Consew 225 loose stitches on circle

[Cihowe]

Any suggestions on how to resolve this? While sewing leather in a straight line it sews perfectly but at random times on radius it starts loosing tension on bottom. Makes a slight noise when it’s starts. 
Thanks for any help.

[Wizcrafts]

Check to make sure that the top thread is staying all the way inside the tension disks. Add some mmore top tension. Verify that the check disk is properly threaded and that the spring tension is good, the bottom stopper holds the thread taut until the needle pierces the leather, and that the little set screw is either in the center, or to the left in the curved slot. Finally, change needles.

[Cihowe]

I can’t understand how it sew so good going straight but somehow looses tension when turning a radius. 
Check disc spring is holding pressure on thread until needle enters material. Adjustment screw in check disc is just left of center. Also change needle and retreaded with no help.

[AlZilla]

I don't know if I'm seeing it right or if it's some kind of optical delusion, but the stitches on the bottoms of your circles look much longer than the lead in stitches at the top. None of the stitches really look taut to me, anyway.

In these pictures at least, it doesn't look so much random as it seems to happen when the circle gets really tight.

The holes look a little big, too. Are you using the right size needle?

No answers, just an observation. Definitely looking forward to the solution.

[kgg]

2 hours ago, Cihowe said:

I can’t understand how it sew so good going straight but somehow looses tension when turning a radius. 

 

1 hour ago, AlZilla said:

I don't know if I'm seeing it right or if it's some kind of optical delusion, but the stitches on the bottoms of your circles look much longer than the lead in stitches at the top

To many unknowns to start with. 

i) what model of sewing machine are you using??

ii) what thread size are you using??

iii) what size of needle are you using??

iv) is the machine threaded correctly??? Need photo's showing thread from spool to the eye of needle??

v) Did you do a drop test or use some other method of setting the bobbin tension????

My take:

When you make a circle type seam manually without using a circle guide the sewing speed and controlled movements both have to be properly matched. Particularly with drop feed machines there can be a tendency to twist / turn / move the material to quickly. With drop feed and walking foot machines there is definitely points in the sewing cycle where there is no downward pressure on the material. If you move the material at one of those points you can drag up from the bobbin extra thread and get poor stitches. Those poor stitches do not necessarily appear at that stitch point but in the following stitches because there is so much slop / extra thread in the bobbin thread which then can become a self compounding issue. 

My observation:

At your starting point of the seam you did not lock your stitches and the knot / loop is visible. The knot / loop should be buried in the leather which usually indicates a tension problem. If you don't lock your stitch it will cause a tension issue. Typically 3 stitches (4 holes) forward and then reverse back through those holes and then do your seam. Another method is start your seam the distance 4 holes in would be and reverse back 3 stitches then forward. The second method reduces the amount of thread in each hole by 1/3.

kgg   

 

[AlZilla]

This shows the difference in stitch length. But, style points for hitting that stitch hole in the middle twice!

[Cihowe]

1 hour ago, kgg said:

 

To many unknowns to start with. 

i) what model of sewing machine are you using??

Consew 225

ii) what thread size are you using??

v92 a&e polyester 

iii) what size of needle are you using??

size 20

iv) is the machine threaded correctly??? Need photo's showing thread from spool to the eye of needle??

No photos for now. It’s in my shop

v) Did you do a drop test or use some other method of setting the bobbin tension???

Just by feel 

My take:

When you make a circle type seam manually without using a circle guide the sewing speed and controlled movements both have to be properly matched. Particularly with drop feed machines there can be a tendency to twist / turn / move the material to quickly. With drop feed and walking foot machines there is definitely points in the sewing cycle where there is no downward pressure on the material. If you move the material at one of those points you can drag up from the bobbin extra thread and get poor stitches. Those poor stitches do not necessarily appear at that stitch point but in the following stitches because there is so much slop / extra thread in the bobbin thread which then can become a self compounding issue. 

My observation:

At your starting point of the seam you did not lock your stitches and the knot / loop is visible. The knot / loop should be buried in the leather which usually indicates a tension problem. If you don't lock your stitch it will cause a tension issue. Typically 3 stitches (4 holes) forward and then reverse back through those holes and then do your seam. Another method is start your seam the distance 4 holes in would be and reverse back 3 stitches then forward. The second method reduces the amount of thread in each hole by 1/3.

kgg   

You are probably right. After messing with tension and slowing down while turning leather it seem to do better.

 

[kgg]

@Cihowe

I would do the drop test for tension on the bobbin thread. If it needs to be adjusted turn the tension spring screw a 1/8 of turn at a go. If you over tighten that screw it will flatten the bobbin thread tension spring and you will have to replace the spring. Once those have been over tighten they are never right afterwards and you will never get consistent bobbin tension.  

kgg

[friquant]

43 minutes ago, AlZilla said:

This shows the difference in stitch length

I used to get longer (or shorter) stitches when turning tight circles on my pfaff 535. I was driving it like a racecar, meaning taking the corner at a constant, appropriate speed and rotating the fabric (cardboard, actually) at a smooth, constant rate. The center of pressure of the feed dog was not concentric with the needle, but rather more aft and off to one side. So when the needle was in the air, the fabric (cardboard, actually) would rotate around that offset center of pressure. It would make one length of stitches going straight. But longer stitches turning left, and shorter stitches turning right.

Edited 14 hours ago by friquant

[Cihowe]

3 minutes ago, kgg said:

@Cihowe

I would do the drop test for tension on the bobbin thread. If it needs to be adjusted turn the tension spring screw a 1/8 of turn at a go. If you over tighten that screw it will flatten the bobbin thread tension spring and you will have to replace the spring. Once those have been over tighten they are never right afterwards and you will never get consistent bobbin tension.  

kgg

I have to get another bobbin spring because I have over tightened it.

[friquant]

6 hours ago, Wizcrafts said:

Check to make sure that the top thread is staying all the way inside the tension disks

This happened to me a couple days ago on my Jianglong 341. The TEX 270 thread would be inside the tension disks at the beginning of the seam, but by the end of the seam the tension disks would be flat together with the thread only skirting their perimeter. That's when I decided to add some tension to the smaller/auxiliary tension disks right next to them, which I had never found a use for previously. But it seemed to keep the thread properly seated in the main tension disks.

[friquant]

1 hour ago, kgg said:

I would do the drop test for tension on the bobbin thread

How does one do the drop test with a vertical hook shaft?
I tried it but the bobbin fell out of the bobbin case cap.

[kgg]

3 hours ago, friquant said:

This happened to me a couple days ago on my Jianglong 341. The TEX 270 thread

I think some of your problem is you are using Tex 270 (V277) which the machine is not rated for. The 341 / 1341 clones of the Juki LS 341 or 1341 are rated for a #24 needle which will accept Tex 210 (V207) but the machines typically will only sew that in thinner material. A lot of clone machines rate their machines on the max size thread you can stuff through the eye of the needle vs Juki rates their machine on what it can sew with the max size top thread and bobbin thread in max. sewing thickness. That is why you see the Juki LS-341 or 1341 rated for V138 thread not V207.

1 hour ago, friquant said:

How does one do the drop test with a vertical hook shaft?

Insert bobbin in the top cap and through the tension spring so the bobbin spins counter clockwise when you pull on the end of the bobbin thread. I leave about 4 to 6 inches of end thread dangling.

Place the bobbin and cap in the palm of your left hand.

With your right hand grab the end of the bobbin thread and lift the bobbin case of your hand. If there isn't enough tension the bobbin will just spin in your hand and probably fall to the floor. You should be able to lift the bobbin and case off your hand otherwise you have to tighten the little screw by turning it clockwise about 1/8 of a turn. You do not want to flat that little spring or unscrew the screw to much as if the screw comes out chances are you will never find it. Try again. When you get the tension just about right you should be able to lift it off your hand. Once you can lift the bobbin off your hand try giving the end of the thread a couple of quick jerks it should cause the bobbin to spin slightly and yet be lifted off your hand. 

kgg

  

[kgg]

11 hours ago, friquant said:

The TEX 270 thread would be inside the tension disks at the beginning of the seam, but by the end of the seam the tension disks would be flat together with the thread only skirting their perimeter.

I forgot to ask if you could provide a photo of how you have your top threaded.

kgg