Rolled hem would be one needle and two loopers, is this what you meant?
Make sure you move the blade to right so that you are cutting wider than the stitch being formed, you want the fabric to roll to the underside inside the stitch.
I would set top looper tension to 3 and bottom looper tension to 6 first off (needle at five, normal tension) first off and test serge with the stitch length at normal 2 or so, so you can see if the fabric is rolling under for you. There is proabably a stitch finger in the throat that you need to change too, sometimes its on the foot, (change with a screwdriver) and sometimes just a finger down on the needle plate.
Then adjust the two looper tensions making lower thread nestle up against the needle on the bottom of the stitch, and the top looper thread wrapping right over to bottom as well. Once this is happening, then turn stitch length down to close up the stitches.
It does depend on the weight of fabric too, and if you want to seam curves.
I find its best done with wooly overlock thread on top looper to "fill" in the overlocking appearance and fully cover the fabric.
I hope this is of help, if the tensions just wont behave then one of them might be faulty and machine need a service, I get mine done at least every 2 years to keep timing and tensions right.
Answers & Comments
Rolled hem would be one needle and two loopers, is this what you meant?
Make sure you move the blade to right so that you are cutting wider than the stitch being formed, you want the fabric to roll to the underside inside the stitch.
I would set top looper tension to 3 and bottom looper tension to 6 first off (needle at five, normal tension) first off and test serge with the stitch length at normal 2 or so, so you can see if the fabric is rolling under for you. There is proabably a stitch finger in the throat that you need to change too, sometimes its on the foot, (change with a screwdriver) and sometimes just a finger down on the needle plate.
Then adjust the two looper tensions making lower thread nestle up against the needle on the bottom of the stitch, and the top looper thread wrapping right over to bottom as well. Once this is happening, then turn stitch length down to close up the stitches.
It does depend on the weight of fabric too, and if you want to seam curves.
I find its best done with wooly overlock thread on top looper to "fill" in the overlocking appearance and fully cover the fabric.
I hope this is of help, if the tensions just wont behave then one of them might be faulty and machine need a service, I get mine done at least every 2 years to keep timing and tensions right.