Question about Sewing Machines
Your tension is a balancing act of the upper tension which you can adjust easily and the bobbin tension in the bobbin case. It can be your stitch is not balanced and it is not a tension problem but a burr on the hook or a clearance issue elsewhere. I usually start with a visual inspection using a new size 80 needle. With the presser foot down and the machine properly threaded with good quality normal sewing thread the needle should bend about an 1/8 to 1/4 inch when pulled out the back and to the side. This indicates the upper tension is normal. When adjusting the bobbin thread tension a simple gauge you can make is a wooden clothes pin with three pennies glued to it. You clip the bobbin thread into the pin and hold the bobbin case. Then you adjust the tension such that it just lifts the pin off the table. This crude device is much easier than trying to yo yo the bobbin case and adjust the tension with out dropping the bobbin on the floor.
Posted on Jun 07, 2014
Lots of possible issues, but first, check your bobbin case. Take the bobbin out and clean around the inside with a cotton bud. Replace the bobbin and hold the thread and let the bobbin/bobbin case dangle free (take care that the bobbin doesn't slip out of the case. The bobbin case should stay stationery. If you **** the thread upwards , the bobbin should unwaind (this is a very very rough guide). If the bobbin unwinds when just holding the thread stationery, screw in the tension screw on the side of the case a fraction until it doesn't. Conversely if it doesn't unwind when jerked, try unscrewing it slightly. The adjustment is fairly critical and should really be done with a proper gauge and weights. If the bobbin tension is OK, are you sure you're threading the top thread properly ... you should always thread through the pre-tensioner, tension discs and takeup arm with the presser foot lifted - this ensures the thread will lay down between the tension discs properly. Put the presser foot down only when you're threading the needle. If the top tension is too high, try cleaning the tension discs - you can do this fairly simply by turning the tension down to 1, or 2 and with the presser foot up, thread some thick wool through the pre-tensioner and tension discs. Drop the presser foot and drag the wool through slowly - this should clean the fluff and muck out of the discs. Failing the above, you may have a problem elsewhere, such as the check spring or maybe even a problem with the hook/shuttle. In this case, you'd be best to have it checked-out professionally. By the way ... when did you last have your machine serviced ???!!! Also, when did you last remove the hook/shuttle, clean round the hook race firmly with a cotton bud and re-oil it ? You may find the latter will cure your problems ! Good luck and get back to me if I can be of any further help.
Posted on Feb 14, 2012
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Posted on Jan 02, 2017
SOURCE: bobbin tension
Bobbin Tension Adjustment:
1. Do you have a genuine Bernina bobbin casing and not an Oriental copy? If yes, proceed as follows:
2. To set the bobbin tension, wind a genuine Bernina bobbin with Metrosene thread, type 1161 white thread as your "gaging thread". Load the bobbin case so that the bobbin turns CW. Attach the bobbin case to the hook body from the machine. Wind a couple of revolutions of thread around your index finger with the assembled bobbin case and hook body dangling about 6" to 12" below your finger. Gently and rapidly move your finger back and forth in a "sideways" motion about 1/4" to create a gentle vibration on the bobbin assembly. (Do not shake the bobbin assembly up and down). When the tension is right, the bobbin assembly should fall slowly and as you stop the movement, the assembly should stop.
The adjustment is found on the small screw, holding the flat tension spring against the bobbin case. If the tension is too tight, one must loosen the screw (past) the desired location and always make the adjustment by tightening to the correct position.
There are other checks for tension imbalance and associated problems on the bobbin case that I won't go into here. For further information I can help you later on.
Top Tension Adjustment:
1. The top tension rarely changes and can be depended on throughout the life of that machine providing that tension assembly is maintained occasionally. This can be done by blowing out the tension disks with the presser bar lever in the up position. One can also drag or pull a piece of sized percale or muslin through the disks with the presser bar lever in a down position. Perhaps both methods can be employed.
2. Load the top of the machine with Metrosene 1161 thread in a dissimilar color. I prefer to use a pastel color so as not to create an optical illusion of imbalanced tension.
3. Sew a satin stitch (.25 on the Nova 900) in sized cotton muslin with a thin piece of paper between two plys of fabric. The width should not exceed 4.5mm (standard width on the 900 Nova), however the newer machines have wider stitch widths so one must adjust as specified. The result will be a slight amount of top thread in symmetric lines on both the right and left sides of the satin stitch.
Typically, the top tension will not need adjusting. If the Nova 900 needs adjustment, please ask for additional help.
Posted on Nov 28, 2008
SOURCE: Bernina 66 troulbe with tension
the Berlina uses a reverse hook; from say, singer; over time your hook has slipped and is barely looping the thread: adjust your hook to enter the thread loop about 1/4" before the needle raises to make the stich then readjust the tension on both the bobbin and, the needle
Posted on May 03, 2009
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