The concept

The knockbox had a similiar story behind it as the tamper.  I wasn't particularly thrilled at having to use the
standard  aluminium boxes with the bolt drilled through it.  Not only do they make an awful racket each time
you knock out the grounds, but they don't look too great either.  I always felt a little uncomfortable with the
espresso machine customers to present to them a gleaming new machine and next to it was a catering insert
fashioned into a knockbox.    I think from the initial concept to a finished product it has taken over 1 year,
and even then we have been modifying a few small details.

The knockbox consists of a round stainless steel tub, which is 15cm in diameter. The front part of the box (12cm
high) is lower than the back part (18cm) so that it can act as a splash guard to prevent errant grounds from
soupy pucks flying everywhere.  The box is small enough for the home enthusiast but also large enough for
medium volume coffee stores.

The main features of the box are:

  • One piece stainless steel tub with seamless welding on the bottom and the side
  • Custom made rubber parts
  • Custom made stainless steel studding through the core of the actual rubber knock bar
  • No visible nuts or bolts
  • Non-slip base that cushions the impact on the wrists and deadens the sound
  • Top rubber gasket (fixed in place) protects the box and the portafilter in case you miss
  • 1 spare rubber bar is included with each box















If you click on the pics it will open a larger image in more detail.  Click back on your browser to return.
bumper knockbox
Heavy duty construction

We have received a lot of complimentary feedback from our batch of first users - the gist of the feedback has
been how well made the box is and that it is extremely strong.  A common problem of a regular knockbox is
that the bar breaks, the rubber wears through (it is inevitable) or the holes in the side of the box split.

I designed this box so that it can withstand a lot of abuse and is hopefully the last knockbox you will need for
some time.  The bar that runs through the rubber is a custom made stainless steel bolt - in fact all components
of the box are custom made for us.  The end nuts that hold the bar in place are stainless steel with a rubber
skin. They look fantastic too.  












The pics above L to R.  Bottom gasket with the Bumper logo.  Bumper end nut that secures the steel bar in
place.  Steel bar with end nut unscrewed.   You can click on each pic. to enlarge.












The pics above L to R.  How the top gasket is fixed to the bar.  Bumper end nut. The bar again and how it
secures the top gasket in place.
Quality and additional info

The stainless steel box is finished in a brushed patterm which we feel looks a lot better than a mirror finish.  The
steel tub is very thick and will sustain the force of the portafilter without too much fuss.

The tub is a one piece construction with no visible seams from welding.  The box has been designed so that it
is easily cleaned in cold or warm water, do not put into the dishwasher.












Included in 1 knockbox set is

  • 1 steel tub
  • 2 nuts to secure the bar
  • 2 (1 as spare) rubber bars
  • 1 M10 steel stud
  • 2 (1 as spare) top gasket
  • 1 packing box












Above pics L to R.  Knockbox packing box.  Inside knockbox packing box.
You can enlarge by clicking on each photo.
Just Java Ltd. 2006 email
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