Another turn with a good bolt
Looking back on my first year of Science-Fiction-Create
This week, the last in 2020, I thought I’d share a few of my stories again. With each, I’ll add a bit of commentary.
For this first re-post, I’m sharing a somewhat overlooked installment. Maybe it was the timing. Or perhaps the subject. Either way, this story deserves another turn.
I honestly love the quarter-twenty. It’s convenient and solid. If any bolt is “perfect,” it’s this one. The question for me - could I write an entertaining story about a fastener? I wanted to know, so I gave it a spin.
Celebrating the quarter-twenty bolt
Nearly ideal - it's a fastener fit for almost any use
First published Nov 2, 2020
Approx. 775 words; 4 minutes read time
It's the fastener of choice - at least for DIY-ers in the US. The quarter-twenty is a workhorse, a go-to screw with many purposes, not too small and not too big. For me, and many makers like me, it's about as close to perfect as a bolt can be.
We all know what threads are - those spiral rings that allow one to screw (verb) a screw (noun) into something. Threaded fasteners differ from nails, which are driven or pounded into a substrate. With screws of all kinds, it's righty tighty, lefty loosie. Unless, of course, they are reverse threads like on bicycle pedals.
A "screw" means a threaded fastener that goes directly into something else such as a piece of wood, plastic, or thin metal. A "machine screw," rather, threads into a matching threaded hole. And a machine screw that goes into a nut? That we call a "bolt." Yes, a machine screw and a bolt are the same thing - the only difference is what you do with each.
The fastener commonly called a “quarter-twenty” is a machine screw/bolt.
The "quarter" in quarter-twenty means 1/4 inch (0.25 in) - the width of the bolt. And "twenty" is the number of threads per inch (abbreviated TPI). This nomenclature is standard for Imperial/SAE thread sizes.
There's a numbering system that confuses things, though. The standard sizes smaller than quarter-twenty often use these (e.g., a #10-32 bolt is 0.19 inches wide with 32 TPI). But the naming means the same thing - the first is the width, and the second denotes the threading.
Of all the machine screws/bolts, the quarter-twenty stands alone. Those smaller look and feel, well, small. The quarter-twenty is hefty. It’s a real bolt. But not too bulky, particularly when you hold it up to its bigger brethren.
A quarter-twenty is almost magically different - a chimera of many fasteners, great and small.
As such, the quarter-twenty is a Goldilocks size that fits almost any project. It has enough steel to make it healthy, but the thing is not so chunky that it gets in the way. The bolt that has both precision and power. Ready for anything, it won't let you down.
That's a quarter-twenty.
The size is easy to work with. A quarter-twenty’s threads are "coarse" and well-spaced. Having a broader pattern makes it hard to cross-thread. And in tapping (i.e., making a threaded hole), it's difficult to screw up. Makers new at “threading” often learn first using quarter-twenty for this reason.
Another cool thing about quarter-twenty bolts: they are everywhere. It's the standard thread size on camera mounts, for example. And if you need a replacement for a lost quarter-twenty, they are easy to come by. Those "bolt and nut sets" found in the quick-mart hardware aisle almost always have a few quarter-twenties in them.
For my latest build, the 'Evil Dead' chainsaw, I used mostly quarter-twenty machine screws. The main body panels are bolted together using them. So too is the wood handle as-well-as its aluminum attachment to the saw. Even the chain bar goes on with two quarter-twenties. In all, I used twenty screws of various kinds - thirteen of these are quarter-twenty.
Despite their utility, quarter-twenty bolts are rarely used in manufacturing these days. Almost all production has moved over to metric sizes. Metric has one main advantage over its Imperial/SAE counterpart - the dimensions are more intuitive.
Based on their actual sizes in millimeters, an M4 bolt is what it says - a 4 mm wide bolt. And we readily know that it's two millimeters smaller than an M6. So it goes, up and down the regimented metric scale. The sizes themselves are not superior to Imperial/SAE - but how we use and compare them is certainly easier.
In metric, the closest common bolt size to a quarter-twenty is an M6-1.0 (that's 6 mm wide with a thread pitch of 1 thread each mm). An M7-1.0 metric bolt is closer in actual size, but odd-sized metric fasteners are less commonly available.
As is, the M6 feels too small. And an M8 is too big. I often see M8-1.25 machine screws used where I feel an M7 - or better still, a quarter-twenty - would have been perfect. Modern flat-screen televisions, for example, use M8s almost exclusively to attach to wall mounts. It's a good bolt, the M8, but it's overkill. The thing is basically a 5/16 inch, which is a beast of a fastener.
No, I'd rather have a quarter-twenty any old day.
If asked, I'd say quarter-twenty is my favorite bolt. Yes, I have a favorite bolt. Weird? Perhaps to some. But if you make things like I do, I bet quarter-twenty is at the top of your list as well.
Still unsure about my quarter-twenty praise? Take one for a spin. Find some parts needing attached and go at it. The bolts are just the right size to hold, and you’ll likely already have the wrench and screwdriver needed to crank them down.
After a few twists and turns, I’m sure you’ll agree - the quarter-twenty is the bolt that can do it all.
Until next time. Science. Fiction. Create.
JRC