PDA

View Full Version : Kinda OT? Industrial sewing machine



Tommo
11-16-2012, 10:49 AM
So, (get it?) I have this Bernina sewing machine that's been stretched about 13" and converted to take a Consew bobbin.
Machine worked great for years, but all of a sudden I can't get it to either stay timed correctly or keep it from ruining the thread w/in about five strokes. I've gone the route thus far of therapeutic dissasembly/reassembly with the bobbin and carrier, ingeniously set up w/ a bevel drive (not by me).
I cannot feel or see anything obviously wrong. I'm running out of ideas, and this machine has to work or I lose money w/ it just sitting there. I need fresh ideas, so if anyone has any relevent experience or otherwise, I'm willing to listen.

Mike P
11-16-2012, 03:02 PM
So it can be timed, or so you think it is, until you try to sew with it, right? Is it the top thread that's shredding?

Have you polished the hook, and everything near the hook? The tinyest little burr can foul up the thread every time. Also check the feed dog plate for burrs in the needle hole (where the needle passes down through the deck of the machine).

Upper tension is ok?

Can you operate the machine slowly, with it tipped up out of the table and watch the thread form a loop, and watch the hook grab the loop, etc.... Sometimes you'll be able to see where/when in the process the snarl is happening.

Mike P

MrFluffy
11-16-2012, 03:58 PM
So, (get it?) I have this Bernina sewing machine that's been stretched about 13" and converted to take a Consew bobbin.
Machine worked great for years, but all of a sudden I can't get it to either stay timed correctly or keep it from ruining the thread w/in about five strokes. I've gone the route thus far of therapeutic dissasembly/reassembly with the bobbin and carrier, ingeniously set up w/ a bevel drive (not by me).
I cannot feel or see anything obviously wrong. I'm running out of ideas, and this machine has to work or I lose money w/ it just sitting there. I need fresh ideas, so if anyone has any relevent experience or otherwise, I'm willing to listen.
I just had to change the bobbin case on my wife's machine (janome computer controlled thing), and after a period of naughtyness its now itself behaving again. It was doing exactly this, sewing a few then going out of time. We ordered case and feed dogs as they feel rounded, but havent had to put the feed dogs in yet.
Very curious about how the extension has been done, do you have any inside pics? my wife has a little gracie quilting frame and has been asking me what I think of extending her high speed brother when I have time as a project...

Bob Fisher
11-16-2012, 04:00 PM
Everything Mike said ! I would also look at the needle. There is also an adjustment to set the distance between the needle and hook, sometimes gets knocked away by a jam. If the hook doesn't get cleanly through the loop, it will shred the thread.All of this of course, depends on the timing forming an appropriately sized loop at the right time. My machine is at times just as useful as the lathe or any other machine in my shop. Bob.

maweis
11-16-2012, 04:23 PM
Have not worked on that brand of machine, but have worked on several sewing machines from toys to industrial.
As said in the previous posts, burs in the thread path, both top and bottom. Needles with burs in the eye and slightly bent, not correct length, to not seating completely in the holder which causes the hook to miss the loop
and even tension control and pickup spring can drive one to drink. Drive dogs worn or not at the right height, or timed, with the pressure foot pressure not adjust just right. My 86 year old mother, who still customs
sews complains that todays materials and coatings are harder to work with then the older stuff. Some of the new material seems to be slicker and just does not feed right. Have found bad bobbins (burs) and mismarked
new needles which causes one to think.

Mark

Oldbrock
11-16-2012, 04:37 PM
Look inside. My daughter has an industrial walking foot Pfaff and the rocking shafts inside had the locknuts on the center pivots come loose letting the support center type screws back off letting the rocking shafts wobble and causing all kinds of trouble. I adjusted the centers and locked the locknuts and all was well. Probably not that but it's worth a look. Peter

GadgetBuilder
11-16-2012, 05:36 PM
My wife has a Brother ULT embroidery/sewing machine which I maintain. Quite a bit different from your commercial machine in that the bobbin holder is plastic. However, some of what I've learned may apply, see:
http://www.annsultfixit.com/UltFixit.html#Burrs

In general, anything that disturbs the top thread on the way to the rotary hook can cause the thread to break. A bad needle, bad thread, thread not coming off the spool smoothly, problems with the top tension, a burr anywhere along the thread path, junk in the needle holder preventing it from seating, etc. I've only seen one instance of timing problems- it caused failure to stitch rather than thread breakage - but that's not to say it couldn't cause thread breakage.

Dr Stan
11-16-2012, 06:57 PM
I just ordered a variable strobe at work where we have close to 400 sewing machine heads. It should make the lives of our sewing machine mechanics a whole lot easier. You may want to beg, borrow, steal, or buy one to help see just what's going on with your machine.

Tommo
11-16-2012, 08:10 PM
Good replies, one and all. I spent the most part of today with it. I got to the point where it will sew a straight stitch all day long but as soon as I put it on zig-zag it misses on the right and/or ruins the thread. I'm thinking the timing might be a hair's breadth off between picking up the thread on the left and the right. I time it on straight. Observing it on z/z, it appears the hook's timing is a wee bit retarded, so it actually pierces the thread.
Short of deducing the minute of angle where it's off, I think I can adjust the timing to suit by splitting the difference.
Another thing I noticed was that if I just walk the machine through the cycle it will pick up the thread regardless, but it will still shred the thread. And since the cloth is still in there when it happens it's impossible to see where it's taking place. Without the cloth in there it won't shred. This would lead me to believe it's either a thread or a needle problem. I've changed needles, sanded the presser foot... I think I'll change thread next, I don't know what else to do.
Tomorrow is another day, I'll hit everything with the 600 grit again.
@McFluffy, I don't know who did the extension or how they did it but it's very convincing. Dont' know what's going on inside the machine but underneath the drive has been extended by means of longer shafts and bevel gears. The conversion to the Consew bobbin was done with what I can only imagine to be great difficulty.
@DrStan, I have a timing strobe, if I just figure out to make the machine run on 12V DC...! Some other day.

Dr Stan
11-16-2012, 08:33 PM
@DrStan, I have a timing strobe, if I just figure out to make the machine run on 12V DC...! Some other day.

That reminds me, I forgot to mention the strobe is $1000.00. :)

Gunney
11-16-2012, 09:38 PM
Many moons ago, I used to repair Berninas (other brands, too, but mainly Bernina). Early on I learned that whenever I got a machine in for repair, the first thing I would do was replace the thread and needle. It has been a long time ago, but I think I always kept some Guterman (not sure of spelling) thread in my tool box. Sometimes the thread that came in with the machines would be really cheap thread and my theory is that the cheaper thread has variations in diameter and loose fibers that cause just enough variation in thread tension to cause problems. You wouldn't believe how many times just changing the thread and needle would fix a problem.

Bob Fisher
11-16-2012, 10:35 PM
Who would have ever thought that there was that much knowledge about sewing machines on a machining site? But then again, they are all machines, they just produce different results. Bob.

Tommo
11-17-2012, 10:43 AM
In all fairness, this isn't your average machine. I own a small sail loft; I've worked in sail lofts that had machines that could sew through plywood! It's common for sailmakers to make changes, conversions etc to machines; stretching is common. Usually this kind of work is farmed out to 80 y.o. machinists because they have the skillset necessary to do it. The gentleman that did this one passed away two years ago after slipping on a patch of ice and whacking his head.

Black Forest
11-17-2012, 11:28 AM
In all fairness, this isn't your average machine. I own a small sail loft; I've worked in sail lofts that had machines that could sew through plywood! It's common for sailmakers to make changes, conversions etc to machines; stretching is common. Usually this kind of work is farmed out to 80 y.o. machinists because they have the skillset necessary to do it. The gentleman that did this one passed away two years ago after slipping on a patch of ice and whacking his head.

I was going to ask what you use the machine to sew. I have a sewing machine that will sew through 7/8 of harness leather. It is air operated. Perfect for us hobbyists because it will sew as slow as two stitches per minute. It is great for doing repairs on my horse equipment because I can go back into the same holes.

Grind Hard
11-17-2012, 11:32 AM
Who would have ever thought that there was that much knowledge about sewing machines on a machining site? But then again, they are all machines, they just produce different results. Bob.

Not that long ago this very same group of people helped me fix my friend's ultra-complex embroidery machine, sight unseen... just by asking a few questions.

Machine is chugging away making her lots of money. :)

Black Forest
11-17-2012, 11:42 AM
When I was very young I took my mothers brand new Berninia sewing machine apart. I just couldn't figure how the threads could cross without the thread coming out of the needle. It was magic to me.

I couldn't get the machine back together and I had to accompany my mother to the store where she bought it and hand them the box with all the little parts that I had no clue where they went. Mother was not happy with her son.

bborr01
11-17-2012, 12:44 PM
This thread is very timely.

I have had a Consew walking foot industrial sewing machine for the last 10 or 15 years. Used it for doing lots of repair work and making a few things like a seat for a mini-bike that I was restoring to a lot of covers for equipment, etc.

Well, I had a Rand McNally atlas that was pretty new but the plastic cover got torn off. Soooooo, I look at it and decided to try to repair the binding with stitching instead of staples. It worked great. Next up was cutting the tabs off from manila folders and running them through the printer, put machine manuals in them and stitch bind them. It also worked great. That is until I put a few too many pages in it and broke the needle.
It wouldn't pick the thread up from the bobbin after that and has been sitting for a while until I got the time to check in with this board and ask how to fix it. It looks like I have enough information alread from reading through this thread to fix it.

Thanks Everyone,
Brian

Tommo
11-17-2012, 08:23 PM
Thought I'd follow up w/ the solution. For some reason, the pillow block that holds the shaft for the bobbin carrier was juuuuuust slightly off. I had to drill the hole holding one side of it out about .010" bigger so I could cant it a bit to make the hook pick up on the right. I have no idea how it had worked in the past. The guy who sold it to me said, "The more you look at how a sewing machine works, the more incredible it seems that it works at all."
He wasn't kidding!