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Back tacking, lock stitching, weight bearing seams,

sojourner

Well-Known Member
Joined
Oct 14, 2014
Messages
1,706
I am still obsessing with my industrial sewing machine setup on stitch length equality (fwd and reverse). My reverse is slightly smaller than fwd. I am working on adjusting that, but it is challenging on my model. Even then, from what I have seen, making fwd and reverse stitches even length does not work at all stitch lengths.

Now I am trying to determine the “correct” way to back tack to ensure the seam does not come apart.

I did not find anything in the parachute riggers handbook on this.

I believe there are basically 2 different ways to lock the stitch in.

I will mention only the locking at the beginning of a seam.
Ending is just symmetric reverse of beginning

1. Go fwd a couple stitches, go reverse same amount of stitches, go fwd until other end.

2. Start further in, go reverse a couple stitches, go forward to the other end.



1 would seem stronger, but with stitch length being slightly off, not seeing the stitches land exactly in the same holes would be irritating to me.

2 would seem easier for anyone wanting everything is same hole, but would it be just as strong?

What are all the saddle fabricators doing wrt stitch length equality forward and reverse and their back tacking?

Thx
 
Like you said, both will work fine. Personally I do fwd, reverse, forward. All you are doing is preventing those loose stitches from being able to be pulled apart. If it is in an area that strength is a concern, I'm going to run a straight stitch only bar tack (bc i don't have zig zag) over the end anyways.

In regards to your varied stitch length depending on direction, have you tried using the hand wheel for at least the reverse stitches? My guess it that it is not a mechanical/out of adjustment issue. It is more likely varied traction. Feed dogs are going to advance fabric much more aggressively in forward than reverse. ESPECIALLY when sewing thicker stacks of fabric.

I fully support striving for a very high level result but you are the only person who will ever notice that those stitches aren't all in the same holes. But if you really want it perfect, and using the hand wheel does not help, you can also manually shift the fabric until the needle is lined up perfectly with the hole. Tedious but effective.

Sent from my SM-G991U using Tapatalk
 
Like you said, both will work fine. Personally I do fwd, reverse, forward. All you are doing is preventing those loose stitches from being able to be pulled apart. If it is in an area that strength is a concern, I'm going to run a straight stitch only bar tack (bc i don't have zig zag) over the end anyways.

In regards to your varied stitch length depending on direction, have you tried using the hand wheel for at least the reverse stitches? My guess it that it is not a mechanical/out of adjustment issue. It is more likely varied traction. Feed dogs are going to advance fabric much more aggressively in forward than reverse. ESPECIALLY when sewing thicker stacks of fabric.

I fully support striving for a very high level result but you are the only person who will ever notice that those stitches aren't all in the same holes. But if you really want it perfect, and using the hand wheel does not help, you can also manually shift the fabric until the needle is lined up perfectly with the hole. Tedious but effective.

Sent from my SM-G991U using Tapatalk

Thanks!

I am using the hand wheel going forward and reverse on a double piece of paper. And measuring the stitches. I am constantly getting about 0.5mm less on each back stitch.

I know it doesn’t matter, but it is really bugging me. But I don’t know if it is bugging me enough to manually shift the fabric. I guess my laziness wins out over my OCD.

That said, I freed up the related parts for stitch length regulation. I am going to keep at it for a couple days. And if no success, call it good.

Thx for your reply.
 
I thought of another option that will work in a lot of scenarios. Forward, spin piece, forward, spin piece back, forward. Should five perfect results. Just make sure to spin with needle in down position. Can be a bit of a pain if you are dealing with a bigger piece but this is what I used to do when using a machine with no reverse.


Also, you said industrial but I assume no walking foot?

Sent from my SM-G991U using Tapatalk
 
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I thought of another option that will work in a lot of scenarios. Forward, spin piece, forward, spin piece back, forward. Should five perfect results. Just make sure to spin with needle in down position. Can be a bit of a pain if you are dealing with a bigger piece but this is what I used to do when using a machine with no reverse.


Also, you said industrial but I assume no walking foot?

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Thanks! I have found an easy work around. It is a walking foot / unison feed. Consew 206RB4.

Earlier I posted that reverse stitch is exactly 0.5 mm shorter. I have been viewing schematics of parts of the RB4, the RB5, the similar Seiko STH-8BLD3, trying to figure out how to adjust the reverse length when there is no adjustment for it.

Finally it dawned on me. Just add 0.5 mm when I back tack. Duh!!!

I have a needle positioner, so single stitch at a time should not be an issue. I just tested 2, 3, 4, 5, 6 and 7mm length forward stitches. Stopped and added 0.5 mm length for reverse, stopped again and subtracted 0.5mm to go forward again, and at all these stitch lengths, same holes forward and reverse.

I think our exchange definitely sparked the idea in my mind. Again, thanks! Definitely helpful to me.

I feel silly and relieved.
 
I don't have the same machine at you (I have a juki 1541). But I did have to adjust my forward and reverse stitch length to get them equal. It was tedious but the end result is very nice. I started at a short stitch length, as I found it easier to tell differences in the stitch length the more stitches I sewed. I slowly crept up on equal lengths. Then I changed to a longer stitch length and made further adjustment. Keep at it and you can achieve equal stitch lengths!
Since you have a needle positioner it should be easier. But I found it crucial on my machine to have the needle at the bottom of the stroke before reversing, then same thing before going forward again.
 
Is it appropriate to put a dab of seam sealer at the terminations? When I hand stitch non-life support items, I always do that (for some stuff, I put super glue on a toothpick and then with magnification touch my termination stitches).
 
Is it appropriate to put a dab of seam sealer at the terminations? When I hand stitch non-life support items, I always do that (for some stuff, I put super glue on a toothpick and then with magnification touch my termination stitches).
That works. I do the same on some hand sewn things like leather work.

Sent from my SM-G991U using Tapatalk
 
I don't have the same machine at you (I have a juki 1541). But I did have to adjust my forward and reverse stitch length to get them equal. It was tedious but the end result is very nice. I started at a short stitch length, as I found it easier to tell differences in the stitch length the more stitches I sewed. I slowly crept up on equal lengths. Then I changed to a longer stitch length and made further adjustment. Keep at it and you can achieve equal stitch lengths!
Since you have a needle positioner it should be easier. But I found it crucial on my machine to have the needle at the bottom of the stroke before reversing, then same thing before going forward again.

thx for the input. i will keep in mind the point about keeping the needle at bottom dead center before reversing. thx.

to test length, i hand wheeled 11 stitches, which gave me 10 lengths between stitches. the divided total length by 10. and did the same with reverse.

for 206RB4 model, and i am guessing prior versions, it doesn’t have the parts to adjust stitch length to make them even. At least as far as i can tell. it had a pinch screw, but changing the location does not change anything. this is different than RB5 and new seikos. the newer ones have the pinch screw on a different part.

i believe/guess that these machines were made to have equal fwd and reverse when perfectly in tune.

maybe i could mess with the tuning more, but i went overit twice already. plus, my stitch length selector changes in 0.5 mm adjustments, and since my reverse is always 0.5 less than fwd at current setup, as it is easy to crank the length knob one click, i’ll call it good for now.

i guess it will add to the “character” of the machine.


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