Pfaff 1245 Thread To Short?

[sandyt]

Hello everbody,

I need some help with my pfaff 1245 with efka control box. I have had this machine for almost 10 years without any problems. Untill today. The machine has a automatic thread trimmer/cutter. Everything seems fine BUT the thread through the needle is to short after cutting???? So, the next new stitch will pull back the thread through the needle.

I have already dowloaded a manual and tried to check a few things. I think everything is good. I say think, because the manual is in English witch is not my first language. I can read it ofcoarse but al the technical terms make it diffycult.

Does anybody know where to look?

Thanks in advance.

[gottaknow]

There are several things that can make your needle thread cut too short. I'll try and describe each one so you can check them. First of all, most sewing machines with underbed trimmers should leave about a 30mm tail thread after cutting. The most common is too much tension on the needle thread when the knife cuts. When the knife is cutting, the needle tension discs should release most of the tension. When you accuate the pedal back to the cut position, there is a signal sent to the knife solenoid to engage a cam that runs the knife through its cutting cycle. Included in the cycle is having the tension release pin push out the tension disc to reduce the tension. To check it, simply cut the thread and watch the tension discs. They should release the same way they do when you lift the presser feet. If they don't, that is likely the problem. The tension release pins wear down over time and get shorter, so eventually they don't push the discs apart enough.

Next is fairly simple to do. Remove the throat plate and clean out the knife are completely. A bunch of thread trimmings, fuzz, etc can throw off the timing of the knife and delay the cutting. The take up lever moves during the cut cycle and may pull your thread back. After cleaning, replace the throat plate and test.

The next thing is the pre-tension. it's the smaller tension disc the thread goes through. What this does is keeps the thread clamped during the cut cycle so it can't rebound back. Simply tighten it some and test again. Most machines have a sweet spot where they like the pre-tension set. It should be just tight enough so the thread doesn't slip back through it.

Lastly, your check spring travel could be too much and is actually pulling your thread back or it could have too much tension for the size thread you are using.

These are the most common factors relating to your needle thread cutting too short. Good luck!

Regards, Eric

[Wizcrafts]

If the only changed is the thread, I vote for the check spring having too much travel, or tension, or both.

Edited November 2, 2015 by Wizcrafts

[sandyt]

Hi people, thanks very much for the tips. I solved it just now. Did not sleep last night!! It was the tension release bar. Adjusted it several times. But everytime I made the same mistake. When adjusting, the presserfoot should be manualy lifted. My machine is air operated so it was already up. I thought that will do. But that was not the case. You have to operate the presserfoot manualy.

Finaly my haertbeat can go down ones again. It was realy frustrating.

So thank you very very very much people for guiding me in the right direction.

Greetings from Holland...

[sandyt]

Now I read your post again, I realize your first hint was correct Gottano!! Thanks!

[sandyt]

Oh Wizcrafts, I did not even change the threads. The machine was setup as it was for the last year. Don't use it that much. I oil the machine more often than I use it. I guess the release bar just neaded adjustment. Thanks for helping!

But due to al the 'playing' with the machine, I noticed the machine is also equiped with air operated reverse. The solenoid doesn't get a signal from the control box. Checked al the wires. Everything is oke.

But I could just put a manual switch and a 24 dc powersuply on it. Project for a rainy sunday.

[gottaknow]

Glad you got it fixed!

Regards, Eric