Serger stitch not forming right

The 335 has a two thread chain stitch (stitch type 401), and the overlock side (right needle side), is a three thread plain overlock. If you are describing the plain overlock as the problem, I would first suggest the following in re-threading:

1. Thread the upper looper
2. Thread the lower looper
3. Thread the needle last (important)

If the needle threaded, you cannot re-thread the lower looper without breaking the thread.
In order to thread the lower looper, the lower looper must pass by the needle thus picking up the needle thread. So, instead of threading the lower looper thread underneath the needle thread, the looper would be threaded on top and cannot sew without breaking the thread.
Make sure that the threads are bedded between the tension disks. Check this by stretching the thread fore and aft of the tension disks as well as visually noting that the threads are not accidentally threaded behind the disks. You can also loosen the tension disks when threading so as to allow the threads to bed deeply between the disks.
Please reply with your observations.

Hello Mary.
By the question, it looks like the lower looper is making loops? If so, check that you are using the correct needles for your serger and that the needle or needles is/are inserted correctly:
- needles must be all the way up into the needle shaft
- needles must face with the flat side to the back and the groove to the front
- use at least needle size 12/80, not smaller

Check these few items, if the loops are still not forming:
- re-thread the serger from the start, keeping in mind to thread in the proper sequence (upper looper, lower looper, needles)
- make sure that the lower looper thread lays on top of the upper looper thread and is passed to the back of the serger and then under the presser foot when threading
- make sure that the thread are securely engaged IN the tension assembly
- make sure that the serger is set for 3-thread or 4-thread overlock (i.e. that the upper looper converter is not engaged)
- check all tension setting
- stitch length should be around 2.5 - 3.5

Let me know how it goes.
Happy serging!

SKIPPED STITCHES ON A SERGER

1. Is the needle bent or worn--replace

2. Is the needle inserted correctly into the needle holder--check needle

3. Is the Serger threaded correctly--rethread

4. Is the presser foot pressure right for the fabric--adjust
5. are the needles the correct ones for the serger
6. Possible timing problem--need to be checked at a sewing machine shop

For knits with lycra in, you are best to thread up four threads and seam with the 4 thread marrowing stitch like this, preferabbly with ball point needles in your overlocker, size 80. Use cones of polyester thread, 3,000 metres or 5,000 metres rather than normal thread. (Although if you have trouble matching thread colours you can use a small reel on the left needle as this is the thread that will show on the right side of the garment.)




Start with your machine tensions on 5, both needles in and threaded, stitch length of 2.5 and no differential (set it on zero) and test stitch. Using stretch or ballpoint needles is a good idea too to avoid any deflection and skipped stitches. Then practice serging on some fabric scraps, double layer and look at the seam, if it is tunnelling (pulling up the fabric), then move the cutting blade to the left. Test again and if still tunnelling, then loosen off the tension on the top and bottom loopers by a half number and test again.

If the opposite is happening and the threads are looping off the edge of the fabric, then move the cutting blade to the right to trim less fabric, test again. If still too loose, then tighten up the top and bottom looper tensions by a small amount and test again.

You want the seam to lie flat, the two looper threads to meet right on the cut edge and the needle thread to be just visible from the right side when you press open the seam.

There is always a small amount of adjustments needed on an overlocker when setting up for a new project as every fabric will behave differently. Don't tighten up the tension on the needles much past 5 though, or you may get thread breakage.

If you find that the seam is flutting then you can use the differential feed to adjust for this too.

There is some good overlocking info on Debbie Cosgroves website, www.sewing.about.com, with images which may help too.

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.

Have you used an overlocker before? If not, I'd suggest that you obtain a user manual for it as they are completely different to a sewing machine and at some point you will need to rethread it. You can purchase one from here
http://pages.sewing-machine-manuals.com/173/PictPage/3923709707.html

This machine makes three and four thread seams, which is a combination of two needles and two loopers. For the three thread seam you can use either the left or right needle which gives you different sized seams. For the four thread you use both needles, one goes through the middle of the seam and the other is on the left side securing the seam. On most overlockers you are able to move the cutting blade too and this will reduce or increase the amount of fabric being trimmed from the right side.

This page http://sewing.about.com/od/sergersoverlock/ss/serger.htm will give you some general information on sergers/overlockers too.

So adjusting tension is a matter of changing the tension on the top and lower looper threads to close up against the cut edge, or moving the blade over to make the seam a little wider or narrower. You may also need to finess the left needle tension so that the seam doesn't pull apart, I always test serge two layers and then pull open from the right side and see if the needle thread is showing (it will show a little bit but you dont want it so loose that it pulls open. Only tighten the needles in very small increments though, as you'll break threads and needles if you turn them up too tight.

Hard to explain without seeing what your machine is seaming now. But as a rule of thumb, start with all four tension dials (or 3 if doing a three thread seam) on 5. If the tension dials are correctly calibrated then this should give you a pretty good seam. You may wish to lengthen the stitches, I usually work with stitch length of 2.5 (same as your sewing machine stitch length) Stitch length will be a dial on the right side beside the flywheel or in front of the blade area. The blade adjustment should be a little knob near the blade area too. There will be a lower fixed blade and a moving upper blade which sits against the lower one, they work like scissors to trim the fabric. So to adjust the blade, you will need to take the pressure off the upper blade, then wind the knob to move it left or right.

Different weights of fabric will behave differently on the overlocker so you do need to adjust tension for each new project. For example, if seaming a jersey knit you'd use a four thread seam, this gives elasticity and strength and you can join two garment pieces with this seam. You'd probably make a 6mm or 7mm wide seam, the left needle will secure the fabric and the loopers will encase the fabric smoothly while the right needle secures them and gives extra strenth to the seam.

But on organza for example, I would make a very narrow three thread seam using the right needle as the organza will roll inside the overlocking if you cut the fabric too wide.

And on something like curtains I would neaten the edge with a wide 3 thread seam using the left needle to get a very wide seam, the fabric wont roll so you'd need to loosen the two loopers a little to smoothly encase the cut edge.
For example, on this image above you can see that the looper threads are laying a little off the edge of the fabric in places, particularly the lower looper, (the side that looks like Y's where you can't really see the middle needle thread), so I would tighten the lower looper about .5 on its dial, then test again.

I hope that this makes sense to you, you will need to test serge, and adjust one dial at a time, test again and look at the result, then maybe adjust another thread until you are getting a smooth looking seam.

A rolled hem on any overlocker is formed by using the right hand needle only, and the two loopers to form a narrow three thread seam. You also need to retract the seam width finger as Trial2962 said. This is a little finger that sits on the stitching plate and the loopers form the stitching over it. By retracting it, the looper threads can form a narrow seam and in fact, roll the fabric inside the seam. You need to move the cutting blade as far right as it will go so you are trimming as wide as possible from the needle, turn the tension on the top looper rigth down to 2 so it is very loose and this thread wraps around to the underside. And tighten the lower looper tension to about 7 so it hardly shows and sits right up against the needle thread. Adjust and test until you get the seam looking like this, then turn the stitch length dial (on the right side by flywheel) down to 0.5 to close the seam right up tight. Lastly, if you can source it in the right colour, buy woolly overlock thread and run this through the upper looper only, this thread is fluffy and when not under tension, relaxes and "fills" out so the seam appears like a continuous coverage over the fabric.

You will need to practice a few runs and go slowly on corners, a curve is obviously much easier to serge than a right hand cover so if you can, cut the fabric with curved ends, much easier to get a great finish. When you chain off at the end, you need to unravel the tail threads and pull them inside the seam for a few mm with a needle to get a smooth finish, then trim the tail and seal with a drop of Fray Stop.

You should take it for service. It could be slightly out of time.

• the factory default settings are 4,4,4,4 and M
• Change the needles
• use a can of air spray ( compressed air can sold in computer stores) to ensure there is no fabric or dust under the needle plate

Most likely is the left looper thread is trapping the needle threads.

Remove the threads and start over in this sequence....

Left looper - right looper - left needle - right needle.

If you thread the needles before the lower looper, the needle thread wrapped over the looper will be under the looper thread and will never be free to form a stitch, so the threading sequence is critical.