Which needle to use
Because denim is a tough fabric, it is advised to use heavy duty needles that are specially made for sewing denim or a universal one that’s at minimum size 90/14. If the denim is too thick, switch this to a size 100/16 needle so that it does not break.
Structurally, the needle should have a reinforced blade construction and this will help to minimize the risk of breaking, bending or skipped stitches.
Once you have identified such a needle, the next step is installation and this is not a difficult task. Simply push the needle into the clamp until you hear it click into position, then tighten the clamp screw firmly using a screwdriver or Allen wrench.
Which thread to use
Apart from the heavy-duty needle, you also need to use heavy duty jeans thread, especially when putting in some topstitching.
If such a thread is not available, you can substitute it for a strong polyester thread or upholstery thread, and this comes in very handy when flat-felling.
Alternatively, you can just use 2 spools of thread at once to achieve the same strength and outcome, but this is not recommended.
As for the threading, the process is no different as compared to using a regular thread, in which you are supposed to fill the bobbin then thread the upper and lower part of the machine.
The best speed settings
Even if you like stitching at fast speeds, with denim, you have to slow it down a bit because the machine will be having a hard time stitching through.
Additionally, you also need to move at a slow pace so that you do not make any mistakes when lining out the stitches.
To determine the best speed that works for you and your machine, it is recommended that you practice first using scrap jeans fabric at different speeds. This will help you pick the most optimal pace where you are neither too slow to delay the work nor too fast to ruin the stitching.
In most cases though, you will find that the best speed for denim sewing is about 800 to 1100 stitches per minute. With this in mind, you can adjust the speed slider controller to the pace that works for you.
Thread tension to use
Thread tensioning is basically the control of how tight the spool and bobbin thread is pulled. This is usually set manually on most machines, in which they have a variable setting from loose to tight.
Most sewing machines come with a manual that you can refer to on the tension that is required for different fabrics but generally, you need a higher tension for thick and tough fabrics such as denim.
The top tension dial is numbered or labeled differently in different machines, but in most cases, you get a range of 0 to 9, which indicates loose to tight respectively.
With the normal setting being at the middle (4), you will have to adjust this to a higher number by turning the tensioning dial that is located either at the front or top part of the machine.
Type of presser foot to use
Even though a standard presser foot might work, it is recommended to install one that is specifically suited for denim such as a roller foot, which actually contains rollers that help in feeding in the fabric as the rollers rotate. This reduces the friction in the feeding process while also preventing slipping, puckering or jamming, giving you an easier time.
When using specific brands of sewing machines such as Bernina, you can use specific presser feet such as the labeled jeans presser foot, which is customized fully for this thick fabric. An edgestitch foot is also a good option to consider.
The best stitch pattern to use
The best stitch to use on denim seams is the topstitch, which is a straight stitch, because it is both decorative and functional, though you can use a thread with the same color as the fabric if you don’t want the stitch to be visible. A specially designed foot called the edgestitch foot is used to produce the topstitch with a sewing machine.
However, this does not mean that you are limited to this design. You can also go for the zigzag stitch or even any of the decorative stitches, depending on what you want to create, but these are not ideal for seam stitching.
Something important to note though is that you should play around with these settings on the selection panel while practicing on scrap fabric before actual use so that you do not ruin your creation.
Presser foot position
The presser foot can be raised to 2 different positions using the presser foot lifter.
Unless you are working on larger projects like quilts or blankets, you do not need an extension table to sew denim clothes. Some machines offer up to 23 inches working space which is sufficient when you do your work.
However, an extension table is still ideal because it gives you a larger surface to lay all the material for easy feeding, which leads to neat stitching.