Tension on bc1700 super bike will not adjust

Usually, the upper tension should work in tandem with the bobbin tension so they actually pull against each other. If the upper tension is too loose, then the bobbin tension will not be pulled up into the fabric. Try tightening the upper tension and see if that makes a difference. The two threads should meet in the middle of the fabric.

However, on occasion, the bobbin tension is, in fact, too tight and can be adjusted. Be sure to mark the setting BEFORE making any adjustments (so you can reverse your changes) and make tiny incremental adjustments to the bobbin tension, ie 1/8 to 1/4 turn. A little adjustment makes a BIG change in bobbin tension.

Understanding Thread Tension Threads

top tension too loose
tighten it up

Be very careful adjusting the tension on the bobbin case. Generally, most tension issues are regulated using the upper tension adjustment unless the bobbin case is broken or someone has attempted to adjust it incorrectly. In any event, adjustments to the bobbin case should be made ONLY 1/8 of a turn at a time--then do a test stitch. Before making any changes, mark with a permanent marker where the screwdriver slot meets the bobbin case in the event you have to return it to the original position.

If the top thread is looping or knotting under the fabric (bird nesting), the upper thread is too loose or it is threaded incorrectly.

If the top thread is pulling the bobbin thread to the top of the fabric, the upper tension is too tight.

Tension is ideal when both threads meeting in the middle of the fabric.

...

try a new needle--one that is for the fabric being sewed
then try to adjust the top thread tension again, if the stitches remain loose and the tension won't adjust then the tension knob needs to be checked to see if there is something wrong with it.
also check to make sure the bobbin is inserted correctly into the bobbin case, if the bobbin is not turned the right way in the bobbin case the sewing machine will not stitch correctly.

See solution I suggested 10 seconds ago. Hope it helps. Jimmy

The bottom stitch is affected by the TOP thread tension :) First go back and make sure your bobbin tension is correct since you adjusted it. It should drop slightly when held suspended by danging it by the thread. If it reels out to the floor it is too loose. If it doesn't drop at all it is too tight.

Now that you have that adjusted look at your top tension. If it is loopy on the bottom side of the stitch the TOP tension is too loose. Increase the top tension.

Now take some scrap material and set machine to a wide zig zag, medium length stitch and sew a bit. Compare the top and the bottom sides of the stitch. They should look identical. Remember the TOP side effects the bottom and the BOTTOM tension effects the top side. Adjust accordingly until they look identical with no loose threads or loops and no puckering (puckering means it's too tight).

There is a tiny screw on the side of the bobbin case.

Mark the **** (in the screw head) position on the bobbin case with tiny dab of nail polish so you will know where the original setting was.

Left/loose and right/tight.

If you are adjusting because the bottom stitching is loose/loopy, first try threading the machine with the presser foot up to see if this solves the problem.

The tension for the motor belt is adjusted by loosening and altering the position of the mounting bracket of the motor....do not overtighten, it needs to have some give or you will overload the motor.

pucker is caused by too loose or, to tight adjustment of: the thread tensioners both the bobbin tensioner and, the needle tensioner need to be adjusted: to adjust the needle tensioner turn the side knob clockwise is tighter counterclockwise loosens; the bobbin tensioner is a tiny screw on the bobbin holder adjust both tensioners until your stich loops' both top and, bottom are tight but, the machine does not break the thread

Check all the tension units are clean and clear of lint

Ensure sharp new needle/s,

Make sure that when you thread the machine the presser foot is up so the thread goes between the discs and not to one side, and that you have threaded through all the guides.

It may be there is lint trapped between the discs, this will keep them slightly apart and reduce the actual tension, sometimes dramatically.

If tensions appear correct, and the thread is definitely in the channel between the discs, but still too loose and looping, try raising presser foot and remove your thread.

Now, with a 2" (50mm) wide strip piece of fabric 8 - 10" (20 - 25cm) moistened with methylated or denatured spirit, gently insert the fabric strip and clean between the discs with a see saw / to and fro action.

Now set up machine with 4 different colours, so you can easily see any changes you make.

Factory setting for all 4 tensions = 3.........try this setting first before altering anything.

Sew a test sample about 75mm (3") and look at the result, front and rear.

You will see anything tight or loose, so just adjust a little at a time with test samples each time.

If the actual knobs read anything other than the 3-3-3-3, after you have made your adjustments and are happy with the balance of tensions, it is quite simple to remove the knob....very gently pull it off towards you (without altering the new found correct tension !!) and pop it back on to read 3.

Hope this is all easy to follow, If you want any more help with this, just post back here, or, drop a line through the "Contact Us" page at www.bargainbox.com.au