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--- when_things_go_wrong [2016/02/21 20:12]
192.168.1.35 [Move it, move it, move it.....]
+++ when_things_go_wrong [2016/02/22 09:01]
192.168.1.35
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 {{:pulling_the_looper_thread.jpg?800x600|}}
-===== Needle thread looping on the wrong side =====
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-Another reason for stitches skipping is the wrong needle type. Warning the following does not apply to certain brands of coverstitch machines, it applies to all those that use the ELX705 system. When sewing knits, especially those with a lycra content (trademark for a brand of spandex), I use ELX705 SUK needles. The SUK needle has a regular ball point which is best suited for knits. The ELX705 regular needle has a light ball point and is best suited for wovens.
+Another reason for stitches skipping is the wrong needle type. Warning the following does not apply to certain brands of coverstitch machines, it applies to all those that use the ELX705 system. When sewing knits, especially those with a "lycra" (a spandex brand trademark) content, I use ELX705 SUK needles. The SUK needle has a regular ball point which is best suited for knits. The ELX705 regular needle has a light ball point and is best suited for wovens.
 {{:going_wrong:needle_packets_regular.jpg?|}}
 {{:going_wrong:needle_packets_suk.jpg?|}}
-When I run out of ELX705 SUK needles size 90, I use an ELX705 regular size 90 rather than an ELX705 SUK size 80. The right size is more important than the right type for avoiding skipped stitches in my opinion.
+When I run out of ELX705 SUK needles size 90, I use an ELX705 regular size 90 rather than an ELX705 SUK size 80. With knit fabric, the right size seems more important than the right type for avoiding skipped stitches. All in my experience of course.
-I only switch to size 80/12 for very delicate fabrics, but if your experience differs, please do what works for you!
+I only switch to size 80/12 for very delicate knit fabrics, but if your experience differs, please do what works for you!
-==== Move it, move it, move it..... ====
+In the examples below I used my Babylock Coverstitch machine for top stitching woven fabric. The top image shows the 2 needle narrow coverstitch going over rick rack trim. This did NOT work well, I had several skipped stitches. The reason I used my BLCS machine was that I had the right color thread in it and my sewing machine was threaded with a different color for other parts of the same project. I was lazy and left the ELX705 SUK (ball point) size 90 needles in the machine and they did not work well on the woven cotton fabric and rick rack trim.
+{{:going_wrong:topstitching_rick_rack_with_2_needle_narrow_skipped_stitches.jpg?|}}
-Another important cause of skipped stitches is stitches getting too short because the fabric is not feeding adequately. The stitches may get shorter as I sew over a hump or they may get shorter because there are an uneven number of layers or heavier fabric underneath the pressure foot.
+In the second image I used the same SUK needles with the chain stitch and stitched two rows close together. There I had no skips. I am guessing that it wasn't just the needle point that caused the skip, maybe the fact that there were an equal number of layers every time the needle pierced, improved the stitch regularity? The skips in the previous example always happened in spots where the needle was just piercing the cotton between the rick rack. Maybe this affected the thread tension or maybe there was some subtle slipping while sewing??
+{{:going_wrong:topstitching_rick_rack_trim_with_the_chainstitch.jpg?|}}
-Please notice the rick rack trim I attached with the coverstitch in the images below.
+In the third image I changed to ELX705 regular needles size 90, and did several rows of two needle narrow coversticthing, some over a seam with rick rack and some over a single layer of cotton fabric and rick rack and in all cases not a single skip. So far my conclusion is that the reverse is true for woven fabrics; the wrong needle type may cause skipped stitches.
-Both examples were done on my Babylock Coverstitch machine. the top image shows the 2 needle narrow coverstitch going over rick rack trim. This did NOT work well, I had several skipped stitches. The reason I used my BLCS machine was that I had the right color thread in it and my sewing machine was threaded with adifferent color for other parts of the same project. i would normally not choose to use my coverstitch machine for this but I learned something valuable. Do you notice the stitches sometimes going through the rick rack and sometimes only going through the cotton fabric? That's where I got skips, the difference in number of layers caused the skip. My best guess is that with this constantly changing number of layers there is an irregularity in the feeding/needle penetration, much like left and right tyres going over different surfaces, and this difference may translate in a skipped stitch.
+{{:going_wrong:rick_rack_trim_with_elx705_needles_90_no_skips.jpg?|}}
-{{:going_wrong:topstitching_rick_rack_with_2_needle_narrow_skipped_stitches.jpg?|}}
-In the second sample I used the chain stitch and stitched 2 rows close to one another so that the needle was always penetrating the same number of layers and I didn't have a single skipped stitch. Something worth remembering.
-{{:going_wrong:topstitching_rick_rack_trim_with_the_chainstitch.jpg?|}}
+==== Move it, move it, move it..... ====
+Another important cause of skipped stitches, is stitches getting too short because the fabric is not feeding adequately. The stitches may get shorter as I sew over a hump and to compensate for that I snip like [[Hemming#Snipping the side seam|this]] or use a [[The Janome 2000 CPX#Getting over those humps|hump jumper]].
+With the Janome 2000 CPX it is also possible to set the looper tension temporarily to "tight" while going over a hump. That may help prevent skipped stitches but I still prefer to concentrate on keeping the fabric moving and if necessary, I gently pull the fabric behind the pressure foot.
@@ Line 62: / Line 61: @@
 I have tested this only on a Babylock BLCS, a Janome 2000 CPX and a Pfaff 4874 so my experience does not cover other brands of machines and therefore the following may not correspond with your experience.
-On my Babylock simply increasing the diferential setting usually gets the fabric moving.
+On my Babylock simply increasing the differential setting usually improves the feeding of heavier fabric or multiple layers.
 On my Janome and my Pfaff machines I need to increase both the stitch length and the differential to enhance the feeding.
-Even feeding is most likely to happen when the bulkiest part underneath the pressure foot is right there where the longer continuous feed dogs are. In the image below you can see that these longer feed dogs are on the left and right side. In the centre there are several short feed dogs but there is a large space where there id no feeding to allow for the needles to move up and down.
+Even feeding is most likely to happen when the bulkiest part underneath the pressure foot is right there where the longer continuous feed dogs are. In the image below you can see that these longer feed dogs are on the left and right side. In the center there are several short feed dogs but there is a large space where there is no feeding to allow for the needles to move up and down.
 {{:going_wrong:feed_dogs.jpg?|}}
-Now imagine topstitching a seam and the bulkiest part is in the centre. The longer feed dogs may get little or no hold of the fewer layers of fabric beside and feeding will not be even.
+Now imagine top stitching a seam and the bulkiest part being in the center, being fed by those short feed dogs? Beside it, going over the longer feed dogs, there may be just one layer of fabric or fewer layers of fabric. When that is the case the risk of irregular feeding increases and with it the risk for skipped stitches. So I prefer to do top stitching so that the bulkiest part of a seam is being properly gripped by at least one of those longer feed dogs. My Babylock Coverstitch machine seems to have more effective feed dogs in the center as well as a better positioning of the pressure foot, so the risk for skipped stitches is considerably less on a Babylock BLCS.
+I intend to expand a little on this in the chapter on [[Top stitching#Top stitching and feed dogs|Top stitching]].
-When I pick a differential setting that is suited for the fabric and application, the fabric should move evenly. When the number of layers changes, the feeding may slow down, resulting in the stitches getting shorter and eventually the looper thread not being connected properly to the needle threads. Another reason for poor feeding is the degree of stretch of the fabric. As the lycra content goes up, the fabric gets more and more elastic and this often results in short stitches, because between each movement of the feed dogs, the fabric has a chance to recover its natural  with the looper thread skipping. Lycra knits vary between moderately to VERY stretchy and only the extremely stretchy ones are a challenge when coverstitching.
-How come? I get less (a lot less) skipped stitches with my Babylock CS and in part I credit the Babylock feeding system for that.
- bunching up underneath th pressure foot. I notice that I do not have this problem with my Babylock, so I wanted to understand the difference because that might help me find a way to solve the skips on the Janome.
-The feed dogs are different. They differ in length, width and type (the Babylock seems to have more little points that grip the fabric). The major difference IMO is in how far the pressure foot extends BEYOND the feed dogs. The back edge of the Babylock pressure foot lands 1mm behind the feed dogs and the edge of the Janome pressure foot lands 4,5 mm behind the feed dogs. THAT is what can easlily cause the fabric to slow down or stop moving.
-One solution is to make the stitch longer because then the feed dogs make a larger movement and the risk of bunching up is reduced. In fact if you try this, you will probably notice less skips. But the disadvantage is that as the stitch gets longer it gets less stretchy, a hem f.ex. risks snagging and eventually the thread may break.
-My conclusion is that on the Janome VERY STRETCHY fabrics perform best with a stitch length around 3 and simultaneously supporting the movement at the back by gentle guiding the fabric away from the pressure foot while stretching in front of the pressure foot with the other hand. I stretch the fabric in front so that the maximum amount of thread goes into the stitch and once the fabric recovers, the stitch will look shorter and be very stretchy.
-Please note that for most lycra fabrics this is not necessary, I am talking about the very loosely knit and stretchy ones.
-Is that clear as mud?? smile emoticon
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 {{:going_wrong:thread_between_discs.jpg?|}}
-Which is why it is always a good idea to test on a scrap
+Which is why it is always a good idea to test on a scrap!

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