Need to find the right size bobbin for my elna su 68

SOURCE: I need to thread an

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SOURCE: Elna walking foot

If your SU is an Air Electronic model i.e. 80's model, Elna didn't make a walking foot to fit. However, if you've got a walking foot that is the same height from sole plate to the screw fitting as a standard Elna foot then you could give it a try. The walking foot connects to the presser bar with a screw but the needle bar also needs to hook into a secondary lever on the side of the walking foot to make the foot actually move. Probably sounds very confusing . Check the movement of the foot manually by hand turning the fly wheel to see how it works before you actually use with the motor to minimise any problems if the foot doesn't fit.

Also you'll probably only be able to do straight stitch with this foot due to the clearance around the needle plate.

SOURCE: Elna SU missing stiches and breaking thread

it sounds like the needle hook timing is out. You need to get the needle in the lowest position and measure the gap from the needle to the hook point on the bobbin shuttle. It should be 1/4". You will need to remove the foot and foot plate to be able to see. I use a 1/4" drill bit as a gauge. If you need to adjust it, you will need to remove the free arm cover to the right of the foot and loosen the 2 allen head screws that hold the drive gear. Adjust the gap, tighten the screws and retry. Usually if the needle catches the thread to early, it will make a bad stitch and the upper thread will break. If it catches to late, it will make thread loops and the machine will skip stitches. Good luck, these are a good machine and worth fixing. Phil

SOURCE: have a 1970's elna su supermatic but cams don't work

There are two types of discs - single and double.
For the thinner single discs do as follows:
1.Turn stitch width knob to "0"
2. Turn stitch length knob to "0"
3. Insert the single disc
4. Turn the top selector to "A"
5. Make sure the needle selector is in the centered position.
6. You may now choose any stitch length or width you wish. I usually try "3" for the width and 1/2 for the length to start.

For the thicker double discs do as follows:

1.Turn stitch width knob to "0"
2. Turn stitch length knob to "0"
3. Insert the double disc
4. Turn the top selector to "A"
5. Make sure the needle selector is in the centered position.
6. You may now choose any stitch width.
7. The stitch length must be put on "A" - this is the difference between the single and double discs!
I hope this helps!

SOURCE: how to thread bobbin on Elna SU

Please describe the type of bobbin you have. Is it held inside of a removable metal casing? Or is it a dropin type? Is the sewing machine what is known as a "freearm" which you can put a sleeve or trouserleg over or is it a flatbed type? When I know this I can help you further.(I used to sell sewing machines).