When and how should I time my APQS machine?

May 25, 2014

The good news is that APQS machines are carefully set at the factory by skilled technicians; and because of the synchronous belt drive, the timing rarely needs adjustment.

When it does, it’s typically the result of something unusual happening, such as a cleaning rag getting swept into the hook assembly (hint: keep yours well away from the hook area when oiling or cleaning the machine) or a needle jam or needle break. If neither of these disasters has happened to you and you still are wondering if the timing needs adjustment, here’s what to look for:

  • Skipped stitches: On stitch-regulated machines, does it happen in stitch-regulated mode but not in manual mode? Check to see if there is a needle hole in the fabric where the skipped stitch occurred (by moving thread out of the way). If there is no needle hole in the fabric (it looks like a long stitch), your stitch regulator encoder wheels probably need adjustment. However, if it happens in both stitch regulated and manual mode, then the timing might need adjustment.
  • The needle hits the bobbin: First make sure you have correctly inserted the needle with the scarf to the back of the machine and that the needle is inserted all the way into the needle bar shaft. Make sure the needle is not bent, try a new needle. Listen for clicking noises and check the bobbin edges for wear or burrs.
  • Frequent needle breaks: If you are sure the needle is inserted correctly, and that other factors such as bulky seams or improper machine movement are not causing the breaks, then re-timing may be necessary.
We have outlined the very basic timing steps below. If you prefer, you can also view a video that describes the process on our YouTube channel.
Timing your machine is not difficult, but it does require a few basic tools and a little patience. You’ll need a new MR 4.0 needle to properly time the machine. In addition, you’ll want the tools and supplies listed below:(Click here to watch a video about proper timing tools)
  1. Short Phillips screwdriver with a #2 tip
  2. One long straight-blade screwdriver with a narrow 3/8-inch wide tip (often called a cabinet maker’s tip)
  3. Another long straight blade screwdriver with about a 4-inch shank
  4. A strong magnifying glass or jeweler’s loupe
  5. A flat file
  6. Emery cloth or abrasive cloth (very fine sandpaper will do in a pinch)
  7. A fine-point permanent marker
You will also want to evaluate the condition of your hook assembly before you re-time your machine. Some minor blemishes like burrs or scratches can be removed with emery cloth. However, if you have severely jammed a needle, it’s possible that the bobbin basket and hook may be permanently damaged. Evaluate the hook with your magnifying glass to search for scratches or burrs. You may choose to order a new hook assembly from APQS before you begin re-timing your machine.
While it’s possible to re-time your machine without completely removing your hook assembly, you’ll find that the process is typically much easier if you take the preliminary step to remove your hook and re-buff the hook shaft. Filing the hook shaft removes any loose metal shavings that were displaced when the hook was first added to the machine. Those extra particles make it difficult to precisely adjust the hook if they are still present, because the hook assembly will tend to catch on them as you reposition the assembly. It only takes a few minutes to remove the hook and file the shaft, but it could save you tons of time when you’re ready to set the hook rotation and clearance.
You’ll follow four basic steps to re-time your machine. Click here for a pdf of these instructions, including photos.

1. Check the needle bar depth.

Every subsequent step depends on having the proper needle bar depth. Take your time and make sure your setting is correct according to the timing photos in the timing document listed above or in your machine manual.

2. Adjust the hook rotation.

The hook point must pass behind the needle in just the right spot in order to capture the top thread loop and complete a stitch. You’ll use the fine-point permanent marker to help place identifying marks on a new needle. It’s very hard to see exactly where the hook point passes behind the needle without these marks. The marks will help you make sure the rotation happens correctly in relation to the needle.

3. Adjust the hook clearance.

The hook point must actually touch the back of your needle with each pass, nudging it gently out of the way. If you have even the slightest air gap between the needle and hook point, you will continue to have skipped stitches. That’s because your movements with the machine will make the needle flex and bend. If the needle flexes too much, the hook point once again misses the top thread completely and cannot form a stitch. Don’t rely on the naked eye to judge hook clearance. Use a magnifying glass, add some good light, and look for that needle tip to wiggle each time the hook point passes behind the needle. Of course, you don’t want the hook point to slap or strike the needle hard; it should deflect the tip slightly.

4. Reposition the hook retaining finger.

The hook retaining finger holds the inner portion of the hook assembly stationary (the bobbin basket) while the outer portion rotates around to form the stitch. If you didn’t know any better, you may look at the hook finger and the bobbin basket notch in which it fits, and assume the finger should be shoved into the notch completely. Actually, the hook finger tip should only be in the bobbin basket notch about 1/3 of the way. That’s because your top thread must pass between the hook finger tip and the bobbin basket notch with every single stitch. If the finger is too close, your top thread will get pinched and could break.

Before you take off and start sewing with your newly timed machine, turn the fly wheel clockwise through a few revolutions to check everything again. You can also use your needle up/down function (if equipped) to test the hook and needle relationship. If everything looks good, thread up the machine and test your newly timed machine!
Call us for help at 800.426.7233.