Curly Q in Top Thread

[friquant]

The past week i notice my top thread is sometimes curling around the bottom thread. A few curly Q's along the seam. It seems most noticeable with thin materials.

I'd like these stitches to be straight. (The bottom side actually looks better, which is rare for me.)

Ive tried changing the bobbin tension and the top tension. 

I've tried adjusting the thread take-up spring.

Needle is size 125 (Singer 20). Machine is pfaff 545 H4

Fabric in photo is a single layer of thin canvas-looking stuff (0.4mm thick).

Thread in photo is TEX 70 polyester UNbonded but I get the same effect when using TEX 90 polyester bonded.

First photo is top side

 

 

Second photo is bottom side

Edited April 12 by friquant
better photos

[Northmount]

  On 4/12/2025 at 2:18 AM, friquant said:

The past week i notice my top thread is sometimes curling around the bottom thread. A few curly Q's along the seam. It seems most noticeable with thin materials.

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There  was another recent post about thin materials and thick thread that made the point, the material has to be thick enough to be able to properly bury the knot.  So vice-versa, the thread needs to be thin enough ...

It is very hard to adjust the tension with a single thin layer of material, and thread that is more than half the thickness of the material.  For test runs, use a stack of material the same as the material and same thickness as you are going to sew.  And your thread has to be thin enough to be able to hide the knot.

[Wizcrafts]

  On 4/12/2025 at 2:18 AM, friquant said:

Needle is size 125 (Singer 20)

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The needle size is very good. But, you didn't state whether it is round point or some leather point shape. When sewing cloth, or any woven, or synthetic, or embroidered object, always use a round point needle. I use and recommend Schmetz Serv 7 needles, which can be bought in packs of 10. They have a larger eye than most other walking foot needles. The only ones with a larger eye are Schmetz Go needles, which must be purchased in boxes of 100.

Are you using system 135x17 or system 190 needles in your Pfaff H4 (high lift) machine?

[friquant]

  On 4/12/2025 at 3:04 PM, Northmount said:

There  was another recent post about thin materials and thick thread that made the point, the material has to be thick enough to be able to properly bury the knot.  So vice-versa, the thread needs to be thin enough ...

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Glad it's not just me, and sad there's no easy fix! 😁

[Tigweldor]

Top tension is to high.

Look at the first pic - you can see the bottom thread pulled right through the fabric onto the top side. - thus producing the "curly Q"

Either back off your top tension or increase bobbin tension.

This is going to take some time by trial and error - you just have to fiddle until both of the threads knot in the middle of the fabric. 

But that is a normal common procedure - that most all of us are confronted with when changing thread size or switching to a different material to be sewn.

 

Greetings

Hans

Edited April 12 by Tigweldor

[friquant]

  On 4/12/2025 at 3:34 PM, Wizcrafts said:

The needle size is very good. But, you didn't state whether it is round point or some leather point shape. When sewing cloth, or any woven, or synthetic, or embroidered object, always use a round point needle. I use and recommend Schmetz Serv 7 needles, which can be bought in packs of 10. They have a larger eye than most other walking foot needles. The only ones with a larger eye are Schmetz Go needles, which must be purchased in boxes of 100.

Are you using system 135x17 or system 190 needles in your Pfaff H3 machine?

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These are round point needles. Organ MTX 190 (R)

Reading up on Schmetz Serv 7 needles now...

[AlZilla]

  On 4/12/2025 at 3:34 PM, Wizcrafts said:

I use and recommend Schmetz Serv 7 needles, which can be bought in packs of 10. They have a larger eye than most other walking foot needles. The only ones with a larger eye are Schmetz Go needles, which must be purchased in boxes of 100.

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That's just PHD-level sewing knowledge that you aren't gong to find anywhere else.

[kgg]

  On 4/12/2025 at 2:18 AM, friquant said:

Needle is size 125 (Singer 20). Machine is pfaff 545 H4

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  On 4/12/2025 at 2:18 AM, friquant said:

Thread in photo is TEX 70 polyester UNbonded but I get the same effect when using TEX 90 polyester bonded.

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The correct size of needle for Tex 70 (V69) is a size 100 (#16) in thin, a size 110 (#18) in thicker possibly a 120 (#19) in real thick.

The correct size of needle for Tex 90 (V92) is a size 120 (#19) in thin, a size 140 (#22) in thicker.

Here is a good chart for needle size versus thread size: ( https://www.tolindsewmach.com/thread-chart.html )

I could be mistaken but the PFAFF 545 H4 uses 190R needles to allow for the addition sewing capacity height wise of the H4. Thin materials will always pose a problem as there really isn't enough material to hide the knot sort of like trying to sew a sheet of paper. That combine with an oversized needle for the thread size and you can get funky stitches.

 

kgg

 

 

[friquant]

Here are two samples on different materials 

The first is 0.1mm printer paper. The stitches are uniform. No curls

The second is 0.4mm canvas. This one has curls. 

125 needle, round point

TEX 70 unbonded  thread

[friquant]

Here's one more sample of the 0.4mm canvas.

This time I've marked the curly Q's with black marker

 

To be clear, it's not the bottom thread showing through that I'm trying to fight. I understand that is a tough challenge on thin fabrics. But the curly Q's are new to me, and I'd like to know what is causing them, or how to make them go away. 

 

It reminds me of when I allow a long piece of thread to double over on itself, then the loop that is formed curls together. 

[friquant]

@kgg Suggested a smaller needle. Here is a sample with a size 100 needle, front and back. 

 

[kgg]

  On 4/12/2025 at 5:32 PM, friquant said:

Suggested a smaller needle.

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I don't think you will ever get a good stitch when the material is .4mm thick and the bobbin thread is .292 thick and the top thread is .292 thick for a total thickness at the knot of .584. I think you would have to down to something like V33 thread.

I think the stitch line in the paper versus the fabric has to do with the paper being rigid and the fibers fabric move as the needle enters. The lack of fabric friction, the fabric weave, the thinness of the material and the V69 being UNbonded probably is causing the thread to twist/curl. 

Try a seam with 3 layers and see what happens.

kgg

Edited April 12 by kgg

[Wizcrafts]

@friquant

Try some #46 bonded thread with a #14 round point needle. This material may not like bonded thread. Try household polycore thread, which is close to number 50, which is close to bonded 46. Reposition the check spring to the center position.

[Wizcrafts]

  On 4/12/2025 at 3:59 PM, AlZilla said:

That's just PHD-level sewing knowledge that you aren't gong to find anywhere else.

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Thanks!

One reason for me using Schmetz Serv 7 needles is that the larger eye is a little less likely to get clogged up when I sew through double-sided leather basting tape from Wawak, or contact cement, or other glues.

[MikeRock]

Wiz,

Do the curlicues have anything to do with the twist of the thread, left vs. right?

 

[shoepatcher]

using right or left twist?

glenn

[Wizcrafts]

  On 4/13/2025 at 3:53 AM, MikeRock said:

Wiz,

Do the curlicues have anything to do with the twist of the thread, left vs. right?

 

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Sometimes, if the thread is very coily, knots will form on the top of the leather. The same twistiness can cause the thread to jump out of the business area of the tension disks, or bobbin spring. Weaver thread is known for this problem in the darker colors. Black and dark brown are the worst offenders in this regard.

I try to counteract clockwise coily thread by wrapping it counterclockwise around two holes in the top thread guide post on my Cowboy CB4500. It really does help cut down on the twisting at the needle.

[MikeRock]

Wiz,

Thank you.  I had a similar problem and changing twists cured it. 

God bless