If you take one thing from this article, take this: raise the presser foot before you thread. Not as a convention, not because a manual says so, but because the tension discs are mechanically clamped shut when the foot is down and the thread cannot get between them.
Why the presser foot position matters
The tension unit is a pair of friction discs squeezed together by a spring. Lifting the presser bar operates a release mechanism that removes the spring force from the abutting friction discs, opening a gap between them. Thread that you feed in while the foot is up drops into that gap and is gripped when you lower the foot again.
Thread it with the foot down and the thread slides past the outside of the closed discs. The machine will sew. It will just have essentially no upper tension, which produces a loose loopy mess on the underside of the fabric. This one mistake accounts for a large share of “my machine is broken” reports.
The upper path, in order
- Raise the needle to its highest point by turning the handwheel toward you. This also raises the take-up lever so its eye is accessible.
- Raise the presser foot.
- Place the spool on the spool pin and secure it with the correct cap. A cap smaller than the spool lets thread slip underneath and jam.
- Run the thread through the first guide near the spool pin, then down the front channel.
- At the bottom of that channel the thread turns around a U-bend and comes back up the second channel. This is the tension unit. Give the thread a firm tug to seat it fully.
- Coming up the second channel, catch the thread in the take-up lever eye, right to left on most machines.
- Back down through the lower guides, including the small guide just above the needle clamp. This is the one most often skipped and it matters, because it sets the thread’s approach angle to the needle.
- Thread the needle. Most domestic machines thread front to back. Some models thread left to right or right to left, so check the manual, and note that the thread must enter on the side with the long groove.
Winding and inserting the bobbin
Wind bobbins on the machine, not by hand. Hand winding produces uneven layers and inconsistent tension, and the bobbin thread will drag differently as it unwinds. Run the winder at a steady moderate speed rather than in bursts, and stop when the bobbin is full rather than overfilled.
Direction of unwind is the part people get wrong. On drop-in bobbins there is usually a diagram on the machine showing whether the thread should come off clockwise or counterclockwise. Front-loading cases have a slot the thread must be drawn through and under a tension spring. Insert it the wrong way and the bobbin thread pays out with no tension at all, which produces nests underneath.
Safety around the needle area
Anything that involves putting fingers near the needle, hook or wiring is worth doing with the machine switched off and unplugged, and with the foot pedal moved out of the way so it cannot be knocked. Domestic machines are designed against a dedicated safety standard, IEC 60335-2-28, the particular requirements for sewing machines within the household appliance safety series, which covers electric sewing machines for household and similar use including machines used by non-specialists in shops and light industry. That standard governs how the appliance is built. It does not remove the need for you to isolate the machine before working on it, and any concern about a machine’s wiring, smell of burning, or a damaged cord is a job for a qualified repair technician rather than a home fix.
Rethread first, always
When a stitch fault appears, resist the urge to adjust anything. Remove the upper thread entirely by cutting near the spool and pulling it out through the needle in the direction of travel, rather than yanking it backwards through the tension discs. Then rethread from scratch with the foot up. Take the bobbin out, check it is seated correctly, and put it back.
Do that before you touch the tension dial, before you change needles, and certainly before you conclude the machine needs a service. It costs ninety seconds and it fixes a surprisingly large fraction of problems outright.