Cobra 4 Dropping A Stitch

[bushpilotmexico]

Just got my Cobra 4 a couple of weeks ago and after almost 30 years of hand stitching I've been tackling the learning curve of the Cobra 4. Can't say who is winning me or the machine!

I've been practicing sewing bullet loops and you can see that it's dropping the odd stitch. They are always at the top where I have finished sewing on the diagonal and now am stitching vertically down.

I raise the pressure foot, turn the leather, lower the foot and start sewing...I know immediately the bobbin thread hasn't been caught.

I'm using 277 thread top and bottom and am waiting on thread I ordered from Steve, 207 to be exact that I can use in the bobbin. The leather in the belt is 7/8 oz and the loop material 2/3 oz calf.

I'm sewing slightly over 5 stitches to the inch and my bullet loop material measures about 7/8" so it usually works out that if I start just at the top of the calf skin the last stitch finishes just past the bottom of the material.

Now when I lift the pressure foot, swing the leather around and start sewing up the diagonal the last stitch will fall too far forward so using a technique I learned on YouTube I use the reverse lever to move the needle back to where i want it to penetrate then drop the lever into forward and hand cycle the needle down and just up past center. I then position the calf skin and begin to sew down. That's where I occasionally drop the stitch or so I think.

Today I went ahead and sewed on 20 bullet loops on a belt I am making, I dropped two stitches all on the top, I knew immediately it had happened so I just raised the needle, lifted the pressure foot, cut the threads, cleaned up a few threads and resewed and you'd never know anything had happened, a couple of double threads that's all.

I am open to suggestions as to why this is happening? On a straight run the machine doesn't miss a beat with no dropped stitches.

[25b]

Sending you a pm...

[Colt W Knight]

Are you letting your needle bottom out and start back up before stopping, lifting your presser foot to turn the piece?

[25b]

Yeah, I sent him that 20 minutes ago.

[Wizcrafts]

Turning the work clockwise, especially with black, twisty thread, can cause the loop on the right of the eye of the needle to turn away from the hook, or even dissolve. You can counter this by rotating the orientation of the needle so that the eye is slightly to the rear on the right side. This prejudices the loop towards the approaching hook. It also changes the appearance of the holes.

Another workaround is to try to increase the amount of slack thread that gets fed to the needle. This slack thread is what forms the loop that is picked off by the hook. The check spring that is mounted on the lower disk axle is responsible for the thread slack. The shorter the travel, the greater the slack. But, don't overdo it to the point where the slack thread gets split by the point of the needle.

If you have really twisty thread, try wrapping it around two holes in the top post. One direction may be more effective than the other for cancelling the twist. Light colors are less twisty and softer than black, which is double dyed. This can vary from batch to batch. Order another spool of 277 to see if it is less twisty.

Edited August 11, 2015 by Wizcrafts

[bushpilotmexico]

I appreciate all the helpful comments. The thread I am using was supplied by Cobra Steve so I have to assume that the thread wouldn't present the problem.

Wizcrafts you say "You can counter this by rotating the orientation of the needle so that the eye is slightly to the rear on the right side. This prejudices the loop towards the approaching hook. It also changes the appearance of the holes." I have the needle inserted into the machine as recommended so as I sit facing the machine do I rotate the needle slightly clockwise or counter clockwise?

It's obviously a turning problem and I have been careful to make sure that the needle is slightly above dead center before I lift the pressure foot and rotate.

Thankfully I haven't dropped a stitch when straight sewing. I'll have to go back and practice some more and try to see if I can somehow duplicate the conditions to drop the stitch and then I'll know how to correct it or better yet prevent it.

Still hard to beat the appearance of some well done hand stitching but my 74 year old fingers just can't take the strain any more. The last cowboy belt I made had over 600 stitches sewing the liner and took me a little over 7 hours. That's not counting the hand stitching in the two holsters.

[Art]

Really nice work.

Make sure that the needle comes up from the bottom at least 3/16 inch. Experiment with more if necessary. What you are trying to accomplish is the hook capturing the thread enough that the rotation won't pull it out. In my experience, you can bring the needle up 1/4 inch or more without problems.

Art

[Wizcrafts]

Are you sewing the diagonal rows in forward or reverse? I reverse on the diagonals, then sew forward to secure each loop. I draw the stitch lines on the leather with silver ink as a guide and sew over them. I make a big dot at the end points and adjust the last stitch to hit it. I use the right toe foot when sewing bullet loops.

[bushpilotmexico]

As a newbie I watched John Bianchi sewing loops in his video and following his lead I am sewing forward on the diagonals I can sure try sewing backwards and then forwards on the loops.

I guess the Cobra came with the left toe foot attached....with the right toe foot on you would definitely be able to see where you are going especially when sewing backwards on the diagonal.

When you sew backwards and if the last stitch isn't going to go in your big dot end point do you do the reverse technique that Al shows in his video and using the lever adjust the needle forward to hit your dot? Then you would begin sewing down the loop.

I did ask which way you turn the needle clockwise or counterclockwise?

Much appreciated

[Wizcrafts]

Turn the needle counterclockwise so that the plane of the eye faces slightly to the rear, from the right side of the needle.

[bushpilotmexico]

Are you sewing the diagonal rows in forward or reverse? I reverse on the diagonals, then sew forward to secure each loop. I draw the stitch lines on the leather with silver ink as a guide and sew over them. I make a big dot at the end points and adjust the last stitch to hit it. I use the right toe foot when sewing bullet loops.

I tried your suggestion and it works like a charm with no missed stitches, just have to practice backing up...thank you very much for your suggestion. I just finished stitching a cowboy belt and it only took me 15 minutes that would have been 7 hours hand sewing.

It would be difficult in the belt and holster business to be competitive if you had to hand sew although hand sewing well done is hard to beat.

Thanks,

bushpilot

[Wizcrafts]

I am glad my suggestions have solved your sewing problem.

[bushpilotmexico]

I am glad my suggestions have solved your sewing problem.

Just sewed 20 loops on a new belt using your suggestion and it worked like a charm, not one dropped stitch. Thank you again.

[gottaknow]

You rock Wiz. Seriously.

Regards, Eric