Pfaff 1245 Random Upper Thread Loops

[dikman]

Have you tried going up one needle size?

[Burkhardt]

8 hours ago, LordHoot said:

but even at max tension and proper balance between bobbin and top thread, stitches are still weak

Those 2 things can't happen at the same time.

[kgg]

16 hours ago, LordHoot said:

Sewing mainly 1000D, 400D nylon and various width of nylon webbing.

Looking at you photo's again of where you are sewing the nylon webbing I wonder does this problem still happen? Have you tried sewing two or three layers of the webbing to give extra the thickness? Sometimes you need the extra thickness to allow for the bobbin and top thread to form and tension properly. I know if I tried sewing that webbing with my Juki 1541S, which is probably very similar capabilities wise to your PFAFF 1245, I would run into the same / similar problems. However if I used my Juki 1181N, walking foot machine, it would sew fine. My Juki 1541S hates thin stuff.

kgg

[LordHoot]

8 hours ago, kgg said:

Looking at you photo's again of where you are sewing the nylon webbing I wonder does this problem still happen? Have you tried sewing two or three layers of the webbing to give extra the thickness? Sometimes you need the extra thickness to allow for the bobbin and top thread to form and tension properly. I know if I tried sewing that webbing with my Juki 1541S, which is probably very similar capabilities wise to your PFAFF 1245, I would run into the same / similar problems. However if I used my Juki 1181N, walking foot machine, it would sew fine. My Juki 1541S hates thin stuff.

kgg

All previous tests were done with 2 layers of webbing, which is roughly 2-2.4 mm thick.  I did a test run with 4 layers which is around 4 to 5 mm and it definitely made better stitches, had to adjust tension to have the knot in the middle and then loops disappeared, stitches were tight.  I tried 8 layers but it was too much for the machine,  it seemed like the needle deflected and hook didn't always catch the thread. What I usually sew with this machine is 2-4 layers of webbing, sometimes with other fabrics. I need it to sew 2 layers perfectly as it's used for pocket flaps and loops would be very visible. Could it be like you described, the machine is not suitable for this kind of work?  Is there a way to adjust the timing so that it would handle lighter fabrics?

Edit: How does this machine compare to an Adler 267 in terms of sewing light/medium fabric? Do you guys have recommendations on sewing machines for that type of work?

Edited March 9, 2023 by LordHoot

[kgg]

16 hours ago, LordHoot said:

I tried 8 layers but it was too much for the machine,  it seemed like the needle deflected and hook didn't always catch the thread.

 

On 3/8/2023 at 8:45 PM, LordHoot said:

Setup: Bonded nylon thread, #69 (A&E) both top and bottom, usually all black but using green to help see the problem, 135x17 DP17 110/18

To help prevent needle deflections I would suggest either

i) move up to a 135x17 size 20 or 21 needle when sewing thicker materials or

ii) change the thread size to V92 and use a 135x17 size 22.

kgg

[LordHoot]

Quick follow up: thanks for the help, I managed to find a hook timing setting that made a little stronger stitches ( 1.6 mm instead of 2mm on the needle bar after BDC ) works well for 2 layers of webbing, but tension setting is very finicky. Reduced take up spring tension a bit, but corners remain hard to adjust. I also tried a size 20 needle and it works with 8 layers. I had to adjust the knee lifter motion range to lift the needle foot high enough to turn. I'll finish what I started and probably look into purchasing a lighter machine. Do you guys have any recommendation on light/medium duty machines for nylon webbing/fabric?