody's much forwarded inbox glurge that concatenated the SOHO story with the Mars Climate Orbiter story.

    As for the Columbus story -- it is way more complicated than that (upthread I mentioned The Catalog of Shipwrecked Books -- my copy is down to just about 6mm unread now, and is still holding my attention).

    http://smbc-comics.com/comic/pood
    [​IMG]
     
  29. Aug 6, 2019 #119

    mpitfield

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    The reason I said I didn't want to argue those points was, number one I didn't do any fact checking, however it wasn't required to make my point. If your intention is to focus on, and point out factual errors, in your gotya moment, then I am afraid that you missed the point.
     
  30. Aug 6, 2019 #120

    jlabrasca

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    Its spelled "gotcha" >smile<

    edit: forgot the >smile<
     
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