Unpredictable

[dukealien]

Unpredictable

Like hand-dyed threads drawn tight across a loom  "hand-dyed" is difficult to say and doesn't fit the theme of tension in the rest of the stanza.  "Hand-spun," perhaps?
a parent winds the sturdy warp stretched wide
but taut, a shed built strong but leaving room  had to look up "shed" in this context - saw at first a slanted roof

for life to wield the shuttle children ride.  "wield" a bit off - perhaps something simple like "run"
The final vision cannot be discerned  perhaps "finished" vice "final?"
as colors side by side are amplified  good, better than "multiplied."

as weft threads slide then deftly are returned;  a lot of passive voice here for a parent's active engagement
an artisan allows the work to speak
a language of its own that's only learned

by following the steady fall and peak.  perhaps "constant" vice "steady," which makes it sound plain rather than remorseless
The siblings give no thought to what's unseen,  the three Fates?  just a thought...
all consequences cloaked in life's mystique.  perhaps "with" vice "all"

They'll hold each other close as they careen
through life, no distance in the years between.  perhaps emphasize closeness rather than negating distance to simplify and add impact.

Any and all crit welcome.

pulled from the practice threads for something to do 

In moderate critique, and not having looked at the previous critics or responses...

The notes above are off the cuff and not lengthily considered, so, take them lightly.  Suggested alternate words may alter your intended theme or meaning,

I noticed no problems with meter or rhyme.  The apophatic concluding line seems unduly circuitous (give a kid a new word and he works into every conversation, not so?)  Not sure the title matches the work, which stresses learning to deal with shocks and vicissitudes rather than their being, in fact, unexpected.

Hope there's at least one useful insight above!  Do parents share Lachesis' work?  Or only try to keep the thread from fraying before its time?