Tension, timing advice

[Nuttish]

Hi all, I'd be grateful for some help getting my Pfaff 1445 going. I previous posted about feet, which I got from Hong Kong. They're mediocre but acceptable quality given the rarity of the machine. The machine wouldn't have been a bargain if it were free considering the time and expense that's gone into it. But hey, we've got another machine so I'll consider this thing a hobby. 

I've got the hook correctly timed, but I'm finding that it's very difficult to correctly balance relative top and bottom thread tension, or top dog pressure may be incorrect, or the bobbin case opener isn't correctly timed or distanced. Or all of these. Compound feed is accurately synchronized, needle bar centered in all dimensions, all stroke lengths are correct, bottom feed dog height properly set to ~.020" (.5mm) per the service manual. I've got a new needle plate, feed dog, and feet, which feed perfectly straight. I do need to take the needle plate over to the buffer and ease some of the edges the thread goes around. No problems with inconsistent tension between the cone of thread and tension rings.

Top thread is correctly routed per the operating manual (unusual design and route). Bobbin thread is correctly placed and pulled.

Pictures attached.

Symptoms are:

• Occasional skipped stitches and slightly inconsistent bottom stitch; the bottom and top quality don't match consistently

• Backtack thread tension is very loose

• Starting the stitch occasionally results in a squirrel's nest mess of thread on the bottom

• When I get the top and bottom tension balanced such that the thread is more or less locking in the middle of my material, I occasionally find when turning the handwheel that the top thread is very tight as it crosses over the top of the bobbin and the motor may even slip on the belt

I strongly suspect some kind of binding or tension issue is causing thread to get pulled off the bobbin or through the top inconsistently.

I'm running a 3/4" HP servo motor with what I believe are the correct thread/needle combination for layers of 3 - 6 oz chrome tanned and retanned vegetable tanned leathers (the same size combination has always worked quite nicely on another machine). 

[shoepatcher]

Nuttish,

I am not seeing a bobbin case opener in the picture.  It may be there but I do not see it in the picture.  Give us a few more pics of the bobbin case area without the flip down guide.

glenn

 

 

[Nuttish]

Thanks very much for the quick reply! See attached.

[Uwe]

If the thread is too tight wrapping around the bobbin case, your top-to-bottom drive shaft timing may be off. One quick way to check is that when the thread is wrapping around the farthest point of the bobbin (directly opposite the needle), the thread take-up lever needs to be at its bottom-most position.  The thread should not snap around the bobbin case.

Make sure when you make adjustments that you use the specs provided in the Pfaff 1445 Adjustment Manual. If enough things are just a little bit off, it may add up to a bunch of trouble. 

As for the occasional bird's nest underneath when you start sewing, it's probably because you're not holding both threads taught for the first few stitches. 

Edited October 29, 2016 by Uwe

[Uwe]

I had a similar problem when I was working on my Juki LU-563 clone. In that particular case the issue was resolved by shifting the timing belt by one notch. It seems your problem is similar, except the Pfaff does not have a timing belt to synchronize upper and lower drive shafts. Perhaps there are marks on the drive gears that need to be aligned. 

Here's how the machine worked after the timing belt adjustment (and re-timing the hook):

 

Edited October 30, 2016 by Uwe

[RockyAussie]

Excellent videos Uwe  Thanks for sharing your knowledge.

[Darren Brosowski]

Before playing with timing it may simply be that the swing arm - the bit to the left of the triangle in the second still from Uwe is not set to allow your thread thickness through.

If the thread does not run through cleanly your stitch will look like crap so just undo the screw and open the gap a bit

 

[chasman52]

Nuttish:

Didi you solve your problem? I'm having similar problems