- Joined
- Dec 3, 2020
- Messages
- 209
I added a cheap Hall-effect tach to my benchtop mill-drill, and it has worked properly for a year of light hobbyist usage. It was mounted right next to the Fwd-Off-Rev switch, so I just ran a couple leads right from the hot side of the switch to power it, so it was on whenever the breaker to the mill was on. The mill uses 220V and this tach says 120-240V on it. It worked fine on 220V.
(The LED display is actually bright and easy to read in real life, but the camera didn't capture it.)
Now it doesn't work, and the only thing that's changed is I'm powering it with its own cord plugged into 110 V. Well also the glued-on magnet flew off, who knows where, so I replaced it, but it's a good strong rare-earth magnet — getting two of them unstuck from each other is pretty difficult. I think it's the same kind of magnet used previously.
Now it reads HHHH which I think means the signal is above the High threashold, but then it blinks some random and way-too-high number like in the 6000s to 9000s briefly, never the same number twice, then goes back to HHHH.
Any ideas? I think the answer is "don't buy cheap Chinese crap" but unfortunately I have modified the front cover of the mill to fit this tach, and I don't want a big empty space where it was. Plus I want a tach!
I tried the magnet both up and down, in case polarity matters (I think it does) but same results. I tried tweaking the air gap, from actually ticking as it goes around, to a big gap like 5 mm, symptoms don't change.
Anything else to try before I ditch this junk? Oh putting it back on 220V isn't practical, the mill is now on a VFD, which is mounted pretty far away. The motor is 3-phase now of course.
Got any suggestions for a decent tach that'll run on 110V? I prefer that over the ubiquitous ones that need a 12V wall-wart, but I'd settle for 12V if it'll fit in the hole I made in the front cover of the mill. Honestly I'll probably just buy another identical one since it'll fit. Much as I hate to reward companies that make disposable crap.
Thanks,
Mark in Seattle
(The LED display is actually bright and easy to read in real life, but the camera didn't capture it.)
Now it doesn't work, and the only thing that's changed is I'm powering it with its own cord plugged into 110 V. Well also the glued-on magnet flew off, who knows where, so I replaced it, but it's a good strong rare-earth magnet — getting two of them unstuck from each other is pretty difficult. I think it's the same kind of magnet used previously.
Now it reads HHHH which I think means the signal is above the High threashold, but then it blinks some random and way-too-high number like in the 6000s to 9000s briefly, never the same number twice, then goes back to HHHH.
Any ideas? I think the answer is "don't buy cheap Chinese crap" but unfortunately I have modified the front cover of the mill to fit this tach, and I don't want a big empty space where it was. Plus I want a tach!
I tried the magnet both up and down, in case polarity matters (I think it does) but same results. I tried tweaking the air gap, from actually ticking as it goes around, to a big gap like 5 mm, symptoms don't change.
Anything else to try before I ditch this junk? Oh putting it back on 220V isn't practical, the mill is now on a VFD, which is mounted pretty far away. The motor is 3-phase now of course.
Got any suggestions for a decent tach that'll run on 110V? I prefer that over the ubiquitous ones that need a 12V wall-wart, but I'd settle for 12V if it'll fit in the hole I made in the front cover of the mill. Honestly I'll probably just buy another identical one since it'll fit. Much as I hate to reward companies that make disposable crap.
Thanks,
Mark in Seattle