Cobra 4 backstitch problem

[aaron8771]

Hey all, new to this forum, been browsing it for a few years. Just received my new Cobra 4. Works wonderfully especially compared to the Boss stitcher that I have been using. Except for one problem. When I start sewing, I back up three stitches then I'm on my way. Looks great. The issue is when I'm ending my stitching run, I back stitch 3 and I have a mess on the bottom. This happens every time. I've been practicing using 14 oz and two 8 oz veg tan. Stitches look good, knots appear centered. I'm using 277 bonded nylon with 25 needle.  After looking closer at my back stitches, the bobbin thread is laying flat on the bottom of the leather. I've done about 25 backstitches and none of them have worked out. Like I said, starting out the backstitch is good, only when I'm finishing off my run it does it. Any thoughts? Thanks in advance.

[Brooks125]

I believe you have a tension issue.  When you back stitch, the threads now have 2 threads in the hole, instead of one.  It will take some practice, but I corrected the problem by adjusting the top tension tighter ONLY when I am coming forward by my back stitch.  I have a CB3200, and adjusting the first tension wheel on top does the trick.

[aaron8771]

Thanks. I think I read that on here somewhere and it was on a Cowboy. I just think it's odd when I start, I back up 3 then go forward and it's fine. But at the end I reverse three stitches and that's when it does it. 

[Northmount]

If you reverse at the wrong point in the stitch cycle, you may loose the loop that was being formed.  Try making sure the needle is on it's upstroke (after the hook has caught the loop).

Tom

[aaron8771]

Thanks. Its definitely on the upstroke when I throw it in reverse.

Edited April 15, 2018 by aaron8771

[RockyAussie]

2 hours ago, aaron8771 said:

Hey all, new to this forum, been browsing it for a few years. Just received my new Cobra 4. Works wonderfully especially compared to the Boss stitcher that I have been using. Except for one problem. When I start sewing, I back up three stitches then I'm on my way. Looks great. The issue is when I'm ending my stitching run, I back stitch 3 and I have a mess on the bottom. This happens every time. I've been practicing using 14 oz and two 8 oz veg tan. Stitches look good, knots appear centered. I'm using 277 bonded nylon with 25 needle.  After looking closer at my back stitches, the bobbin thread is laying flat on the bottom of the leather. I've done about 25 backstitches and none of them have worked out. Like I said, starting out the backstitch is good, only when I'm finishing off my run it does it. Any thoughts? Thanks in advance.

What type of 25 needle are you using? A point style I would expect to do that maybe. Tri maybe LR I would not expect. Just a thought.

[CowboyBob]

Are you sure your going around the 2nd tension on the side 1& 1/2x?

[aaron8771]

Second tension is wrapped twice

[brmax]

Ya might give this a try. Letting the needle come up almost out or at least to see the scarf or knowing the scarf is well above the feed dog top. For me this requires real slow stitching at start and the end.

These methods seem to work better for myself. I also think even if a blanket foot is used this shuttle design needs more time or the needle being raised. I mention blanket foot as sometimes the single foot pressure can be adequate but may slip/turn with smaller pieces. This I found needed more of my attention, sometimes another added turn down on the top foot pressure so not to miss the full length of the stitch. 

This slipping may not be as pronounced with a flat bottom foot that doesnt press down directly on the stitch. In anycase I cannot use the reverse on the shuttle hook yet as on my non shuttle flatbeds. No doubt these can be thrown in reverse any time with perfect results. So possibly a bit different learning curve I experience.

 

Good day

Floyd

[aaron8771]

Thanks Floyd, I'll experiment with letting the needle up a little more (when I get time) and let you know.

[aaron8771]

Still not backstitching properly

[Colt W Knight]

On 4/15/2018 at 5:27 PM, aaron8771 said:

 

I had this exact same problem making my GPS collars. I added the lube pot filled with silicone and the problem went away. Don't ask me what the problem was ( I suspect the thread was getting hot).

 

[brmax]

I have to ask, does the needle hit the holes correctly.

In this situation I recomend to let the needle scarf be seen coming up and out of the leather piece totally. Stop then move lever to reverse stitch. 

Its just me arm chairing this so be patient, if thats not possible we can joke & laugh a bit first. 

 

Good day

Floyd

[Willie0]

My machine does this as well, especially with thinner leather.  If it is a nice project I leave the thread really long and hand stitch backwards to lock them in. 

[aaron8771]

Good idea WillieO. 

[aaron8771]

Floyd, holes do line up. 

Had needle point in leather. Put in reverse. Hand cranked back one complete stitch. Thread is caught around barrel.

Tried uploading pics. Tried.

[aaron8771]

[brmax]

As that needle is coming up, try to time it with that take up lever on the side as it gets close to TDC. Then ease off the go pedal, hit the bell to let them know your hittin the reverse. 

Once the patterns get working you may find the needle can cut threads so sometimes it can really be a pain. 

Good day

Floyd

[Wizcrafts]

Aaron, it could be that your timing is retarded a bit. Check it out by following these few steps...

1. Sew a few stitches in the normal direction, to lock the thread into the leather. Use about 6 stitches per inch (spi)
2. Hand wheel until the needle reaches BDC (bottom dead center) and begins to rise and the top thread loop is just being picked off by the tip of the hook, then stop.
3. Visually check the position of the take-up lever. It should be near the bottom of its travel.
4. Continue watching the take-up lever as you slowly hand wheel the machine a small amount. Stop when the take-up lever is at its BDC position.
5. Now look at the bobbin case/shuttle and note the position of the top thread that is passing around the case.
6. If the top end to hook timing is spot on, the top thread should be half way around the shuttle and bobbin case with the take-up at the BDC position.
7. If the take-up has not yet reached BDC, the timing is retarded. If it has passed BDC and started up, it is advanced.
8. If the above is the case, the hook position needs to be fine tuned one way or the other until the top thread is half way around the shuttle with the take-up at BDC.
9. Your machine is probably more forgiving in normal direction sewing than in reverse. Also, the longer the stitch length, the more critical the static timing becomes.
10. If you need to retime the hook, do so with the stitch length lever in the zero feed position (only moves up and down, about halfway between forward and reverse stitching)

[Zandeosaddles]

Hi. I set my machine according to Uwes video on you tube. I also realised the shuttle race spring screws need to be rather loose.Thread binds between shuttle and driver. after 5 years of struggle I finally have it right.