Stitching Troubleshooting Cobra Class 4

[CowboyBob]

Looks pretty good,but if you had the 207 in the bobbin it would hide the knot better.

[Wizcrafts]

48 minutes ago, CowboyBob said:

Looks pretty good,but if you had the 207 in the bobbin it would hide the knot better.

And weaken the stitch strength to that of the thinner #207 thread. This is where trade-offs happen in the leather sewing business. If one sews a gun holster with #207 thread in the bobbin, there is no point in using anything larger on top, except for appearances.

A properly balanced tension system on a 441 type machine should easily hide the knots of #277 thread between two layers of 8-9 ounce leather. If the knots keep moving up and down, either the spool of thread is poorly bonded, or is twisty coming off the spool, or the top thread is lifting and lowering inside the top tension disks, or the check spring action is too strong, or the bobbin spring is worn where the thread feeds out of it, or there is crap in the bobbin case, or the bobbin thread starting stub sticks out and interferes as the bobbin turns inside the case, or the bobbin length or end shape is out of specs.

[jrprottas]

I'm also in the process of learning about my new Cobra Class 4. 

It takes quite a bit of force to pull my workpiece out of the machine. Videos make it look very smooth and easy. What am I doing wrong? Which tension points might be the culprit?

Also, do schmetz needles have some size identification on the needle itself?

Thanks, Jeff

[Hildebrand]

@jrprottas make sure you are stepping down hard on the pressor foot release peddle.  When you push it all the way down it releases the top tension, also on videos I have watched they sometimes grab the thread on the end of the machine and pull down creating slack so you can pull the work out easier.

Todd

[Wizcrafts]

1 hour ago, jrprottas said:

It takes quite a bit of force to pull my workpiece out of the machine. Videos make it look very smooth and easy. What am I doing wrong? Which tension points might be the culprit?

Jeff, when you push all the way down on the foot lift pedal the top tension disks should be opened up by a lever underneath them that gets pushed up. Examine the tension disks while somebody pushes down on the pedal to see if this is happening. If the lever does move up into the disks but they don't open it could be that the tension spring has been tightened so far that it has no more give to let the disks separate. If so, back off the top tension spring and back off the bobbin tension to balance the knots.

The hand lift lever, with the ball end, should also provide enough lift to separate the tension disks.

Sometimes new 441 clones are setup with fairly high bobbin tension. I recommend backing it off until there is a smooth flow with a little spring tension, but not free flowing. This will give much more range of adjustment on the top disks and lower roller.

If the top and bottom tensions are not too tight and the disks are opening with the lifters but the thread is very tight, check the thread path to see if it is twisted around a guide, or caught under the thread spool. If the thread is looped around the top post, try just feeding it straight through the upper hole, or even sideways through the second hole, but not through any other holes. This will relieve a lot of thread tension, depending on the stiffness of the thread.

[CowboyBob]

Don't forget to always stop & start with the take up lever @ the highest point,to make sure the needle thread is released off of the bobbin.

CB441 manual pg5.pdf

Edited January 2, 2020 by CowboyBob

[dikman]

On 1/1/2020 at 3:47 AM, Wizcrafts said:

Sometimes new 441 clones are setup with fairly high bobbin tension.

My new CB4500 was like that, it took a lot of force to pull the bobbin thread, I had to back off the tension a bit.