HOW TO THREAD A LOCKSTITCH SEWING MACHINE
No matter if your sewing machine is an antique or a brand new model, if it is a lockstitch machine the basic mechanism is the same. All home zig zag machines are lockstitch. Lockstitch have bobbins.
A lockstitch sewing machine has a spool on top that ends up being threaded through a needle, and a bobbin that gets threaded into a bobbin case. All bobbin cases may not be the same, but they all use a metal plate (called a spring) where the thread goes under to maintain a tension. They all also have a little screw where you can change the tension if you are using a non-standard thread.
The lockstitch machine has even top and bottom threads on either side of your seam. If your stitches aren’t even then you need to adjust the tension. The top and bottom threads get twisted around each other when the needle goes down into the throat plate hole and the race spins around where a hook grabs the thread above the needle hole and twists the bobbin thread over then back under the needle thread. The needle thread is on top and the bobbin thread is on the bottom.
Start by making sure the presser foot is in the raised position. Remember that the foot must be down in order to sew or the tensions and feed dogs (the “teeth”) won’t engage and you’ll get a loopy, loose mess instead of a seam. Then turn the handwheel towards you until the needle is in the highest position. The take up lever will also be in the highest position. The take up lever moved up and down, and may be hidden inside a slot.
Put a spool of standard sewing thread on the the spool holder (or, pin), making sure the thread isn’t catching on a nick or cut in the spool itself.
Bring the thread end through the first thread guide which is on the top of the machine and will line up to the right of the tension assembly. There may be a little tension disk to put it through first (counterclockwise), or a wire hanger. If it doesn’t line up logically it might be a bobbin winding tension, so look at it carefully. There can be up to four thread guides before you get to the needle tension (Tension disks) assembly.
Thread around the first tension disk or curved slot where the tension assembly might be hiding. This is threaded from top right, around the bottom, and back to the top on the left side. You will feel the drag a bit, but this will increase when you engage, or drop, the presser foot. The needle thread tension disks may have a number face on it so it’s easier to gauge your tensions. Turning the dial to the right will make it tighter, left will be looser. Make sure it comes up and over any hanger pin, or the little wire that sticks out of the side of the needle tension assembly.
Next thread upwards through the hole in the take up lever. To find it turn the handwheel. The handwheel is on the far right side of machine and turns toward you, counter clockwise. The take up lever is the long pin in the long slot that goes up and down when you turn the handwheel or run the machine.
Thread down through front thread guide.
Thread through needle top thread guide.
Turn the thumb screw to loosen and take out your needle to inspect and replace if necessary. Remember a size 14/90 sharp is general purpose. A ballpoint needle can be used for knits. Larger holed needles are used for heavier topstitching threads. A double needle can be used for knit hemming and for topstitching a pin tucked look. Skinnier needles, like 11/70 should be used for very light fabric and a larger 16/100 should be used for denim and canvas. Needle tensions should be tested on a scrap of your fabric before you begin sewing up your project. Put your needle back in, keeping the slot in the front. Thread the needle from front to back. If it is an industrial machine or an antique you may have the needle positioned with the front of it facing the left. Really old Singers may have the needle facing the right. If you’re not sure check the race and bobbin case and see how the hook moves. The hook must come up the front of the needle to hook the thread. Trial and error may be necessary.
Place the bobbin in the bobbin case, threading into the little slot and hearing it click under the plate. It may have an obvious slot in top loaded bobbins. Bobbin cases that you remove to load will also have a little tooth or fangs that the thread needs to come under. Place the bobbin case back in, using the holder and making sure the opening is up. It will click into place if it’s in there properly. Pull about 4 inches of thread out.
Holding the needle thread, turn the handwheel towards you until the needle goes all the way down and back up, bringing the bobbin thread up. Pull loop and needle thread out about 8 inches. Now put your fabric in with one thread on top and one on bottom. Drop the foot and let ‘er RIP!