One of the things that makes engineering a bit inaccessible to newbs is the language that is always used but rarely explained. It differentiates the young from the old like a weathered beard, a list of expensive mistakes or a drawer full of wires too short to ever actually use.
Cutting and stashing wires is easy enough, fucking up and costing someone money is even easier and growing a beard is a little tricky… I should note here that engineers don’t crop their beards; An engineering beard is a product of laziness, not fashion. Though I had a fitter suggest to me that engineers like to grow beards because they need something to hide behind…
…But the language, in absence of any form of engineering jargon dictionary takes a lot longer to pick up. So, I got bored the other day and wrote an article with 10 engineering terms that should give you at least as much cred as a dirty mustache. Enjoy and add a few more in the comments section if you feel so inclined.
From middle english, meaning to break the corner
When you make a part that has a sharp corner on it, gouge your hand on it, get angry with it and take an angle grinder to it in order to remove the corner. After you knock the corner off, the small 45 degree angled section with a burr on it to to cut yourself on rather than a sharp corner to gouge yourself on is called a chamfer. If you cut yourself on burr you left on the chamfer, get an angle grinder again and chamfer the chamfer. Objects in high traffic areas tend to become spherical over time. It’s common practice to chamfer hard corners on turned parts to avoid cutting your hands on them and also so you can slip a bearing on without catching it on the edge. When I was in FSAE, we had a rule of thumb wherein if the thought of rubbing a turned part on your genitals makes you flinch, you probably should have chamfered it.
This is a tough one to find a proper source on as all online dictionaries refer to a spigot as a tap or a plug. Maybe this is American. Anyway, in English/Australian mechanical engineering, a spigot is a short cylindrical projection that inserts into a bore of some kind. I think this one may have come about because before spigot came to mean a tap, it was used to mean a plug/cork.
A pair of bosses on a thing perpendicular to its main axis. Those cannons you see in old war movies are mounted on trunnions so that they can be aimed up or down. We obviously don’t do this anymore, but it’s a common way to mid-mount pneumatic cylinders so that they can pivot.
A triangular stiffener used to stiffen a joint between two members. If you stand up straight and hold one arm out horizontal, you’d get tired after a while. If you put a triangular brace between your waist, your elbow and your armpit, you’d look stupid but be less tired. This brace would be a gusset. I know that was a bit of a weird example but I used it for a reason: If you happened to be wearing a shirt or jacket with diamond shaped expansion sewn in at the armpit, that would also be called a gusset. The word is shared between engineers, armourers and habidashers. So here’s an engineering gusset.
Here’s the other type of gusset. If you run afowl of Chuck, it’s probably the last gusset you’re ever going to see.
A jig is a piece of equipment used to hold a tool in an operation. It’s different to a fixture. A fixture holds the workpiece where a jig holds the tool. If you drill some holes in something and then drill through that something into another thing using those holes as a guide, that’s a jig because you’re holding the tool (the drill bit). If you make a device that clamps and locates the workpiece, then it’s a fixture.
When you put a backboard around a bin of some kind to prevent spillage, it’s sometimes referred to as a hungry board.
The practice of welding a hard material on top of a soft one to produce a hard face. I’ve heard of this being done to axe heads and digging equipment back in the old days. These days, we just weld a plate of something hard on top because welding labour is costly. Also it’s something I find myself doing when I’m working through a dodgy suburb at night.
An adjustable spacer that is designed into a machine way in order to take up any slack. Sometimes, these have a slight taper to them so that you can slide them in or out a little bit in order to adjust them. Sometimes there are screws pressing against them that can be tightened. There’s a picture below of each type. Overtightening the gibs tends to make the mechanism too stiff to operate. Conversely, having them too lose may result in unpredicted or unwanted movement. Thus, a person who talks a lot without thinking could be said to have his brain gib too tight, and jaw gib too loose.
You can see a gib here in the vertical way of my Deckel FP1. It’s the parallelogram shape at the top-middle.
I also used gibs here in my English wheel. This is a low tech way of doing it. They’re straight, not tapered and tensioned by the allen keys.
Part of a pulley. Specifically, the rollery pulleyish round part of a pulley. A sheave plus an axle and two side plates is a pulley.
When you’re designing ladders or stair cases, the rise is the vertical height between steps/rungs. The run or the going is the horizontal distance between steps or rungs. A guy I work with told me a story about an ex-employee who was adamant that the Australian standards for the rise and going of a staircase was specifically calculated so that a woman could walk up it without her tampon falling out. I’m not even kidding, he really did think that.