How to make machine movement stop if spindle stops

cad cam man · Post by **cad cam man** » Fri Dec 10, 2021 4:39 pm

Hey guys I have had a recent issue with my pm727v cnc conversion ....nothing to do with acorn yet....let me explain.. I was running a part that had a pretty good run time and I still have the stock BLDC spindle motor that came with the pm727v and as I was running the part the motor got hot causing the motor to cut in and out and shortly after it shut down but the machine kept going until I hit e stop . My question is how could I get the control to see that the spindle has stopped working and stop as well ? I have been meaning to add a spindle encoder to be able to do rigid tapping I just haven't got around to it yet would this help?? Any suggestions would be appreciated

Miamijerry · Post by **Miamijerry** » Fri Dec 10, 2021 5:22 pm

One method which could work is;

A current sensing relay, set for the minimum current (Speed) of your spindle, and trips the estop circuit.

I use these current sense relays for a pool pump failure circuit

cncsnw · Post by **cncsnw** » Fri Dec 10, 2021 5:24 pm

A spindle encoder would provide one version of that type of protection. See Machine Parameter 78.

If that is not available, then you will have to explain why heat was "causing the motor to cut in and out".

Does the motor have a thermal cutout in its windings, which is intermittently opening? If so, there is little you can do with that. Perhaps a current-sensing relay as suggested above. You would need to add PLC code to keep track of when the spindle *ought* to be running at speed, since only then do you want to fault when it is not.

Is the motor controlled with a contactor and overload combination (i.e. magnetic motor starter), and you have the overload set to automatically reset itself? If so, and if the overload has a second set of auxiliary contacts, then you can wire those to a PLC input to indicate spindle fault.

Is the motor controlled with an electronic controller (e.g. a VFD) which is detecting overload and automatically stopping the motor, but which you again have configured to automatically reset and restart? If so, you need to wire the VFD fault signal to a PLC input.

rk9268vc · Post by **rk9268vc** » Sat Dec 11, 2021 1:25 am

acorn has a spindle thermal E-stop input that is selectable in the wizard. You just have to figure out how to wire it

cad cam man · Post by **cad cam man** » Sat Dec 11, 2021 11:04 pm

Rk9268vc, do you know anything about this spindle thermal E-stop ? That is exactly what I'm after

Gary Campbell · Post by **Gary Campbell** » Sat Dec 11, 2021 11:21 pm

Does your spindle motor have a thermal switch or thermistor with external connectors? If so, then you can wire it to an input that will halt motion. Most motors do not

ShawnM · Post by **ShawnM** » Sat Dec 11, 2021 11:25 pm

Slightly different than your BLDC spindle motor my HSD spindle motor on my CNC router has two thermistors inside the spindle that monitor temperature and can be used to trip a thermal alarm. If the temp of the spindle rises above the set point of the thermistor it will trigger an input. You could easily add a temperature sensor to your motor that once it rises to any set point you choose can trip any input on the Acorn with a warning BEFORE it just shuts down.

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How to make machine movement stop if spindle stops

How to make machine movement stop if spindle stops

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