Needle Guard Adjustment Screw

[friquant]

I hadn't noticed this before, but I think it's an adjustment screw for the needle guard. (Jianglong 341)

 

Looking closely, I could see a hexagonal shape behind the round hole. 1/16" (1.7mm) hex wrench seems to fit.

Or from a different angle:

Here I removed the needle guard and you can see the set screw that sits behind it:

 

I've been wanting the needle guard to be stiffer anyway. (What good is a needle guard that just gets out of the way when the needle comes by?) Using this adjustment screw will mean there is a support closer  to the bulge in the needle guard, so I expect it to flex less when the needle presses against it.

[Wizcrafts]

That's a nice adjustment system. The shuttles on my walking foot machines have a thin steel plate that can be bent in or out to limit the position of the needle. However, in my experience, the needles seem to almost always get pulled away from the hook and deflector shield. It would probably have more protective effect on larger needles, like #22 and up than on thin needles, like #18 through 20.