Ferdco Super Bull / Cobra Class 4 Issue

[SARK9]

I don't have a machine that is remotely similar to yours, but if one of my smaller machines was showing frayed thread in the stitches, I'd look closely at the operation of the check spring. The needle could be clipping the top thread if the tension is released too early on the downstroke, also,  if the loop is formed a bit too close to the scarf of the needle when the hook arrives, it could nip the thread a bit as its picked up. That is something to double check-Your manuals should outline the adjustments.

 

-DC

[Darren Brosowski]

If the picture is the top then I agree with SARK that it could be the take up spring.

The inner grooving foot should not cause a problem unless there is a burr on it somewhere so check that first.

If the foot is clean an smooth then check the take up spring. There are two springs and it could be as simple as the spring you see on the outside is not locked into the primary spring. The loop on the primary spring can break off and the secondary spring just flops around

 

 

[Yetibelle]

There are many Class 4 timing videos, while it may not be exactly the same as yours it is the same principle action to make a stitch. 

 

 

[Trox]

It's easier, cheaper to make a copy or clone just like the real thing; than make it different. Therefore, you can trust they are all the same. Of course there have been some modifications/improvements and different material qualities. I'm sure we can help him get his machine sewing as it should. Nevertheless, that the dealer job in the first place. Just return it and demand they fix it and pay for the transport. Is it not a brand new machine and you paid for a fully operational sewing machine. If you want a DIY project you can buy it direct from China yourself to a fraction of the price. I'm sure any of our dealers would have replaced/repaired it and not told you to seek advice here on their mistakes. If the dealer will not help you, then tell us where we should not buy sewing machines. Let them earn their pay check like our dealers have too.  

Tor  

[Uwe]

Open the bobbin cover and turn it over by hand very slowly and just observe what's going on. Most of the time it'll be obvious what is causing the thread to fray, either rubbing against something or running over a sharp edge or whatever. Does the thread get frayed before it ever gets to the eye of the needle? Running and snapping the feet dry like you did will surely cause some sharp metal edges somewhere. Sending the head back for repair on the dealer's dime seems excessive at this point and risk more damage than it may fix.

Figure out how to take a close-up video of the hook movement with thread and leather like the one posted above, except focus on the hook instead of the thread stand in the background (usually done by touching and holding the area on your smart phone screen that you want to be in focus until the focus locks.) Get a $10 phone holder (a scotch tape dispenser works nicely in a pinch) and put the phone on a stable surface. Horizontal video rocks.

Edited July 6, 2016 by Uwe