I have scattered information about polyester settings throughout the community form but have not consolidated it yet to one place. So this post will be for that and I will keep updating it. I have also been going back through fabrics and playing with the cut settings and so you will see that being added as well as more polyester fabrics.
Engrave Settings: Full speed, 13 power, 270 LPI
Cut Settings: 300 speed, full power
All photos are of results after I engraved and then washed the fabric! I have washed these items continually over the past 2 years and they have not had any issues holding up.
Most the time velvet is not interfaced with things such as neoprene that can help strengthen the fabric and melt the design into the fabric. So therefore, you want to have higher oz velvet. I have used Joanns premier velvet the most:
Settings: 7 power, full speed, and 270 LPI
A lower cost option is this lighter eight velvet:
Micro Velvet Fabric 100% Polyester 45" Wide $9.99/Yard Sold BTY
Settings: 5 power, full speed, and 270 LPI
Settings: 550 speed and 22 power and 270 LPI
A fun use of the scrap fabric has been making butterflies. I have been using the suede scrap for it usually
Cut layer was full power, 300 speed. Engrave layer was full speed, 13 power, 270 LPI.
Here is the post with the original svg if others want to do it: Leather butterflies