Singer 7-33 Stitching problem & parts

[hackish]

9 hours ago, mikesc said:

Any chance that you have a speck of dirt inside of the spring tensioner ( the barrel part that it sits in ) or even in the spring coil, that would make it stick just ever so slightly from time to time and give a "loop"..had that problem with a totaly different machine, was driving me nuts until I thought strip and clean it and maybe inspiration will come to me whilst I do that, there was the tiniest amount of dirt on a cotton bud when I cleaned it, put it back together and its sewed perfectly from then on..then again maybe I just let the gremlin out when I stripped it.

I've had the shuttle spring in and out probably 5 times so it is definitely clean. For the lower tension on the machine itself I can watch the tension pulley rotate with each stitch so there is nothing evident there. I've had every part of the machine I can think of apart several times. I may have reached my limit of frustration. I think I should buy a few parts I know need replacing and buy a Consew 733-5 or 733-25. The number of hours I've wasted on this machine I probably could have bought a new one anyway.

[Singermania]

You also have a lot of white crap coming off the thread... starting right at the top (secondary) tension unit, if that is normal for this kind of thread then 'ok', but if not it indicates to me the top thread is under considerable strain.  I have eight or so 7 class Singers and a few even bigger Adler, but don't recall any of them doing that.  With regards to rotation off the bobbin, I find it can go either way and is not critical.   Lastly you are sewing tight weave webbing, this stuff sticks to or closes up around the long left groove in the needle not allowing the thread to hide in there...(yes technical speak), try going up a needle size to increase the size of that groove.

Look forward to hearing your results.

[hackish]

28 minutes ago, Singermania said:

When these type of problems occur its a good idea to swap the thread for a completely different brand or type, replace the needle.   Some machines simply don't like some threads.   Also both of your top tension units are wound up tight, I'd back them right off and try again.   Overtight on top will drop stitches.

I have coates, american eford and a DJA (made in the USA) branded thread. The factories are primarily using coates. I will try backing everything off again. The frustrating thing is that I can't tolerate a single messed up stitch. Since a harness is a life saving device you can't just rip out a faulty seam and do it over a bunch of times. Lots of $$$ and time in the trash if the machine messes up.

[hackish]

6 minutes ago, Singermania said:

You also have a lot of white crap coming off the thread... starting right at the top (secondary) tension unit, if that is normal for this kind of thread then 'ok', but if not it indicates to me the top thread is under considerable strain.  I have eight or so 7 class Singers and a few even bigger Adler, but don't recall any of them doing that.  With regards to rotation off the bobbin, I find it can go either way and is not critical.   Lastly you are sewing tight weave webbing, this stuff sticks to or closes up around the long left groove in the needle not allowing the thread to hide in there...(yes technical speak), try going up a needle size to increase the size of that groove.

Look forward to hearing your results.

I think the thread is under a lot of strain at this point. I've been starting with the bobbin loose as hell and then cranking the top tensions up every pass to see if it is getting better or worse. I'll then add a bit to the bottom and repeat the process.

[Singermania]

Yes I understand what you mean about getting it right, with leatherwork there can be no compromise !!

 

[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.

[TinkerTailor]

[Gregg From Keystone Sewing]

22 hours ago, hackish said:

Wanted to share some success...

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.

 

Sweet, it takes effort on both sides, and you were able to understand and articulate what parts you were after to make this machine work.  You never know how these things are going to go when I send out parts and someone else does the work, glad I was able to be a part of getting your machine back up and running.

Edited October 12, 2016 by Gregg From Keystone Sewing

[hackish]

Next question I have... does anyone have a Singer class 7 that has been modified for higher lift? This machine was supposed to have 1 1/4" lift but I never thought to measure it when it arrived since my bigger priority was getting it to sew. I measured it yesterday and it has 0.750" excluding the height of the feed dogs. I would like to see any photos of how the mod is done so I can send them to the original seller and explain that it definitively does not have the modification done.

 

[CowboyBob]

Lift the foot up all the way & you'll see where it hits the casting,you take all the parts off & put it in a bandsaw & cut the underneath side of the casting(where the needlebar comes out) & fill in the slot on the lifter handle backet (flat piece in the side) w/braze so the slot is shorter.

[mikesc]

27 minutes ago, CowboyBob said:

put it in a bandsaw & cut the underneath side of the casting(where the needlebar comes out)

You've just got to love the nonchalance in that phrase.

[hackish]

The seller claims it has been modified. He's sending instructions so I'll run through and verify them. I don't have a "stock" 7-33 to compare it with. I'm particular enough that I'd put something like this on a mill and cut it so you couldn't tell but there aren't many people who are this anal. Can anyone snap a photo of a modified or unmodified specimen?

[Gregg From Keystone Sewing]

We normally put these into our 1960s Bridgeport to cut the frame away, but hacksaw has and may be done in the future as well!  I've seen my dad cut the frame away on these with a hacksaw more than once, and is perfectly acceptable.  Looks like someone did this highlift with a hacksaw as well, and machine may have shown up to us in that condition.

Kindly note this is not the only thing we do to get this machine to one inch of presser foot clearance from Singer factory standard 9/16"  

[hackish]

Sure took some looking to see which part was cut. I'm pretty confident that this thing was never modified to 1 1/4" lift. 3/4" difference is a _LOT_. I can see there was some hackery done to the lifter link. Maybe I can bling the machine up and cut a piece of 1/8 SS with a relocated slot. Looking at how the mechanism lifts, I suspect I could take some material off the machine frame and some off the lifter assembly. I pulled the link off and the piece is cracked anyway.

[Singermania]

Yeah that's a pretty ordinary modification.   Singer in their wisdom work out what they think the max for these machines might be, you can go greater but expect to put the machine under extra stress.    There are new machines on the market with the kind of lift you are talking about.

[1985]

On 10/6/2016 at 2:04 PM, Constabulary said:

I don´t know the Class 7 machines but can you try to adjust the needle bar hight or is the needle bar pinned? I would guess you have to lover the needle bar a little bit.

As I am no means an expert on the industrial machines but I do own a 7-33 , not actually used it yet, until I check and clean a few things first, As it was stated you did fix the issue changing a couple of things , so I thought ill still suggest what I check ,

But its usually obvious to blame the tension but as it stitches then at some point the thread gathers or misses a stitch surely there has to be other factors that all may contribute to 1 issue, as I say I am no expert but some times its not the obvious that is the usual culprit for the issue,I my self run through a list , not all but it helps to check not the obvious. 

Left or right twist thread top side- needle thread to thick or thin for the groove in the needle - pushing the work through when should only guide- needle plate hole become to big allowing the surrounding material to raise down and up around the needle snatching the thread- check to see if bonded nylon does not untwist in fingers and thumbs when testing, Thread on the spool,make sure its not sticking together as it comes of the spool and needs to come off smooth ,but not to loose` neither to tight -If using thread that needs wax make sure the thread is getting its lube- check thread is not fraying ie rubbing on all passage ways it runs, check correct needle for material and thread- needle not bending as it pushes through material- check for wear grooves in inside and out where thread passes, 

I suspect different softer materials it may not happen but hits a problem with certain tighter material or thickness , this it where the needle thickness and point is very important,and so thread, if theses were all checked correctly and tension correct then I suspect it was a number of things contributing to the issue. not just one,