Bobbin thread bunching - Brother SE-270D Computerized Sewing Machine

SOURCE: thread bunching

I discovered that when the thread is knotting up on the underside of the material that it is usually the threading on top and has nothing to do with the bobbin.

SOURCE: Bicor vx1005 ...thread keeps bunching

Try a different bobbin. Look for one that is a little narrower. I had the same problem and changing to a narrower bobbin fixed it.

SOURCE: Threading and Bobbing

http://www.brother-usa.com/manuals/default.aspx?ProductGroupID=3&WT.cg_n=Support&WT.cg_s=Manuals

SOURCE: mass bunching of thread in the bobbin compartment

it had nothing to do with the shuttle, it is the upper thread is not in the tensioner. lift the presser foot up and thread the machine even if you have to hold the thread on the top and pull on the bottom to make it go in the tensioner it will help, if a machine loops on the bottom it is the upper tension if it loops on the top it is the lower tension

SOURCE: Bobbin thread bunching up.

Thread the machine with the presser foot up and see if this will remedy the problem.

If not, refer to the manual to be sure the threading and bobbin are set up as they should be.

If the bobbin thread and top thread continue to not link together, it could be the timing needs to be adjusted.

In this case, take the machine to a Brother dealer for service along with a sample of the stitching.