Problem with timing and tension adjustments on a consew model 18

Sewing on double layers of leather can be challenging, and it's important to have the machine properly adjusted to handle the thickness. Here are some adjustments you can try:

1. Needle size: Make sure you are using the correct needle size for the thickness of your leather. A larger needle may be required to penetrate the layers.
2. Tension: Adjust the tension of the upper thread. If the tension is too tight, it can cause the needle to break or skip stitches. If it's too loose, the stitches may be uneven.
3. Presser foot pressure: You mentioned you have already adjusted the presser foot pressure, but to clarify, turning the adjustment screw clockwise will increase the pressure, while turning it counterclockwise will decrease it. You may need to increase the pressure for thicker materials.
4. Stitch length: Increase the stitch length for thicker materials. A shorter stitch length can cause the machine to struggle to sew through the layers.
5. Speed: Slow down the speed of the machine when sewing on thicker materials. This will help the machine to handle the thickness and prevent skipped stitches or broken needles.

If none of these adjustments work, you may need to take the machine to a professional for further inspection and repairs.

I am not sure about this particular machine but in most machines there will be a nob on the front loose low numbers like 0 1 -2 work well on number 3. If the nob is not on the front check and see if it is on the side.

If the thread is looping under the fabric, it is a top tension issue.

Make sure you are using a new needle and that the needle/thread/fabric are compatible.

Verify it is threaded correctly and that the thread is firmly seated in the tension disks.

If the top thread is still looping under the fabric, then the upper tension is too loose.

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Sometimes the needle scarf is not large enough to protect the thread as the needle pierces the leather, so the thread is not pulled back up with the needle.

Try different needles and thread.

Also, be sure to thread the upper thread with the presser foot in the raised position so the thread will seat properly in the tension disk. To increase the upper thread tension, turn it toward a higher number and retest.

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THE SPRING THAT TIGHTENS AGAINST THE THREAD IS BENT OUTWARDS. IT MUST BE BENT INWARDS BY KEEPING THE TIP HELD UP WHILE YOU PUSH DOWN ON THE SPRING WITH A SMALL SCREWDRIVER. THIS WILL BEND THE METAL INWARDS. NOW, WHEN YOU TIGHTEN THE SPRING AGAINST THE THREAD IT SHOULD TIGHTEN AND LOOSEN AS YOU ADJUST IT. TO ADJUST YOU JUST NEED TO HANG THE BOBBIN FROM YOUR FINGER AND BOB IT UP AND DOWN. WHEN YOU ADJUST IT PROPERLY THE BOB WILL CAUSE THE THREAD TO EXTEND ONE INCH. THIS HAS NOTHING TO DO WITH TIMING SO DON'T BE CONCERNED ABOUT THIS.

Good day!

please try this simple tips:

Good day!

A sewing machine operator can often help themselves when their machine does not operate properly.
Here are some simple instructions, which if properly used can save time and mechanics service calls.
TROUBLE;UPPER THREAD KEEPS BREAKING;
This could be trouble;================Do this;
1.Top tension to tight================loosen tension 1 turn
2.Machine improperly threaded=========check threading
3.Thread twisted on guide post========"
4.Thread twisted out of tension======="
5.Take up spring bent or broken=======Check action of spring
6.Thread jumped off pull off finger===Check threading
7.Needle bent or burred===============new needle
8.Bad cone of thread==================try another cone
TROUBLE;LOWER THREAD KEEPS BREAKING;
1.Bobbin tensionspring to tight=======Loosen tension slightly
2.Bobbin threaded wrong===============check threading
3.Bobbin wound to tight or uneven=====try new bobbin
4.lint or thread on bobbin case=======clean inside case
5.Lint or thread inside hook==========clean inside hook
6.Bobbin case nicked bent or burred===check/change case
TROUBLE;MACHINE STARTED SKIPPING STITCHES;
1.Needle bent or burred===============change
2.Needle set in crooked===============Check
3.Thread jumped off take up spring====check threading
4.Thread jumped off pull off finger===check threading
TROUBLE STITCHES SHOWING LOOPS;
1.Forming loops on top of cloth=======Tighten bobbin tension
======================================or loosen top tension.
2.forming loops on bottom of cloth====Tighten top tension
3.Bobbin placed in case incorrectly===remove and replace
4.Bobbin thread slipped from under====check threading of
tension===============================bobbin case
5.Lint or thread in top tension=======clean between tension discs


Thank you and good luck.

The stitch length adjustment is the same as some other Consew post models, located on the manual advance wheel
See :
http://consew.marginspluslive.com/images/products/instruction%20manuals/287RB.pdf
page 4

Hi,
Your knee pad raises the presser foot and in turn releases the disc tension. The mechanism for this is in the front of the machine. If you can remove a nose piece this will be a lot easier to see,
There is a pin that pushes the tension discs open and quite often this has been removed or adjusted so a to not release tension when the presser foot is raised {more likely if this was a production machine} If someone took the tension control apart to accomplish this that my guess as to question 2.
The best part about Consew is the parts are common and the whole tension assembly isn't expensive. You can find service manuals on their website (see link) http://www.consew.com/Files/112347/InstructionManuals/206RB-5.pdf

Where does it break? You change tension at the top via the tension discs the thread passed through, and at the bottom by adjusting the small screw on the bobbin case - the screw on the front part of the spring. Thread size matters as well as needle size. For everyday upholstery I use #69 nylon thread, and "G" bobbins.
If the thread's breaking at the hook you may need to adjust timing. But most commonly thread breaks because of improper tension, threading, needle or thread size.

Check the condition of the top pressure discs and the bobbin case tension. Check for wear in the hook - is the bobbin case seated correctly? Check the tension spring in the bobbin case. I doubt timing has anything to do with the problem. Unless the hook's picking up the top thread a little late, thereby "spearing" the thread. The hook could be catching the thread loop too late. Sounds to me like there's a parts or a small adjustment problem. You don't mention thread or needle size. That's another area of concern at times.