Lower Tension Adjusting

My Necchi Lelia was giving me some loose stitches yesterday.  Adjusting the upper tension and presser foot pressure had no effect, so I pulled out the bobbin case and checked the tension on it. I have a spring tool that supposedly tells the proper upper and lower tensions 

but I have used it before and am not happy with the results. 

Tension always seems way too tight after adjusting to the tool's marks. 

I read somewhere on the internet that proper Class 15 bobbin case tension could be found by filling a bag with just under 1 1/2 ounces of sugar and hanging that bag of sugar from the bobbin thread.  Not wanting to keep a bag of sugar around to invite ants, I opted for a bag of metal washers instead.

I broke out my cheap-o balance scale 

and measured out 1 1/2 ounces of washers and put them in a zip-lock bag.

Adjust the tension screw on the bobbin case until the bag of sugar slowly drops. If the bag stays suspended, tension is too tight; if the bag drops like a rock, tension is too loose.  

When you have the adjustment just right, re-insert the bobbin case in the machine and adjust upper tension to achieve a balanced stitch. 

I adjusted the Lelia's bobbin tension until the bag dropped slowly and put the bobbin case back in the machine. Stitches were ALMOST perfect, maybe just a tiny bit tight - I had to increase upper tension to '5' to balance the stitches but it gives me a starting point. I will remove washers from the bag one-by-one until I have a measuring device that gives me the result I want.

My next thought is to use some of that left-over spring wire to make a homemade tension scale.

Ed's Vintage Sewing Machine Shop

Ed

Replacing a Necchi Power Cord

The other day I lifted my Nora out of the cabinet to install a light bulb and noticed that the power cord was a bit on the worn-out side.

On my next parts order, I put three replacement cords in my cart and they arrived today. If the Nora had a peculiar cord, I probably wouldn't have been able to find a replacement but, fortunately, this is the same cord used by Lelia, Mirella, Esperia, Supernova and probably other Necchis, so replacement was available.

 I think most people who read this blog know how to replace a power/foot control cord but some might be hesitant so I thought I would go through it step-by-step for those folks.

First, unplug the power cord so you don't get shocked.  Tip the foot control over and remove the screws from the four corners of the bottom plate.

Lift off the bottom plate and insulator below to expose the connection points for the power cord.

Unscrew the two terminals and remove the connectors.  Remove the grommet from the old cord.  Install the grommet on the new cord before connecting the terminals because you can't do it afterwards.

Separate the two wires about 3-4 inches and tie them in a simple knot. This keeps a portion of the cord inside the foot control and relieves any strain on the ceramic guts of the foot control.

Connect the two wires to the two terminals.  On a two-wire system, it makes no difference which wire goes to each terminal.

Reinstall the grommet in the slot in the back of the controller,

set the insulating blanket on the terminals to keep the energized terminals from contacting the metal controller bottom plate and reinstall the bottom plate.

You're now ready to plug it up and take it for a spin!

Necchi Supernova Tension Release Adjustment

Frank was also having a problem with the upper tension release.  He said the disc opening lever “N” in the figure below that is supposed to press the disc opening rod in the back of the tension assembly was not close enough to the end of the release rod to do its job and release the upper tension.  If his machine had the tension assembly removed for any reason or the tension knob had been bumped, the position of the tension mechanism could be incorrect.

Hopefully, this procedure will correct that problem.

It is very important to check whether the position of the tension mechanism is correct.

-          Set the presser bar lever in its intermediate (embroidery) position.

-          Check that the disc opening rod “B” in the below figure is as close as possible to the disc opening lever “N” without actually touching.

-          Ensure that the thread take-up spring can move freely without rubbing against the machine arm.  Distance “a” in the below figure should be about 1/16” (1.5mm)

If an adjustment is needed, loosen screw 048050 GEB and move the entire tension mechanism along its axis (do not rotate it) then tighten screw 048050 GEB firmly.

Ed

Ed's Vintage Sewing Machine Shop

Removing a Supernova Balance Wheel

The first time I had to remove the balance wheel from a Necchi Supernova, I was a bit confused.  I removed the nut but there was no torque washer underneath and the balance wheel would not come off the shaft tail.  When I finally learned, I took photos and now Frank is having the same issue so I decided to post those photos to help Frank and anyone else who hasn't figured this out yet.

STEP 1 - Loosen the two screws in the knurled nut and unscrew.

STEP 2 - The entire inner circle is the torque washer.

STEP 3 - Slide the washer off the shaft.

STEP 4 - Remove the belt and slide the balance wheel off the shaft tail.

Installation is the reverse of removal. If the balance wheel does not spin freely when winding a bobbin, try swapping the two screws in the knurled nut. One is longer than the other and that's how Necchi solved the problem of the torque washer being installed backward.

Ed

Ed's Vintage Sewing Machine Shop
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