13x40 lathe slow start, and keeps resetting internal circuit breaker.

[saberforge]

I have a microkinetics 13x40 cnc lathe.

Yesterday I noticed the spindle was starting up slow, stuttering for a few seconds like it was struggling before getting to the normal rpm, where as usually as soon as you turn the lathe on, the spindle gets up to the rpm its set at almost instantly.

It persisted today, and then the internal circuit breaker inside the back panel tripped, and seems to be doing that about every 20 starts or so.

I removed the black plastic panel that covers the electrical connections going to the spindle motor, and noticed a burned connection that leads into the motor case.

Here are a few pictures.

The burned connection is the center connection with the melted white plastic below it. The wire connects at the back of that white mount unit and is conected to two other wires via the L shaped bracket on the top of the white plastic mount.





Any help would be greatly appreciated.

[Al_The_Man]

Connections like that usually are a symptom of a previous bad contact connection.
You can either source another terminal block or connect the termination with separate ring terminals and machine screws and nuts.
Al.

[saberforge]

Would that bad connection cause the slow start up I am experiencing intermittently?

Do you know where I might source a new terminal block, or the ring terminals you suggested I use?

[Al_The_Man]

Terminal block you would need to go back to the source or a motor re-winder, ring terminals, Home Depot.
Bad connection, intermittent 1 phasing.
Al.

[DMF_TomB]

i have seen before where electrical wires lugged or connected over time the connection get corroded and hot. i have seen many times electrical tape on fire from the heat.
.
a hot connection is using current in series with the motor, thus the motor has a voltage drop and with low voltage it has trouble getting up to speed. on startup many motors use 4x the rated current at rated voltage until up to speed. this high current can cause the bad connection to get hot extremely fast.
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some factories use infrared camera to scan electrical connections. basically an electrician can point the camera at electrical wires and find the hot ones even if only a few degrees hotter.
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on a welding machine cable electrode holder i would every year pull the wire out of electrode holder and check wire and cut some off if needed and reinsert wire. a welding electrode holder with a bad connection get hot and you can feel heat through the gloves. it is the electrical connections that are not touched that can get hot and go unnoticed for a long time.
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aluminum wires and lugs get corroded and hot much faster that copper.