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Chaly

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Reply with quote  #1 
I thought all issues with my Supernova camstack were resolved.  Initially, after working intermittently, I removed the camstack assembly and soaked in alcohol. This appeared to resolve the issue and the camstack rotated perfectly - for a while.  A few weeks ago, as I was sewing decorative stitching, the cam stack stopped rotating right while I was sewing.  I was perplexed - how could this be caused by a gummed up mechanism - working fine one moment and then suddenly stop?  I also heard an unusual noise right before it stopped.
 
I’m detailing this issue for any Necchi Supernova owners to illustrate that a non-moving camstack may not be due to a gummed up mechanism.
 
I did not really want to remove the camstack assembly and take it apart but I felt it was my only choice to get this machine functioning again. So -I completely took the assembly apart to see if I could figure out the issue.  The Yahoo Necchi group has a  service manual and some cam stack illustrations and some directions on removal - and this helped a bit.
 
See photos 1) assembly top, 2) assembly bottom, 3) camstack cylinder, 4) camstack parts.
 
I didn’t see anything that looked broken.  There was no gummed up oil but I did again clean each part.  Upon re-assembly, it appeared that the pin (see top assembly for location of pin) that goes into one of the metal pieces inside the camstack cylinder was loose and was not staying in position. After about 5 reassembly tries and moving/twisting the pin to make it a tight fit, I got it working.  The problem was the pin got out of position and this results in the camstack not working - it affects the tension and release on the main spring that goes around the cylinder.
 
The reassembly wasn’t too difficult since I took lots of photos but getting the pin right was a challenge.  Also, getting the whole assembly seated properly back on the machine takes some practice.  One must make sure the backstitch pin, the stitch width pin and the cam release lever are all in place exactly.  This takes a bit of practice as it’s hard to see underneath the assembly as you are seating the unit back on. I just kept adjusting all the levers until everything fit.
 
Also to note - if you look at the top of the assembly - there is a bar with two nuts - one long and one tiny.  This is the adjustment for the amount of backstitch for the decorative stitches.  I’ve adjusted mine to be in perfect alignment and to match the stitches in the manual - but just a half of turn on these nuts can make everything off.  One should be careful to mark the position of these nuts in case they accidentally get moved - and of course do not mess with them unless you are prepared to do lots of decorative test stitching.  I think later models of the Supernova have an easier adjustment - a specific adjustment lever - for this purpose.
 
I took lots of pictures, did my research on the Yahoo group and was able to resolve my issue. The camstack rotation is now - after a few weeks and many yards of decorative stitching - very stable and working fine.  I believe my initial issue was dirt and old oil and then for whatever reason the pin became loose.
 
So, if your Supernova camstack is not working after cleaning and removing the old oil, you should check the unit’s function by removing it from the machine and if the pin seems not to be providing the right tension and release to the main spring then the unit may have to be taken apart and reassembled.  The great thing is that the camstack parts are solid and none look like they could wear easily or break.  The main spring around the camstack is very heavy wire.
 
This was a bit of work for me - it took about two days to figure out and resolve.  But it was very worthwhile.  This machine is really fantastic in its functions with gorgeous decorative stitching, very smooth running, and such fun to use in a treadle. 
camstack top.jpg  camstack bottom.jpg  camstack.jpg  camstack parts.jpg 

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Jim/Steelsewing

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Reply with quote  #2 
Chaly. Wow.

I have one SN where the camstack seems gummed up and unresponsive. I'm going to have to give some of your tips a try here. It's been sitting on the self just waiting... and it is getting colder here... It might be time. Thank you for the photos and the explanation.

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Kitcarlson

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Reply with quote  #3 
Working on camstack, great for skill building. A challenge, with success, is a major motivator. Excellent work!
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Chaly

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Reply with quote  #4 
Quote:
Originally Posted by Kitcarlson
Working on camstack, great for skill building. A challenge, with success, is a major motivator. Excellent work!


Thank you!  I now feel confident to deal with these Supernova camstacks should another one come my way for repair.  My biggest motivator was to get this machine functioning since I'm so impressed with it capabilities for decorative stitching.  Then I wanted to share this info  since I've gained so much valuable help here on machines and it is something I can give back.
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NDNavy

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Reply with quote  #5 
Chaly,
Thank you for posting this and sending me the link.  I will try the same thing with mine in the near future and will take photos.  I will most certainly contact you for advice if I run into difficulty!
Darin

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Chaly

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Reply with quote  #6 
Darin - Have fun with this project.  Take lots of photos.  For adjusting the nuts you do not have to remove the camstack assembly.  Start small and just use one test cam that has backstitching (I used the preassembled cam III).  Then every adjustment you can compare with he same pattern.  Once this cam is perfect then the other cams should follow suit without any further adjustments.  
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Neno

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Reply with quote  #7 
Hey Chaly - I just picked up a Supernova and combed through most of it. It was mostly intact aside from some components, the camstack being one of them. The spring slipped apart from the e-clip being pulled. So, by the time I dug into it, the pin had already pulled out of alignment. Do you have any feedback as to where the pin should fit inside the cylinder? My attempts to get the cam to rotate on activation has led to it just wandering a bit (walking clockwise and counterclockwise) without an actual advance in rotation.
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Chaly

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Reply with quote  #8 
Neno - Welcome!

The Supernovas are great but a bit complicated at least compared to what I'm use to working on.  But I was able to figure my issue out with the Service Manual (I'll attempt to add a PDF file here of the manual) and lot's of trying different combinations.

It's hard to explain the pin but first make sure it's well seated and not loose.  Then I just kept trying different ways of putting together until it finally worked.  It was hard for me to see the pin but it was a matter of feeling how it all went together.

Once I had it all apart and say nothing was broken then I figured it must just have been something loose and I was determined to get it back rotating again.  Just keep trying and maybe the diagrams in the Service Manual will be of some help.

Sorry I can't be more specific but I know it's possible for you to get it back together properly so it will work -it's kind of like a complex puzzle!

ETA:  Start on about page 108 of the manual for the diagrams.


 
Attached Files
pdf _Necchi Supernova Service manual.pdf (2.03 MB, 19 views)

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Neno

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Reply with quote  #9 
You're a savior! Thanks so much. So it's hole A or as I kept reminding myself 11 o'clock (brake retainer 12, B hole 1oclock). What I did wrong, and I seriously hope this helps someone out of my rut, was the spring tension once assembled. That adjustment was my last; I rotated the unit until it stopped, leaving about 1/16" of the spring protruding past the locking plate. Once that was set, the brake worked flawlessly!

Thank you so much! I can't wait to put it to use tomorrow and figure out if all of the timing is still within tolerance.
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Chaly

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Reply with quote  #10 
I'm so glad to know you got it rotating.  Keep us updated on your progress to let us know how it sews and functions.  This is really a great machine on many fronts.
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JustGail

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Reply with quote  #11 
I'm glad you got your Necchi going again.  I still haven't gotten back to working on mine.  It stopped straight stitching after oiling and dinking about trying to get feed dogs to drop.  I did look at the manual but chickened out at doing any more disassembling than taking off the stitch width plate.  That's when I figured out that it would do straight stitch with the plate off, and nearly straight if I moved the lever to the left of the left stop button, so I've been using it that way.  

I also found that page 61 figure 54 in the manual has some formatting oddities that made my head hurt.  That lead to being distracted by doing cut and tape trying to get the diagram to make sense to me.  Here's the result, I'm not 100% sure I have the part numbers pointed to the right bits though...

Necchi_Service_Manual_pg_61_corrections_cropped.jpg 
Let me know if there's any corrections that need done and maybe this could be put with the full manual?



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Chaly

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Reply with quote  #12 
Wow - you've been busy pouring over that illustration.  I've never had to mess with my stitch width  plate regulator but have noticed that left to the stop is not the location for a complete straight stitch.  Mine is working fine in all the width settings.  Of all my machines, my Necchi SN sews  the widest.

I'm sure you just need some adjusting there and if it was me, I'd very minimally work through all the adjustment possibilities following the manual as best as possible.  I tend to use the Service Manuals for the very basics because for the most part the illustrations are hard for me to read and they never explain exactly how everything works - so I like to figure it out by trial and error.  I always take lots of pictures and make sure I'm confident to put everything back properly - otherwise I won't attempt and will work on my confidence!
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Neno

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Reply with quote  #13 
Here's a helpful link: https://issuu.com/davidmannock/docs/necchi_service_manual_bu-bf_nova-mi

I find that it's the most "complete" manual in regards to format. Also note that these Necchi manuals went through revisions and what seems like translations as well. So some of the info is missing, other is a bit confusing (referring to diagrams on different pages, etc.)

Since joining this group, I have also joined the Necchi Sewing Machine group on Facebook. The ladies overseeing that group do a fantastic job at cutting down as much clutter as possible. There's a Supernova group as well, run by Carl, who works on these machines.

According to Carl, the most common issue with Supernovas is the zig zag being out of adjustment. Link below to a very thorough post

https://www.facebook.com/431264750411044/posts/1195286944008817/
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Neno

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Reply with quote  #14 
As an update, I *finally* operated my automatic cam! The needle position lever was seized, stitch length mechanism wouldn't advanced beyond a 2.5mm stitch (j-hook adjustment on the automatic mechanism - rod was too short and preventing the knob from working past the 2mm point), and my straight stitches started skipping in the center and left needle position (bind in the needle bar pivot, gap between needle and shuttle was non-existent in center and left position due to bind and my needle was a bit too high causing the thread to miss it).

It has been an adventure! Still fine tuning as well.

By the way - calling this a "cam stack" is an inappropriate name. That name was borrowed from the Necchi Lydia machines, which is literally a row of cams. If you are reaching out for help from folks, I'd suggest to use whichever terms are used to describe the parts from the user & service manual. It'll help narrow down your question.

If I can be of any assistance, feel free to ask! I don't know it all, but I do know the struggle... Now! Haha! No regrets though. I love this machine.
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Chaly

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Reply with quote  #15 
Neno - it sounds like you're having a lot of fun and figuring out all the machine's intricacies as well.  I'm not on Facebook and use the Necchi group at group.io as a resource. The Necchi Yahoo group got moved to group.io and they have a lot of good info, files, and photos that have been extremely helpful for me with my Supernova- necchisewingmachineclub.group.io

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Neno

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Reply with quote  #16 
Ah, I was so bummed to see the Yahoo group was gone and didn't realize it was moved. Great to know all isn't lost!
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