March 12, 2013

Sewing machine needle details

I thought I would give a little insight on the Needle! It's so small but has the potential to effect the outcome of your work both positive and negative.

The whole story on needles can be found out there on the net, I am just going to focus on two very important aspects:
  1. The features that make the needle work
  2. The size issue

Thanks to this great section drawing I am able to describe these two inter-related topics.

The bobbin hook is always on the opposite side of the groove in the needle (3) or the groove in the needle faces away from the hook that is spinning or oscillating around the bobbin.

The notch in the needle (4) is the area where the hook passes by the needle to pick up the thread loop. The hook passes by incredibly close to the needle (approximately .002" - .001")

Sequence of events:
When the needle is driven thorough the material the thread is of course held close to the needle, as the needle begins to retract however there is a difference in the amount of drag from front to back. The difference is a result of the front groove. When the needle retracts, the thread on the hook side (4) drags on the material thus forming the loop. The loop is suspended in space and is large enough for the hook to fly by and pick it up, awsome!

So a couple of hard learned lessons regarding this very short time-span event...
  • If the fabric lifts with the needle no loop will be formed and therefore no stitch can be made. I learned this on my wheel feed machine when the leather picked up very slightly and caused no stitch to be formed.
  • Too big of a needle will not allow for the required amount of drag on the hook side and also result in no stitch being formed.
  • If the outer part of the thread is being striped from the thread core you have too small a needle.
Ultimately the correct size needle and thread are required. Needles should be treated as disposable items, don't try to conserve them, just buy more.

Cut - away drawings are so cool:

And now you know how a VW bug works :-)

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