I have a new to me AVL TDL 24 shaft with CD IV. This is a different
type of dobby than I am used to, as the arm picks up all the shafts
that are not activated, so a malfunction raises a shaft. I can weave
between 30-80 picks perfectly, then 3 raises with every pick. AVL is
telling me to increase tension on #3, which I have done; now the
spring on 3 is noticably tighter than any others. I'm having a hard
time understanding how a spring tension can be OK for 80 picks and
then fail completely.
When it fails, the finger is extended beyond the wire. I have to take
the front of the head off for the finger to return. I know that there
are people out there that know more about troubleshooting AVLs than
they do; I think I know a few things they don't. Does anyone have any
thoughts on this? This is a 1991 loom that I bought reconditioned
from AVL. The fabric that it is making is gorgeous, it's so easy and
smooth, until 3 fails, and then begins a tedious process of recovery.
Have you also asked around Facebook or Ravelry?
After the last communication from AVL telling me to .increase spring tension (this one spring was now tensioned to the point it was extended even when at rest, and treadling was noticably more difficult), I told AVL that unless they had an alternative, this should go back to them for repair. This is a reconditioned, used loom with a warantee (this is assurance that I paid for). I am willing to try to fixa problem they missed (in AVL's defense, this would not have been seen in routine testing, but was probably why it was sold to them), but I have spent days on this that I can't afford at this time of the year. I have 21 yards of warp on this that took 3 days to thread in the seeming random echo threading, and I am peeved My very expensive new toy is dead in the water. We all know it has a bad solonoid, but AVL has yet to admit it.
It would rub me the wrong way to. That's a lot of warp to have to weave off with a faulty mechanism.
I had to fix a problem this morning on my CD4. The little wire-grabbing toggle had twisted sideways for shaft 2, causing it to never grab the wire. The displaced shaft 2 wire was also screwing up shaft 1. It turns out I had let my fly shuttle dangle before the shafts dropped & it caught on the upper heddle bar causing things to bounce around inside the CD4 box. I've done this to myself a couple of times & decided to dodge that problem by increasing the resting height of my fly shutle handle.
When performing diagnostics it may be worth running the CD with the head off the loom to see what it is doing. If the shaft 3 solenoid is periodically not firing then you should see it.
It may also be worth blowing compressed air inside the box to dislodge any dust & lint that is lodged in the solenoids.
Increasing shaft 3 spring tension should only help if you have (for example) many more ends threaded on shaft 3.
Thanks, Nancy! I was looking at your post trying to figure out how to run the head separately, and I realized allI had to do was plug it in off the loom. This is a new loom (new to me, freshly oiled from A V L) . So, no dust. I suspect the previous owner got tired of working around #3 not working, realized that selling it to a new owner as good would get them sued, and decided to unload it on AVL as a trade in (I know it was a trade in). I had my DH treadle for me while I watched from above, and saw nothing weird, but then #3 was extended beyond the wire. Will try your suggestion tomorrow. I have about 40threads on 3, on a 48" 24 shaft loom.
AVL wants me to slack off the warp tension and treadle to see if the problem persists with no tension on the warp. I am going to do this and see what happens, but even if it does work, I can't weave with a slack warp..
Nancy, when I tried to run the head off the loom, it wouldn't work. I got the first treadle, where all the shafts lift because the plungers are all extended for the start up test, but it won't do anything else.
And I agree that one spring shouldn't have to be different than the other springs in its group unless you have a structure, like huck, with a lot of ends on one shaft.
OK, I let off the spring tension and completely slacked the warp; it worked just fine, but this is not usable.
I left the spring, and gradually tensioned the warp to a workable tension. Still working.
So far, I have three day's production, about 24' of cloth; no errors. I also started leaving the heat on at night. The other CD IV proved to be sensitive to heat, maybe this one doesn't like cold.
After two days of good production, a d showing me jusr what this thing can do, it's back to lifting #3 when it shouldn't. At this point, I have asked AVL for a new solenoid.