Poltergeist?
 

Hello Quilters, Has anyone ever had a machine sew by itself? My computerized machine (I don't know if it's against the QB rules to name the brand) occasionally sews by itself after hours of use. With no pressure on the foot pedal, the presser foot and needle just start going up and down until I shut the machine off. If it was turning out quilts I wouldn't complain, but it just knots up thread under the throat plate. The machine is just over a year old and the problem started a few months ago. It doesn't happen every time and, of course, didn't happen in the repair shop so they couldn't diagnose or repair the machine.

Hmmm, I have several different brands of machines and not had any of them do this. When it does it again maybe disconnect the foot pedal from the machine and see if it stops it or keeps going just to try to diagnose where the problem is occurring.

Excellent suggestion Sandra. Keep us posted on your ghost hunting, Mitch.

I did try unplugging the machine and restarting it, cleaning it, detaching the foot cord, cleaning the foot pedal, ect, ect, ect Nothing ever helped.

I had a Pfaff passport 2.0 that did that. It sometimes would not sew. Lights would come on, just would not sew. Sometimes it worked fine. Yes, one time it just took off while I was staring at and then went full speed and it would not shut off until I pulled the plug. Brought it in a couple of times. It never did that at the dealer. The tech thought it might be just the tiniest speck of dust or static that would trigger it. I still have that machine, but should probably just bring it to the recycling center as I can't sell it anyone and I sure don't want to use it. It is a boat anchor. Let me know if it is the same machine

What a fascinating issue to be having!

First thing I would rule out is your home electricity. Do you have any other problems with flicking lights or power surges? Is your electrical panel equal to the modern demands?? If you still have fuses are they all secure and in good condition??

Do you use a surge protector? While I'm pretty confident in my power and such any thing over $100 and/or computerized is plugged into a surge protector first. I would first try that at the outlet you use. Then you can leave set up and just use an extension cord to try a different outlet. Then I would try physical placement to see if it does the same thing in a different corner of the room or house.

My Janome MC11000 does that from time to time. I haven't tested my theory, but I think it may be the foot pedal. It has not had the easiest life. For now though, I just let it go on as it is only for an inch or so and very seldom. Maybe once or twice during a long sewing session. It also never does it during a embroidery session, so I' sticking to the foot pedal theory.

Poltergeist redux
 

Thank you Detectives! It's a Bernette b79. I have tried unplugging it and rebooting, unplugging the foot pedal and rebooting, sweet talking, and cursing. I do suspect it might be the foot pedal. And I think it's the only thing left to try. The store just sent me a different pedal so that is my next trick. Also, if it happens again, I will pull the foot pedal cord out while it's stitching. I do use a surge protector snd tried a different outlet. My lights never flicker (including the one that is plugged into the same surge protector), nor do I have trouble with any other appliance, including my computer that is plugged into the same outlet but a different surge protector. It was just cleaned and serviced and it was perfectly well behaved in the repair shop. ::Sigh::

I was having that problem with my Singer, but finally figured out that I was the culprit. Many times during sewing, I will get up to do something. Often, as I walked away, I would hear/see the machine stitching away. Took me awhile to figure out that when I stood up, I would unconsciously move the foot pedal barely under the platform base of the table I sew at, which is elevated 3 inches off the floor. Walking and moving around would vibrate the floor/table and since the pedal was wedged under the base, it would sew on its own.

Thanks. Checked that. I even tried moving the foot pedal while it's happening and it doesn't stop. This didn't even start until just over a year of using the machine and I'm up and down constantly.