Adjusting The Lower Thread Clamp Opening Timing - Brother HE-800B Service Manual

7. ADJUSTMENT

7-13-3. Adjusting the lower thread clamp opening timing

Sewing start
1. Loosen the set screw (2) of the feed arm support (1), and then align reference line A of feed guide shaft B (3) with the edge
of the feed arm support (1).
2. When the feed mechanism moves by 6 - 7 mm, the opening plate (4) moves and the lower thread clamp (5) opens.
3. To change the opening timing, loosen the set screw (2) and move the feed guide shaft B (3) to the left or right to adjust.
* The end of the thread which is being held by the lower thread clamp (5) is wound around inside the seam. If the opening
timing is too early, it can cause problems such as poor winding or pulling-up of the lower thread. If the opening timing is
too late, it can cause problems such as stretching, uneven seams or bird's nests at the sewing start, depending on the
type of material.
4348Q
Note: After moving the lower thread trimmer cam lever (6) back in the direction of the arrow, move the feed mechanism.
If the feed mechanism is moved when the lower thread trimming has been carried out, the mechanisms will press
against each other, which may result in damage to the lower thread clamp (5) and the opening plate (4).
105
Approx.
6 – 7 mm
Lower thread winds around seam
HE-800B
Lower thread releases from
lower thread clamp
0752D
4347Q
4349Q