Bottom stitching is loose - Bernina Artista 180

top tension must be adjusted to fix loose stitches of bottom stitches
adust the top tension one letter or number higher and sew on a scrap
piece of fabric till stitches look correct,, here is a free manual
http://www.singerco.com/uploads/download/36952a1312a6d8436174ef874f3662471a946b64.pdf

try adjusting the top tension to one number or letter higher until the stitch looks good
also change the needle

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).

Usually thread too loose on the bottom is caused by the upper tension being too loose. The top and bottom tensions work together with the top thread making the underside of the stitch seem too taunt or too loose and the bobbin thread causing the top side of the stitch to be loopy or too tight. Select a large zig zag stick and sew a couple of inches. Then examine the stitch. It should look identical on both sides. Look to see which side is drawn too tight, the zig zag being smaller on that side with threads from the bottom threads pulled through. Then adjust the two tensions so that they make a uniform, identical stitch.

Also, when the bobbin tension is right you can hold the bobbin dangling by the thread and it won't spool out to the floor but will let loose a bit with a slight flick of the wrist. Too loose it will just spool out. Too tight and it won't drop at all. When you get that set right then do the above zig zag test to see where the top tension should be set.

Check the upper tension unit for loose threads or fluff. This causes the discs not to completely close when the presser foot is lowered.

if stitches on top is loose then remove bobbin case and tighten small screw on it. if stitches on bottom of fabric is loose then tighten top thread tension.

Welcome to FixYa!

Loose bottom stitches come from the top, not the bottom. Seems weird, but that's the way sewing machines work.

The dial tension should be set at the mid range and make absolutely sure that you have the machine threaded correctly. Both things will cause a sloppy bottom stitch.

Thanks!

If you find my solution helpful, I'd appreciate a FixYa rating....

You don't want to adjust the bobbin tension, you'll want to try adjusting your stitch length, as well as the regulator tension.

I found a screw on the bobbin case (where you put the cotton for the underside stitching) which was very loose. I tightened it and that created more tension for the bottom thread which solved the problem.

If the top stitch is loose, then you need to tighten the bobbin tension: if the bottom stitch is loose, tighten the top tension. Hope this helps. It could also be the size needle and thread you are using for a particular fabric. Different fabrics require different notions.