Singer 7-33 Stitching problem & parts

[TinkerTailor]

On 10/8/2016 at 5:24 PM, hackish said:

Don't quite understand what you mean about the second tensioner. It's wrapped all the way around the tension disc to make sure it doesn't slip. The manual was printed in 1918. That was before nylon was invented so I expect old cotton thread only needed a single loop.

The lube pot does add some tension to it but it's consistent. I expect that would be at most a tiny change while the problems I'm having are not tweaks to stitch quality, they're major problems. The thread is coated (resin perhaps) and that's what the white flaky stuff is - I could omit the pot.

I can try shimming it. It would be nice to eliminate slop, but the feed dogs fit so well in the needle plate that the slop is only there when I've taken the plate off.

The shuttle tension spring is not really rough but I feel like its related to the problem because it is limited on the amount of tension it can apply. I'm not sure how much is necessary when sewing such thick material. I might spend a few more hours this evening to see if I can make any headway.

On the machine, there are 2 tensioners, one at the top of the machine and one lower down, On the lower one, is it a roller type or a tensioner with 2 discs? If it is the disc type, pull the thread on both sides firmly to make sure it is seated between the discs. As to the lube pot, how can you be sure it is smooth and not causing tension problems? If you are not using it, rethread the machine without it and see if the problem goes away.

Another thing to note, If that machine was used for only 207 for 50 years or so, it is possible that some of the thread path parts are worn in and have grooves that are too small for a 346. There may be grooves in the tension disc or a groove in the takeup lever. Any of these will cause thread abrasion and increase the amount of fluff and fraying of thread as well as causing tension inconsistencies. This also affects bobbin tension adjusters, some people will keep more than one around for when they are switching thread size to eliminate this problem. Unfortunately for you, parts are not nearly as accessible as for say a modern juki walker.

 

Have you thought of rebalancing the tension with a weight on the thread draped over a pencil or with a fish/luggage scale? There are tutorials to do this. You basically pull on the thread with the scale and try to get the top and the bottom to measure the same, then attempt sewing. There is also a way to use a weight on the end of the thread draped over a pencil, and you adjust the tension until the weight will just pull out the thread on the top and bottom. These methods should at least get your tensions close to even and then you can adjust for the material at hand. As to how much weight is good for a pull, someone else is going to have to pipe up because I cant remember. I think it was around 8 oz for my 441, i may be wrong.

Edited October 10, 2016 by TinkerTailor

[Constabulary]

Some of the above hints may sound stupid for you but sewing machines are sometimes a bit self willed and even the tiniest change (even different brand thread or different needle or thread path) can cause some issues. Thats not always the case but it happens. And it gets even worst when two or more smaller issues come together and you have to locate and eliminate them. I still would leave out the wax pot and try a different thread (not same thread from a different spool) and also a thicker needle.

Edited October 10, 2016 by Constabulary

[Singermania]

Yes, Constabulary is on the money, different thread, bigger needle and back off the top tension on both units.  If the primary (bottom one) has a revolving disk encased in other flat disks and felt, make sure its oiled and able to rotate.

[TinkerTailor]

10 minutes ago, Singermania said:

Yes, Constabulary is on the money, different thread, bigger needle and back off the top tension on both units.  If the primary (bottom one) has a revolving disk encased in other flat disks and felt, make sure its oiled and able to rotate.

I couldn't see in the photos which type of tensioner it was. When I first got my 441, I got the 2 upper tensions way out of wack with each other and it caused all sorts of issues with uneven stitching, it wasn't until I went back to square one with the tensions using a weight that I got it close enough to stitching nice that I was able to fine tune it.

Hackish, don't get discouraged and don't let the machine beat you. It is just a machine, You can beat it.

The other thing is, with any machine that is new to you, try not to switch more than one thing at a time. If you change thread and needle at the same time, and the problem goes away, you never know which one caused it.

Go step by step. You have already eliminated some of the obvious and tried the standard fixes, so it must be either something you have not tried or a combination of things.  First, since you played with the tension so much, back them all off and make them even but fairly loose. Then try to stitch. if its good, fine tune. If not, next change thread to a different style, if it gets better, keep the thread, if it does not change, go back to original thread. Then change the needle, same thing, if it gets better, keep it, if not go back to old needle. Next wrap the thread the other way around the top tensioner. Its probably wrong but maybe not. Then do it to the bottom. Then skip a tensioner. Then skip the other one. The steps above can be done in any order, the idea is to discover which part of the mechanism is the culprit by eliminating the all possiblilities one at a time,. If you ask around the correct way to thread a 441 style machine, there are a few methods out there, and most will work. Not all work for everybody in all situations but none are wrong. Your solution my be in adding an extra wrap on a tensioner or even skipping one altogether. You are manufacturing modern materials in a machine from way before the plastic age remember. It may be commonly used for this but never was specifically designed for your situation, and as such you may have to do things not in the way intended.

 

[TinkerTailor]

I also wanted to pass on a story of a machine fight I have been dealing with for years. I have an old Volvo 242 from the 70's. It has a perfect body and interior When i bought it, it had low mileage and the schoolteacher told me it like to be driven with the choke half way on. The car ran good, and i assumed it was just a carb rebuild, so I bought it for really cheap. Shipped the carb away and had it rebuilt, same problems, ran crappy with the choke off. Went through the ignition system, it was all out of wack. Set the points and the mixture and the timing to factory specs and the car would not even run. Over the course of a year and one 20 dollar part after another I replaced the fuel lines, vacuum lines and basically the whole ignition system. Still runs like crap without the choke, and burns buckets of gas with it. I have gone through every dealer repair manual and 2 different other manuals trying to find the problem. Nothing. Funny thing is the engine has great compression. The other day noticed that there was what looked like another older timing mark on the crank pulley, way off from the white painted one that I (and the previous owner) had been using to time the engine.

2 days ago, I pulled the distributor out and it had been installed 1 tooth off into the motor and the whole car had been tuned to barely make it work that way. Someone even painted a new timing mark to go by. With the distributor in correctly, i set the engine to factory specs and it runs like a top.....

I am the 3rd owner, the schoolteacher hated it and sold it off, I know she bought it running like crap. I wonder how long the original owner drove it that way as well. It only has 125000 miles. That is just broke in as old volvos go.

You never know what someone has done to a machine in the past. And sometimes the root of the problem is only found after eliminating all the other obvious solutions.

[hackish]

Ha, TinkerTailor I like the 242 story. I ran a garage/performance shop for a number of years so I've seen a few of the 242's - even one with a mustang 4.6l engine in it

The thing that frustrates me is every time I've bought a used machine it's been a basket case. So I'd figure out what's wrong, order a basket of parts and rebuild it. Time and money with each iteration costs me more than a new machine. People swear the older machines are better and to a point I agree because of the quality of steel and casting/machining. Every day people yell at me because their repairs are still not done because of this one machine. Weeks and weeks of this with no resolution in sight.

I'm good with mechanical things and I have a solid understanding of how most of the machine works (Ok I still don't quite get the walking mechanism) but everything I've done has shown no progress. Traditional adjustments have had the expected consequence - dropped stitches, cut thread, stitch knot moving up and down. As soon as this fine weave confluence wrap material is introduced it all goes to hell. I don't think there is even a repairman's manual giving details of adjustment. That knowledge was probably lost as generations of mechanics retired.

The sewing is a critical junction and if it ever did fail, the user would die. Not maybe die, 100% fall thousands of feet to the earth. The stitching has to be 100% perfect. No hidden nicks inside the stitch, no skipped or missed stitches and proper tension on all 168 stitches of the pattern. Even the thread is traceable right back to the date and batch of chemicals used to dye it. I even examine the needle and log when it was changed.

It's a holiday today in the North so I may get some time to play with it still but honestly I feel like I've tried everything I can think of.

[TinkerTailor]

Happy canadian turkey hangover day..

[Darren Brosowski]

I have seen this before in a machine with a long take up stroke.

What you have is a little bit of thread left on the top that the take up lever has not pulled through but the bottom stitch looks fine. The problem has to exist between the tension discs and the eye of the needle.

Look for anywhere that the thread could be getting snagged between those two points.

 

[shoepatcher]

hackish,

Might just be me  but  the tension spring in the shuttle looks to be a little bent in the picture, . i.e. look at the clearance opening of the spring to the shuttle.  It looks large in the photo but in the illustration in the Singer manual, the opening is much smaller between the spring and the shuttle where the bobbin goes.  Again, it might just be the way the picture was taken.

glenn

[hackish]

Wanted to share some success... finally. Many thanks to Gregg from Keystone. Not only very knowledgeable about the machines in general, but also able to identify and supply all the parts I wanted to replace. The parts that arrived were also good quality.

So... what was the problem? I can't say for certain but I can rule a few things out. I feel like the issue was probably the lower tension spring. The one Gregg supplied was a slightly different shape than the ones I had here. I think it will require just a little fine-tuning of the tension to make the stitches as perfect as I can get them.