Causes of bad stitch draw-in

If the stich is not drawn in well while sewing, the causes often are:

• the bobbin thread is too tight
• the turning of the bobbin thread is uneven
• the bobbin thread is too loose
• the feed is unsteady or does not match temporally to the sewing mechanism
• the stich hole or the sewing foot slot are not rounded well
• the thread is twisted too much

For double lockstich sewing machines, needle and bobbin thread must be calibrated to each other in a way that the plaiting of needle and bobbin thread is drawn into the middle of the fabric layers. This ensures a maximum elasticity and durability of the seam.

The bobbin thread tension mechanism consists of a brake spring and a tension spring who are fastened on the outer side of the bobbin case and press to the case wall. While threading, the bobbin thread will be led behind the tension spring. The bobbin thread tension mechanism is meant to brake and control the roll-off of the bobbin thread. The tension can be adjusted by a screw..

Bobbin thread mechansim: Bobbin case wall (Spulengehäusewand), fastening screw (Befestigungsschraube), tension spring (Spannungsfeder), bobbin thread (Greiferfaden)

The thread tensions for the double chain stitch are adjusted correctly when the needle thread creates a point-shaped loop on the bottom side of the fabric and when the hook thread can be drawn easiliy through the loop. The regulation of the hook thread tension can be made by a disc tension or wheel tension.