More Help Please With My Cobra 4

[Averya]

Before bugging Steve again, I thought I would ask if someone on this forum could advise me. I finally got the tension adjusted for my 136 thread, after hours of frustration. Now I'm having issues with backstitching. The machine will go along nicely, then when I try to backstitch it won't pick up the thred at all. Does anyone have any idea why this would happen. I sure wish I knew someone with a Cobra 4 who lived in Oregon....I would gladly hire them to help me with this machine!!!!!!

[Wizcrafts]

Here are a couple of things you should check, or readjust for problems sewing with #138 thread.

• Needle size: Use a #22 or #23 maximum needle size with #138 thread (aka, T135). Too large of a needle makes too big of a hole, which lets the loop dissolve before it can be picked up.
  
• Thread post: Wrap thin thread, like #138 around the top thread post one full turn before feeding it into the the upper tension disks. This provides some back pressure to keep the thread from lifting/twisting up in the disks and out of the primary tension position.
  
• Check spring: You may have to alter the tension and maybe even raise the starting position of the check spring to ensure that the check spring is not destroying the formation of the loop in the eye of the needle.
  
• Needle orientation: Sometimes it helps to slightly rotate the needle counterclockwise to aim the loop towards the oncoming hook. This tends to help more when the timing is very close, or other factors are interfering with the loop.
  
• Needle brand: Use a Schmetz needle if at all possible. They tend to produce the best loop under any given configuration.
  
• Needle point: Leather point is preferred
  
• Timing & Needle bar: You may be able to find a better vertical orientation of the needle bar by lowering the needle in its mount very slightly. If the thread pickup improves, the needle bar should be lowered in its clamp, inside the head. It is secured with two screws. Constant pounding can cause the needle bar to slip upwards, throwing the timing off (especially in reverse).
  
• Horizontal separation between the needle and shuttle may be to great. This is not so easy to fix. There is a spacer that goes into the end of the arm, before the shuttle mounting plate. If the spacer was designed for very large needles, like #25 and larger, a #22 needle may be too far away for a marginal loop to get picked up by the hook point.
  

Edited December 5, 2012 by Wizcrafts

[Averya]

Wow! Thank you so much for your advice. I am using a #23 needle, but I plan on printing out your suggestions and going through them one by one. I can't tell you how much I appreciate your time in listing the possible fixes for my problem.

[Art]

I would not worry about calling Steve, he lives for this stuff. I wouldn't worry about the tension. The instructions call for a double wrap on the upper tension disks, this should be enough. When backstitching, start 3 or so stitches from your desired starting point and stitch Back to your desired starting point, then put the needle down and come up 1/4 inch (always cranking the handwheel towards you) and shift to forward. Repeat this procedure on finishing your stitchline, sewing back 3 or so stitches from the finish point. Going forward-back-forward like a regular sewing machine is just putting too much thread in the same holes if the needle is sized properly. Remember when changing direction, needle down, needle up 1/4 inch, shift direction lever, sew.

Check timing; Take off needle plate, take thread out of needle, move direction lever to center (0 length) position, put needle down (remember handwheel, sometimes called the balance wheel, toward you from top always, never back up), raise needle 5/32 inch and look at the point of the shuttle (hook), it should just be intersecting the needle at the scarf.

Is needle inserted correctly, thread groove on left, scarf on right, threaded left to right.

Art

[Averya]

Thanks Art....I appreciate your advice also. I will keep it for future reference as I know so little about this machine. The needle was inserted correctly. I will certainly use your advice on backstitching too.

I spent this afternoon following WizCrafts printout and he was "spot on". When I lowered the needle, it began to sew perfectly as well as backstitching. I took the head off (which was a bit scary for me) but it was actually very easy, dropped the needle bar as suggested, and reinserted the needle to the proper position, and everything worked like a charm. I did raise the check spring also. Thank you again WizCraft.......I've been struggling with this machine for quite some time.

As an aside....I did talk with Steve when I was first having difficulties and he walked me through the necessary corrections. However, once I changed thread and needle size, I began to have problems again.

Anyway.....thanks to you both...this board is awesome.

[Ran]

I would not worry about calling Steve, he lives for this stuff. I wouldn't worry about the tension. The instructions call for a double wrap on the upper tension disks, this should be enough. When backstitching, start 3 or so stitches from your desired starting point and stitch Back to your desired starting point, then put the needle down and come up 1/4 inch (always cranking the handwheel towards you) and shift to forward. Repeat this procedure on finishing your stitchline, sewing back 3 or so stitches from the finish point. Going forward-back-forward like a regular sewing machine is just putting too much thread in the same holes if the needle is sized properly. Remember when changing direction, needle down, needle up 1/4 inch, shift direction lever, sew.

Check timing; Take off needle plate, take thread out of needle, move direction lever to center (0 length) position, put needle down (remember handwheel, sometimes called the balance wheel, toward you from top always, never back up), raise needle 5/32 inch and look at the point of the shuttle (hook), it should just be intersecting the needle at the scarf.

Is needle inserted correctly, thread groove on left, scarf on right, threaded left to right.

Art

Art...when you refer to "....raising the needle up 1/4" before changing direction, do you mean just coming up a 1/4" from as low as the needle goes? Or do you mean having the needle 1/4" above the workpiece? I've been a little confused too regarding the proper backstitching procedure. Also, if not making a loop (in other words, when sewing in a straight line that doesn't end where one begins), MUST we backstitch at the beginning as well? I hope I'm making sense.

Oh...and Averya...I hope you don't mind my butting into your post...

[Art]

I mean to come up an 1/4 inch from bottom dead center, in the forward direction. As far as backstitching goes, it will lock in the loose ends. Backstitching is the easiest way, but pulling the thread through to the backside and tying it off works too. Also burning off with nylon or poly and squishing the thread against another while it is still soft will work also. Even when backstitching, I like to pull the top thread to the back so there isn't something sticking up. This is more important with big thread as it is sometimes quite obvious.

Art

[Ran]

I mean to come up an 1/4 inch from bottom dead center, in the forward direction. As far as backstitching goes, it will lock in the loose ends. Backstitching is the easiest way, but pulling the thread through to the backside and tying it off works too. Also burning off with nylon or poly and squishing the thread against another while it is still soft will work also. Even when backstitching, I like to pull the top thread to the back so there isn't something sticking up. This is more important with big thread as it is sometimes quite obvious.

Art

Thanks Art. I'm gonna try this on some scrap material. I recently tried the 'burn' method using a soldering gun. Seems to have worked well. We'll see, I guess.

Randy

[Rayban]

Randy.....try a Bic.

[Ran]

Randy.....try a Bic.

K..