Stitches Skipping

[RVacc]

TO start let me say that myself and my lead mechanic have both given this machine the once over.  Its a Juki LU-1508-N.  I am not sure what is causing it to skip.  we have retimed the hook and needle and by the shafts, new needles, we have replaced the hook and nothing seems to be working.  Could a spool of thread that is wound too tight be the cause of it? The leather we sew is not very thick it vaires from 3 oz to 6 oz.  Any tips would be greatly appreciated.

[kgg]

14 minutes ago, RVacc said:

I am not sure what is causing it to skip. 

Some of the typical corrupts are:

i) Needles. The correct system for the Juki LU-1508N is 135 x 17 for fabric and 135 x 16 for leather. Use a correctly inserted and sized needle for the thread size. You may have to go up a needle size or two when sewing thick or tough material so the loop of the top thread can be correctly formed and caught by the hook.

Buy brand name needles like Schmetz. I have tried other brands was never never really satisfied with them. I early on converted to Schmetz and only use Schmetz needles in all my machine with excellent results. I replace my needles when they have about 8 hours of sewing time on them or when I find they are getting dull whichever comes first.

A good chart for thread size vs needle size: www.tolindsewmach.com/thread-chart.html

ii) Needle bar height. Maybe set a little too high or low so the needle doesn't catch the bobbin thread properly.

iii) Bobbin area. May have a build up of old thread lint.

iv) Thread. Poor quality thread particularly black noticeable on 8 oz spools. Buy good quality brand name thread

What size of thread are you using? Any chance of posting a picture of how you have the machine threaded from the top of thread spool to the eye of the needle. There maybe something there?

kgg

[Constabulary]

Sometimes it helps lowering the needle bar just a tiny bit. Also rotating the needle a few degrees toward the took tip could help.

It also happens that the hook is set to far away from the needle. In that case you have to move the hook saddle closer to the needle. Just a guess w/o knowing your machine

[Burkhardt]

4 hours ago, kgg said:

Some of the typical corrupts are:

i) Needles. The correct system for the Juki LU-1508N is 135 x 17 for fabric and 135 x 16 for leather. Use a correctly inserted and sized needle for the thread size. You may have to go up a needle size or two when sewing thick or tough material so the loop of the top thread can be correctly formed and caught by the hook.

Buy brand name needles like Schmetz. I have tried other brands was never never really satisfied with them. I early on converted to Schmetz and only use Schmetz needles in all my machine with excellent results. I replace my needles when they have about 8 hours of sewing time on them or when I find they are getting dull whichever comes first.

A good chart for thread size vs needle size: www.tolindsewmach.com/thread-chart.html

ii) Needle bar height. Maybe set a little too high or low so the needle doesn't catch the bobbin thread properly.

iii) Bobbin area. May have a build up of old thread lint.

iv) Thread. Poor quality thread particularly black noticeable on 8 oz spools. Buy good quality brand name thread

What size of thread are you using? Any chance of posting a picture of how you have the machine threaded from the top of thread spool to the eye of the needle. There maybe something there?

kgg

Not having any idea what the machine is knowing you do, could it be flagging depending on what leather they're sewing?

[RVacc]

On 11/23/2022 at 11:16 AM, kgg said:

Some of the typical corrupts are:

i) Needles. The correct system for the Juki LU-1508N is 135 x 17 for fabric and 135 x 16 for leather. Use a correctly inserted and sized needle for the thread size. You may have to go up a needle size or two when sewing thick or tough material so the loop of the top thread can be correctly formed and caught by the hook.

Buy brand name needles like Schmetz. I have tried other brands was never never really satisfied with them. I early on converted to Schmetz and only use Schmetz needles in all my machine with excellent results. I replace my needles when they have about 8 hours of sewing time on them or when I find they are getting dull whichever comes first.

A good chart for thread size vs needle size: www.tolindsewmach.com/thread-chart.html

ii) Needle bar height. Maybe set a little too high or low so the needle doesn't catch the bobbin thread properly.

iii) Bobbin area. May have a build up of old thread lint.

iv) Thread. Poor quality thread particularly black noticeable on 8 oz spools. Buy good quality brand name thread

What size of thread are you using? Any chance of posting a picture of how you have the machine threaded from the top of thread spool to the eye of the needle. There maybe something there?

kgg

Thread:                A&E T-135 bonded

Needles:              Schmetz 135x17 130

 

 

[kgg]

1 hour ago, RVacc said:

Thread:                A&E T-135 bonded

Needles:              Schmetz 135x17 130

The thread is from a excellent manufacturer as well as the needle manufacturer however my suggestions are:

i) Change the needle from 135 X 17 which is a fabric needle to a 135 X16 for leather.

ii) Change the size of your needle to a minimum #22 (140) for V138 (T135) thread but I would recommend start with a #23 (160) and in thick or tough leather you may have to even move up to #24 (180) needle.

iii) When selecting a needle for a particular thread size a good reference chart can be found at  ( https://www.tolindsewmach.com/thread-chart.html )

When a needle is to small for the thread the thread loop isn't formed properly as there isn't enough space and so the top thread can get held against the side of the needle hole. That means the thread doesn't form a proper loop for the hook to catch.

kgg

[RVacc]

20 hours ago, kgg said:

The thread is from a excellent manufacturer as well as the needle manufacturer however my suggestions are:

i) Change the needle from 135 X 17 which is a fabric needle to a 135 X16 for leather.

ii) Change the size of your needle to a minimum #22 (140) for V138 (T135) thread but I would recommend start with a #23 (160) and in thick or tough leather you may have to even move up to #24 (180) needle.

iii) When selecting a needle for a particular thread size a good reference chart can be found at  ( https://www.tolindsewmach.com/thread-chart.html )

When a needle is to small for the thread the thread loop isn't formed properly as there isn't enough space and so the top thread can get held against the side of the needle hole. That means the thread doesn't form a proper loop for the hook to catch.

kgg

I will look into different needles. We are currently having a problem with stiches and stitch holes pulling and showing on turned pieces. the only 2 things i can think of is either the needle or that it is an issue with out leather.

[Burkhardt]

6 hours ago, RVacc said:

I will look into different needles. We are currently having a problem with stiches and stitch holes pulling and showing on turned pieces. the only 2 things i can think of is either the needle or that it is an issue with out leather.

The 135x16 are the leather needles as @kggsaid that cut the leather vs just piercing it will leave a better hole for the stitch to lay.

[RVacc]

On 12/1/2022 at 7:06 PM, kgg said:

The thread is from a excellent manufacturer as well as the needle manufacturer however my suggestions are:

i) Change the needle from 135 X 17 which is a fabric needle to a 135 X16 for leather.

ii) Change the size of your needle to a minimum #22 (140) for V138 (T135) thread but I would recommend start with a #23 (160) and in thick or tough leather you may have to even move up to #24 (180) needle.

iii) When selecting a needle for a particular thread size a good reference chart can be found at  ( https://www.tolindsewmach.com/thread-chart.html )

When a needle is to small for the thread the thread loop isn't formed properly as there isn't enough space and so the top thread can get held against the side of the needle hole. That means the thread doesn't form a proper loop for the hook to catch.

kgg

Does the needle size for leather vary between Juki and Consew? we have both machines so im trying to cover all bases.

[kgg]

13 minutes ago, RVacc said:

Does the needle size for leather vary between Juki and Consew? we have both machines so im trying to cover all bases.

There two things you need to know. The sewing machines needle system and the needle size capability. The needle system for the Juki 1508 is 135 x16 for Leather and 135 x 17 for fabric and the size of needle is dependent upon the size of thread you are using within it's thread size sewing capability which for this model can handle needles from V46 to V138.

The Consew may use the same needle system but without knowing the model number who knows.

kgg