Gia Report post Posted July 6, 2020 (edited) 57 minutes ago, Pintodeluxe said: If the thread was forced into the wrong slot, and not really threaded correctly, it would certainly cause problems. You were right to suspect timing issues. That's the first thing I'd check if it wasn't forming stitches at all. If it's leaving loops on the bottom, you need more upper tension. Assuming the bobbin tension is okay, try rethreading it, and make sure the thread snaps in the pre-tension disc. With Pfaff's you can actually hear it snap into the disc. If you're out of tension disc adjustments, then look to add more passive upper tension IE: go through both guide holes before the pre-tension disc (threaded right-to-left on both holes). Good luck with it. I had rethread it many times, added tension, the timing hook is ok as well but this is how it sews: half holes half stitches.. Edited July 6, 2020 by Northmount replaced 3rd party links with the pictures Quote Share this post Link to post Share on other sites
Pintodeluxe Report post Posted July 6, 2020 This is the picture that had me worried. Immediately after you go through one guide hole it doesn't look like the thread is snapped down into the groove. It looks like you need to move the thread back towards the tension assembly plate to find the groove. If you make that one mistake, upper tension will be all over the map, and would explain the erratic stitch formation. Quote Share this post Link to post Share on other sites
Northmount Report post Posted July 6, 2020 @Gia Please upload your pictures to this site rather than to third party hosting services. When files are moved/deleted, or permissions are changed, or host decides not to allow them to be used in this manner, the thread becomes useless without the photos. I have copied your photos and uploaded them here. Tom Quote Share this post Link to post Share on other sites
Gia Report post Posted July 6, 2020 Just now, Northmount said: @Gia Please upload your pictures to this site rather than to third party hosting services. When files are moved/deleted, or permissions are changed, or host decides not to allow them to be used in this manner, the thread becomes useless without the photos. I have copied your photos and uploaded them here. Tom I will, thank you! Quote Share this post Link to post Share on other sites
Northmount Report post Posted July 6, 2020 Have you had the plate that surrounds the feed dog off? Does the machine make a noise that is different than what it used to be like a twanging noise? When you turn the wheel by hand, does it get hard to turn with each stitch, right from the first stitch? Tom Quote Share this post Link to post Share on other sites
Gia Report post Posted July 6, 2020 28 minutes ago, Pintodeluxe said: This is the picture that had me worried. Immediately after you go through one guide hole it doesn't look like the thread is snapped down into the groove. It looks like you need to move the thread back towards the tension assembly plate to find the groove. If you make that one mistake, upper tension will be all over the map, and would explain the erratic stitch formation. I don't hear any snaps when I thread the pre-tension disc, and it doesn't go more deeper than you can see in the picture. The only snap I can hear is from the tension discs with the springs. Quote Share this post Link to post Share on other sites
Gia Report post Posted July 6, 2020 11 minutes ago, Northmount said: Have you had the plate that surrounds the feed dog off? Does the machine make a noise that is different than what it used to be like a twanging noise? When you turn the wheel by hand, does it get hard to turn with each stitch, right from the first stitch? Tom No, it wasn't off when the problems occurred. There is no noise, I can easily turn the wheel by hand. The only thing I did different from before it was to sew Velcro on leather - with 140 needle for leather and 20/3 thread. Quote Share this post Link to post Share on other sites
DonInReno Report post Posted July 7, 2020 (edited) The first step should be changing the needle with a new one. This eliminates the possibility of a bent needle causing problems. How close does the hook come to the needle? Ideally the hook should pass as close as possible without actually bumping the side of the needle. It’s had to tell from the video, but the hook doesn’t look to be very sharp - it’s normal for a hook to get more dull every time a needle breaks or gets deflected into the sharp point of the hook. A dull hook makes it harder for the hook to catch the thread from the needle and makes needle/hook clearance extra important. Edited July 7, 2020 by DonInReno Quote Share this post Link to post Share on other sites
dikman Report post Posted July 7, 2020 (edited) 4 hours ago, Gia said: I don't hear any snaps when I thread the pre-tension disc, and it doesn't go more deeper than you can see in the picture. The only snap I can hear is from the tension discs with the springs. The thread comes out of the hole at the right and should go BEHIND the little collar, not in front.. The thread bunching up on the bottom is an indication that you're losing top thread tension. Edited July 7, 2020 by dikman Quote Share this post Link to post Share on other sites
Constabulary Report post Posted July 7, 2020 (edited) 1 hour ago, dikman said: The thread comes out of the hole at the right and should go BEHIND the little collar, not in front.. agree but this would not cause any of the shown issues I think, this is just a thread guide with a very weak spring. 15 hours ago, Gia said: Update: the hook timing seems to be perfect.. the hook meets the needle about 1.8mm after it starts rising. Here is a video with the timing: and have you checked the needle bar height? Not catching the thread loop usually is a timing issue, either needle bar to high (I still think this is the problem) or hook too far away form the needle (or both). If it was me I would lower the needle bar by 0,5 - 1mm and check again. Its easy to revise if this is not the problem. Loops at the bottom are either caused by too low or none top tension or a way to high bottom tension and this is a separate problem. BTW - your tension unit looks like it is put together from different (not OEM) parts. The tension disc are not Pfaff, there is a small pin cut away which would hold the OEM Pfaff tension discs in place ( Pfaff discs have notches). The tension release disc is from different machine too. I do not say this is causing the issues (but who knows when parts are bubba'ed) but I just wanted to have it mentioned. Question: is there a small pin inside the the threaded tension post which holds the discs spring and nut? EDIT: Picture shows a non Pfaff tension unit (principles are the same) but in this picture the position of the small pin is more obvious. So is this pin present inside the threaded post? If yes and it is too long (who know since your TU is bubba'ed) it could cause a tension release. Another question: are you using a knee lifter or foot pedal for lifting the presser foot? Edited July 7, 2020 by Constabulary Quote Share this post Link to post Share on other sites
Constabulary Report post Posted July 7, 2020 This is the Pfaff TU and IMO the position of the tension release pin is not really obvious I´d say but just for completing here is the OEM Pfaff TU Quote Share this post Link to post Share on other sites
RockyAussie Report post Posted July 7, 2020 With the bobbin case in your hand can you pull the bobbin thread fairly easily? Sometimes needles hit the case when they break and the damage can cause a sticking of the bobbin as it revolves. I am guessing that the bobbin case is not letting the bobbin thread come out smoothly. Try another bobbin and another bobbin case if you have them. Quote Share this post Link to post Share on other sites
jimi Report post Posted July 7, 2020 (edited) Maybe the problem is you need a smaller needle?? or thicker thread?? Edited July 7, 2020 by jimi Quote Share this post Link to post Share on other sites
Gia Report post Posted July 7, 2020 Thank you so much for all your answers! The tension system is obviously not as complex and good as the original one, but however, after adjusting the tension again and changing the needle with a new one, I am able to get a perfect stitch on leather. I suspect that the problem was the strong adhesive on industrial Velcro, which remains stuck on the needle and it pulls the thread. I am thinking to call a mechanic to see if I need to change any parts. All the best, Gia Quote Share this post Link to post Share on other sites
shoepatcher Report post Posted July 7, 2020 Spray needle with silicon spray. Will make the adhesive not stick to the needle. glenn Quote Share this post Link to post Share on other sites
dikman Report post Posted July 7, 2020 If it's now sewing ok why would you need to change any parts? Quote Share this post Link to post Share on other sites
Gia Report post Posted July 7, 2020 11 minutes ago, dikman said: If it's now sewing ok why would you need to change any parts? Because the tension unit has a cheap feeling and the pre-tension disc has no spring, which makes it difficult to put the thread behind it. Quote Share this post Link to post Share on other sites
Matt S Report post Posted July 7, 2020 53 minutes ago, Gia said: Because the tension unit has a cheap feeling and the pre-tension disc has no spring, which makes it difficult to put the thread behind it. If it ain't broke... Quote Share this post Link to post Share on other sites
Gia Report post Posted July 8, 2020 11 hours ago, shoepatcher said: Spray needle with silicon spray. Will make the adhesive not stick to the needle. glenn Good point, thanks! Quote Share this post Link to post Share on other sites
