Outer Presser Foot Stutter on Cobra 4

[JLSleather]

So the "fix" for a bushing with too much "play" is to "one-side" it in the hole?  Okay ...

 

 

 

[brmax]

Its dry. 

It may be possible to remove the top presser spring retainer nut totally. In doing this a better oiling of these parts surely could be tried.  This seems to be a new machine fit type issue though a pain i think a bit of time and youll be off n stitching.

I had earlier tried myself manually lifting the presser foot on mine  at its mount point and this is handy. 

Have a good weekend

Floyd

edit: oh the ole  chatter roller ya!

Edited March 24, 2017 by brmax

[MrLentz]

4 minutes ago, JLSleather said:

So the "fix" for a bushing with too much "play" is to "one-side" it in the hole?  Okay ...

 

 

 

Yeah - I am not sure, it did stop it from skipping. My guess is that when the outer foot is going up, the inner foot is pushing down - and due to how the linkage is set up there must be some lateral force on the outer foot bar with the spring. Both feet use that same spring for tension, so the inner foot looks like the lateral force is counteracted by applying equal force using the bushing against the wall. Without enough pressure on the bushing plate, the rod probably bends ever so slightly. Same with too much pressure is my guess as well.

[Uwe]

I think the vertical plate adjustment is just a normal adjustment for this machine's design and does not indicate a loose bushing or some other defect.

The bearing wheel presses against the vertical surface as it rolls up and down. That vertical surface needs to be in the right plane to keep things aligned properly and provide a leverage surface for the bearing wheel. If the vertical surface is too far away the linkages put horizontal pressure on the presser foot bar and deflect it or press it sideways against the upper and lower bushing walls, rather than guide it straight up and down without sideways deflection or pressure.

 

Edited March 24, 2017 by Uwe

[brmax]

Thats what gets my goat, i got all worked up on mine and so got ready. Did work outs! Push ups everything. Even brang all the tools in, a new pot of coffee. 

I made the call and like : do this, i did and it was fixed and done. Dam coffee in my cup was still steaming. 

Floyd 

[JLSleather]

From the video, I'm thinking that the noise (which is more obvious when you slow the video down to 1/4 speed) is from the SPRING contacting teh casting in the low end. "One-siding" the shaft in the busing wouldn't be my first "plan", but ..   If the shaft is off by that noticeable amount, a guy might think about an eccentric bushing to allow it to pull back in the right place.

Question is, does it look like the needle itself is moving laterally with each stitch?  

[Uwe]

I vote for letting the man enjoy his stutter-free machine.  

[JREESER1]

I second that motion, Uwe! If he is happy with the fix, that should be all that matters.

jr

[MrLentz]

haha, well as long as it is not a patch for a bigger problem i'm fine with it!

[Uwe]

I really do think the fix was a normal adjustment and I don't see any indication of some major flaw that needs to be worried about.