Sewing welt to Velvet .. Having problem with Velvet making small puckers. when sewing on Welt.
Velvet. Ugh! A couple of things to try. Tug, slightly, on the fabric and cording, before and after the needle while you sew.
Use steam but be very careful not to touch the steamer head to the fabric.
Try fabric dressing, also known as wrinkle rid, spring crest, fabric releaser, and many other names. Just a small spritz may help. (this is also great to raise crushed nap on velvets).
Of course test all this on a scrap piece first.
And whenever possible talk the customer out of velvet. :)
In addition to the "tug" method that Kody suggested, it may (or may NOT) help to widen the stitch length. Or back off a little on the adjustment at the top of the presser bar.
Also, I have had some luck by pre-sewing the welt at a stitch length of about 4 SPI, and then sewing it to the panel at 5 SPI.
All these, and other gimmicks may or may not work. Lotta factors to consider.