Hook to Needle Distance: A Compromise

[friquant]

How to always have the hook to needle distance be next to nothing?

At first I thought the thread was shredding when I stitched in reverse with long stitch lengths. 

(Thread is Selric brand TEX 135 UNbonded polyester)
(Machine is Jianglong 341 (clone of Juki 341 but with even longer stitch lengths))

On closer inspection, the thread wasn't being torn actually, but in reverse with long stitch lengths (about 8mm) the hook was not catching all three strands of the thread. It might catch one or two.

Here are some photos (recreated) of what it can look like when the hook tries to bisect the thread.
Then I will continue my question in the next message..

Edited yesterday at 12:25 AM by friquant
grammar

[friquant]

Original question, continued...

I spent some time moving the hook saddle over to reduce the hook to needle distance. The Juki 341 manual says to make the adjustment with the stitch length set to 3mm, but the Juki 341 has a maximum stitch length of 6mm. One could interpret this at least two different ways: A. Set stitch length to 3mm, or B. Set stitch length to half of the maximum. (The Jianglong 341 that I'm actually working on can make 8mm stitches)

Here are photos after my hook to needle adjustment, with stitch length and forward/reverse shown in red text. You will notice that long stitches in reverse prove to give the largest hook-to-needle distance, and I conjecture it was this large hook-to-needle distance that previously had the hook only catching one or two strands of the UNbonded thread.

Since the adjustment, it seems to be doing fine with long stitches in reverse. (Not bisecting the thread anymore.) It makes sense that if you must optimize for either forward or reverse, one would almost always optimize for forward stitching. But here's another avenue I have not used but am considering:

"Set the hook-to-needle distance to zero for long stitches in reverse, and use the hook needle guard to keep the hook from clobbering the needle in all other scenarios."

This might get us down to zero hook-to-needle distance in all scenarios. But we'd also be deflecting the needle (elastic deformation) a little bit on all but the long reverse stitches.

I'd be curious to hear how others have achieved a satisfactory hook-to-needle-distance compromise on machines that can make long stitches in reverse.

Edited yesterday at 12:35 AM by friquant
Add paragraph about jianglong having longer max stitch length than juki manual

[Constabulary]

You probably have to play with the needle bar height. Have you checked the NB height / needle - hook timing? Procedure should be mentioned in your manual. If it was me I´d probably try lo lower the NB a tiny bit so you will have a bit larger thread loop. But thats just me from a distance. Hard to tell what it going on when not in front of the machine.