thread going wonky every few stitches.

[SonderingSusan]

Hey Everyone,

Ive been trying to solve this problem with ym thread for two days now, and just can't. I've changed needle, changed tensions every way , rethreaded and changed thread. every few stitches the bottum bobbin is visible on the top, then it will do a few good stitches, then a few ones where the bobbin thread is showing on the top. all/ any advice and opinions welcome! In the photos it is the navy thread, with a cream bobbin thread. \thanks for taking the time to give your opinion! I'm wondering, could my bobbin case be at fault?

 

 

 

 

[Mark842]

At first glance I'd say your needle is too large for the thread and leather your using. If the hole from the needle is too large you can adjust tension till your blue in the face but i won't stop the knot from showing because the large hole lets come through the top or bottom. The fact that yours is intermittent on top means your tension is probably not the issue. Give us a little more info. Machine, thread size, needle size and thickness of leather.

 

[BDAZ]

Occasionally when I screw up the tension, I use a fine point marker, the same color as the thread and touch the upper loops and presto! They disappear! Details will help diagnose the problem,, which could be a tension issue if the leather is a bit thin for the machine.

Slainte!

Bob

Edited June 13, 2018 by BDAZ

[Ferg]

Possibly your needle size. 

Does your project have different thicknesses of leather in the stitching path? Tension is critical when this is so. Thin leathers, as in single layer, are very difficult to keep the thread knot in the center.

Even though smaller thread having less strength, is some times the only alternative. 

You should reset your tension to what I call "Default". Adjust the tension screw on the bobbin with no thread running through, until it is snug. Don't get carried away, you can mess this up if you make it tight.

Now back the tension screw out 1/8th turn, rethread the bobbin. Machine tension should be set midway or as close as you can set it to the middle.

Sew a couple inches in the thinnest leather you will have for given project. Knots may or may not be in the middle of the leather thickness. If not, repeat with the bobbin tension until the knot is in the center.

Remember that very thin leather isn't sufficient to cover the knot unless you use very small thread with appropriate needle. You may need to adjust the bobbin tension two or three times before you get any improvement. 

Top tension may need slight adjustment after you have changed the bobbin tension several times.

Ferg

[Bugstruck]

Make sure you have enough foot pressure and that the leather isn't lifting. Simple as this is, make sure the bobbin thread is spooling off in the correct direction. Can cause some bottom tension variance. The needle hole size may be a bit large but that much variation I'd think a real tension issue, not just needle size. Saw you had two thread weights, but that isn't likely a contributor. Don't know your machine type but it would help to know that. Pull a good distance of thread slowly from the bottom bobbin, should remain consistent to the feel. Any hitches there, check, could be some dirt under the tension spring or debris in the bobbin area. Rarely too much thread tail from the winding can create some tension anomalies as it spins in the case. All worth a check regardless.

If that reveals nothing, pull the thread out of the needle only and give that a top thread slow long pull with the pressure foot down. Sometimes you can lighten tension to more easily check for consistency on that upper thread pull. If you feel any changes in pull on the top thread, check from the needle back to the spool, path, tension engagement (thread partially seated in the discs or dirt in the upper tension assembly) and how the thread is coming off the spool. De-spooling catches or hitches alone will do what you have there but are not usually the culprit unless the thread is old or the tower isn't directly over the cone. Do that pull check at a couple of take-up lever heights if all is good on the initial test, very rarely an older take-up lever wear point grabs more in one position than another, rather unlikely but possible.  If all that checks out it's below the needle plate almost certainly.... 

Then you would check for any burrs in the thread path below the plate and that the latch clearance is adequate. Simply not engaging the latch tang properly into the fixed side of the needle plate will do what you have but generally creates a bigger thread issue on the bottom. Make sure the latch can move freely. Hand crank it over and run some fabric through so you can see what the upper thread is doing, you may just spot the issue that way here. Make sure there is no dirt in the hook area/rotation surfaces and all is lubed.

All the above is assuming a vertical axis bobbin but mostly applies regardless. I think you mentioned and I assumed the needle is known good. You can slide test that on some thread.

Not always but very often, the above steps find the problem for me. Actually, I can't think of a time they didn't.     

[SonderingSusan]

Hey @Bugstruck,

 

Thank you so much for your detailed reply. I have gone through all the steps i can myself that you have suggested to no avail. The one question i have is what part is the latch tang? Ive googled it and got no clear answer. and what exactly do you mean by latch clearance?

Ive put the bobbin into the bobbin case both ways and I'm getting the same problem with the stitching.Also , in relation to my foot pressure, when i got the machine, i was finding that i had way too much pressure on the foot, it was marking my leather permanently, so a technician cut a piece of the foot spring which solved the problem. i keep the foot pressure as heavy as ai can at the moment. 

@Mark842My machine is a highlead cylinder arm GC2268 and I'm using a 37:20 AX1 NEEDLE/ NM 130 SIZE21/ 135X16 RTW DPX 16. i ws using one a little smaller but the thread was getting caught up in it frequently.im using 20 thread on the top and 60 thread on the bottum (bonded nylon).(please ignore the red thread- that is clearly a needle which is way too big- the navy thread is the one I'm fociusing on)

@Ferg , thanks for that adivce, that is very usefull. My project had slight variation in thickness, but the problem is occurring on this piece of leather which is one standard thickness , its about 0.3mm , also on 0.4mm and all leather I've tried.

Thank you all for taking the time to reply to me about this.It really makes a day so much easier when you can talk to others about workshop problems!

S

Edited June 15, 2018 by SonderingSusan

[Ferg]

I have never suggested this to anyone before but..... with leather that thin and if you do not need the functionality of the cylinder arm, you may get better results with a good "domestic" machine.

I have a flat bed Consew I use for thin stock. It can be very frustrating some times.

Ferg

[Bugstruck]

3 hours ago, SonderingSusan said:

Hey @Bugstruck,

 

Thank you so much for your detailed reply. I have gone through all the steps i can myself that you have suggested to no avail. The one question i have is what part is the latch tang? Ive googled it and got no clear answer. and what exactly do you mean by latch clearance?

Ive put the bobbin into the bobbin case both ways and I'm getting the same problem with the stitching.Also , in relation to my foot pressure, when i got the machine, i was finding that i had way too much pressure on the foot, it was marking my leather permanently, so a technician cut a piece of the foot spring which solved the problem. i keep the foot pressure as heavy as ai can at the moment. 

@Mark842My machine is a highlead cylinder arm GC2268 and I'm using a 37:20 AX1 NEEDLE/ NM 130 SIZE21/ 135X16 RTW DPX 16. i ws using one a little smaller but the thread was getting caught up in it frequently.im using 20 thread on the top and 60 thread on the bottum (bonded nylon).(please ignore the red thread- that is clearly a needle which is way too big- the navy thread is the one I'm fociusing on)

@Ferg , thanks for that adivce, that is very usefull. My project had slight variation in thickness, but the problem is occurring on this piece of leather which is one standard thickness , its about 0.3mm , also on 0.4mm and all leather I've tried.

Thank you all for taking the time to reply to me about this.It really makes a day so much easier when you can talk to others about workshop problems!

S

Susan,

How thick is that leather and are you getting this on two ply sewing or only one ply? What needle size and thread weight? What needle point? Don't worry about the tang (as I called it). Thought you had a flat bed and don't think that applies to your machine. 

I am aware you may very well may have already done all this but just in case......This may not be a machine issue as some others observed. Assuming you've done most of my and Ferg's/others recommendations, I'd back the upper tension off until that bottom thread was laying almost flat, little or zero knot pull-up occurring from the top thread tension. Then walk the top tension up slowly and check and then some more and check, until you see bottom thread on top, then back the top tension off and see if you can get those knots to re-bury with any consistency and not flat line that bottom thread. Those knots may be popping through the top at random if the material resistance to the knot formation is not reasonably consistent. Other materials are more prone to your problem such as ballistic nylon where getting a consistent knot placement in the material can be difficult to unachievable (all material related and no adjustment will make it perfectly consistent unless you have enough plys). The knots may need to favor the bottom to keep from popping through in your instance. Single ply and thinner leather will do it and if the tensions on both sides are on the higher side (and thread larger as was mentioned earlier) it can add to that. You keep trying and so will we. Might even get one of gurus in here who sees something we haven't. Your in reasonably good hands but I can surely attest, a pro I'm certainly not. Some of these guys and gals have sewn almost everything on a very wide range of machines and seen about every variance and failure possible. Would be nice to see some more of them chime in as this one should not be quite this difficult to resolve.