Why Can't I Pull the Knot Into the Work By Increasing Upper Tension?

[councilman24]

The way I look at needle size is that anything not a simple uncoated woven fabric needs the top end of any table and usually even higher.  Leather, neoprene, coated fabric etc.  I routinely use nothing smaller than a 19 for 69 nylon and often a 21.  I haven't found a table yet that I think works for non woven or thick, dense webbing/fabric.

 

[williaty]

OK, so I'm back at it after a long wait for parts to come in.

So, sewing with v207 thread and a #25 needle, I get the same results with the bobbin thread lying flat against the bottom of the work and the knots not pulling up into the holes. I also checked (as suggested) that the bobbin tension was as low as physically possible by removing the hook/shuttle and it's associated race, cleaning the crap out of all of it, and putting it back together with the bobbin tension screw as loose as can be without falling apart. Cleaned, stuff works a little more snappily and I think I may have identified the problem.

 

When the needle begins to rise out of the work, about the time the eye gets to the leather the work is pulled up off the needle plate about 1/8" before suddenly snapping back down with a click. I am assuming that what's happening is that the force needed to pull the knot into the hole is greater than the force exerted by the presser feet. So the work rises a little bit. Since the needle rises faster than the presser foot, eventually the inside foot strips the work off the needle but the timing of this delayed withdraw is completely messed up so the knot is never pulled into the work. The adjustment for the pressure foot pressure is already maxed out but I can hold the work with a hand on each side of the presser feet and lift the work into the air (force the feet upwards) without much trouble. On my 206RB-5, the pressure foot pressure is so high that I can't grip the work tightly enough to get it to lift. I have pulled out the presser foot pressure adjuster, the spring below it, cleaned everything, and reassembled for max pressure foot pressure.

 

Thoughts?

Edited March 17, 2021 by williaty

[Wizcrafts]

15 minutes ago, williaty said:

Thoughts?

Yeah. Use a #24/180 needle with #207 thread. It has less trouble pulling up the knots while letting the leather stay down. Also, oil the leather to soften it up before sewing it on that machine. It is an upholstery machine from the 1920s. You may need a stronger pressure spring if you intend to sew hard veg-tan leather with it, using #207 thread.

[CowboyBob]

On 1/23/2021 at 11:50 AM, williaty said:

I just bought a used Singer 42-5. I verified at the seller's that it was sewing properly with the thread left in the machine by the last user. When I got it home and started to clean it up, I again verified that the machine would stitch properly before tearing anything down to clean it. At this point, I did notice that the lower tension seemed absurdly tight but I've never used a shuttle based machine before so I have no frame of reference for how much is too much. After getting a few things cleaned up, I started trying to answer my real question about the machine, which is how big of thread it'll actually use. I wound a bobbin with 207 and re-threaded the whole machine. The machine formed a stitch after that but the knots were all on the bottom of the work. I increased the top tension to try to bring the knots up into the work. No dice. Figuring that maybe I was right about the bottom tension feeling weirdly high, I lowered the bobbin tension until it felt about the same as pulling 138 out of my Consew 206's bobbin case. Still no dice. I then maxed out both of the upper tension adjustments. At this point, the knots would sort of lodge in the hole on the bottom of the work but would not pull into the center of the leather. By feel, the bobbin tension is in the realm that I'm used to from other, properly functioning, machines but the top tension is so tight you can pluck the thread between the takeup lever and the needle, or the takeup lever and the last tension disc, and get a high pitched plink out of it like plucking the string on a violin. I just can't believe this is how things are supposed to be.

 

Any idea what would be causing the knots not to pull up into the work with the top tension so high?

 

Machine: Singer 42-5

Thread: Bonded nylon v207

Needle: Organ 135x16 Size 23 D/TRI point

When sewing leather most people want as small of a needle hole as possible,that is what our chart is for.Your 42-5 has the barrel shuttle & you shouldn't have a problem sewing 207 w/a#23 as long as your bobbin tension is loose enough.As others have pointed out some times you might need a larger than recommended needle for stiffer leathers which also may require more foot pressure to hold on also.We do stock the 135x16  up to size#25.

One more thing are you sure you wrap your thread around the second tension 1 & 1/2 x?

[williaty]

21 hours ago, Wizcrafts said:

Yeah. Use a #24/180 needle with #207 thread. It has less trouble pulling up the knots while letting the leather stay down. Also, oil the leather to soften it up before sewing it on that machine. It is an upholstery machine from the 1920s. You may need a stronger pressure spring if you intend to sew hard veg-tan leather with it, using #207 thread.

Can you give me any help on finding a stronger pressure spring? That is one thing I had wondered about but I have no idea how to source a spring other than the one it shows in the parts book for the machine.

13 hours ago, CowboyBob said:

When sewing leather most people want as small of a needle hole as possible,that is what our chart is for.Your 42-5 has the barrel shuttle & you shouldn't have a problem sewing 207 w/a#23 as long as your bobbin tension is loose enough.As others have pointed out some times you might need a larger than recommended needle for stiffer leathers which also may require more foot pressure to hold on also.We do stock the 135x16  up to size#25.

One more thing are you sure you wrap your thread around the second tension 1 & 1/2 x?

I started with a #23 needle and it wouldn't pull the knots up. I asked here and the dominant response was "#23 is too small" so I ordered #24 and #25 needles.

 

I am not going around the 2nd tension more than once. Based on the partial manual I have for it, the thread enters the 2nd tension at 12-oclock. Wrap anti-clockwise back to 12-oclock, passing behind the "staple" which I am assuming is the pin that sticks out, then back down and over the pin, under the check spring, and up to the takeup lever. So the 2nd set of discs is threaded from 12-oclock anticlockwise to about 2-oclock once all is said and done. I can try going around once more but if it's already lifting the work off the needle plate, won't that just make it worse?

[Uwe]

If the thread snags for some reason at any point during the stitch cycle and pulls more thread from the spool, it will be impossible for the machine to pull the knot tight, regardless of needle size or thread tension settings. Take some pictures or better yet post a video snippet via YouTube so we can see what’s going on. The problem with you telling us what you see is that you may not even know what to look for.