Needle positioner.

[toxo]

Do these go wrong often? I have the Jack type and I keep resetting it but it doesn't stick. Dave at College isn't in today so can any of you guys shed any light?

[Pintodeluxe]

Could be electrical or mechanical problems.  The most basic mechanical thing to check is the position of the sensor on the handwheel.  It needs to stay in a fixed position.  If the sensor or the bracket bend out of position, it won't tell the servo when to stop.  

[toxo]

The unit is solid. Just paid for a new mounting kit to accomodate the bigger handwheel. I've had the back off and adjusted the two wheels so It's just how I want it. Do some sewing and a while later it's all over the place again. It even switches between up and down. In F1 it's supposed to be needle down when foot off but sometimes it switches. Only thing I haven't tried is pulling the plug or maybe there's a reset button. Dave at College sewing  who sells em might know something but he wasn't in today.

[Pintodeluxe]

Sometimes mine looses my preference when I power off the servo.  Then I have to hit the selector button again for foot up / foot down preference.  

[dikman]

I take that this has only started since fitting a larger handwheel (pulley?)? When you change the ratio between the handwheel and motor pulley some needle positioners won't work properly as the electronics in the servos isn't designed to cope with the increased ratio. Mine became inconsistent when I replaced the handwheel with a larger pulley so I removed the positioner (didn't need it as the machine was now slow enough to put the needle where I wanted it).

[Constabulary]

I´m not sure but I think I somewhere read that the NP works up to a ratio  of 1:1.5 or 1:2 but I´m really not sure. I ordered my 1st Servo with NP - figured its does not work with my SR so I took it off. I do not miss it >> what dikman said

8 hours ago, dikman said:

(didn't need it as the machine was now slow enough to put the needle where I wanted it).

[toxo]

8 hours ago, dikman said:

I take that this has only started since fitting a larger handwheel (pulley?)? When you change the ratio between the handwheel and motor pulley some needle positioners won't work properly as the electronics in the servos isn't designed to cope with the increased ratio. Mine became inconsistent when I replaced the handwheel with a larger pulley so I removed the positioner (didn't need it as the machine was now slow enough to put the needle where I wanted it).

I think you've got it dikman. It's puzzling though because the two discs are fixed and where you put em should stay the same. Maybe College will know something later. If not I'll have to take it off.

[Matt S]

Silly question (and I'm sure you've checked already) but is the cup of the sensor completely rigidly fixed to the handwheel? Once before I've had to use one of those extension bosses (original handwheel didn't come equipped for a sensor) and I hadn't sufficiently tightened the big retaining screw. Turns out the extension boss was rotating slightly, throwing the timing of the discs off.

[toxo]

8 minutes ago, Matt S said:

Silly question (and I'm sure you've checked already) but is the cup of the sensor completely rigidly fixed to the handwheel? Once before I've had to use one of those extension bosses (original handwheel didn't come equipped for a sensor) and I hadn't sufficiently tightened the big retaining screw. Turns out the extension boss was rotating slightly, throwing the timing of the discs off.

Yes Matt. The original boss that attached to the handwheel was nylon? with the thicker pulley the original center screw was much too short so I bought a kit from College that included a steel center boss and longer screws as well as extra L shapes etc. Everything is solid. Its a very simple principle. On the little circuit board there are two U shaped sensors . There are two discs with cut-outs, one for needle down and one for needle up. When the cut-out reaches the sensor it stops the motor. I've adjusted both discs so all is good but after a while it changes, Maybe things have to be done in a certain order, I was expecting a call from College today . Maybe they were busy. Personally I think I have a poltergeist. When I first got on it today it worked perfectly on pressing the button it was on F2 which should have been F1. After some sewing it went out of whack again.

Yesterday I used an allen key on a presser foot and put it on the table in front of me. Two minutes later I couldn't find it. I searched everywhere. I even used my extended magnet so search places I couldn't see. This is the point where I knew I had a poltergeist and the hairs went up on the back of my neck. I picked up a different allen key to do the job and actually said out loud " OK you bastard, you've had your fun but you can't win". I sat down to the machine and looked down and there, poking out from under the treadle was a third of the missing allen key in plain sight.

[Matt S]

15 hours ago, toxo said:

Yes Matt. The original boss that attached to the handwheel was nylon? with the thicker pulley the original center screw was much too short so I bought a kit from College that included a steel center boss and longer screws as well as extra L shapes etc. Everything is solid. Its a very simple principle. On the little circuit board there are two U shaped sensors . There are two discs with cut-outs, one for needle down and one for needle up. When the cut-out reaches the sensor it stops the motor. I've adjusted both discs so all is good but after a while it changes, Maybe things have to be done in a certain order, I was expecting a call from College today . Maybe they were busy. Personally I think I have a poltergeist. When I first got on it today it worked perfectly on pressing the button it was on F2 which should have been F1. After some sewing it went out of whack again.

Ah fair enough, just thought I'd mention it cos that could be a reason why the timing of the discs is slipping.

I run a couple of those Jack servos with needle positioners, and very rarely have an issue once I've got them setup right. The discs will slip just a little bit over time with hard use but by the time it's noticeable it's about time the machine gets a proper service so I do it all at the same time.

 

Quote

Yesterday I used an allen key on a presser foot and put it on the table in front of me. Two minutes later I couldn't find it. I searched everywhere. I even used my extended magnet so search places I couldn't see. This is the point where I knew I had a poltergeist and the hairs went up on the back of my neck. I picked up a different allen key to do the job and actually said out loud " OK you bastard, you've had your fun but you can't win". I sat down to the machine and looked down and there, poking out from under the treadle was a third of the missing allen key in plain sight.

Well I certainly can't help you there, I leant my bell book and candle to someone and they never came back