Inconsistent bottom stitches

[Zac]

Hi Everyone!

i hope everyone has been well. I’m having some issues with the bottom thread and inconsistent loose stitches. For reference my machine is a Seiko LCW-8BL and I am using M20 poly cotton thread and a size 22 leather needle.

The bobbins are wound smoothly the thread seems to be coming off the spool ok and the it doesn’t seem to be happening with my other slightly lighter threads.

I would have thought this machine would be capable of this size thread? I don’t have any larger needles but could that be the issue? Or should I just stuff around with tension a bit more? Any hot tips?

Thanks again!

 

 

[Matt S]

I use the same machine (well, two of them) with TKT20 bonded nylon and size 22 needles (Schmetz LR, for the record). Definitely not a capability issue.

Have you tried a fresh new needle and made sure that it's perfectly seated? Sounds obvious but it's often the "obvious" stuff that I miss!  Next thing for me would be to increase the top (needle) tension a bit. Maybe half a turn or one turn. Then if that doesn't fix it completely unthread the machine and rethread it slowly and carefully, looking for wear and dirt buildup anywhere the thread touches.

Just a thought, is that black thread? Are the "well behaving" threads black? Black thread often behaves a little crunchier than other colours, something to do with the dying process. How fresh is it? Do you use thread lube?

[Pintodeluxe]

I've had machines do that, and discovered it was a faulty bobbin case.  I know you did mention that the bobbin was unspooling ok.  I would slowly pull a fair amount of bobbin thread by hand.  Is the bobbin tension smooth and consistent, or does the tension seem to increase sporadically?  

Also, do pre-wound bobbins result in the same inconsistent stitch?  

Best of luck with it.  

Edited October 29, 2020 by Pintodeluxe

[Zac]

Thanks Matt and Pinto.

I’m using the exact same needles so that’s good to know I can rule out that as the problem. I changed to a new needle and played with the tension with no luck. The Bobbin definitely seems to be running smoothly too. 

I have some M25 thread from a different brand (black the same as my problem thread) and it doesn’t have this issue at all so I used the M25 bobbin with the M20 and although there are less loops there are still loops.

It’s new thread but I don’t use lubricant, so I guess that will be next thing to try.

Very annoying! Hard to test too as I really need a good run to see the issue which is a massive waste of material! I’m sure I’ll get there eventually!