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Juki 8700 Tension Problem - Scrap Metal?


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#1 Der Zuschneider

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Posted 06 April 2011 - 04:00 AM

It looks like the machine has a Chinese problem which turns the machine into scrap metal...

Had someone made the experience with the machine, the stitches are not tight enough to secure jet pocket corners.
If you change the tension tighter the machine produces unquiet seams even with longer stitches.

Means the machine is unable to sew dart tips and jet pocket corners which turns those machines into scrap metal.
It can also be the needles they produces are dull, when you use brand new ones.

I am fiddling with that problem for quit a time, was thinking it is me. It looks like it is a Chinese production problem.
You can see the mess with a 10x magnifier.

If I cannot solve the problem then you can only sew with this thing grandmothers hand bags only.

Many people will not be aware of this cause they donít look sharp at their work or think they cannot do better.
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#2 rs232

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Posted 06 April 2011 - 04:11 PM

Have you increased the bobbin tension at the same time?

#3 Der Zuschneider

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Posted 06 April 2011 - 10:18 PM

Nothing is perfect in Life, better avoid Chinese production. Soon I get a Singer 306k, maybe I have more luck.
Let's see how much 8700 they sell when my comment here pops up in Google worldwide.

They better come out of their furt chairs and show up soon!
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#4 Schneidergott

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Posted 07 April 2011 - 02:31 AM

Had a similar problem, but my machines are not Chinese made. I think it is the bobbin case (Spulenkapsel), which seem to be the weakest part. After a while that little springy metal plate tires and the stitches get messy. Once I replaced the bobbin case it was back to normal again.
But don't buy the cheap bobbin cases on US Ebay. Problem is to find anything else nowadays. :Black Eye:

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#5 A TAILOR

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Posted 09 April 2011 - 06:54 AM

try adjusting the needle shaft.
lower the needle till it gets to the lowest point, before it returns back up.
now loosen the screw that secures the needle shaft. allow the shaft to slide down till the needle sits on the bobbin case.
then raise the shaft just a tiny bit. this allows just enough space for the thread to pass between the case and the needle.
hold the shaft at that position and tighten the securing screw.

if that does not work. our own dear "gott" may have the solution for you.

Edited by A TAILOR, 09 April 2011 - 07:00 AM.


#6 Der Zuschneider

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Posted 09 April 2011 - 02:36 PM

I organized me a Singer 306k zigzag, maybe this machine can do it. I needed zigzag so badly.

Posted Image
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#7 Schneidergott

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Posted 09 April 2011 - 04:32 PM

I think it's that little metal spring plate on the bobbin case that causes the trouble:

Posted Image

This one was made of decent West German steel, so it's still doing it's job well.

At least I would give it a try first before I touch more vital parts of the machine. I mean, even a German engineer can screw up things! :p

"Nur der ist Meister seiner Kunst, der immer sucht, das Gute zu verbessern und niemals glaubt, das Beste schon zu haben."
"Only he is a master of his art who always seeks to improve the good and never believes to have the best already"

http://www.dressedwell.net/ It's snarky, but fun.


#8 greger

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Posted 09 April 2011 - 06:35 PM

Nothing like putting in the wrong part. What happens can be, Wow! Won't do that again!

#9 P.T.

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Posted 10 April 2011 - 06:48 AM

You can get genuine Juki parts through the mail online. The pricing is surprisingly reasonable. Juki has an online catalog has schematic drawings and it's here: http://www.juki.com/parts.html I don't think end users can buy from Juki directly but there are resellers that don't charge any markup from the prices displayed there. E.g., Henderson Sewing in Alabama: http://www.hendersonsewing.com They also have cheaper aftermarket replacements for some parts.

I placed an order with them recently. Haven't got it yet but they called me to confirm the day after placing the order and the lady was really friendly, offered to give me some sample needles and things like that.

Edited by P.T., 10 April 2011 - 06:49 AM.


#10 Der Zuschneider

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Posted 10 April 2011 - 06:53 AM

SG is right, I need a new bobbin case probably. I wouldn't meddle with the parts, only what is replaceable.
Like my new singer needs a few new parts. Feet and bobbin case. Needles 206x13 size 12 (80)

I love my new Singer 306 from 1954, hopefully I can make it work nicely.

Edited by Der Zuschneider, 10 April 2011 - 12:01 PM.

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#11 P.T.

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Posted 10 April 2011 - 11:45 AM

You tried adjusting the bobbin tension, right? I heard from lots of people that this was something that should never be attempted--baloney. Check the specs, but I believe on the standard single-needle industrial it's supposed to be about the same tension as the bobbin + case weighs. So you lift the loaded bobbin case up by the thread and adjust the tension screw until it just barely wants to slip down from its own weight. Sew with it a little, then pull the case and make sure the tension has stayed the same.

Anyway that bobbin case is $7. http://www.henderson...B93837146C7CB8F

#12 Der Zuschneider

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Posted 10 April 2011 - 12:02 PM

You tried adjusting the bobbin tension, right? I heard from lots of people that this was something that should never be attempted--baloney. Check the specs, but I believe on the standard single-needle industrial it's supposed to be about the same tension as the bobbin + case weighs. So you lift the loaded bobbin case up by the thread and adjust the tension screw until it just barely wants to slip down from its own weight. Sew with it a little, then pull the case and make sure the tension has stayed the same.

Anyway that bobbin case is $7. http://www.henderson...B93837146C7CB8F


Very exact! But I have not bought a new case right now.
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#13 jeffrey2117

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Posted 20 June 2012 - 12:58 PM

I organized me a Singer 306k zigzag, maybe this machine can do it. I needed zigzag so badly.

Posted Image



Hello Der Zuscheider,

Very nice machine, very beautiful. I like the old machines myself and they usually are very reliable.

The safety issue that you should be aware. The ancient wiring harness for the switch pedal, motor and plugs will be cracked or rapidly degrade from age with increased usage and cause shorts into the electrical system.

I will replace the wire and connectors myself. I replace the old aluminum wire cable with heavier guage copper cable from the hardware store.

The original connectors cannot be found and you must substitute with suitable replacements.

I learned to do this after I faced these problems and it cause a machine needle to go through my finger.

Kindest regards,

Jeffrey2117

p.s. I had to buy a tool for cutting,crimping and stripping the wire
"An intelligent man knows he is ignorant, a ignorant man knows he is intelligent".

#14 Der Zuschneider

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Posted 20 June 2012 - 10:45 PM

Yes, I have seen that with the wires. But it still works. I use the machine very rarely, only for zig zag on canvas.

The thread can be closed, the 8700 has no tension problem.

Edited by Der Zuschneider, 22 June 2012 - 10:04 AM.

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