Sewing machine help

[tearghost]

I posted a message asking for help on what machine to buy got that figured out, but in that message I talked a bit the machine I have. So here it is, it's a jack JK-6380. The trouble I'm having is when I start stitching, pictures show my problem. Black thread is my top stitch that lay's flat on the top and the beige thread is my bottom (bobbin). The pic showing the black and beige thread is the top of the leather and the pic with just the beige thread is the bottom. I have never used a sewing machine, please any help I can get is well appreciated. I know it's got something to do with tension but I don't know what controls what and how to adjust the tension.

Thank you in advance for your help.    

[Bugstruck]

Looks like you have little or no bobbin tension but read on, that may not be all going on here. Make sure the bobbin is spinning the correct direction (I think clockwise on yours as viewed from this side you insert the bobbin- when you pull thread) and is engaging beneath the bobbin tension spring fully.

I don't know your machine but I believe your upper thread path may be incorrect. Check this first in your manual or go up to superior sewing, they may have one to download.  That take-up spring is reverse operating to my rotary hook machines. Forgetting that, I don't think the thread should come off the take-up spring (on the lower tension assembly) and dive under that chrome bar to the left before it hits the guide (above the take-up spring). I think it should go from the spring through the small guide above the spring and to the take-up lever (upper arm with hole).

Once you have the upper and lower thread paths sorted out and checked, if it is still doing the same thing, tighten the bobbin tension in small increments, maybe 1/4 turn and see if that helps.

Some other with better knowledge will likely come to assist and advise if I am giving any incorrect information -or- add to what I'm saying.

 

  

 

[tearghost]

6 minutes ago, Bugstruck said:

Looks like you have little or no bobbin tension but read on, that may not be all going on here. Make sure the bobbin is spinning the correct direction (I think clockwise on yours as viewed from this side you insert the bobbin- when you pull thread) and is engaging beneath the bobbin tension spring fully.

I don't know your machine but I believe your upper thread path may be incorrect. Check this first in your manual or go up to superior sewing, they may have one to download.  That take-up spring is reverse operating to my rotary hook machines. Forgetting that, I don't think the thread should come off the take-up spring (on the lower tension assembly) and dive under that chrome bar to the left before it hits the guide (above the take-up spring). I think it should go from the spring through the small guide above the spring and to the take-up lever (upper arm with hole).

Once you have the upper and lower thread paths sorted out and checked, if it is still doing the same thing, tighten the bobbin tension in small increments, maybe 1/4 turn and see if that helps.

Some other with better knowledge will likely come to assist and advise if I am giving any incorrect information -or- add to what I'm saying.

 

  

 

I will have to try this. Thank you

[Constabulary]

try a needle 1 size up or bottom thread one size smaller.

[kgg]

Hi tearghost,

It does look like a tension problem. I think the your machine is very similar to the Juki du-1181n, so I think if you go to the Youtube video titled " Industrial Walking Foot - Juki DU-1181N" by Phillip Miller it should help you figure out your tension problem.

Keith

 

 

 

[Bugstruck]

9 minutes ago, Constabulary said:

try a needle 1 size up or bottom thread one size smaller.

Thought that for a moment too. I does look like he's already down a thread size on the bottom. Guessing 138 and 92 but can't tell, maybe 92 and 69. I zoomed that fist photo and the needle looks adequate size to the thread but worth a check. He's not fraying or busting thread at least. Time will tell it and you guys will get him there.

[brmax]

It looks like the top top tensioner is way tight, with that I truly dont understand yet the bottom tensioner/ take-up. 

Im interested on that assembly fore sure. 

Good luck

Floyd

[Bugstruck]

7 minutes ago, brmax said:

It looks like the top top tensioner is way tight, with that I truly dont understand yet the bottom tensioner/ take-up. 

Im interested on that assembly fore sure. 

Good luck

Floyd

Tearghost,

Floydd is correct that does look tight but it may or may not be. A very rough test is (once you know the thread paths are good) pull the thread out of the needle and pull on it, straight down with the presser foot lowered (that engages the primary tension discs). Should feel tension-wise about what it would take to pull a fully loaded coffee mug across a reasonably smooth wood table top (not formica). Get it there, re-thread and try that as a start point for upper tension. It is impossible for us to observe and know your tensions. It is a feel thing or a load gauge thing if you are as technical as some. Feel works good enough. Bobbing tension should feel much less. Maybe like an empty coffee mug on formica.    

[Bugstruck]

Tearghost,

From what I just observed I now believe your upper tread path below that chrome bar is correct, so disregard my prior comment. Stay with that path.  

[SARK9]

3 hours ago, brmax said:

It looks like the top top tensioner is way tight, with that I truly dont understand yet the bottom tensioner/ take-up. 

Agreed. The main upper tension spring's coils are fully compressed, we can't tell what loading is also being contributed by the upper pre-tensioner above it.  The thread looks completely taut running into the first guide before the pre-tensioner, with no hint of a normal catenary curve.  Check for a snag coming off your thread cone, or a loop on or under anything. Back off the main tension to a looser "starting point" and observe the results. Good luck!

-DC

[dikman]

My first thought was that the top tension is way too high (assuming there is a little tension on the bobbin). Is that top pre-tensioner necessary? looks like the lower slot in its guide will let you bypass it and just go straight down to the lower tensioner. Might be worth a try. Either that or back of the top tensioner so it's not doing much.

[Bugstruck]

2 hours ago, dikman said:

My first thought was that the top tension is way too high (assuming there is a little tension on the bobbin). Is that top pre-tensioner necessary? looks like the lower slot in its guide will let you bypass it and just go straight down to the lower tensioner. Might be worth a try. Either that or back of the top tensioner so it's not doing much.

Exactly what I thought when looking at that top stitch and I still am guessing as nearly everyone is saying, that is likely high. When I looked at how loose the bottom stitch was it got me thinking he probably has very, very low bobbin tension, regardless. I've messed mine up with that flat-line top stitch once or twice but not with that loose a bottom. A miss-directed bobbin won't get my bottoms that loose. Lint/dirt behind the bobbin spring?  Curious to find out but I think he's fighting it on both sides.  

Hey Tearghost, you probably know who I'm responding to but if not, you have an AAA-team member on machinery  on your issue now. I'd take advantage of Dikman if you are still fighting it. I'll to back to the bleachers and spectate for a while.

[dikman]

Bugstruck, thanks for the compliment but I'm a rank amateur, compared to others on here, when it comes to sewing machines!

On the other hand, I just bought a min-lathe (Chinese, of course) and spent the last three days stripping it and re-building it so it works properly.

[tearghost]

Thank you to all for your help, I got it running the way it should. The problem was all in the bobbin tension it was way to loose.

[Mark842]

You are threaded incorrectly on your top thread. I found this video for you

(skip in to about 20 seconds) . It shows very clear how to thread it and it will make a big difference in your tension. If you have adjusted the tension to get it stitching better how you have it now you will probably have to adjust it again after threading it correctly.

Things I've learned in years of sewing...always try to correctly adjust your tension by adjusting the top thread tension. You should seldom if ever have to adjust the bottom tension. I have machines I've been sewing on since the 70's that I have never touched the bottom tension on.

Think of the tension as a tug of war that you want no one to win. In your photo the top thread is winning the tug of war pulling your bottom thread to the top. Reducing top tension should resolve the problem. The incorrect way you are threaded is probably the cause of too much top tension. In a perfect stitch the knot for the lockstitch is in the middle of your project where it can not be seen.

Things that are important...the right needle size and thread size for what you are sewing.  If your needle is too big you will have trouble hiding the knot. If it is too small you will have flagging (what you are sewing will be lifted off the plate when the needle comes up) issues and thread fraying.

If your still having issues it would be helpful to know what size needle, thread, and how thick the leather you are sewing is.

 

[Bugstruck]

Actually Tearghost threaded it right and the video is technically incorrect. Either way would work fine and nothing a very minor top tension tweak would not cure between those two paths. I route my top threads differently sometimes depending what I am doing. Fully intentionally with the results I want. Don't do it often and not where I'd baseline a machine or recommend a newbie start though. Once one has a good grip on tensions you can play around a little and sometimes  a combo the machine likes is found. My 4500 for example doesn't get the 360 degree lower tension wrap on 138 or 92. Needs it on 207 and up. If I drop that wrap to 180 I often don't have to adjust upper tension much. Bobbin tension maybe, that needs some snugging when the thread gets light. 207 and up I leave it alone. Most of my machines don't need bobbin adjustment across the thread weights they handle but those that are wider spectrum sometimes do and sometimes the sewn material asks for a loose or tight stitch upper adjustment alone can't achieve without unbalancing the stitch. Rare but occurs. Usually at the extremes of material.

Great find on that video. one of the best threading videos I have seen. You did better than I did. I told him his correct path looked wrong right out of the gate and had to correct that comment. Glad he got it sorted out.