Necchi BU Nova and tensioner troubleshooting

Necchi BU Nova

I have three Necchi BU Novas

• one with no motor at all, which I will call "Motorless Necchi"
• one with a motor with wiring so bad that it looks like it would burn your house down.  Named for the purposes of this blog "Bad Wire Necchi"
• the only working one in an original (if terrible looking) Necchi case.  We'll call this one "Motor Necchi"

Motorless Necchi

Eventually the global pandemic will end and I will be willing to go to the NC TOGA, an annual swap meet for vintage sewing machine enthusiasts.  Not this year, though.   This machine could go into a treadle, and I have heard that a minor modification will allow it to fit into a Singer treadle.  I have not seen or tested this myself so I'm not going to comment on that further.  When I get back to the swap meet I will take this one to sell.  Unless one of my local friends wants to buy it through the front-porch-drop method!

Bad Wire Necchi  

In most cases external motors are interchangeable on vintage sewing machines.  I have a box full of motors and I had planned to replace the one on the Bad Wire Necchi and offer it for sale at the "friends and family" price (because not having the original motor destroys the "collectability" value).

The first problem I encountered was the fact that the motor mount is completely different on the Necchi than on most of the vintage machines I see.  For starters, the thingy (motor controller plug receptacle?) that the motor controller (aka foot pedal) plugs into is built into the motor mount.  This wouldn't create a problem if I replaced the motor because the new motor would need a different motor controller wiring system of its own.  Does this make any sense at all?  

This photo fails to show you the motor mount and doesn't even do a very good job of showing the two attachment screws.  But I'm not getting the machine back out to take more photos. 

The Necchi attachment of the motor mount to the machine is much better than the typical mount because it has two bolt attachment holes which will hold the motor more securely than one would do.  The bolt holes are also positioned lower on the pillar.

"No problem", I thought to myself.  "The trusty Dremel can grind away a bit of the motor attachment post on the replacement motor and I can just slide it into place on one of the bolt holes."

Motor and hand wheel MUST align properly

No such luck.  Even if I did that the motor would not be aligned with the drive shaft on the Necchi sewing machine.  And that is a deal breaker.

Even if I could mount this replacement motor, it would not align with the hand wheel

So Bad Wire Necchi is in an indefinite time out.  Last summer Missie gave me a lesson in taking apart a motor and doing all the necessary stuff to get it in good working order.  And it really does not seem too complicated.  But I'm not all that confident in my ability to do this myself.  Eventually I may get desperate enough to tackle a motor by myself (and with the help of that ultimate guru, YouTube).  I have several machines that need this kind of help.

Motor Necchi

I had tested this one before and had marked it "best of the BUs".  That was probably in 2018 because I know I acquired two Necchi BUs at the 2018 NC TOGA.  Linda may have forgiven me by now for beating her to this one.  She wanted the case and failed to talk me into letting her have it.

I still had the piece of cloth on which I had tested the stitches in the machine and it looked fine.  But when I re-tested it this time there was a small problem with the upper tension which left a tiny loop on the underneath side at intervals.  Problems which show up on the underneath side are usually problems with the top tension.  Problems which show up on the top are usually problems with the bottom tension.

See the glitch, near the center of the lower line of stitching

Easily 90% of the tech support calls* I get from friends and former customers involve "nesting" of thread on the bottom, also referred to as "thread mess".  These are highly technical terms, you understand.

*if you buy a machine from me, if you are a friend or family member, or a family member of a friend, or a friend of a family member or just someone who once upon a time got my phone number from someone, you can call me on the phone for technical support.  I'm much less willing (translation: completely unwilling) to do this by typing into my computer however, and more likely just to give you a link to a blog post.  Like this one.

So, thread mess on the bottom is probably upper thread tension problem and I love these calls because most of the time I can help the person fix it in a minute or two over the phone.  Here's what you do:

First of all DO NOT BEGIN BY ADJUSTING THE TENSIONER.  That is probably not the problem.  Most of the time the thread has just ended up in the wrong position in or behind the tensioner.  If you already adjusted the tensioner, no worries.  You can always adjust it back again after trying what I recommend below.

not easy to see the discs on the Necchi tensioner, but the thread must go between them

Un-thread and re-thread the machine.  Make sure your presser foot is UP while you do it. Lifting the presser foot opens the tensions discs (they move a bit apart from one another) allowing the thread to seat itself properly inside.  Make sure the thread is going IN BETWEEN  the tension discs and not behind them (this is a problem on some models but not all).  When you lower the presser foot the discs will move back together and the thread will have tension on it as it should.

no easier to see the discs from the other side

And of the calls I get about thread mess on the bottom, this has always helped.  As far as I can remember, which admittedly is not very far.   People have brought machines to me but not for this.  Because we have fixed it over the phone.  

And although I specialize in vintage rather than modern machines, the same troubleshooting goes for modern machines where the tensioner is hidden from sight within the machine.  Un-thread and re-thread with the presser foot up.  Take two aspirins and call me in the morning.

Didn't work on Motor Necchi however.  In the hopes that writing about the troubleshooting process might be helpful to someone, I'm going to detail the steps I followed.  You start with the quickest and easiest things first.  Do one thing at a time and check by sewing a test line after each step.

• Un-threaded and re-threaded as described above.  Didn't solve the problem.
• Replaced the needle, because a burr on the needle can affect the way the thread flows through.  Still no luck.
• Replaced the bobbin because a bobbin with a rough spot or badly wound thread can cause trouble.  No luck.
• Took out the bobbin race and checked the point.  If the needle strikes this it can cause a roughness on it.  The pointy tip of the race did feel as if it might have a burr on it.  I took some 400 grit sandpaper and smoothed it down.  It felt smoother after that but this still did not solve the problem.

By this point I was getting worried because it seemed likely that the problem was INSIDE the tensioner.  And I was just not in the mood to disassemble an unfamiliar tensioner.  However there was one more thing I had heard of but had never tried.  The dollar bill trick.

• Took a dollar bill and used it to floss the inner surfaces of the tension discs.  The theory, as I understand it, is that the printing on US currency is slightly abrasive and the bills themselves are tough enough to stand up to this treatment.  The edges of the dollar bill did get grubby and whaddaya know--it worked!  I'm guessing that the gunk that was in there had been sporadically interfering with the flow of the thread through the discs.  With at least some of the gunk removed the thread stopped stuttering and the tiny loops created on the underneath side of the fabric stopped forming.

Along the top edge of the bill you can see the gunk it removed

Is this a lazy way to solve the problem in an incomplete fashion?  Yes.  Should I still disassemble the tensioner and give it a thorough cleaning?.  Also yes.  Is this going to happen?  No, it is not.  Not any time soon at least.

So Motor Necchi is up and running and I find I DO NOT want to sell it.  The speed and power are impressive.  Speed is easy to evaluate, and although I don't have a quantitative way to test it, this machine goes like blazes.  I can FEEL the power and I do have a testing procedure for this.  Here it is:

• Set the stitch length to "medium", whatever is in the middle of your stitch length lever or whatever is the default setting on your electronic machine.
• Take a long length of muslin or something like quilting cotton.  I tear off a width-of-bolt strip about four inches wide.  Using two different thread colors allows you to see if the tension is balanced.  This time I had black thread on the top and a pale pink in the bobbin.
• Fold the fabric with the short sides together.  So now instead of it being 42 inches long it is 21 inches long.
• Sew a couple of inches.  ANY machine ought to be able to handle two layers of light cotton!
• Needle down, raise the presser foot and fold the end of the fabric up to the needle.
• Presser foot down, sew a couple more inches.  Now you are sewing through four layers of cotton.  Again, any machine should be able to handle this.
• Repeat. (needle down, presser foot up, fold, presser foot down, sew).  Now you are sewing through eight layers.  Usually I stop at this point.  Most of the machines I test, even those lovely all metal vintage machines, are going to balk at doubling the layers again.
• HOWEVER, Motor Necchi sewed through sixteen layers like butter.  I didn't feel the need to try 32 layers.  And anyway I had gotten to the end of the fabric by then.

Each time you fold it up, you are doubling the number of layers you are sewing through

Number of layers

There was black thread on the top

There was pink thread in the bobbin.  Note the perfect tension no matter how many layers there were.

And I'm in love.  I have a lot of machines I'm in love with.  I always want to downsize the herd and I have downsized quite a bit (I'm down from around 100 machines to around 75).  But I don't want to part with this one.

I did run into a problem while I was testing this machine.  I'm going to tell you about it and what I tried that DID NOT WORK and what eventually did work.  This is the special niche that the DragonPoodle blog fills:  screwing up and telling you all about it so that you don't need to go down the same wrong road.  You're welcome.

The problem started when I tested the bobbin winder.  A badly wound bobbin such as the one shown in the photo is a recipe for a sewing disaster.

NOT wound on the Necchi.  This one came in a bag of vintage bobbins that I bought at a thrift store.  I find that putting the bobbin on a skewer allows it to spin as I pull the old thread off.

I released the clutch knob as one does to wind the bobbin.  Releasing the clutch means that the needle bar stops going up and down.  When you are ready to sew again, you tighten the clutch back up.

The bobbin winder worked and the bobbin filled smoothly.  However, when I tightened the clutch the handwheel began to slip.  This meant that the machine began slowing down more and more as I sewed.

 I removed the clutch knob by loosening the small screw, shown from the underneath side in the photo.

 

I also removed the clutch washer from the end of the handwheel.

The clutch washer is the silver colored thing shown above

Then I removed the hand wheel and cleaned all of the surfaces with alcohol and q-tips and paper towels.  This is just good basic maintenance on an old machine.

Put it all back together and the problem still existed.  The hand wheel was slipping on its shaft.  i gave this a lot of thought and basically came up with nothing.

So I tried something that I had no reason to believe would work, and indeed, it didn't.

Don't bother doing this at home

 I tried adding plumber's pipe tape because that was the only thing I could think of, and because I had it on hand.  First I tried it on the threads of the clutch knob itself.

 Didn't solve the problem and it tore itself up inside the threads and was a pain in the neck to pick it all back out again.

Next, I tried wrapping it on to the hand wheel shaft.

This also didn't work although it was easier to remove the result after the pipe tape moved itself to the back of the shaft.

After more head scratching I took a closer look at the interior surface of the hand wheel.  Unlike all the other hand wheels I have seen, the Necchi has a deep groove in the middle and had something that looked like an old cord in there.

The red box highlights this interesting feature.

So maybe the purpose of whatever the heck the cord-like object inside was to grip the handwheel and it has given up its grip?  I really have no idea.

But I did have a very thick rubber band thingy.  I always save those big blue rubber bands that come holding broccoli stems together because they are the PERFECT thing to improve the grip on a treadle belt.  I didn't have any of those on hand but I had something that had come with a garment.

I cut a strip off of it the same width as the hand wheel grove and used a skewer to poke it down in there.  Went around the groove twice.  Sorry, no photos because by this time my hair was on fire.  Used a rubber mallet to pound the hand wheel back on to the shaft.  That puppy is NOT going to slip.  And it sews just fine now without slowing down.

It's also never going to release for bobbin winding purposes.  But Linda kindly informed me that where I originally went wrong was in releasing the clutch knob in the first place.  "I never do that" she said. 



Do you have a Necchi BU Nova?  What has your experience been with it?