Cobra Class 4 Shuttle Timing Issue

[Wizcrafts]

Thanks for the correction Bob. It's my day off and the machine is 4 miles away from home.

The whole deal is to have enough rotation between BDC and the arrival of the pointed hook to have it pick off the loop that forms on the right side of the needle. There is a best position for this to happen.

Edited June 28, 2015 by Wizcrafts

[iknowthisguy13]

So is the bolt supposed to be on the back or am I one of the lucky ones? What newbie mistake is not allowing the bobbin thread to be picked up? And thank you for the tapping trick!

[Wizcrafts]

So is the bolt supposed to be on the back or am I one of the lucky ones? What newbie mistake is not allowing the bobbin thread to be picked up? And thank you for the tapping trick!

Yeah, shuttles are expensive to replace. I know.

The bolt is where it is! That's why I loosen, then finger tighten it, so I can turn it with my fingers (in theory!). The eraser protects the shuttle when you need to hit it to move it.

[iknowthisguy13]

I give up. I can't get the needle thread to engage the bobbin thread at all now.

[Wizcrafts]

I give up. I can't get the needle thread to engage the bobbin thread at all now.

Set the hook so it intersects inside the scarf of the needle, a bit over the top of the eye, after it has raised about 3/16" from BDC, with the stitch lever at zero.

Next, pull out the thread and rethread the machine. Do not skip any part along the path. As experienced as I am, I have forgotten to go through the take-up lever once or twice! No take-up, no sew.

Make sure the thread path is unobstructed from the spool onward. It must flow freely until it gets to the top tension disks. It must sit all the way down between those disks to maintain top tension. The little steel loop on the lower right of the disks can be repositioned slightly to get the thread well into the disks. From there, go down and once fully around the lower disks, the through the guide over then, then through the loop in the "check" spring* attached to that assembly. From there, up through the take-up lever, down through the clip guide, the wire guide, and the hole above the needle mount, then through the eye of the needle, from left to right.

Before testing, lift the presser feet with the foot lever, they should go up high, at least 7/8" or higher (mine lift a bit over 1"). Pull on the top thread at the take-up lever and ensure that it flows freely. Lower the foot lifter and try pulling again. It should be hard to pull the thread, meaning you have (adjustable) top tension.

Load bobbin thread counterclockwise, through the slit in the bobbin case. Adjust the spring tensioner for a modest pull on the bobbin thread. It should neither be jammed or totally loose. A smooth steady pull is best, generally speaking. Rotate the hand wheel toward you from the top, in a counterclockwise direction, manually (depress the speed pedal slightly to free the internal brake, if your motor has one). If you rotate the wheel the wrong way the machine will not sew!

Watch as the needle goes down and starts back up. The hook should intersect the needle above the eye and you should see a loop form to the right. The hook should then pick off the loop as you continue rotating. the wheel.

* The check spring's job is to maintain tension on the top thread as the take-up lever moves down. It should hold that tension until the needle contacts the top of the material. This is to keep the needle from piercing the top thread due to too much slack. OTOH, it must give up and stop before the needle starts back up, after BDC. Otherwise, no loop will be formed. The check spring is set by the dealer before the machine is shipped and is usually spot on.

Report back. Over.

Edited June 28, 2015 by Wizcrafts

[Art]

Ok,

Sounds crazy, but is the needle in correctly, by that I mean slot on left, scarf on right? I know the guy that sets those machines up, and it should run like a rabbit right out of the box.

Art

[iknowthisguy13]

Rethreaded the machine, all the tensions check out, the hook intersects the needle as proscribed. Needle is in all the way (new needle) long groove on the left. Small loop forms and does nothing.

Bobbin threaded and installed correctly. tension seems appropriate there too.

[Wizcrafts]

There is a movable stopped under the check spring, secured by a flathead screw. Loosen the screw and adjust the metal stopped so the check spring stops a little higher up. Try again. The standard position is the arm of the spring faces more or less horizontal.

Approximately how much upward travel is your needle making before the hook arrives over the eye?

[Wizcrafts]

As I pointed in before, make sure you are rotating the wheel towards you from the top, which is in a counterclockwise direction on the shaft, from the read of the machine. Modern sewing machines almost always rotate CCW. They will not pick up the bobbin thread or form stitches if you turn the wheel the wrong way. It is an easy mistake for a first time sewer to make.

Edited June 28, 2015 by Wizcrafts

[iknowthisguy13]

3/16" of an inch to the best of ability. I am turning the wheel in the correct direction. Is the loop that forms suppose to drop down and hook immediately below the hook that forms it? If so, this isn't happening.