Outer Presser Foot Stutter on Cobra 4

[MrLentz]

Hello,

I just purchased a new cobra 4 sewing machine and have been noticing that when sewing slowly the outer presser foot comes up in a very jumpy manner. Kind of like a stutter. It kind of concerns me that the rod holding the outer foot might be off in some way - and I don't want to continue any damage to this new machine if something isn't set right. Anyone have this issue with that outer presser foot when it is pulling up? Still does it even when I pulled the foot off.

The rod is pushing up on the large tension spring on the inside of the case, so my thoughts are that this could just be some physics about the slow speed against a high pressure spring. Any thoughts? Just want to make sure either way before moving forward!

 

[JREESER1]

If you just purchased a new machine, call the dealer and describe your concerns. I'm sure they can ease your mind and find a solution if there is a problem.

jr

[Wizcrafts]

Lol, the jumping of the presser bar is probably caused by an off-axis hole bored into the top tension adjuster bolt. Just loosen the lock nut and rotate the adjuster a little until the presser bar moves freely.

[MrLentz]

16 minutes ago, Wizcrafts said:

Lol, the jumping of the presser bar is probably caused by an off-axis hole bored into the top tension adjuster bolt. Just loosen the lock nut and rotate the adjuster a little until the presser bar moves freely.

I did try that in 1/8 turns to see if there was a good location, but doesn't seem to make a difference. That's my concern though - is a poorly drilled hole in the case, would that mess up the machine in the longrun? Kind of bummed because I also am having a problem with the needle holder and bar. Apparently the needle is skewed off to the right by about 1/16 inch and just about hits the holster plate even when installed entirely to the right. I am getting a new needle holder to see if that is the issue, but overall it's starting to seem like I might have a lemon.

23 minutes ago, JREESER1 said:

If you just purchased a new machine, call the dealer and describe your concerns. I'm sure they can ease your mind and find a solution if there is a problem.

jr

I have been asking Steve at leather machine co, but no answers on this part so I wanted to see if anyone else had a similar issue

[Uwe]

I'd take the faceplate off and carefully observe how everything moves as you slowly turn the hand wheel. Give it a good oiling while you're at it. You might be able to tell where it catches and causes a stutter.

Sometimes the foot lift linkage needs to be adjusted a little to line things up just so for smooth movements. Also check if a screw may have worked itself loose during the break-in period, which happens on occasion with new machines no matter how careful the technician is.

The vendor's tech support is your first line of problem solving, be sure to keep trying to give him a shot a fixing your problem. The dealers keep saying that it's their setup work, initial adjustments, and after-sale support that makes the difference between all these virtually identical clone machines. If you're going to end up doing the work yourself, you might as well order a machine on alibaba.com and save a chunk of money up front. At the same time, even the best vendor has absolutely no control over which screws the user turns, which may cause issues.

It's not yet time to lose sleep over potential off-center holes and lemonade.

But it is time to break out the camera phone, dust off your youtube account (or get one) and post a video snippet of the problem. The only thing that's certain is that this won't be the last time words alone will not sufficiently describe a problem.

 

Edited March 24, 2017 by Uwe

[Uwe]

As a follow-up, I actually caused a similar problem on my Adler 205 once, where the foot lift linkage started making odd clicking noises. I took me a while to realise where the noise came from and that I myself had caused the machine to make these noises after adjusting the manual foot lift height. A very subtle tweak to lower the manual foot lift height a small amount brought the machine back to silky smoothness and banished the clicking noise. In my case the clicking noise was caused by an internal sliding block that was stuttering as it moved on the shaft. The Adler's mechanism is different enough from your 441 class machine to not be of help in debugging your case. I'm just mentioning it to illustrate that small adjustments can have unintended side-effects, and that some issues only manifest themselves at very slow speeds and could easily be missed during initial setup. The clicking noise actually went away when speeding up the machine. No off-center holes or lemon castings, just plain old user error was the root cause in my case.

Here's a video snippet of my Adler 205 making the clicking sound:

 

[MADMAX22]

Regardless I would still leave it alone till you talked to someone at Cobra. Looks like they have a limited lifetime warranty but dont know the details so who knows what voids it. 

[brmax]

If when you sit next to it and manualy lift up on the foot at the mounting is there noticeable drag. You could remove the side for a better oil app possibly. I had a great talk with the tech at leather machine so do give them a shout back in the shop

good day

Floyd

[MrLentz]

Thanks everyone for your replies. Yes I am getting back in touch with them to keep troubleshooting this. I know from this forum they have good support which is why I chose to buy from there. I have wiped out the interior of the case and oiled every moving part, so it's probably a bit more technical at this point.

Here are two videos of the stutter.

https://dl.dropboxusercontent.com/u/277783/IMG_0203.mp4

https://dl.dropboxusercontent.com/u/277783/IMG_0202.mp4

 

 

[MrLentz]

Ok, just to clear this problem up - it has been solved. Leather Machine Co got back to me after seeing the videos, it turns out the problem had to do with the steel plate on the inside back of the case where a roller bearing rolls up and down it as the presser bar lifts. Turns out the plate was not close enough to the bearing, so I loosened the top screw on it, applied pressure pushing it closer to the bearing, then tightened the screw back down. Problem solved!