Follow

Procedure for Machines Not Detecting Bobbin Run Out - or giving False Thread or False Bobbin Breaks

Check the bobbin tension using the Melco Bobbin Tension Gauge (Pt# 34746). It should be between 18 – 22 gf / 180 – 220 mn depending on which version of bobbin tension gauge is used. If it is not, check to ensure the bobbin case is clean and undamaged. If the bobbin case is in good condition, adjust it to the proper tension.

Check the speed the machine is set to run. The Melco machines are calibrated to run at 1100 stitches per minute. It can be adjusted to run at lower speeds or higher speeds when needed for special applications and will slow itself down for longer stitch lengths. However, in general the machine will run well with the speed set at 1100 on flats and 900 – 1100 on caps.

Check the Acti-Feed lower limit. If the lower limit is too high the machine will respond with false thread and or false bobbin breaks. Different applications will require different minimum settings. For example caps may require a higher minimum because the material is thicker. Adjust the minimum as needed for the application and to give the desired sew quality without false bobbin or false thread breaks.

Check the hook finger gap using the hook finger gap gauge (Pt# 009027-01). If it is too tight it can cause false bobbin and false tread breaks. If the thread is dragging as it passes between the hook and the retaining finger the machine will over feed thread. It can also cause real thread breaks if the finger to hook gap is too close to allow the thread to pass.

 

For Machines Not Detecting Bobbin Run Out

Note: The default settings for TBS Calibration are, Sensitivity 0, Feed Adjust 20.  (Feed Adjust does not appear by default and should only be adjusted under the direction of Melco Technical Support.)

If after checking the previous setting the machine is still not detecting bobbin run out, adjusting the sensitivity to be more sensitive may solve the problem.

  1. Go to Tools then Settings and in the TBS Calibration box, adjust the sensitivity to -50.
  2. Run the test design “Bobbin Break Test” (file attached to this document). If the machine does not get a false bobbin break, run the machine until the bobbin runs out to see if it is detecting. If it does, run several other designs to ensure proper adjustment.
  3. If it does get a false bobbin break, adjust the sensitivity up to -40 and repeat the test. Continue adjusting the sensitivity up or down until the machine detects bobbin run out but does not give false bobbin breaks. Run several other designs to ensure proper adjustment.

 

For Machines with False Bobbin Breaks

Note: The default settings for TBS Calibration are, Sensitivity 0, Feed Adjust 20.

If after checking the previous setting the machine is giving false bobbin breaks, adjusting the sensitivity to be less sensitive may solve the problem.

  1. Go to Tools then Settings and in the TBS Calibration box, adjust the sensitivity to 20.
  2. Run the test design “Bobbin Break Test”. If the machine does not get a false bobbin break, run the machine until the bobbin runs out to see if it is detecting. If it does, run several other designs to ensure proper adjustment.
  3. If it does get a false bobbin or break, adjust the sensitivity up to 30 and repeat the test. Continue adjusting the sensitivity up or down until the machine detects bobbin run out but does not give false bobbin breaks. Run several other designs to ensure proper adjustment.

If after following this procedure the problem is not resolved, call Melco Technical Support for further assistance.

Was this article helpful?
0 out of 0 found this helpful