Pfaff 4145 (combination of Pfaff 145 and Pfaff 4143)

[Brtz]

As we are going into details of my Pfaff mentioned in the previous post (link below) I created a new topic dedicated especially to this machine. 

So the bottom of the machine also has been cleaned up. Here are some photos including the looper Uwe asked for.

The previous user forced the machine to work with 190 system needles, so knowing from the manual that this machnie is using 134 system needles I had to lower the needle bar to make the eye of the needle in the looper's range and also correct a looper timing. 

The looper has a flat sided shaft so losening the allen screws marked with green arrows allows to move the loper only left or right (closer or further to the needle scarf). Having no idea how to change the rotation of the looper I decided to loose both screws on the bottom gear marked with green arrows. Turning the lower gear turns the upper gear opposite and the looper as well. Turning the gear on its shaft also allowed to make no changes in the feed dog eccentric position. I am not sure if I did it properly - but have no service manual and no easier idea how to do this.

The looper catches the thread properly and now I have to figure out the thread tension issue - explain later.

I have a problem recognizing the unknown function of the brass foot I found on the right bottom of the machine (orange arrow). This is a block of brass fixed on the end of the vertical pushing rod. This rod can be pushed up and down. I can block this mechanism by changing the silver lever (blue arrow) position. Up position of this lever allows pushing the rod up or down and down position of this lever disangage (blocks) this function. The rod on its upper side is connected by the system of four arms with the kind of slider fixed to the lower horizontal shaft of the machine. Pushing this rod up changes the needle and presser bar position but only in their extreme forward or backward position. When both needle bar and presser bar are in their extreme forward position pushing the rod moves both bars 3-4 mm further to forward. The same situation is in extreme backward position of those bars; pushing the rod moves both them 3-4mm further to backward. I pressumed it would be a kind of 'afterburner' of the stitch lenght - but there is no possibility to pass the whole cycle of sewing while needle bar and presser bar are hitting one another and stucking in mid-position when the rod is pushed up. Does anybody have an idea of what this rod might be for?

Bert

 

Edited October 31, 2017 by Brtz
update

[Uwe]

This is turning out to be such a cool machine, I'm getting envious!

I'm not sure I've ever seen a walking foot chain stitch machine with a rotating looper like that before. 

When you get a chance, please post a link to or upload the manual you found for the machine.

As for the small lever and the connected push bar, I'm guessing it's for temporarily adjusting the stitch length to be longer than the one dialed in with the large lever. This is very useful because you can only temporarily shorten the stitch length with the large lever by lifting up. To increase the stitch length temporarily with the large lever, you'd have to turn the adjustment knob and then you'd loose your set stitch length.  Both levers together give you quick single step stitch length adjustments in both directions to line up with existing stitch holes, turn a precise corner, or to step over something. The push bar with the brass block at the bottom is likely intended for use with a knee lift mechanism so that you can keep your hands on the project while you fine-tune the stitch length for a specific stitch.

Using the small lever to override stitch length does not override the maximum stitch length in the rear set by the mechanical limits. I'm guessing you let go of the small lever again before the feet get to the very rear of the movement, especially if you're overriding the longest normal stitch length to be even longer for just one stitch. Letting go of the small lever sets things up again for a normal length next stitch.

Since the movement of the  small lever / push-up rod is adjustable in its travel limit, you can also use this feature as a quick-select alternate stitch length setting. You can then quickly switch between the two pre-selected stitch lengths by pushing up on the small lever.  The knee lever especially would be useful to switch to a longer stitch length for a short run during part of the seam.

I can't wait to see a demo video of this machine stitching!

 

 

Edited October 31, 2017 by Uwe

[dikman]

My first thought on seeing the brass block was also a knee lifter contact point, judging by the scratches on it.The blue knob is interesting as my Pfaff 335 has a position for such a fitting and I've always wondered what it would be used for.

[Brtz]

Spent half a day working on tensions. Uwe's film really helped, thanks. 

Here is the looper of my Pfaff 4145 in action. Greetings, Bert.

 

[gottaknow]

Greetings Bert,

I'm attaching a simple description of the cycle of a single thread chain stitch with a rotary hook. It's a simple stitch formation, but different than what most people encounter. I watched your video and I believe I see the looper hitting the needle. Make sure the looper is as close as it can be without deflecting the needle. Also, make sure the hook point is entering in the middle of the needle scarf. You may need to adjust your needle bar height to accomplish that. Have fun!

Regards, Eric 

[Brtz]

Thank you Eric, I am going to correct the looper settings due to your comments. As I said I still work on the check spring action thus not every cycle the thread loop is created when the needle starts going upward or sometimes this loop is very narrow. Closing the point of the looper to the needle scarf let not to miss the loop by the tip of the looper. However yes, the point of the looper touches the needle slightly now. From the other side as whole hook of the looper is curved in the needle-opposite direction the tip of the looper is missing the scarf a bit further to the right side then the point of the looper (see pic.) Maybe that is the reason the looper is missing the thread loop temporarly? Bert

[Uwe]

I suspect the tip of your looper is worn from touching the needle. In your diagram the tip of looper is pointing away from the needle. I think it used to point towards the needle before it was worn off. 

In the video, the looper is deflecting the needle a lot. I'm guessing as the lopper tip wore off over time, it was adjusted towards the needle to make it pick up the thread at all, causing even more wear on the looper.

The only part number reference I could find is Pfaff 102025 (In the Pfaff 4143 Parts Manual: Pfaff 4143.pdf) . Alas,  that part does not appear to exist anywhere online or physically from what I can tell. With a little luck, you may be able to regrind and polish your existing lopper tip a bit, or perhaps a looper from another machine will be compatible . 

Edited November 3, 2017 by Uwe

[gottaknow]

If that is the true shape of your looper, it's bad. The face of the looper should be flat and parallel with the needle scarf. People that don't understand how chain stitch machines work, will often damage loopers. There is virtually no reason to modify the shape of any looper, but especially one on a single thread machine. It is the shape of the looper that determines how long the looper keeps the triangle open so the needle can descend down through it. If the looper has been ground or reshaped in any manner, the machine will skip or not sew at all, no matter how you set anything else.

It's easy to change needle length on this class of machine without changing anything but the needle bar height.  You rotate the looper until the point is dead center on the needle, hold that position, insert the different needle, and move the needle bar until the looper is in the same spot. The machine doesn't care how long your needle is as long as you don't change the rotational timing of the looper. 

As for tension, the tighter the tension, the smaller the thread loop, looser it gets bigger. That makes it necessary to make tension adjustments when you use different thread. Also, when you turn the machine by hand, your loop size will be bigger than when you sew under power. Without question, the most common adjustment on this class of machine is the thread tension. Have fun!

Regards, Eric 

[Brtz]

I am attaching the zoomed photo of my looper. It does not look grinded or reshaped... so you think that is bad looper? I also wouldn't like to try reshaping it by my own.

Can you also have a look of how I am threading the machine?. There is still something wrong I am afraid. I have tension discs totally loosened and the check spring is set to the lowest workable power. But the friction resistance of the further thread guides (sloping arm, arm-shaft and on the needle holder) is still too big. The resistance is tightening the thread when I am trying to sew stitches longer than 4-5mm and the good starts to ripple. Changing the pressure foot power makes no effect. On shorter stitches it's better but still far away from ok.  

What am I doing wrong?

Bert

[gottaknow]

I can't tell if your looper is bad from the angle of your picture. Of course the definitive test is to compare it to a new one. They don't usually bend because of the hardening, they just break. As for the tension, try removing any extra wraps like at the post on top of the head. There are no hard and fast rules for all the thread guides. You use what the thread and sewing conditions require. As I said before, on these types of machines, tension is your main adjustments. It appears to be threaded right, but check any reference you may have. Don't be afraid to try different thread paths. It also appears your thread is too heavy for your test fabric. That will cause gathering. 

Regards, Eric