20” planet mag starter issue and loud clang

[Bob Cooper]

I’ve just started experiencing two symptoms that may or may not be related. I have a 3 phase jet 20” planer and the mag switch is starting to act up. The other night I had to press the start button for an extended period....it would come up to speed quickly but if I released it the motor would dis-engage. It’s been slowly getting worse. Before this sometimes I’d need to press it once or twice to get it to hold

The other symptom is I will get a loud clank. Almost like metal is hitting the shroud but this only seems to happen when I have the start issue and once it’s running it’s fine so I don’t see how there could be interference so I’m thinking it’s just the inertia of the motor being engaged hard by the starter.

Any suggestions and have you experienced this before?

[Bill Dufour]

Take the cover off the contactor and push the armature with a dry piece of wood to close the points. Hold for a second and release. If the motor stays running the stop switch is okay. repeat 5-10 times to verify.
Sounds like a dirty stop switch not holding good contact. But the noise makes me think it is the contactor armature sticking. I would pull the plug then blow out the stop switch of any dust. I suppose it could be the start switch as well. Does it chatter on starting?
If that does not do it check the moving parts of the contactor for rust and dust. Cheap Asian contactor the points may be burned. Run some paper through them while holding them closed by finger pressure. I prefer contactors where gravity opens the points not a spring which can jam,hang up or break.
I like to install a plug between the switchgear and the motor for ease of replacement and testing. If this was my tool I would unplug the motor from the contactor and see if the bare contacter makes the noise or not. Also makes it much easier to hear any chatter with no motor noise to mask it. Intermittent electrical problems are hard to track down.
Bill D

[Bob Cooper]

Bill:

Thanks. i'll give that a try tonight or this weekend and post what i learn.

[Bill Dufour]

A contractor without motor noise to mask it is a very loud clang of metal on metal. I suppose it could just be a loose cover rattling from the impact. The one on my lathe will hum sometimes. Took the atrmature out and wire brushed off the rust to make it better. Still happens ocansionaly.

[Bob Cooper]

I took the cover off and all looks pretty clean of dust. Pressed the “on” and it started up smoothly. Pressed “off” and it disengaged as expected. Pressed “on” again and nothing. Pressed several more times and about after the fifth time it started smoothly.

I actually think the issue might be the switch which seems to be a 24V AC switch. I *think* when I press it grounds the circuit and energizes the contractor but I need to get the DVM out to be sure I’m reading this right. I’d post a picture but I’m on an iPhone.

To clean anything out or to even get to the contractor I’d need to pull this thing apart.

Next I’ll get the DVM out to make sure I understand how it works and after that I’ll focus on the 24V switch

Make sense?

[Bill Dufour]

https://www.theautomationstore.com/control-wiring-3-wire-control-start-stop-circuit/

[Bob Cooper]

Bill...that was very helpful. I figured it out tonight so feeling pretty good even though what was causing all the grief was a very simple switch

So it was the on/off push switch mechanism. I’ll post some pictures tomorrow when I’m on a computer instead of a phone.

I could tell that the switch — both on and off — didn’t seem to be making good contact so I just disassembled it, cleaned everything with 220 grit sandpaper and reassembled. Problem
Solved.

Thanks all for the help

[Bill Dufour]

Switches can be tricky. they test good with meter but fail under high voltage and high current. Fuses the same as well. I have used a strip of paper bag to clean contacts while holding them closed with finger pressure. No real chance of too much like with sand paper and no grit embedded in the soft contacts to cause wear.
Bil lD

[Bob Cooper]

here's a couple pictures of the entire mechanism -- it's the grey on/off switch that was the culprit. Then a picture of the pieces ready for re-assembly.
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