hey tested fans adam savage here in my cave with a quickie show and tell and it is a
fan gift that came into our post office box uh last week um regular viewers know that i have been
sewing my oats on the big machines on the mill and the lathe i have spent a lot of the lockdown
improving my machining skills and deepening my understanding of the levels of precision that
these machines can uh achieve and that's been a really lovely journey it's also been a rough
journey see my video of making the giant nut and bolt out of brass um it's it is a fits and starts
let's just say it is not a smooth narrative nothing is
um but uh one of my later projects one of my latest machining projects is this which
started out as a giant hunk of inch and a half thick aluminum this is a piece of a build that
is actually going to be fairly extensive and again this started out as a solid billet of aluminum and
i have now made it attached to i mean there's all these things that attach to this you'll see this
um but as i have been talking more and more about the machining and about the precision some fans
have been reaching out and sharing some of their knowledge with me and lei johnson uh from england
has sent me a gift and it is a pair of parallels now
what are parallels well uh in the machinist's world um actually hold on i'm gonna
in the machinist's world uh much of the machinist's job happens here between the jaws oh
here we go sorry much of a machinist's job how do i say this much of the work that a machinist does
this is what happens when i don't think through the camera piece in my head before i say it
um this is my milling machine this is the vice not everything gets clamped into the vise but
most things like a huge amount of a machinist's
um job takes place here between the jaws of the vice and when you clamp stuff into the vise
you want to make sure that it's perfectly flat to the milling bit and so you use things called
parallels and here is my set of parallels they are all slightly different heights starting from very
small to very large and they allow me to precisely place things super flat in the jaws of this vice
i can grab a lot or a little parallels are completely vital tool for milling using a vice
um and every machinist has a set or two i am no different but these parallels these are
of a totally different order um les johnson has actually a story to tell me and i'm going to read
some of it to you because it's lovely in 1985 he started an apprenticeship as a turner a machinist
with uh aircraft manufacturer british airspace as part of his training he made a number of tools
and aids this is something i've seen a lot of that he would use once he left training school
and he says as you well know a tool is something that has to be used and
these particular items sadly are not and will never be used by him again
please enclosed please find and close a pair of parallels as made by all of the british aerospace
apprentices from 1963 2007 when they closed the training school oh this particular pair were
made by me i started their manufacturer in the september of 1985 the very year i moved into new
york city to attend nyu or to pretend to attend nyu um completed them near the summer of 1986
i had just moved into the east village as i moved to the training school and was introduced to and
became proficient on more types of machines um uh yeah here's some take a look at this
so lee uh graciously walks me through the steps of these parallels manufactured now
when you buy machining equipment when you buy machine equipment it is often rated to whether
it's accurate to a thousandth of an inch to a half a 10 000 or even greater um and in general when
you buy the the the entry grave parallels i think mine are entry grade they're accurate to like uh
about a thousandth of an inch plus or minus one that uh across their width and frankly
they're more accurate than that that's just their rating these are made to a much higher standard
um and here is the process the bright drawn mild steel raw material was milled flat and
square on four faces using a vertical milling machine that's what it's behind me there
the ends were then machined to length on the same machine now that machine is totally capable of
accuracy to within a thousandth but when you want to get past that you're going to have to move on
to another machine the center wasted section was removed from each side using a shaping machine i'm
not even sure what a shaping machine is i'm going to have to look that up the apertures were then
drilled bored and chamfered on a jig board machine okay so not a drill press not a mill and these are
all different sized holes a jig board machine i stamped my name on one end of each there they are
l johnson they were sent for case hardening and chemical blueing that's the only part that
li lee did not play any part in both items were then matched ground on a surface grinder now
the milling machine comes in and it cuts and it cuts away material using the edge of a blade
and slices away and it can pull off you know you can pull off a lot of material in a single pass
30 40 000 depending on the material and the type of and the type of bit but when you want to get
to that sub thousandth accuracy you've got to use a surface grinder and that can bring these that
he brought these to a runout tolerance of 0.0002 inches that is 2 10 000 of an inch or one-fifth
of one thousandth of an inch what is a good way to tell you about two tenths um a sheet
of paper is about four thousandths so you can yeah right it's it's surpassingly accurate um
as for what i did with them lee johnson used these
and others liked them while he manufactured parts for the harrier a v a b hawk and t-45 aircraft
in 1990 he hung up his tools and these have sat in a dark corner ever since please accept this gift
for your shop they deserve a better life than being sat in a cupboard for another 30 years
lee thank you uh these i in the close-ups i know it looks like these have some blemishes on them
but as i can lay my fingers on them and feel them i can tell you that they were well loved and well
used and i am honored to have these have a private place in my shop and i will use them
and think of you each time i really appreciate you sending these thank you thank you thank you
um let's see here oh he has one more story uh to give you a little bit of history i use
them to produce the test machinings for the proof of concept for the t45 slatted wing
the t-45 aircraft is a carrier-based variant of the hawk fast jet trainer
the factory in my home village manufactures all the hawk and t-45 aircraft we sold a batch of
t-45 to the u.s department of defense for use in their new carriers but there was a slight
problem the cruising speed for the carrier was not quite what we had been told it was
that meant that when the pilot flew slow enough to land on the carrier he was very close to the
stalling speed and he fell out of the sky rather than landing safely if he came any hotter then he
ran the risk of overshooting the deck and dropping into the water whereupon the runway runs you over
neither outcome is especially pleasing the guys in our design department came up with a modification
to the leading edge of the wing that slid outwards and down when coming into land this changes the
geometry of the wing and allows for a much slower flight speed than before stalling i was chosen as
the machinist to work on the initial prototypes of the machine components therefore geometry was
finalized and released before the geometry was finalized in wreaths for full production before
the geometry was finalized and released for full production manufacture i have a very clear memory
of using these parallels along with a lot of plasticine in an attempt to add mass when milling
a deep thin walled feature i used these parallels because the holes allowed them to be held in place
by the plasticine my test machinings were moved into full production after a successful test
flight by the chief test pilot and all subsequent wings for the t-45 were of this new variant
he says you now own a little piece of aviation you now own a little piece of aviation history
oh he also wears uh phonak hearing aids i have had phonaks in the past and he's obsessed with
omega watches he possesses one the exact make and model of this one and he's a star wars nut lee
once again i can't thank you enough for the parallels for the stories and for the camaraderie
thanks very much man thanks for joining me for this show and tell i'll see you guys next time