Consew 255RB3 breaking top thread in reverse

[sandmanred]

I think I have followed all the procedures to get it timed right per the manual.  It sews great forward.  But the hook is snagging the loop as it closes on the pass that it's not supposed to do anything when in reverse.  It will stitch a bit in reverse but doesn't sound as good and usually within a few inches it snags.  Suggestions on what to look at?

 

 

[Uwe]

That’s very likely a hook timing issue. Hook timing is more forgiving when sewing in the forward direction because hook and needle move towards each other. In reverse, they move in the same direction at different speeds, which trickier to get right. I usually tweak timing a bit (advance or retard the hook) to make sure the machine sews well in reverse at max stitch length; that all but guarantees that it’ll also sew great in the forward direction.

[sandmanred]

11 minutes ago, Uwe said:

That’s very likely a hook timing issue. Hook timing is more forgiving when sewing in the forward direction because hook and needle move towards each other. In reverse, they move in the same direction at different speeds, which trickier to get right. I usually tweak timing a bit (advance or retard the hook) to make sure the machine sews well in reverse at max stitch length; that all but guarantees that it’ll also sew great in the forward direction.

Thanks.  That makes sense.  I noticed that the needle position where the hook is supposed to catch the loop shifts a bit towards the operator a bit when you push the reverse bar.  I was looking for some adjustment(s) to make the needle position front to back when the hook engages the loop exactly the same in forward and reverse but I can't figure it out.  As the needle is a bit closer to me when in reverse I'll time retard the hook a bit from where it is and see how that goes.

[Uwe]

The feed dog (and thus needle) movement should be centered in the throat plate opening. If it’s offset towards front or back, it’ll be hard to get hook timing just right in both sewing directions.

The Seiko LSW manual (Consew 255 is a clone or re-badge of the Seiko) has adjustment instructions starting on page 7.

Edited February 21, 2021 by Uwe

[DonInReno]

Hopefully the gap between hook and needle as as close as possible without touching, the needle guard isn’t pressing on the needle and the condition of the hook point is good and sharp.  Uwe’s videos are always very good about mentioning the hook/needle gap, but some people focus only on timing.

Just this morning I’m looking at a machine that had 20 years of intermittent thread pickup and breakage issues and was “retimed” a dozen times - turns out the hook point was sharp, but it was never adjusted close enough to the needle.

If there is any kind of loop, a sharp hook just barely/almost skimming the needle will pick it up.   If timing is good, hook and gap are good, then maybe some other factor that interferes with loop formation?   I like the idea of adjusting timing so needle has slightly more rise, and more time for a larger loop to form, before the hook intersects needle.  1/8” needle rise instead of 3/32”?  Of course that means needle bar has to drop 1/32” so the hook is still contacting needle 1/16” up from eye.

Let us know what ends up fixing the problem! 

[sandmanred]

The hook was grabbing the loop as it as it should in both forward and reverse.   However,  in reverse it snagged the loop that's just about to knot with the bobbin thread on revolution that's it not supposed to grab anything.  Most of the time after a few stitches in reverse ehe hook breaks the needle thread and keeps on sewing leaving two ragged tails on the bottom.  Other times it breaks it and stops sewing.

I did also find a manual for my model.  The needle and hook had correct clearance.  There were a couple of discrepancies between the Consew and Seiko manuals so in the end I followed the 255RB3 manual.  I think my biggest problem was not using anything to estimate the needle rise and the hook to eye distance.  I found a 2mm shim to help estimate the distances better.  I set it up to the manual and then retarded the hook just a bit, as far as I can tell anyways.  Runs good forward and backward across all stitch lengths.  Thanks both Uwe and Don for your help!

Edited February 21, 2021 by sandmanred

[DonInReno]

Glad to hear it’s working out!