Singer 660 A1 sewing machine

Hi Geoff

​Adjusting your sewing machine tension, and most other plain sewing machines.

Great work you are getting the hang of it, I noticed in your pocket mending video that there was a bit of a tangle on the bottom and that you did not hold the thread when you started sewing. While it is not absolutely necessary to hold the thread ends when starting it reduces the chance of a tangle underneath. Oh and when turning to continue sewing use the hand wheel to set the needle down in the work this gives you something to pivot on. Also do not sew over the loose ends in particular the bottom thread, it can get dragged down into the hook causing a tangle, I think that happened in your video,

You mentioned that only in one place did the red thread come up to the top, that indicates that the top tension is a little light or the bottom tension is tight. The ideal tension is when the top tension and the bottom tension are equal, this will cause the top and bottom threads to link into each other in the middle of the fabric or leather, you should be able to see a row of red dots on the top (The bottom threads showing on the top) and the other colour If you are using two colours showing on the bottom. (The top threads showing on the bottom). It is a good idea to use two colours when setting up the machine, it makes the tension adjustments more easily seen. For most actual work you use the same colour top and bottom.

While it is possible to use two different threads it will play havoc with your tension settings. use exactly the same type of for the needle and bobbin. (The top and bottom threads)

One little test worth trying is to fill a bobbin with thread, then insert it in the bobbin case (Through the flat tension spring on the bobbin case as well) then try suspending it by the thread alone. It should not fall unless you jiggle the thread. Yes it is hanging by a thread! if it does tighten the small screw that sets the spring tension. A fraction of a turn makes a big difference here. There are two screws it is the bigger one.

Then try pulling the thread from the bobbin case, it should feel smooth without undue tension, it is very hard to describe this as it varies depending on the type of thread you are using, certainly it will be no strain for your little finger. If the tension is too light the bobbin can over spin when you stop sewing, a good way to get a tangle on the bottom. If it is over tight you will not be able to equalise the tension with the tip thread.

The top needle thread is controlled by threading it through various eyes and two mechanisms, the tension disk's and the tension spring.

The tension disk's have a similar function to the flat spring on the bobbin case they are used to match the tension top and bottom.

If the thread quality and the machine were perfect machine these would be all that is needed. However the world is not perfect and the small tension spring that flips up and down around the tension disk's is there to compensate for small variations in tension caused by flaws in the thread and also to help the thread pull back up from when it goes down with the needle and a loop is pulled off the needle by the hook and base that transfers the loop around the bobbin case forming a stitch. The spring gives the thread a little tug at the right time to help it release from the hook and allow it to be pulled up again by the mechanism.

Normally the tension on the this small spring is quite light, If you switch to a heavy thread and thick needle for leather you may have to increase it a bit. At this stage leave it alone,

Having set the bottom tension you should be able to adjust the tension disk's alone until you get a regular and even stitch pattern. too tight and the bottom thread will show more on top, too low and there will be top thread showing more on the bottom.

I hope this is not too confusing!

Regards
John

Edited By John McNamara on 27/06/2016 16:23:18

Edited By John McNamara on 27/06/2016 16:24:10

John,

Thanks for the excellent advice.

Am using identical thread, other than the colour - (oxymoron?)

When/how would you use the 'reverse' stitching facility?

Will do the bobbin test.

Geoff - Soda blasting IS dusty as I found out yesterday!

Hi Geoff

Further to the Bobbin test, with a bobbin full of thread inserted in the bobbin case the bobbin case tension should be set so that the bobbin and case can be (Just) held static by the thread, if you lightly jiggle the bobbin and case it will fall by its own weight.

90% of the time this test is about right for the bobbin tension, you should be able to get a good stitch by setting the top tension discs.

One point worth mentioning is that (every) part of the machine touched by the thread should be clean and polished. Check inside the tension discs' is the shaft nicely polished? it should be. any rust will make getting a good stitch impossible.

One other area worth checking and a common cause of bad stitching is the "Needle plate" The half circle plate in the bed with two screws, The hole the needle goes through should be polished with very slightly rounded edges and no burrs. Also check that it is flat across the top with a straight edge. Sometimes it is pushed down by a broken needle. If it is bent take the plate out and carefully straighten it. If the hole is badly scored it should be replaced. it is not an expensive part. If you do need a new one ideally take it to a service centre to match it. The plates are available with different slots for the "Feed dog" the teeth that pull the material through the machine, you have to match them up.

The reason for the reverse lever is not to stitch backwards it is for "Back tacking", it is there to momentarily reverse the stitching to lock the ends of the stitch line. With fabric the one to two reverses and back is about right. for appearance sake it has to be done carefully. Study a shirt pocket for instance note the neatness.

On Leather the reverse pattern can be very ugly, Ideally plan your work to avoid doing it where the sewing will show.

Stitch length?
Again study say a shirt about 2mm, then study a pair of jeans 2-3mm. Note the differing stitch lengths used by the manufacturer. Then have a look at stitched car upholstery often about 3-4.5mm, note how the stitches are further apart. Vinyl and leather requires a longer stitch length, this is because the vinyl or leather will be damaged by a fine stitch, too fine a stitch and the material will be weakened or even cut.

Lubrication:
I do not know if your particular machine has a sump and a pump? Even if it does there will probably be points that have to be oiled. The correct lubricant is water white (clear) machine oil. get it from an industrial sewing machine dealer.

When you place the bobbin and its case in the machine you are putting it in the "hook and base" this is the heart of the machine, it is the little bit of metal magic that forms the stitch. Nearby in the bed is a reservoir that feeds it with oil via a hidden wick or tube. Study it you will see a hardened steel on hardened steel bearing area around the centre part. It must never be run dry, make sure the oil is getting to it. If it is dry add a drop of oil and find the reservoir and fill it with oil.

Always stitch a sample before you start a job you have not done before. Try to tear it apart pull and poke it until you are satisfied with the result.

Regards
John

Edited By John McNamara on 29/06/2016 13:50:56

Hello John,

Played around with bobbin tension as well as the top tension then wondered why the top thread kept snapping.

Checked everything then noticed what I thought was fluf on the top tension check spring only to discover that somehow I had looped the thread round it.

Fixed that and after more adjustment I'm happy for now, but will only find out once I experiment with the material I will be using on the car.

New needle plate fitted as the machine didn't have one.

When I got the machine I cleaned the mechanism as best I could, removed the end cover and found all the pieces of lubricating felt bone dry so soaked them in Singer oil.

Every moving part was lubricated and machine turned by hand then left overnight before powering up.

I think there is too much oil in felt strips, as it is running down the needle bar, but not as much as first.

The sump was empty, so duly filled, and I check the level before using the machine.

No mention of an oil pump in the manual.

Thanks for the advise on 'back stitching', something I didn't know about, but how do you stop the stitch coming loose if not used?

Geoff - Getting there albeit slowly.

Hi Geoff

Glad you are getting the hang of it. The oil pump if fitted in the sump is the submerged type it is driven by shaft that drops down from above. for a slow speed machine it is not needed anyway.

In a factory a freshly oiled machine always tends to drop a little Oil, one of the reasons for the water white clear oil, it does not stain the work. After running for a while the oil will stop dripping. For intermittent use you don't have to oil every day.

Back stitching is really the only way to stop the threads loosening, For machines not fitted with a back stitch mechanism the only other way is to turn the work around, not easy with a large work piece. If you study existing upholstered articles you will find that it is unusual to see the end of a stitch line. it is usually buried inside and not seen anyway.

Regards
John