Top transporter for bi-elastic fabrics
Many denims are nowadays longitudinally and transversely elastic. A longitudinal seam sews without problems due to the threadline that usually exists there - a transverse seam can unfortunately "wave".
If you have not used your toptransporter for a long time:
Here, too, he helps you to achieve a smooth seam (previously, if necessary, a seam sample on a fabric remnant with / without different thread tension - the latter must not be adjusted anymore). Also try different stitch lengths ...
Good luck - see you!
