JUKI MF-7900 Series Engineer's Manual page 107

Adjustment procedures
1. Installing the air-blow wiper
(1) When using air-blow wiper ❶ , remove the top covering thread
trimmer device.
(2) Tighten air-blow wiper ❶ with setscrews ❷ .
(3) Perform piping referring to "6.-(2) Piping of the thread trimmer
device".
2. Adjusting the air-blow wiper
Adjust the air-blow position of air-blow wiper ❶ .
(1) Adjust so that the air outlet of air-blow wiper ❶ is positioned in
the rear of needle and slightly on the lower side of needle eyelet
of the left needle when the needle bar is in the highest position.
(2) After the adjustment, temporarily tighten setscrews ❷ .
(3) Supply air from the air compressor and turn the power ON.
(4) When the back part of the pedal of sewing machine is de-
pressed, the presser goes up and simultaneously air blows from
air-blow wiper ❶ . Re-adjust the position of air-blow wiper ❶ so
that air blows only to the needle thread in the rear of the needle
eyelet.
(5) After the re-adjustment, tighten setscrews ❷ .
(Caution) 1. When air blows in front of the needle, needle
thread slips from the needle eyelet. So, be care-
ful.
2. Adjust the air-blow strength with speed control-
ler ❸ . When the adjustment cannot be per-
formed, install speed controller ❸ reversely.
3. Handwheel may rotate up to the fixed position
when turning ON the power. So, be careful.
Results of Improper adjustment
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