Why People Prefer Imperial to Metric

The Junk Drawer is for those Off Topical discussions where we can ask questions of the community that we feel might have the ability to help out.

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SteveHGraham
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Re: Why People Prefer Imperial to Metric

Post by SteveHGraham »

I still hate Torx screws.

I'm smart enough to know that one of the reasons these demonic fasteners are used is to make things harder to work on. The Subaru thing mentioned above is an example.

As for drain plugs, I like what Chrysler does. Or maybe it's just Cummins, now that I think about it. My truck takes a socket wrench with no socket. You don't even have to think about the size of the socket.

Wait...I think I just accidentally endorsed a covert form of Robertson screw. CURSES! I feel soiled.

I had a dishwasher full of stainless Torxes. Ridiculous! Philips screws would have worked fine, but they didn't want me replacing my own parts.

The gas tank on my Harley is held down by a Torx in the back. Totally unnecessary.

Years ago, I found a set of bits for "tamper-proof" screws, and I bought it. Wonderful thing to have. When I run into a stupid fastener, I pop one of those bits into the old impact driver and keep going.

I'm sure a lot of the people on the forum already have stuff like this, but just in case I'll post a link. Owning these bits will make you feel like a criminal.

http://www.griotsgarage.com/product/113 ... bit+set.do
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Steggy
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Re: Why People Prefer Imperial to Metric

Post by Steggy »

SteveM wrote:You can put a LOT more torque on a Torx fastener than hex, phillips or allen head.
Excepting Phillips, which has a problem with camming out when subjected to a lot of torque, the above is an often-repeated fallacy.

Tests by SPS Technologies and others years ago proved that it was possible to torque any of the "positive drive" head types to breakage without damage to the head itself. The limiting factor in fastener torque is always the body strength, not the head.

Which head to use is a matter of fastener cost, wrenching space and assembly cost. Heading of hex fasteners has evolved into a very inexpensive process, and is a significant factor in why these fasteners dominate. However, the required wrenching space is considerable. When driven by a six point socket, body failure will always occur before head failure. The highest standard strength hex head fastener, grade 8, has a nominal tensile rating of 150,000 pounds per square inch.

The fasteners with the least amount of required wrenching space are the 1936 series socket head fasteners (aka "Allen head"—Allen is a trademark and is not the correct terminology), which are no longer commercially produced. As socket head fasteners increased in strength the head was redesigned to make it possible to commensurately torque the fastener and not damage the head's seating surface. The result was the the 1960s series socket head capscrew, which is what is in current production. The highest strength socket head fastener commercially available is rated at 190,000 pounds per square inch. When driven by an alloy hex driver it is possible to over-torque and break one of these screws, failure usually occurring at the thread runout.

Torx fasteners are not necessarily high strength fasteners, and hence may be readily broken by over-tightening. It may be that this is where the erroneous assumption about maximum torque capabilities arose. Initial commercial claims about Torx's supposedly superior tightening capabilities came from the patent application for the design, not any laboratory testing. Due to the shape of the Torx "star" wrenching pattern, stress risers exist that may cause head failure in high stress applications.

The bottom line is that any of the three common head designs is sufficient in strength to over-torque and break a fastener, even a high strength one.
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SteveHGraham
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Re: Why People Prefer Imperial to Metric

Post by SteveHGraham »

I like Philips screws. I made an outdoor TV cabinet by driving 1/4" Philips wood screws about 3 1/2" into pressure-treated pine. I admit, I had to lean on the impact driver to keep the bit from jumping out, but the screws went in, and this was before I learned to grease them before using them. That kind of torque will cover most of the stuff I get into, and I like the convenience of using the same bit over and over.
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SteveM
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Re: Why People Prefer Imperial to Metric

Post by SteveM »

I hate Phillips. I like the Torx screws Home Depot sells. I don't have lean so hard on the screwgun, and if I'm a few degrees off pependicular, it still works.

Steve
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SteveHGraham
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Re: Why People Prefer Imperial to Metric

Post by SteveHGraham »

Infidel!
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mikeehlert
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Re: Why People Prefer Imperial to Metric

Post by mikeehlert »

Generally speaking, a pair of vice grips and a pipe wrench backed by a cutting torch will solve most dis-assembly problems. Any screw with any head is better than those ultrasonic weld joints on the kids broken toys.

Now putting things back together is a whole new story. At least we are not using pine pitch and twine.

Happy Thanksgiving all
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BadDog
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Re: Why People Prefer Imperial to Metric

Post by BadDog »

Well Steve, if you ever find yourself needing to drive a 3-5" deck screw from an out of line position you'll change your mind in a hurry. I recently I had to do just that, on a ladder, hanging off balance reaching around with my arm like making a hook shot, and driving a 3.5" screw through a brace into a header plate. I challenge ANYONE to do that with a Phillips head screw and driver without butchering several in the process, and possibly going through a bit or two. Even if I had the arm/shoulder/back strength I used to have, I would have pulled myself off the ladder and/or blew out the hole before I could enough pressure on that bit. But with a positive drive, it would have been a complete piece of cake. I hate the Phillips screws worse than you hate the others, and it's 100% related to the inevitable cam-out ruining screws (and bits). Like you, I don't much care anyway when I've got full easy access and the ability to put my back into it, but that's not always the case. And that's why when I have consumed all the Phillips screws I currently have on hand, I'll never buy anything other than positive drive screws again...

Back to the metric thing, I love the metric system in theory, but mostly hate it in real life. But that mostly revolves around dealing with the indigenous systems and familiarity. The main specific issue I have with metric is convenience problem in dealing with fasteners. With a reasonable selection of fractional SAE coarse and fine, I can generally expect to have whatever fastener I may need on hand when the time comes. But not so with metric. It seems "they" choose pitches out of the same source as their waste piles (the kind you flush). Even if I have the right size, there are often 4 or more pitches to deal with, and every industry seems to have preferences. If I had dynamite on hand, I would likely have blown my Kubota (and possibly myself) to bits a dozen times over. Several times even a trip to the local provider of all fasteners proves unproductive. And according to them, it's not unusual. And it's not that they are focused on fractional. They told me that most of their inventory space is dedicated to metric fasteners, and they still have to order or flat turn away customers looking for metric. In my case, they couldn't even order in the Kubota fasteners I needed. They could get it in lower grades, but not what I needed, though fortunately they were able to get me the tap I needed.
Russ
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warmstrong1955
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Re: Why People Prefer Imperial to Metric

Post by warmstrong1955 »

Hey Russ.....Steve only uses balsa wood to build things...... :D

I'm with you....work fine for drywall....building things with timber & 2" and longer screws....not a chance. I buy Robertson.

Bill
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Steggy
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Re: Why People Prefer Imperial to Metric

Post by Steggy »

SteveM wrote:I hate Phillips. I like the Torx screws Home Depot sells. I don't have lean so hard on the screwgun, and if I'm a few degrees off pependicular, it still works.
You've pointed out the one real advantage of Torx fasteners.
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SteveHGraham
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Re: Why People Prefer Imperial to Metric

Post by SteveHGraham »

warmstrong1955 wrote:Hey Russ.....Steve only uses balsa wood to build things...... :D

I'm with you....work fine for drywall....building things with timber & 2" and longer screws....not a chance. I buy Robertson.

Bill
You just like them because they're square, like you.

It's PRESSURE-TREATED balsa wood!
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wsippola
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Re: Why People Prefer Imperial to Metric

Post by wsippola »

I like Robertson - drove at least 5000 of them putting on a new roof over the last couple months. Hate Philips when used with anything requiring any real torque - particularly when disassembling tight fasteners. I'd like torx better if I could find the right screwdriver easier - but that's not the fastener's fault.

I'm surprised at the popularity of Robertson in the States - used to be pretty rare.

As far as the theoretical and lab tested abilities of the fastener head to withstand the breaking torque of the fastener - they should have tested some half rusted real world fasteners you find on the older cars you get to turn wrenches on!
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NP317
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Re: Why People Prefer Imperial to Metric

Post by NP317 »

Harold_V wrote:Beyond that, the idea of converting to metric makes little sense for a country that is filled with machine tools and metrology geared to imperial. Those who are involved in the manufacturing industries are, for the most part, comfortable with the system in use and have little need to change. It has served us well since its inception.
Being raised with the Imperial system, becoming intuitively familiar with the Metric system took dome deliberate effort on my part. When I began working in the Biomedical Electronics manufacturing field in 1976, our company used the Imperial system. By the early 1980s, we had changed to metric in order to sell products worldwide. That alone is a good reason to convert!

The metric system is less prone to mistakes, because it is based on our body parts: 10 fingers in front of our face.
Translating between Imperial and Metric amplifies opportunities for mistakes, as spectacularly illustrated by the 1999 loss of the Mars Climate Orbiter space craft!

Conversely, my home shop machine tools are Imperial, although I will use metric frequently.
~RN
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