Part 5 Thread Tensions
Tracking Down the Problem Part 5 Thread Tensions
Overall Theory:
In reality there are threetensions to deal with in embroidery. The bobbin tension, top tension and the fabric tension. Check your hooping before you begin adjusting thread tensions.
Checking the threading of the bobbin case and upper thread.
The thread should pull out smoothly.
Check the bobbin both in and out of the machine. Overwound bobbins may not be noticeable until the bobbin is inserted in the machine.
Look for damage to the bobbin, bobbincase or thread cone.
Make sure the upper thread is in the pretensioner and tension.
Begin all adjustments at the bobbincase.
Utilizing a bobbin tension gauge you should have 18 – 20 grams.
Do the drop test. Put a fresh bobbin in the bobbincase, thread the bobbincase correctly except for the "pigtail". Hold the bobbincase up by the thread (leave a hand underneath so it doesn't hit the floor!), let it dangle and jerk the thread to test the tension. If the bobbincase drops a few inches and stops you are in the ballpark. If it doesn't drop at all it's too tight. If it hits the floor it's too loose and you forgot to put your other hand under it.
Start top thread adjustments at the pretensioner.
Utilizing a tension gauge, approximately 10 grams.
Without a tension gauge loosen the main tension knob out so it is not putting any pressure on the tension spring. Remove the thread from the eye of the needle, thread it through the hole in the presser foot. Place your finger on the main tension disc to prevent it from turning. Pull off thread. If the thread stops pulling around the main tension disc the pretensioner is working. If not, tighten the pretensioner until the thread flow stops (continue holding the main tension disc so it doesn't turn while you adjust). If the main tension disc doesn't turn when you are NOT holding it you have too much tension on the pretensioner. If the thread repeatedly slips off the main tension disc you have too little pretension.
Main tension adjustment.
Utilizing a tension gauge, measure the tension just after the main tension, approximately 20 grams.
Without a tension gauge back the tension knob all the way off. Turn the knob in 6 – 8 full turns. Sew a 2 inch block I, preferably without serifs. You should see two thirds of the upper thread pulled to the back of the I with one third bobbin thread running down the center of the I. If you are showing more upper thread on the back tighten the main tension. If you are showing more bobbin thread on the back loosen the main tension. Sew again.
Double check your adjustments by sewing a block H or X on all needles. Once the bobbincase tension is set do not readjust it for individual needles, adjust only the top tension.
Check the front for looping or pulling.
For narrow satin stitches (columns of 3mm or less) you may want to run a little tighter bobbin tension, showing less than 1/3 on the back.
Note: These settings have been tried and tested on Tajima Embroidery Machines.