Cobra Class 4 Issues

[WulfLeatherco]

My Cobra Class 4 has developed a serious issue. It stitches for about 10-15 stitches then locks up. I have to back up manually, then it will go again until it locks up. The bobbin holder is very loose, so many that’s the culprit? I’m at a loss and I don’t know where to turn. I’ve been searching for someone in my area who may be able to evaluate and repair, but no luck. Has anyone else had this issue? The photo below is what it looks like when locked. Thank I’m advance for any help!

[chrisash]

Are you holding both ends of the tread i.e. bobbin and tread ends when you start sewing

From the picture the needle thread should not be going through the machine

Edited January 5, 2022 by chrisash

[Handstitched]

Also, check the  very tip of the needle. Even the slightest bit of damage to the tip can cause issues, from my own experience. 

HS

 

[TomE]

I would investigate the shuttle timing.  My Class 4 was incorrectly timed and the walking foot mechanism was out of adjustment.  I was experiencing needle strikes, missed stitches, etc.  I recommend reviewing the DVD that ships with the Cobra machines then watching videos by @Uwe to learn how to adjust the shuttle timing, and the walking foot mechanism.  Most of the tools needed for these adjustments are shipped with the Cobra Machines.

 

[Hags]

I have a class 3. My first thought is when did you last clean the bobbin area? I mean taking the thing apart, looking for burrs on the shuttle hook, blowing it out, reassembled cleaning and oiling? Yes the needle is important, but so is the bobbin mechanism. 

[Uwe]

The photo does look like the shuttle driver is pressing against the bobbin instead of the shuttle hook frame. The whole assembly looks a bit off-center and out of alignment for some reason. You may have an intermittent bind due to parts in the shuttle area that are too loose or out of alignment.

 

Something may have come loose in the shuttle area. Also make sure the shuttle race is properly oiled. 

 

As @Hags suggested, taking the shuttle hook out for a proper cleaning and inspection is probably good idea. 

Edited January 6, 2022 by Uwe

[WulfLeatherco]

20 hours ago, chrisash said:

Are you holding both ends of the tread i.e. bobbin and tread ends when you start sewing

From the picture the needle thread should not be going through the machine

Yes. I've been sewing on this machine for over a year. There's something wrong. 

19 hours ago, Handstitched said:

Also, check the  very tip of the needle. Even the slightest bit of damage to the tip can cause issues, from my own experience. 

HS

 

Thanks for the reply, but it broke the last needle so the one in the photo is brand new. 

[WulfLeatherco]

2 hours ago, Uwe said:

The photo does look like the shuttle driver is pressing against the bobbin instead of the shuttle hook frame. The whole assembly looks a bit off-center and out of alignment for some reason. You may have an intermittent bind due to parts in the shuttle area that are too loose or out of alignment.

 

Something may have come loose in the shuttle area. Also make sure the shuttle race is properly oiled. 

 

As @Hags suggested, taking the shuttle hook out for a proper cleaning and inspection is probably good idea. 

This makes sense. The bobbin holder very loose. Not sure how to take it apart, are there any videos online?

[WulfLeatherco]

2 hours ago, Hags said:

I have a class 3. My first thought is when did you last clean the bobbin area? I mean taking the thing apart, looking for burrs on the shuttle hook, blowing it out, reassembled cleaning and oiling? Yes the needle is important, but so is the bobbin mechanism. 

That sounds like a great plan! I was nervous about taking it apart, but at this point, I'm not sure I can do much more damage. Any tips for disassembly or reassembly would be greatly appreciated. 

[Hags]

The book explains it all  reasonably well. It's just 2 screws and it comes apart. Also several videos on YouTube.  It's pretty easy after you get into it. I love every time I do a bobbin, disassemble the bobbin hook assembly every 2 times. I oil the bobbin hook area every time I oil the machine. I always look at the hook for burrs. One needle strike is all it takes. It a piece of 1500 wet or dry paper cleans it right up. Dont be afraid. You have to get into it at some point. 

[TomE]

To remove the shuttle assembly, loosen the two black screws shown in your picture and gently pry off the retaining ring that the screws secure.  Be ready to catch the shuttle and driver, which can fall out when the retaining ring is removed.  In addition to cleaning and oiling the shuttle race, you can easily adjust the feed dog height with shuttle removed.  This video from @Uwe shows why there is play in the shuttle assembly. 

[Uwe]

I think this is the video @TomE mentioned. I made this video over four years ago and forgot that I had it in my hidden archive on YouTube. 

The Cobra 4 shuttle hook assembly should be identical to this Cowboy 4500.

This topic really belongs in the Leather Sewing Machine Forum. Perhaps @Northmount or one of the other admins can move it there.

 

Edited January 7, 2022 by Uwe

[Northmount]

1 hour ago, Uwe said:

Perhaps @Northmount or one of the other admins can move it there.

Moved.  Thanks for catching this Uwe.

[WulfLeatherco]

On 1/5/2022 at 10:23 PM, Hags said:

The book explains it all  reasonably well. It's just 2 screws and it comes apart. Also several videos on YouTube.  It's pretty easy after you get into it. I love every time I do a bobbin, disassemble the bobbin hook assembly every 2 times. I oil the bobbin hook area every time I oil the machine. I always look at the hook for burrs. One needle strike is all it takes. It a piece of 1500 wet or dry paper cleans it right up. Dont be afraid. You have to get into it at some point. 

Thanks Hags!

On 1/6/2022 at 5:17 AM, TomE said:

To remove the shuttle assembly, loosen the two black screws shown in your picture and gently pry off the retaining ring that the screws secure.  Be ready to catch the shuttle and driver, which can fall out when the retaining ring is removed.  In addition to cleaning and oiling the shuttle race, you can easily adjust the feed dog height with shuttle removed.  This video from @Uwe shows why there is play in the shuttle assembly. 

Thanks Tom!

On 1/6/2022 at 5:49 PM, Uwe said:

I think this is the video @TomE mentioned. I made this video over four years ago and forgot that I had it in my hidden archive on YouTube. 

The Cobra 4 shuttle hook assembly should be identical to this Cowboy 4500.

This topic really belongs in the Leather Sewing Machine Forum. Perhaps @Northmount or one of the other admins can move it there.

 

Thanks for sharing Uwe!! I will take all the suggestions and report back to let everyone know if I’m successful. 

[WulfLeatherco]

On 1/5/2022 at 6:59 PM, Hags said:

I have a class 3. My first thought is when did you last clean the bobbin area? I mean taking the thing apart, looking for burrs on the shuttle hook, blowing it out, reassembled cleaning and oiling? Yes the needle is important, but so is the bobbin mechanism. 

Hag, you nailed it. I watched the videos and search for some sort of timing issue, but when it came down to it all it was was cleaning the bobbing area. I felt like it was a situation dealing with IT at work and all I had to do was reboot my computer. Anyway thanks for the advice!

[Hags]

You are welcome and glad it's resolved!