Backlash issue with Juki 1541 & bonded thread

[aslfkjaslfkjasflkj]

On 12/12/2021 at 5:22 PM, Dream4est said:

20 hours ago, Wizcrafts said:

On 12/12/2021 at 5:16 PM, kgg said:

 

 

 

This is going to be a long post so brace yourself.

Bobbin Winding

This is the thread path for the bobbin winder.

This is my bobbin case which I made sure to clean out before any testing. There wasn't any lint anyway.

When the bobbin is winding it appears to "wobble" not sure if that's normal. Here is the video of this: https://imgur.com/0sp0eqQ

Thread Path

Testing Info

I insert the bobbin so that it spins the opposite way to which the hook spins.

The following images of testing you will see a white line next to some stitches. This white line indicates when I stopped sewing. So you can see where the bobbin thread gets pulled up to the top. Grey on grey isn't the easiest to see but hopefully I have shown it well.

Size 19 Needle Testing

I started off by using a new size 19 needle with a bobbin tension of ~40gf. I tested the tension in a towa bobbin gauge and the bobbin tension was consistent.

To save space here is the rest of the images for size 19 testing: https://imgur.com/a/iWuB4NK

Size 18 Needle Testing

I then switched to a new size 18 needle and I believe I increased the bobbin tension too.

I continued testing and now it got to a point where I wasn't experiencing backlash all the time however it would still occur. At this point my top tension was very tight to the point where it couldn't be adjusted much more. The bobbin tension was also very tight around 75gf. So this wasn't a valid solution.

Rest of size 18 needle testing: https://imgur.com/a/HWBzMsU

I also tested on 1000D Cordura 4 Layers with a size 19 needle. As many have said the 19 needle is too large for this. However when I use the same needle on the 1000D with ripstop lining its as if the ripstop creates a lot of friction and I have to increase my top tension significantly to account for this. Is this something anyone else has experienced?

Backlash Spring Testing

I now decreased my bobbin tension to ~40gf and inserted a brand new backlash spring. However I have a problem. I have seen bobbin cases like this:

This case has a slot for the backlash spring to sit in however mine do not so I insert the spring as follows:

I am unsure as to if I should put it above or under this little piece:

I put it in the tension gauge and as usual the bobbin didn't have consistent bobbin tension. As a matter of fact, this time the tension WITH the backlash spring, the bobbin tension decreased to ~34gf from 40gf which I have never experienced before. It has always increased the tension in the past.

I continued testing using this current setup and sometimes it worked but not all of the time as you can see in the final images in "Size 19 Needle" imgur link.

Here is a video as to what it looks like when sewing: https://i.imgur.com/OwNAM91.mp4

Final Thoughts

I am unsure as to what else I can do with my current setup. All I can think of is to buy a bobbin case with the slots for the backlash spring as pictured above and some genuine bobbins.

Thank you for taking the time to read this wall of text.

 

 

[kgg]

5 hours ago, aslfkjaslfkjasflkj said:

Bobbin Winding

This is the thread path for the bobbin winder.

I use only one location for my top and bobbin thread pins, the location you are using for your bobbin thread guide pin, but I use the metal thread guide for the top thread and the PLA guide for the bobbin thread. This allows me to wind a bobbin at will without having to undo the top thread. Since you are using the standard thread spool stand you need to get the spools as close to the table as possible and the spool stand arm 2 to 2 1/2 times the height above the thread spool bases or you don't allow the thread to properly untwist. My particular setup has the thread going into the top and bobbin thread pin on top of the machine much closer to horizontal then yours to reduce angle thread tension. 

When I wind a bobbin I thread my bobbin thread through one of the outside holes in the bobbin and it then goes to a swing away thread attachment that holes the end of the thread and automatically cuts the thread flush with the side of the bobbin. I hated the end of the bobbin thread floppy around as I sewed or having to un-thread the needle and hold the end of the thread.

6 hours ago, aslfkjaslfkjasflkj said:

Here is the video of this: https://imgur.com/0sp0eqQ

Thread Path

I would use the thread guide pin location that you use for your bobbin thread and replace the flat horizontal top thread guide on the top cover of your machine as it has some severe thread cuts in it which may nick your thread and cause fraying and come out of the last hole rather then second last hole.

I changed the angle of the next guide to the 2 o'clock position rather then the 3 o'clock position yours is in which did change the entry angle into the top tensioner slightly. The guide just before the takeup arm I changed the position to about the 1:30 position as this helped keep the thread from floppy to much to the left and crossing over to the other side and possible intermingling with the downside of the top thread from the takeup arm. Where the top thread enters the flat spring loaded bar just before the top of the needle should be 1) on the right side of the screw however I haven't found that to makes much difference 2) the flat bar tensioner needs to have the screw tightened in so the thread stays basically in one location with a constant tension so the thread doesn't slide or flop about.

See if that helps.

kgg

 

[DrmCa]

You are wasting so much filament. Much of what you are 3D printing only really needs about 1/2 of its present strength. I know: it is tough. I usually overdo it with my designs and have to push myself to scale thicknesses down.

[Wizcrafts]

49 minutes ago, DrmCa said:

You are wasting so much filament. Much of what you are 3D printing only really needs about 1/2 of its present strength. I know: it is tough. I usually overdo it with my designs and have to push myself to scale thicknesses down.

@DrmCa I think you posted this reply in the wrong topic, or sub-forum. Would you like me to move it to the correct location? Let me know where that is.

[kgg]

10 minutes ago, DrmCa said:

You are wasting so much filament.

I know I usually design the old school way, well over expected load and filament is such a inexpensive medium for prototyping. A lot also depended on that they were designed around my golden rule. No additional holes to be drilled or tap into the machine or table top. The bobbin thread swing-away and the supports has to be able to withstand the breaking strength of V138 thread which is about 22 lb (10 kgs) and any additional bending moment loads where as the snips / needle / bobbin holder on the top front of the machine they all swivel horizontally and vertically so they have to withstand my constant grabbing / banging. All my initial designs for my machines have gone through some form redesign and each machine has it own unique set of attachments to speed up or make things a little easier or be able to repurpose attachments made for a flatbed so they can be used on a cylinder bed. 

kgg

[brmax]

Good day

I would suggest you always use the bobbins disc type backlash spring, and the better you are with sew speed the more it is critical. 
In your beginning post photo, “ turn over” the backlash spring; the bent tab Up, needs to be bobbin side. It may be one of those Oh S moments, or it usually is for me.
Everything else in threading is standard looking as the manual looks, holes in guides are your choice of usage, change one and you! Will likely have a different setting than others. So I run with a pattern on all 15 or 13 series as a standard, in thread guides. 
I really think you need the spring corrected 1st. & use it. 
on some older ones there are springs but i didnt know early on, and so heard a tip using a diy cut fabric to sit under the bobbin. Works perfect and its had hundreds of bobbins usage on that machine. Now that i mention it it will get jacked up :/

No matter! troubleshoot in a pattern, it cant be wrong; tech schools only teach that method because its proven in the efficiency realm, times money!

Good luck 

 

[RockyAussie]

On 12/14/2021 at 10:38 AM, kgg said:

Since you are using the standard thread spool stand you need to get the spools as close to the table as possible and the spool stand arm 2 to 2 1/2 times the height above the thread spool bases or you don't allow the thread to properly untwist.

I will just add also that it appears in the first picture that the thread does NOT line up with the hole above in that stand. That will give you a slight loosen and tighten in your tension as the thread is pulled off of the spool. I think that your problem is the thread return spring is perhaps a little strong and could be adjusted off a little and I think it may behave better if you don't hook it in to the first holder just above the thread return spring.

[aslfkjaslfkjasflkj]

On 12/15/2021 at 5:09 PM, brmax said:

Good day

I would suggest you always use the bobbins disc type backlash spring, and the better you are with sew speed the more it is critical. 
In your beginning post photo, “ turn over” the backlash spring; the bent tab Up, needs to be bobbin side. It may be one of those Oh S moments, or it usually is for me.
Everything else in threading is standard looking as the manual looks, holes in guides are your choice of usage, change one and you! Will likely have a different setting than others. So I run with a pattern on all 15 or 13 series as a standard, in thread guides. 
I really think you need the spring corrected 1st. & use it. 
on some older ones there are springs but i didnt know early on, and so heard a tip using a diy cut fabric to sit under the bobbin. Works perfect and its had hundreds of bobbins usage on that machine. Now that i mention it it will get jacked up :/

No matter! troubleshoot in a pattern, it cant be wrong; tech schools only teach that method because its proven in the efficiency realm, times money!

Good luck 

 

Hi, may bad for the slow response.

If you're referring to to the image in my very first post, this was just an issue from the internet. I did it have it inserted bobbin side. I bought a new bobbin case with the slots in for the backlash spring just haven't got round to testing it in my machine yet.

What is the "disc type backlash spring" is it the one in the previously mentioned image? Because I couldn't find the part number in the part book and after some digging I found a backlash spring which had the same part number minus the last digit. B1837241H0C is what I have.

[aslfkjaslfkjasflkj]

On 12/16/2021 at 3:44 AM, RockyAussie said:

I will just add also that it appears in the first picture that the thread does NOT line up with the hole above in that stand. That will give you a slight loosen and tighten in your tension as the thread is pulled off of the spool. I think that your problem is the thread return spring is perhaps a little strong and could be adjusted off a little and I think it may behave better if you don't hook it in to the first holder just above the thread return spring.

You're correct it doesn't however this isn't any way adjust it so that the spool pin sections aligns with the hole. There is the hole to the left circled in the image below. This appears to be more central over the spool. My only concern with this is the fact that its just a metal edge which may cause some issues with the thread? It does feel smooth but obviously it isn't plastic lined as the circular hole.

[Doc Reaper]

This is how they say the bobbin should benever