Coverstitch Three thread 5mm coverstitch - right thread keeps breaking. Have checked and rechecked threading. Help

It might, but note how you adjust so that you can put it back to the original position. Perhaps your fabric is very light and needs more pressure to stop tunnelling.

Hard to say since we don't know the model or what problems, in particular, you are having. Suggest reviewing the owner's manual and following the threading instructions "exactly." Also, be sure that the machine is set up to do the particular stitch which you are threading, ie coverstitch vs overlock. Perhaps you can drop by a Necchi dealer and have them show you on a showroom model.

Here's a manual:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiup8_ajMXaAhUBpYMKHR6qC5IQFggnMAA&url=https%3A%2F%2Fwww.janome.com%2Fsiteassets%2Fsupport%2Fmanuals%2Fretired%2Fserger%2Finst-book-644d.pdf&usg=AOvVaw1V_Sa4aOT_SSPyhJnTYgIa

Offhand, I'd say your machine is most likely an overlocker only. A combination overlocker/coverstitch usually has 5 threads, there is also a way of converting it from one to the other, the manual doesn't appear to mention anything about coverstitch.

You can, however, replicate a coverstitch by using a twin needle on a sewing machine.

check your manual for instructions and or see your Viking dealer for help.

More likely, you need to replace the needles, which are now slightly bent.

I just went thru the EXACT same thing, pulled up YouTube videos and discovered it was all about (1) how the LOOPER was threaded (the video taught me it is called "the puppy dogs head/ears" and that to thread it you follow the path of the ORANGE DOT (which often is combined with either blue/black, but just look for the ORANGE dot path no matter what the other color is with it) and that thread goes: "Around the puppy dog's neck and behind his ears". Honest to God this was part of my problem. (2) TENSION settings: I also discovered that even though the 936 has the adviser has all recommended settings for the stitches, you still NEED to tinker with the tensions. Specifically, I was set up for the WIDE COVERSTITCH to hem a knit skirt. I selected the KNIT MEDIUM (Auto M4) stitch and used these tensions: A needle 4, E needle 6, Looper was ok at 3. It worked like a charm and FINALLY I can do the stitch! Seriously, there are many YouTube videos (many lousy quality) that actually show and explain this stitch and how to set up your machine. Hope this helps!!! Good luck and happy sewing!

I don't think so, the D in your model name would denote that it has Differential feeding but is probably a 3/4 Marrowing stitch only. So this means it would do 3 thread overlock, 4 thread overlock and you can probably set it up for rolled hemming too.

Coverstitch is fairly new to home sergers and is available on some machines along with the 3 and 4 thread stitches, but changing between the regular overlock and a coverstitch takes a few minutes. The model number will usually have a "C" in the name. Also, during coverstitch the blades are disenaged and don't trim your fabric so you still need often to go back with blunt scissors and trim the raw edge.

And sewing coverstitch can be finicky, with skipped stitches a problem. Use high quality thread and XL (extra long) or SUX (stretch extra long) needles to avoid this.

However some manufacturers are now making dedicated coverstitch machines; if you are assembling a garment with your regular serger, you can then just move over to the coverstitch machine to sew the hems and necklines and not spend 20 mins changing over your machine's functions. Much more productive.

You may wish to check out the Brother 2340CV, this is their dedicated domestic coverstitch machine. Link to product info is http://www.brother-usa.com/homesewing/ModelDetail.aspx?ProductID=2340CV

In the meantime, best solution is a twin needle to stitch the hem from the right side of the garment on your regular sewing machine, looks much the same, and you can get twin needles with a 4mm or 2.2 mm gap and in stretch and sharp tips for less than $10 each. Just iron up the hem about 1.5cm deep, and thread up your sewing machine with the twin needle and two spools of same colour on top (I just wind an extra bobbin and use this plus the original thread spool rather than buy two spools).

Just sew really slow as the twin needle builds up a lot of heat and will break if you push it along. I use this finish on all my knit garments and it works just fine. Sometimes I'll iron in a 2cm strip of fusible web inside the hem to give it some firmness in a neckline, then twin needle stitch at about 1.7 from the folded edge.

Hope this answers your question.

That stitch is called a coverhem or a coverstitch. It is made with a coverhem machine which is basically a serger with an orbiting looper. Many upper end home sergers have coverstitch capabilities (Elna 945)

To use a double needle, simply thread two threads the same way that you would thread one. ONLY USE A STRAIGHT STITCH, AS THE NEEDLE WILL STRIKE THE PLATE IF IT ZIG ZAGS TOO WIDE.

Coverstitch machines are very particular when it comes to thread. Use only MaxiLock cone thread. Do not use TruSew or SureLock thread. This can make the difference between working beautifully or not at all.

Your machine cannot do a cover stitch. Check the Brother website, they make a cover stitch only machine, it works much better than any of the serger/cover stitch combination machines, and it is a lot less money.