5: Additional Functional Requirements
Whilst the basic functional requirements should be considered as being essential, the additional functional requirements are more of a wish list, however they do make using the machine easier to use and more versatile.
- Adjustable maximum speed
- This allows you to limit the speed of the sewing machine when the foot pedal is fully depressed, thus giving you one thing less to think about when sewing heavy or dense fabrics which are prone to dropped stitches when sewn a high speed.
- Up/Down needle parking.
- This allows you to set where the needle ends up when you stop sewing. Rather than being in some arbitrary position the needle will end up either down in the fabric or up out of it This is very handy when sewing seams with corners where you need the needle down so that you can lift the presser foot and turn the fabric.
- Adjustable stitch length and width
- Long (6-7mm) straight stitches are useful for basting (temporary stitching), whilst for regular seams you want about a 3mm length, having a machine that covers this range greatly increases its versatility, similarly for zigzag stitch widths.
- Interchangeable presser feet.
- In addition to the standard universal presser foot, there are a range of feet for specialized functions such inserting zips, piping and edge binding, thus it is useful if the machine will accept them, particularly if it employs a quick change system.
- Dual Feed – not to be confused with a ‘walking foot’.
- On a single feed machine the feed dogs lift the fabric up from the throat plate and drag the fabric through the machine against the underside of the presser foot. The problem with this is that if the friction between the presser foot and the fabric is greater than that between the pieces of fabric being stitched – typical on light weight and coated fabrics i.e. ripstop nylon – the fabric layers will become more and more misaligned as the seam progresses. Whilst there are many techniques you can use to overcome this, without having a dual feed, for the novice the dual feed system is the simplest, and typically consists of an additional feed dog on the top of the fabric just behind the presser foot. However if the machine has a dual feed make sure the upper feed can be disengaged and lifted away from the fabric as there are times when it can become a positive hindrance, particularly when doing applique work and you need to rapidly change direction.