Operation
Slim Jim Idrocompresso User manual
page 10
Adjust resting spring length to match groups
Every spring that comes from the manufacturer has some tolerance in its force-displacement
trajectory. To even out differences between springs and thus brew-pressure profiles between groups,
the
“resting” length of the spring can be adjusted by approximately 10mm. On a new machine, spring
force will be matched. You may have to adjust the resting spring length after prolonged use or
machine maintenance.
Notes!
Resting spring length should only be adjusted when the brew-lever in (upper) position as this results in
less strain on the mechanism.
The adjustment allows for a limited difference between minimum and maximum setting. It is not meant
to drastically change the pressure profile of the brew.
procedure
1. Check maximum resting spring force of groups (highest brew-pressure per group).
a. Fill a portafilter, equipped with blind-filter, with water and lock in the group.
b. Flush the group (upper handle).
c. Pull the brew-lever into locking position, then unlock.
d. Press the relief button until the brew-lever has returned to resting position.
a-d is done to reduce the amount of remaining air in the group.
e. Pull the brew-lever into locking position again, wait until pressure is stable, then unlock.
f.
The brew-lever should remain in slightly elevated position and feel firm when pushed up, if
not: repeat b-d.
g. Make a note of the pressure displayed on the pressure gauge
3
.
h. Repeat steps a-g for the other group(s).
i.
Determine what group to adjust.
Normally you will increase the lower pressure until it matches the highest pressure.
Figure 10. The spring-length adjuster disk. Insert a tool in one slot on each side of the group, use
these to twist the disk.
3
Check pressure quickly. When cold water enters the group it gets locked between the blind-filter and
a check-valve. If that colder water heats up, it expands which will lead to extra pressure on top of the
spring pressure and you will see a slow increase in pressure while watching the gauge. To eliminate
for this, the procedure could be done with the heat turned off. However, friction in a cold group is
higher than in a warm group which will lead to other uncertainties in the adjusting procedure.
