Hood · 4-1/4 × 7 in
POWERTEC 70150 rectangular dust hood
The part that turns a hose into a mouth — with a published mouth size and four holes already in it.
Every figure below names its source. Each one is a manufacturer
specification read off the listing itself. The judgments are ours.
Four and a quarter by seven
A hundred and eight by a hundred and seventy-eight millimeters of mouth,
published.
That is a little more than twice the area of a bare four-inch hose, which is the
whole argument for a hood: a round hundred-millimeter mouth pointed at a
two-hundred-millimeter spray of chips catches what happens to come at it.
A rectangle spans the work. Behind a router fence, along a sanding table, under
a lathe.
And the transition is where it loses
A rectangle narrowing to a round spigot has a corner at each side, and air slows
in a corner.
So a hood never performs quite as well as its mouth area suggests, and the
published pages on this shelf about hose drag make the same point about every
change of section.
It is still far better than pointing a hose at the problem.
Four holes, already there
The only mounting provision published on either half of this shelf.
A hood that is not fixed is a dustpan — the point is to put the mouth where the
dust is made and leave it there, and that means screws.
Pre-drilled matters because ABS splits when a bit grabs. The listing also offers
the alternative, which is honest about how the part is often used: set it on a
surface near the work.
Why nominal is not a measurement
A four-inch fitting is not four inches anywhere on it.
The POWERTEC listings on this shelf publish the actual figures: a four-inch
nominal end measures 3-31/32 in across the outside and 3-39/64 in across the
inside — 100.8 mm (3.97 in) and 91.7 mm (3.61 in). The difference between those two is the wall, and
the difference between one maker’s outside and another’s inside is the leak.
That is what the shelf’s own intro means by the adaptors that never quite fit.
Nominal sizing is a naming convention; the join is decided by the sixty-fourths.
No depth
The mouth is published. The spigot is published to the sixty-fourth.
How far the hood stands off the work is not, and on a hood that is the third
dimension: a shallow hood has to sit close, a deep one gathers from further
back.
Availability
Read on the day this page was built: $11 at the American Amazon shop.
Read from Keepa on the day this page was last revised; stock and price both move without notice.
Prices quoted in this text were read on 2026-10-07. The live price is at the top of the page.
