Years ago, most were actual machinists (when Boeing fabricated most of the
parts in house). Now the vast majority are assemblers. Don't let the
moniker "assembers" throw you though - the skills required by the average
assembler, while not the same as a true machinist, are pretty rigourous.
Imagine trying to drill a hole to +.002/-000 on a compound curved surface,
through a stack up of titanium and composite, free hand. If you mess up,
the hole has to be reviewed and repaired, usually with the next size
fasterner, to the same tolerances. Each repair is a costly, time consuming
process. I guess what I am trying to say is that most Boeing "assemblers"
still need to apply that machinist's attitude to their work. It must be
perfect every time.
Remember, if you ever fly on a Boeing airliner, your life depends on
Same thing with airline mechanics. Things have changed, but I remember
the days when airline mechanics made substantially less than car
mechanics at new car dealers.
IME, the shop rate is considerably less for aircraft mechanics
compared to car mechanics (maybe 2/3- 70 vs. 90/hr), but they seem to
make up the difference (and much, much more!) in other charges.
I know a couple guys who are retired McDonnell-Douglas (now
Boeing, of course) tool and die makers. They did actual machine
work, from time to time, but most of their job was assembling
fixtures for parts to be assembled on. A fair bit of that
assembly required drilling holes after the parts were placed on
the fixture, or riveting, or whatever. Some of these fixtures
would fill a good-sized room, but needed to be measured uot
quite precisely. If they set up the fixture right, then those
assembled components would fit to the next component with
relatively little adjustment.
So, I gather that the tool and die makers were the highest class
of machinist at the aircraft makers. But, these planes don't go
together like a Detroit car, where you just hang parts on a
frame and stick the bolts in. When you're only making 50 a year
or something, and the components are so large, there is a LOT of
hand fitting involved, placing panels in place and then drilling
a thousand holes for rivets, then riveting, then smoothing the
rivets. The newest planes have a lot of composite in them,
which takes a lot of detail work in assembling the panels and
laying up the composite before autoclaving.
Browsing thru responses to your question, an important point seems to have
been missed: Namely, aviation blueprints can and do vary substantially from
your 'typical' mechanical drawing. Said differently, there is an entirely
different reference system to be learned, a lot of nomenclature specific to
'lofting' techniques, etc.
Sort of like comparing moldmakers, die makers, mill wrights, etc.
Anyway, it's been a while since I've visited this group, so ...........
That's it. They belong to the International Assoc. of Machinists and
Aerospace Workers union. Same union I was in for 22 yrs. at USAir. Or what
we called the IAMAANPWCSU, International Assoc. of Machinists And Any
Non-skilled Plug We Can Sign Up. In the old days, it was a true craft union
and started with railroad machinists. Turned into one sorry union after
they started enrolling aircraft cleaners and fuelers, etc. They outnumbered
aircraft mechanics and it all went downhill from there. I'm retired and
miss them like a dirty shirt.
I left the assembly line In Everett a little over two years ago for
greener pastures. The bulk of the folks on the line had job titles
like "mechanical assembler/installer" and such. The next point I have
to make is a question: What's a machinist? Purely rhetorical, but the
union helped define the job, and it's a general term used to describe
the union represented hourly workers assembling the airplanes.
As far as precision work, various parts of the airplane have
different tolerances. Hole diameters +/- .003" for the most common
fasteners, some tighter depending on the fastener. Structural
tolerances usually .030", but as other posters have mentioned, since
the airplane is so damn big, hand fitting is a given for a lot of
stuff. Some sections of structure are shot in with a laser to get
really good alignment, and most inspectorss carry a set of feeler
gauges down to .001.
As anyone who has done precision assembly work knows, some parts of
your task can be "sloppy" and some have to be better than the
drawing. It just depends. All of us had files of different types and
sizes and drill bits and reamers were available with just about every
size imaginable, and most folks use the decimal size more than the
letter or number size because a thou or worn drill bit makes a huge
difference in how some fasteners fit.
The tools used are a variety, from generic drills and torquing
tools to highly complex and precise drilling tools that take two or
more people to move and mount to the jig. I can't begin to describe
the myriad of tools we used, drill jigs, assembly jigs, and so forth.
The folks who made the tooling we used had incredibly tight
tolerances, as stackup was intolerable. Those guys are more
machinists in my eyes than the assemblers, but as their rates
continued to go up in what they felt was a captive customer, they got
outsourced and dramatically slashed in manpower. That's why I think
the 737R (replacement) which has been put on hold will likely wind up
in the Southeast rather than here in Washington State, given the high
labor rates here and the lower required assembly skills being
engineered into all new products.