Cobra class 4 reverse issues

[StoneBuiltKnives]

Hello. If I could humbly request some assistance. I recently acquired a Cobra class 4 sewing machine second hand. This is my first sewing machine of any kind. My machine is breaking the upper thread and missing stitches when used in reverse. I believe the timing to be correct but I could be mistaken. In sews fine forward. Thank you in advance! 

[shoepatcher]

we need a video of the machine sewing please.

glenn

[StoneBuiltKnives]

https://youtu.be/XqRU8rubNLA

 

 

 

[CowboyBob]

When you check the timing make sure you have the stitch length on 0 & also make sure the feed dog is evenly set front to back in the needle plate on 0 stitch too.

[kgg]

2 hours ago, StoneBuiltKnives said:

My machine is breaking the upper thread and missing stitches when used in reverse.

Couple of additional questions:

i) What thread size are you using?

ii) What size of needle are you using?

iii) Are you using the same size thread in the bobbin as you are in the needle?

iii) Have done a test of the stitches in forward verses the stitching in reverse? This is done simply by putting a piece of paper (heavier stock or cardboard) under the presser foot as if you were going to sew but without the thread in the needle. Sew as normal for a few of inches and then reverse. This will tell you if the forward and reverse stitch is the same as the needle should fall into the same holes as what was made in the forward direction. It will also tell you that the stitch length you have selected is actually what you are getting.

kgg

[StoneBuiltKnives]

Thank you for the replies. I believe I may have it fixed. I think I underestimated the tolerance for an out of time condition. The hook was just barely protruding at bdc. I adjusted it so it was flush with the housing and so far it is stitching in reverse correctly. I'll update this post if wrong. Thank you again! 

[StoneBuiltKnives]

I spoke too soon. The issue now seems to only occur when back stitching. I'm using 270 thread top and bottom with a 25 needle. Stitching length is consistent from forward to reverse. Am I trying to cram too many stitches into a small area? Again thank you in advance. I'm certainly not sure if this is simply operator error. 

[kgg]

5 hours ago, StoneBuiltKnives said:

I spoke too soon. The issue now seems to only occur when back stitching. I'm using 270 thread top and bottom with a 25 needle.

The #25 needle is good for T270 in thinner / less sticky / less tough materials so go up one size to give a little extra spacing in the hole for the top thread to be able to pull up the bobbin thread. Since most times you will be reversing to lock a stitch the problem will be even worse if the forward and reverse stitches don't match.

A good reference chart for thread size versus needle size can be found at www.tolindsewmach.com/thread-chart.html compliments of Toledo Industrial Sewing Machines.

kgg

[StoneBuiltKnives]

8 minutes ago, kgg said:

The #25 needle is good for T270 in thinner / less sticky / less tough materials so go up one size to give a little extra spacing in the hole for the top thread to be able to pull up the bobbin thread. Since most times you will be reversing to lock a stitch the problem will be even worse if the forward and reverse stitches don't match.

A good reference chart for thread size versus needle size can be found at www.tolindsewmach.com/thread-chart.html compliments of Toledo Industrial Sewing Machines.

kgg

Thank you. I'll try that.

[Burkhardt]

Another thing I noticed is get rid of the death grip on the thread and let the material feed naturally. You don't to pull the thread just hold in place for the first couple stitches then let it go. How tight are the stitches (tension) and where is the knot placement, is it evenly centered? Re watched and found another problem, when you start regardless of direction the thread should be held out in front of arm and slightly to the right. The way you're holding it is maybe the reason it's breaking because no matter the direction of sewing the hook spins in the same direction and it's probably catching the tail and winding it around the hook till it breaks.