Timing Problems On Durkopp

[farmersracer]

Hello every one.

My durkopp 239 has started to split the top thread. This happened after the machine has broken two thick needles. I have allready adjusted the needle bar so that the hook is catching the thread loop at the right moment (in the middle of the slot in the needle). But this means that the needle now has a turn point verry low - far below the hook. I think this creates a thread loop that is to big?

Is there any way of adjusting the shuttle? The shuttle hook is 1/5 of a turn from the needle when the needle is at its lowest point. Is this to far away? The thread loop is realy big when the hook get to the needle.

Is there a clutch in the shuttle that need to be reset? Or is there other timing issues?

In addition to this the feed dog push the leather a little bit backwards at the end of each stitch. This has been a problem for a long time, and has nothing to do with the problem above.

Do you have any tips on this timing problems?

[gottaknow]

From what you describe, your hook timing is retarded, meaning it's getting to the loop taking point too late. When you broke those needles, the hook got "stuck" on them just long enough for the machine to advance itself while the hook stayed in one spot. Simply put, your hook slipped. If you can get your needle bar back to where it was, loosen the hook screws and rotate it clockwise towards your needle to obtain the point of the hook centered in the "scarf" (that little indent in the needle). If your needle bar has timing marks, there will be two of them. The upper most one should be level with the lower needlebar bushing when the bar is at it's lowest point of travel. The mark just below that is used to set the hook. Bring the needle bar all the way down and then raise it until the lower mark is even with the bushing. At this point, the hook should be centered, ready to pick up the loop and form the stitch.

If you have no marks on the needle bar, rotate your machine in the operating direction until the bar is at its lowest point. Let it rise about 1/8" or so, though I don't have the exact measurment for your machine, this should get you close. Loosen the screws on the hook and rotate it until the point of the hook meets the needle. Tighten it here. You'll get smaller loops and your machine should sew. I will search my reference material at work to find the exact needle bar rise setting. There is no safety clutch on this machine. If there was, your bottom shaft wouldn't be turning at all.

As for your split thread. This is most commonly caused by bad hook timing, a dull or broken hook point. Your hook should be very sharp, not at all flat, with no burrs when your let a finger slide off the point. Hitting a big needle with your hook can damage it. You can use 400-600 grit abrasive paper to clean it up. Your hook has a needle guard that is a curved piece of metal attached to the hook body, below the point. When your hook point is centered on the needle, push your needle towards your hook. If the hook point runs into the needle, bend this guard out with a screwdriver until it prevents the hook point from hitting the needle. This will protect your expensive hook. I've attached a picture of your hook so you can see this.

If your feed dawgs are too high, it creates "backfeeding", which will make your material move toward the front of the machine slightly with each stitch. Try lowering your feed dawgs to the point that when they rise above the plate, they are moving straight up or towards the rear of the machine. Never should they move toward the front unless your machine has a reverse.

I know this is a lot of information, but it sounds like you need to start somewhere. Have fun!

[farmersracer]

Thanks - this is great help. I will try to find the needle hight somewere on internet. If you find it in a drawer, please let me know:) Will start tuning the machine this weekend.