The Sewing Place

Restoring a Bernina 840 Favorit

Madame Cholet

Re: Bernina Favorit 840
« Reply #15 on: September 16, 2017, 22:51:46 PM »
Just a quick update - the 840 is looking quite shiny inside now, after a day of cleaning, oiling, more cleaning, wielding cotton buds and artists' brushes, and more oiling... I have also spent several hours gently scraping off old dried-out solidified grease from cams and shafts and things using wooden cocktail sticks... I found 2 tiny oil holes hidden next to the on-off fancy stitch selector ratchet mechanism thingy that were clogged with old grease, and after some careful prodding followed by drops of oil, the fancy stitch selector lever now works!   
0_0
... which means that the needle bar, which was erratically doing its own thing, now behaves as it should... 
8)

I can't see anything wrong with the buttonhole dial mechanisms, so all seems to be well there thankfully.

Unfortunately the stitch width knob is still not behaving, that kind of has me stumped. Not quite sure what to do about that, apart from more oil, heat, and wiggling. I have ordered some tri-flow penetrating oil from the US, which may take a while to arrive, but I have heard people say it is the best stuff for freeing up seized parts in vintage sewing machines.

I need to get hold of some grease at some point, as there are parts in there that need grease not oil. Is anyone able to recommend a suitable grease that I should use?? Thanks!

I shall post some photos soon  :D

[Edited because I was wrong about the grease... someone in the past must have applied the grease, and they were wrong to do it >:)]
« Last Edit: September 17, 2017, 00:11:19 AM by Madame Cholet »
I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

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Re: Bernina Favorit 840
« Reply #16 on: September 16, 2017, 23:28:46 PM »
I don't think you should grease anything on this model, except from motor bearings. I would stick with oil if possible, you will get a smoother machine and it's easier to keep it clean in the long run. The reason for using oil is either because it's cumbersome to reach for regular applications (lids, screws, bottoms, etc, that needs to come off), or close to electronic/electric parts you can't afford the chance of a spill.

 If it's more practical to grease gears underneath or something like that, I like Finish Line Ceramic Grease, it can be found in bike stores, and there's similar stuff available in various brands, Triflow too. I like the slighly opaque - transparent greases with teflon in small tubes or tubs, not the gritty lithium stuff, spray can stuff (usually white) or heavier sticky greases. The current Singer grease is a synthetic transparent type, but there might be more than one type.

For the stitch width knob I'm not sure. Is it a simple turn knob in direct contact with the parts controlling the swing arm? I'm thinking it might not be complicated like the buttonholer and stitch selection knobs in the 800 series. I can feel there are other parts sliding and turning against the setting knob on my 900 Nova. Is it possible to observe, check and poke the parts involved in the back?
« Last Edit: September 17, 2017, 00:16:29 AM by arrow »

Madame Cholet

Re: Bernina Favorit 840
« Reply #17 on: September 17, 2017, 00:04:52 AM »
Thank you so much Arrow, I didn't know that.
The insides of this machine had been slathered in grease - it was everywhere, great big orange jelly-like chunks of the stuff, as well as dried-out crusty bits! Never mind, I daresay the grease may have helped prevent the insides from rusting over the many years the machine lay neglected and forgotten in a cold garage.

The stitch width knob operates by moving a sliding piece that moves up and down a channel in what I have learned is called the rocker lever. Here's a picture of the parts involved (I posted the same picture in my post yesterday).





I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

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Re: Bernina Favorit 840
« Reply #18 on: September 17, 2017, 00:26:24 AM »
There's certainly room for parts sticking or needing tightening up  :S ; there's lots of them! How does the spring action work on it? Sometimes the parts that run up and down the rocker lever needs to have a certain resistance, or at least a part in relation to the lever-knob thing. I have always called this type of part a groove or channel too, the old Singers often have one behind the stitch length lever or turn-knob (my 99 and 201), but there are of course much less parts involved.

Madame Cholet

Re: Bernina Favorit 840
« Reply #19 on: September 17, 2017, 13:33:04 PM »
Here are a couple of photos which show the rocker lever etc.
There is a long spring which attaches to the rear of the stitch width knob, which pulls the knob back to the '0' setting.
(I have unhooked the end of this spring temporarily.)
I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

Madame Cholet

Re: Bernina Favorit 840
« Reply #20 on: September 17, 2017, 13:37:56 PM »
There is no resistance in the motion of the part(s) that run up and down the channel in the rocker lever, they just glide up and down.
I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

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Re: Bernina Favorit 840
« Reply #21 on: September 17, 2017, 13:50:05 PM »
Does the knob turn smoothly or does click in place along the way? I'm wondering what the spring is there for, what does the part it's attached to do?

Madame Cholet

Re: Bernina Favorit 840
« Reply #22 on: September 17, 2017, 14:03:51 PM »
The knob turns smoothly.
At no point does it feel as though anything is 'clicking' into place (in comparison, when I turn the knob on my 807 I feel 2 points where it 'clicks' - they are the buttonhole preset settings).
The long spring connects to a fixed anchor point beneath the fancy stitch selector plate.
The other end loops around a small peg at the rear of the stitch width knob; when the spring is attached it pulls the stitch width knob swiftly back to '0'.
Here's a photo:
I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

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Re: Bernina Favorit 840
« Reply #23 on: September 17, 2017, 14:19:42 PM »
Is there a part that tightens up and make the knob stay in place? I can't make it out by the pictures. (The pictures act up on my side, doesn't always want to go to full size when I click them, but it's a technical issue sidetracking the subject). I'm thinking there might be away to detect if a part is sticky and interferes with the function, or a part is too loose. With all tiny parts it's a bit hard to see what job they are doing in the chain of things. I'm trying to look up how to take of the two part outer knob, they can be a bit tricky or even risky.
« Last Edit: September 17, 2017, 14:35:41 PM by arrow »

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Re: Bernina Favorit 840
« Reply #24 on: September 17, 2017, 14:44:56 PM »
The 840 looks mysteriously close to the 830 and 730, at least the upper parts under the hood.

Madame Cholet

Re: Bernina Favorit 840
« Reply #25 on: September 17, 2017, 14:52:00 PM »
Thanks for your help Arrow, I really appreciate it.
Regarding a part that may tighten the knob - I don't know at this stage.
I'm going to clean the underside of the machine next, and later this evening I'll have another look at the parts diagrams.
I am very hesitant about taking apart the knob, as it looks so complicated  :S

Here's a photo of the underside; I will look into image hosting later, then you should be able to view my photos more clearly I hope  :D

(Personally I love looking at photos of the insides of sewing machines.. :|...)

[Edit to add - the oil pan gasket was already damaged when I took the lid off, but the other piece is present and it was sealing well enough. Someone has worked on this machine in the past quite roughly; it looks as though the nylon stitch selector cam has been replaced, as the screws around there have had their 'slots' damaged. There are a lot of screws which have been damaged on this machine.]

« Last Edit: September 17, 2017, 14:57:23 PM by Madame Cholet »
I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

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Re: Bernina Favorit 840
« Reply #26 on: September 17, 2017, 15:07:40 PM »
I'm always eager to take of lids and cover too lol, I guess that's one of the main reasons I fell into this in the first place. Some greases are reported to ruin plastic, luckily not all. I see the orangey mess you mentioned. I would stick to oil even for the gears under the bobbin area (dirty left side on the picture). If you are lucky, there's oil points reaching them from above, but if there isn't I guess this is the only part on the machine Berina recommended to grease. Oil on plastic gears are debateable, but from the info I have gathered so far, you are not doing anyting wrong by adding oil and tests show it lessens friction and wear even on plastic gears, including the better quality polyester materials. Finish Line Ceramic grease and Triflow grease are suppose to be safe on plastic gears.
« Last Edit: September 17, 2017, 15:19:09 PM by arrow »

Madame Cholet

Re: Bernina Favorit 840
« Reply #27 on: September 17, 2017, 16:01:18 PM »
Having read Fran's excellent 'Imgur' tutorial, I am going to try some hosted images:

Edit to add: good heavens, it worked! Hope you can see them ok now Arrow  8)







« Last Edit: September 17, 2017, 16:06:46 PM by Madame Cholet »
I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

Madame Cholet

Re: Bernina Favorit 840
« Reply #28 on: September 18, 2017, 00:22:38 AM »
Here are two more photos, one of the hook drive gears now the old grease has been cleaned out, and another of the thread guide, which sadly has not fared well.




I nurse unloved vintage Berninas back to health and then just cannot bring myself to part with any of them... 807, 830, 840, 530-2, 930, 910, and a modded 717 in a Singer treadle base.

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Re: Bernina Favorit 840
« Reply #29 on: September 18, 2017, 00:48:46 AM »
Surface rust usually comes off with further cleaning and polishing. Is the thread guide polished steel or chromed? It's best to have it off the body to polish it up, I don't know if replacements are available. Is it glued on? If it doesn't come off maybe carefully polish it with steel wool twined around a match or something like that.  An 840 is a very nice machine, once it was expensive and one of the best. I wonder why it fell in to disfavour and neglect? 10 years in a damp garage?