Today I’m going to talk about timing.

It’s that scary word that we all dread when we take our machines to the shop. Or the reason we take our machines to the shop.

It’s not: (fill in the blank)

Stitching, sounding right, picking up the bobbin thread, making me coffee, whatever.

Or It’s: (fill in the blank)

Skipping stitches, breaking thread, smashing needles, teasing the cat, what have you.

It must be the timing, right?

Not so. Only some of the above scenarios are always a timing problem.   On a well built machine, it’s actually fairly hard to throw the timing off.  Usually a mechanical collision has to happen (needle to something is the most common way).  Less common is “mucking about” in that bobbin area without proper understanding of what’s needed.  A lot of problems we blame on timing are a result of some other problem.

In this next multi-part series, I’m going to explain how to check the timing on a sewing machine, why it’s fairly difficult to throw timing off, what else it could be if it doesn’t appear to be the timing and how to adjust timing.  In this first part though, I’m going to discuss how a sewing machine makes stitches, and what time has to do with it.

In this picture, you can see the process I’m about to describe. (By the way, I found this image on the Internet some time ago.  I claim no rights to it.  If this image belongs to you, and you wish me to take it down, please let me know privately via email, and I will take it down.)

When speaking of a rotating or oscillating hook machine, as in the image above (I’ll discuss the bullet / boat vibrating / transverse shuttle process later), we see the following happen:

1. When forming a stitch, the threaded needle goes down, through the fabric into the hook area. While in descent, the thread is fairly tight against both sides of the needle.  This is the purpose of the “grooves” above the thread on a sewing machine needle .  They let the thread lie into the needle, and lower the friction and resistance the thread would cause trying to travel through the fabric. It’s aerodynamics for sewing machines.
2. As the needle starts to travel back upwards, the thread “puckers” a little, forming a small loop under the fabric.
3. In the bobbin area, there is a “hook assembly”.  This is a round rotating assembly that has a pointed area on it that moves behind the needle when it’s in the down position.  This really is where the magic happens.
   • The “hook” does exactly what it sounds like it does.  The pointed part of the hook assembly grabs that little loop of thread from the needle, and carries it around the bobbin, then lets it go.    This effectively ties a knot in the thread.  Otherwise known as forming a stitch.   Tension, both top and bottom determine where the knot sits in relation to your fabric.
4. Once the needle clears the fabric, the feed dogs carry the fabric back the length of one full stitch.

If you open the slide plate or tilt the machine, you can watch this whole process happen. On a class 15 style machine (where you remove the bobbin case to replace the bobbin), you may want to remove the bobbin case to better see the needle motion.

So, where does the timing come in?

• In order for the stitch to be formed correctly, the needle must provide the thread “in time” for the hook to grab it.
• Or put another way: the hook must be in the right position “in time” to grab the thread when the needle is down.
• Additionally, the feed dogs need to be “in time” with this whole process, in order to not pull on the fabric while the needle is still inside it.

If this doesn’t happen several things can occur, such as: the stitch doesn’t form, the fabric doesn’t advance correctly, the needle breaks, the fabric may be damaged.  At this point, we refer to the machine as being “out of time” or needing to be timed.

Check this post out to learn how to check your timing: Perfect Timing

Clear as mud?  Please post any questions you have below in the comment area. I’ll be pleased to answer them either in future installments of this series, or in reply to the comment.