Pfaff coverlock 4.o looper tension does not change

I don't know your model in particular but generally this is how you set up a serger/overlocker to create a rolled hem. Remove the left hand needle and thread if 4 threads are threaded). Now there is usually a lever around the stitching area that you slide back towards you to remove the stitching finger back (disengaged). Then you adjust the top looper tension looser (about 2-3) and lower looper tension tighter (7 or 8). Leave needle tension at normal tension (5). You may need to move the cutting blade to the right too. The technique is to cut the fabric wider but with a narrow stitch so the cut edge rolls under within the stitching. You want the top looper thread really loose so it rolls right around underneath up against the needle thread, the lower looper thread needs to be tight and almost invisible, pulling the upper looper thread down. I usually do a few test runs and check the stitching. Once happy, I turn the stitch length right down to 1 so it is very dense. This uses a lot of thread up.

Ideally use a wooly overlock thread on the upper looper as this "fluffs" out once stitched and "fills" in covering the fabric edge completely.
some good images here
Sewing Basics Narrow Rolled Hems with Serger Sew Mama Sew Outstanding...

Looper timing is probably out, maybe even a damaged looper. Take it in for servicing.

overlockers and sergers are annoying in that every time you change materials and threads they must be re-tensioned.

Get a scrap piece of material. Thread your machine correctly according to the instructions in your manual. If no manual most sergers are threaded, upper looper, lower looper then needles from right to left. Make sure you thread with the presser foot UP.

You want to balance the stitches Begin by adjusting the looper dials, you want them to meet right at the cut edge. Then adjust your needles. Keep doing test seams until you have them balanced. If you are a novice... try threading with each thread point having it's own color. That will help you identify which thread is giving you fits.

Have fun.

You can purchase a manual for this machine from the following link for $US14.99

http://www.sewingpartsonline.com/instruction-manual-simplicity-sl4300.aspx

I can't see it anywhere for free download unfortunately. But you may find that looking at a manual for another 4 thread overlocker may get you started. If you try this link http://www.singerco.com/accessories/instruction-manuals you can look at the free Singer downloads,
try this link for their 654 3/4 thread model http://www.singerco.com/uploads/download/555_14sh644_654-(e_s_f)-(new-led-version).pdf
it may give you some help now.

Essentially, to change the stitch width you can either move the lower fixed blade wider to cut less fabric or tighten up the upper and lower looper threads in order to close up the stitching.

Moving the blade usually means opening up the front cover door, putting pressure on the upper blade and swinging it up out of the way. Then you can adjust the lower blade, usally by turning a knob near to it. Sometimes this knob will be marked 1, 2, 3.

Adjusting the looper tensions is done by changing the tension dial settings for the thread needing adjusting. If its a standard four thread overlocker that produces a "marrow" seam it will have two needles and two loopers, upper and lower. Generally on most overlockers, the upper looper will be the second from right tension dial and lower looper will be right most tension dial - turn up one half number to tighten, or down one half number increment to loosen, then test stitch again. The needles shouldn't need adjusting too often.

I usually start with all tension dials on 5, test stitch, then adjust from there. Some fabrics will tunnel (pull in) if the seam is too wide so you need to either move the blade to the left and trim more fabric or loosen off the loopers. Or in the reverse, like you are getting, the threads will hang off the edge.

There is some good serger information on Debbis Cosgrove's pages www.sewing.about.com but if you have never used a serger, then getting the genuine manual is probably best.

I don't know your babylock well, some of these have automatic tensions and electronic stitch selection. But a rolled hem is achieved on any overlocker in the following way; the actual dials and knobs might vary a bit.

Firstly there is a stitch finger that you need to change or retract so that the thread can roll the fabric rather than staying flat. For a normal seam this finger sticks out in the area where the loopers and needle form the stitch holding the cut edge flat until the seam is made over it. But for rolled hems you want to retract this finger so it does roll.

On the Bernettes this is a little lever in front of the stitching area that you pull back to retract the finger. Have a look around where the stitch forms and you should see the finger. Some machines, its a part you change on the needle plate with a screw driver, or just move a switch or lever.

You want the right hand needle in place, remove the left hand needle.

Thread upper looper with wooly overlock thread, this is a fluffy nylon that pulls flat under tension but relaxes and "fills" out once its stitched into place. Gives that lovely covered look you see on shop bought tablecloth edges. Your regular thread in needle and lower looper. Usually cutting blade to the right side as you want it to cut more fabric than in the seam so it rolls under. Now loosen off the tension on the top looper, (I use 2 on mine but this is something you need to finesse with each machine), and tighten up the tension on lower looper, (about 7). Leave needle tension alone.

Now test stitch on your fabric, and finess the upper and lower looper tensions until you get the lower looper thread almost not showing, it should be right up against the needle on the underside with the upper looper thread completely wrapping around top and bottom, pulling the fabric under.a seam like this.


Test stitch and adjust upper and lower looper until this is happening.

Now, turn stitch length down to close up the stitching, probably 1 or 0.8 if you want a real satin stitch look to the hem.

Because of the stitch density this uses thread so do the finessing first, then turn the length down.

That's it! Now right down the tension settings you used and keep handy for next time.

no, you need the blade in place and cutting to give an even cut fabric edge. Set up for a three thread using the right hand needle, take out the left hand needle. move blade over to the right so it is cutting wide. Most overlockers there is also a thread finger you need to change on the foot, or a little lever you flick to move this finger forward into the stitching area. Check this on your manual as each make is a bit different.
If you can source it, put wooly nylon thread into the upper looper (knot it onto existing thread and just chain it through, the knot should go through the looper eye fine). Now turn the tension on top looper down so it is looser and tighten up tension on bottom looper, so needle 5, top looper 2 and bottom looper about 7.

Now test serge, the fabric cut edge should be wider than the overlocking seam so the fabric rolls under inside the stitching. Adjust the two looper threads so that this is happening, you want the bottom looper thread to nest right up against the needle stitch and the top looper thread to wrap all the way around too.

Once you've got this happening, turn the stitch length down to 0.5, to close the stitching right up. On some fabrics you'll need to adjust the differential feed too if the fabric is "waving" a bit.

Uneven stitches or sometimes loose when serging could indicate that one of the tension devices is faulting, so if this machine is not new and its doing this, it could need a service. Can you get a regular smooth three or 4 thread seam out if it???

It is always good to just recheck the threading path, make sure the thread aerial is up and that a thread hasn't got caught back on the thread stand somewhere if you're getting something wonky happening, threads stream off overlocker cones through the machine so anything wrong in the thread path will throw off the stitching.

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.

Clean in between you tension plates of your tension units and rethread making sure your cotton runs between the tesion discs.

Loosen the upper tension looper thread by turning the dial to a lower number. The upper tension looper is to tight and pulling the lower looper thread up. Also might want to loosen or tighten the left or right needle tensions depending on the results you get. It will be a trial and error exercise to get the correct adjustment between the loopers and needle thread tensions. Otherwise, you might want to take it to an authorized husqvarna viking dealer for service. You can locate a dealer near you by visiting the husqvarna viking website and clicking on the Dealer link on the left-hand side of the page - http://www.husqvarnaviking.com

Good luck.

Not sure if this will help, but you can try the following:

Remove all the thread from your machine.
ALWAYS RAISE the presser foot.
Rethread from the beginning--be sure to thread in the order specified and verify the thread path is correct for each thread.
When threading the tension disk, grasp the thread below the thread tree and the thread below the tension disk and give it a firm tug. This insures the thread is seated fully.

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