Things I learned or remembered while servicing the 99 twins - Very Long!
 

(This is basically a copy and paste of what I posted on my blog this morning)

So, I sat down at 10pm last night, and figured I’d try to figure out what was going on with the 99s.


Using the one bobbin case between the two, one machine insisted on the bobbin tension being fully tightened in, and the other one only worked with zero tension. You could actually see the spring wasn’t touching anything on the non-screw side. You could stick a dime in between the spring and the body of the bobbin case. Both gave almost, but not entirely acceptable tension balance results.

Additionally, the tension seemed to fluctuate on Jellybean, and possibly the "parts" machine as well (testing was more extensive on Jellybean). Sometimes it would seem that the needle tension was too loose, but a few inches later, with no adjustments from me, it would change, sometimes perfect, sometimes too tight.

The machines were cleaned a couple of days ago, including complete dis-assembly of the upper tensioner, and removal of the bobbin case, and the entire bobbin area cleaned.


Same bobbin case, extremely different results. It seems to point toward the needle tensioner being out of whack, doesn’t it?


Not in this case. I even swapped the upper tensioners into the opposite machines, and got the same results. Yuck. I was hoping for a quick fix, and got a mystery.


The singer manual says the following for adjusting bobbin tension:This is all well and good on a properly adjusted machine with no “issues” needing to be addressed first. No setting on the upper dial would give good consistent tension.


I also noticed in the manual that it says:
[ATTACH=CONFIG]351676[/ATTACH]
Singer 99k bobbin case installed – the bobbin case position bracket is the long finger you see leading to the bottom of the picture. The screw (EE in Singers Owner’s Manual for the 99K) is the one in the middle of the finger with the ruined slot on the top.



Screw EE being the screw that holds the bobbin positioning finger (bracket) in place.


What the heck, I’m an adventurous person, I threw caution to the wind and decided to disregard Singer’s warning. Besides, the screw on both machines was far from unmolested. Both showed evidence of having been tampered with by a non-mechanically inclined person. Additionally, they both were set a little differently from each other. In fact, besides the bobbin spring tension, it was the only thing I could find that looked different.


I made careful note of the position of the positioning bracket on each machine so I could put it back if I needed to, and proceeded to disassemble.


The first thing I noticed is that the position of the positioning finger did affect tension, but in the completely opposite way I had guessed that it would. Moving it further away from the bobbin case cased the upper tension to end up way loose. If the tension was almost balanced at a 4, it now needed a 7 or greater to not ball up under the fabric.


I played with it for a bit longer, on both machines, and didn’t really get the results I was looking for. By now it was after midnight, and I was starting to get frustrated. I knew I had to be missing something simple.


I hit google and bing and struck out. I read a bunch of tension tutorials hoping to find something I was missing. Nope, it didn’t seem like it. I tried googling for model 99 or 66 specific tension issues and decided that google’s polluted. The results weren’t useful at all.


Finally, I recalled a set of pdfs, I’d downloaded a few months ago and went looking for them again. This is where I’d originally found them.

http://www.tfsr.org/publications/tec...achine_manual/


In the end, this is what saved my sanity.


I basically stepped through this tutorial, and had a working pair of machines about 20 minutes later, even though the issue I appear to have been suffering wasn’t specifically addressed in the tutorial, it was a comment about what would cause the bobbin tension to not have enough adjustment that lead me to the solution.
In my case, I got a ziplock baggie, and filled it with 1oz of Kamut berries, tied a piece of the thread from the bobbin to it and tested that way.

[ATTACH=CONFIG]351677[/ATTACH]
Bobbin Case with weight
When the thread just unwound regardless of the tension, I knew where the problem was, and promptly disassembled the bobbin case spring from the case.


There was oil and debris under the spring, but nothing I would expect to hold it out and make it unadjustable. Still, I reassembled, and tested again. I still couldn’t adjust the spring enough. Damn, it looks like the spring must be damaged.


I took a really close look at it (and unfortunately forgot to take a picture) and found that there seemed to be the tiniest little kink in the spring, just past where the thread enters the bobbin case, which meant that it didn’t lay flat against the case, like it does in all of the other tension springs I’ve ever looked at.
Figuring that I had nothing left to lose with this spring, I gently reformed it to lay flat against the bobbin case. I reassembled and tested again. The bobbin case held the Kamut off the desk.

Success!


In the long term, I will likely order a new spring (Singer’s part number for this is 32567 and it’s available at some of the online shops.)


Looking a little further in the tutorial, it shows how to properly adjust the bobbin position finger to keep the mechanism working, and somewhat quieter: I learned / remembered:

• tension problems can be anywhere, and often not where you think they are
• dirt and oil can get in everywhere! Remove those tension springs and clean in between periodically. If your bobbin tension is good prior to this, tighten the spring completely, counting the number of turns it takes to get to full tight (write this down), then remove the spring. This will save you the effort of having to “weigh” the tension like I did above.
• Nearly everything is fixable if you approach it logically and with your “eyes open”. You should never be afraid of disassembling something to take care of it for fear of messing it up. Be careful, be engaged in what you’re doing, and enjoy it. This isn’t something that has to be stressful
• not all parts need to be replaced, sometimes you can fix them, if only as proof of concept
• Sometimes you have to disregard warnings and “Do NOTs” in the original owner’s manuals. As long as you proceed carefully, and document well so you can put it back together, it’s often OK to do this. This is especially true when working on something that you’re not the original owner of
• Google’s polluted
• statistically, you’re never going to be the first person to experience a problem. Also statistically, chances are, your solution is already documented somewhere, you just have to find it.
• pack-ratting is good. It helps you “find” your solution faster if you already have it saved and stored somewhere close

Wow , are you smart, and brave!

ArchaicArcane,

Thanks, I bookmarked this for future reference. I went through a lot of headaches with my second 99K just recently looking for tension problems. They weren't where I thought they would be. As you said, tension problems can be anywhere.

Google IS polluted, no question about that.

Joe

ArchaicArcane,

Just a question.
How big should the gap be? And what do you use to adjust it? I got one to replace the rusted one on my 99K and it came to me with the lever removed. I put it back where it looked like it was, and the machine sews but I'd like to make sure it's right.
Oh and what section in the TFSR manual is this info found?

Joe

that gap in the positioner "Finger" is the reason most home machine are limited in thread weights. Use a heavy ( or fuzzy bulky) thread and that gap ( or lack of) creates extra bottom tension I tried for many hours to find a non standard happy medium with my 306 to get it to use upholstery weight thread (#69)... to no avail, in the end i got a true pin type feeler gauge and set it to manual specs, and it does work very nicely with the threads it was designed for. Fixed some of the Skipping problems I was having with wide Zig Zag stitching. I was lucky to find the Singer service manual... and the gap was spelled out for me ( in thousands of an inch)

So.... Mr. greywuufy would you be willing to share the spec? Kind of like .xxx" with a pic of where to take the measurements at?
I don't have a Singer Service manual for the 66 and 99s and the others that use that design.

Joe

The only Service manual I have is for my 306W... I can share that spec ( after I get home.. its pdf on my computer somewhere)
I do not know if the spec is the same for other machines. What I do know is if you get it to tight... it drasticly increases the bobin tension and throws the balance way off.( but it does reduce the noise in the hook area that people complain about in the 306's)


I should mention that the Books uses the term "check" to describe the action... as in make sure that the Finger lightly "checks" the thread as is passes through the gap.

if you keep that in mind I think you can come very close without a feeler gauge. it just keeps the bobin thread "in check" as the hook roates.... the spring on the bobin case provide the adjustable tension, but a loop is pulled out and then as the loop passes Around the hook, the bobbin no longer has control of it, the light touch of the "finger" just keeps it from "overshooting" due to inertia...... Does that make any sense? it is really easy to see on the 306 as it has a vertical hook that is oriented towards you as you sew.... so in my treadle with no drip pan I can actually watch the action as I slowly rotate it by hand......and trust me i have spent a GOOD deal of time doing just that.

greywuuf,

Yes it does make sense. Somewhere, and I don't remember where, in one of the manuals I saw the spec of .020" for clearance between the spring and hook in a machine with a Class 15 bobbin. This came about because the little spring in the bobbin / hook area in my MW 7 Jewell had been bent to zero clearance and the tension was alllllllll messed up. Birds nests of mega proportions. I took it all apart and straightened it till there was some clearance and all is well again.

I wonder if this could be the cause for the noise in the later Singers with the horizontal drop in bobbins? I've got 5 of them that clatter and tinkle in that area. Hmmmmm, something to check.

Joe

It really comes down to the fact that I had nothing (or at least very little) to lose. They were both unusable machines as they sat.

In my "real life" I'm trained to follow a logic process (computer geek) to solve a problem, so this was pretty much just applying my training to sewing machine repair.

Tension has been my problem for years. (Not just the stuff between my shoulders either!) It's why it was the first post I made here. I started sewing when I was 10, and the machine (a 290C) my dad bought me for my birthday was in the shop more than it was out, but I still think to this day it wasn't because there was something wrong with the machine, I think it was because the operator never learned how to operate it correctly.

I used to run into a tension problem, and immediately be frustrated, and usually quit. (Of course at the time I didn't know it was a tension problem, I just knew there were nests under the needleplate, multiple threads wrapped around the bobbin case, and sometimes needle shrapnel flying at me.)

I've made it my goal to not run from these issues anymore, and in fact dive in head first and fix the harder ones (like these 99s dealt me)

Yeah, remember when it used to yield hits other than ebay, amazon and worthpoint?

I've got it set to about the width of my test thread. It slides through, but doesn't have room to flop about. I found that if it was too tight, it made a snapping noise when the machine ran, and if it was too loose, the needle thread tension was completely messed. So if it's sewing, and not making loud snapping noises every time the needle thread pushes through there, it's probably pretty close.

I used a tiny blade screwdriver, loosened the screw, pushed it around a little, then tightened the screw. There's a pic of that sort of in the tfsr manual. Page H-4
"The lower bobbin area"

I had to go at it in 3 different sessions. I found the problem the day after I got the machines, and made a note to fix it when I did the cleaning. Cleaning day I figured out it was not a simple fix (that's when I found the 2 tension extremes), then the 3rd day, I was just tired of it hanging over my head. Sometimes it works better that way, just step away, instead of getting frustrated. Took me 15 years in IT to figure that one out. :D

Use what you have, eh? I bought the scale for baking, and have an over abundant supply of those berries, so it made nothing but sense. :)
If I read Joe right, the spring he's asking about is the one on the bobbin positioning finger. If that's the case, on the 99 it's actually regulating the needle thread as it comes around and grabs the bobbin thread. That's why pushing the spring too far away from the bobbin case caused my needle thread tension to go haywire. I can post a pic if needed.

Otherwise, all of the principles are the same.

Part of the noise definitely comes from the fact that the bobbin case can rattle around a little, and does when the thread passes through the check point, there's the noise from the "check" as well, other than that, I'm not sure.

Yeah, I spent a lot of time watching that mechanism work in the past few days. :D