nylonRigging

Forward great , Reverse always sloppy .

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I been playing Inspector Clouseau off and on for past few days, and I am finally stumped . It Sunday and I got few minutes, so I will throw this out there .

I have a machine that sews great in forward stitch . Timing looks GTG . tore into and checked timing twice .
Is a simple design, drop-feed . Mitsubishi DB170 .  using E-69 nylon , and 135x17 needle .

( sewing Forward ) .
Sews and looks great threw 2 to 5 pieces 1000 Den. cordura .  Stitching always Looks good top and bottom of material sewn .
When I turn stitch length select knob to 'zero' . The needle in in a stationary position on the plunge .
Using stitch length select knob,  it sews great threw all stitch lengths . Turning the stitch select knob , All stitch move narrow to wide with sewing .
So that all looks/checks out great . sews great all day ....But

pushing the Reverse handle down .. ( sewing Reverse ) .
OK.. Bottom of material, the ' bobbin thread side always looks great ' .
But ( top of material ) , the top stitch is always loose and never tensions right . I used different bobbin tension . I put on a fresh set of Dogs . changed thread .
It not catching/tearing thread . It is just sloppy loose and I cant get the top thread' to tension in Reverse .
 

Anyone have an Idea what I am missing  ?  . I got to be something stupid simple that I am just not seeing ?

...thanks
.

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I do have a couple of questions? Does this occur just with cordura? Have you tried stopping the forward sewing before reversing or are you just depressing the reverse lever while it is still sewing forward? Does this happen when you are sewing at a real slow speed or only when at max. speed? You said you are using 135x17 needle but what size and how often are you changing the needle? Are you using bonded nylon or bonded polyester thread?

A couple of suggestions to try. Try it with same number of layers of softer fabric as a test to see if it does the same thing. For V69 thread you should be normally using a #18 needle. I have had to sometimes use a size #20 needle, depending on the number of layers of 1200 denier ripstop I was trying to sew to get a good stitch. I find with ripstop (more waterproof) and I assume the same with cordura (more abrasive resistant) that type of material has a tendency to dull and bend needles fairly quickly.

If possible can you do a picture of your thread path for the top thread sometimes incorrect top thread paths can cause weird top tension problems with stitches as well as worn tension check springs.

kgg

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My Singer 15-91 acts almost like this. Sews beautifully forwards, makes loops and fuzz on the bottom when you reverse. The sewing machine repair guy locally told me "that's impossible".

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3 hours ago, kgg said:

I do have a couple of questions? Does this occur just with cordura? Have you tried stopping the forward sewing before reversing or are you just depressing the reverse lever while it is still sewing forward? Does this happen when you are sewing at a real slow speed or only when at max. speed? You said you are using 135x17 needle but what size and how often are you changing the needle? Are you using bonded nylon or bonded polyester thread?

A couple of suggestions to try. Try it with same number of layers of softer fabric as a test to see if it does the same thing. For V69 thread you should be normally using a #18 needle. I have had to sometimes use a size #20 needle, depending on the number of layers of 1200 denier ripstop I was trying to sew to get a good stitch. I find with ripstop (more waterproof) and I assume the same with cordura (more abrasive resistant) that type of material has a tendency to dull and bend needles fairly quickly.

If possible can you do a picture of your thread path for the top thread sometimes incorrect top thread paths can cause weird top tension problems with stitches as well as worn tension check springs.

kgg

I using #20 on the x17 . with bonded nylon . I do change needles regularly also .
I don't sew a lot fast long runs most days so I usually keep the RPM's down on my machines . but I did try slow and fast with the speed and also I tried some thinner lighter denier fabric with using Reverse .
This got to be some kind of weird tension problem on the top needle thread . Got to be something easy fix, but just hard for me to see .
I ordered a new tension assembly yesterday . And when get a few minutes tomorrow . I am going to pull the thread tension assembly off and pull apart and go threw it .
Going to replace the Thread Guide Pip on top the machine with one that also has a small tension disks on it . Maybe spreading/smoothing out the tension , then use a lighter Coil Spring reduce some off the main Tension assembly .
--
--
I not had this Head but about 6 months . And it a project almost done . This Tension sewing Reverse problem is one of the last bugs to work out . Normally I would not own this model of machine . But it was one of those 'oddities ' you run across once in while looking around, so I picked it up .The Head is older , probably 80's production . but is pretty nice clean shape . It set-up on new table and new motor, and made a new drip pan . Added a Press-foot lift lever on backside for table foot pedal . added feed Dogs, throat plate and presser foot .

OK this is 'the thing' . It is a Mitsubishi head, ( DB170 ) with factory cast stamp underside of machine . But It NOT the normal model everyone familiar with . That is why it a project  .
Was is a custom run ordered and branded 'Nustyle' , and was ordered from Mitsubishi cast to a 16" long-arm, with 7" of table clearance . That why it caught my eye and bought it .
( Nustyle ) It was marketed as a 'Quilting machine ' , and had a frame setup screwed to the Head for 'free motion' . . BUT now ..  Wham Bam.. it sitting on a flat table looking like a real sew machine . Hopefully It will turn this thing into a good daily stitch workhorse . Just got to smooth this thing out and make the switch to punching nylons .
.

Edited by nylonRigging

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7 hours ago, williaty said:

My Singer 15-91 acts almost like this. Sews beautifully forwards, makes loops and fuzz on the bottom when you reverse. The sewing machine repair guy locally told me "that's impossible".

Williaty, my experience with the bird nest on the bottom, was that the bobbin tension wasn't right and had to be readjusted. It also depended not only the size of thread but whether it was bonded nylon or bonded polyester and whether it was near the end of the thread on the bobbin. The colour of the thread also played a role particularly black bonded nylon.

I have had most of my problems using the 8 oz size spools of bonded nylon thread particularly black, black seems stiffer with more spring-back as it uncoils from the main spool and as it uncoils from the bobbin then bonded polyester. The thread on some 8 oz spools would even spring-back enough to coil under the bottom of the 8 oz spool and jam. To overcome this when I am using thread from any 8 oz spool regardless of colour or type of thread I mount it horizontally to get a more even, smoother thread take off with no spring-back from the spool for the top thread and for when winding the bobbin.

kgg

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update for future reference, anyone with similar ( top-thread tension problems with 'only running Reverse' ) .

It does look much better now running in reverse .  removing and replacing the thread guide pin,  with one with a small tension spring/disks . Then taking out the heavy coil spring out the main tension assembly and putting in a little softer coil tension spring .

I don't know why ? , but Spreading out the tension to both a Pin-guide and main tension assembly , rather than giving the entire burden to the main tension spring/disk assembly . Seems to tighten all of the loose stitching problem up when running in Reverse .

.

 

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