HELP! LMS mini mill (SX2) won't retart after overload fault

[TIGL]

I was milling a big ol' slot in a 2.5x2.5x3.5" of 6061 aluminum and after getting to the right depth (1.25") I realized that it was a a tiny bit too narrow so I tried to take a really light facing cut to widen it out and half way through the machine made an angry buzzing noise and the spindle stopped. The one other time I overloaded it (drilling too wide a hole without a pilot) it didn't make a sound and when I turned the speed knob down to zero, backed off the bit, it restarted with no issues. The last time the fault light turned on until I zeroed the speed. This time I don't think it lit but I'm not positive. Also, the motor was plenty warm but I don't think it was any hotter than it would be after 2 hours of moderately heavy use.

After turning down the knob and trying to restart I also turned off the main power, unplugged it and let it cool for 15-ish minutes and it still didn't want to go so I'm going home and am going to try letting it chill over night before I try again. I searched the manual and didn't find any information on motor faults or troubleshooting. Has anyone else ever had this problem? I'm a pretty freaked out right now, I don't want to have to explain to my boss how I trashed our new toy after all of 8 days.

anic:anic:anic:
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[LEEQ]

LMS has always been real helpful for me. I'd give them a call first thing and see what they say. Can't see why a light cut after hogging it open would kill it. Is it jammed up with something where it doesn't belong? I would peek at everything from the motor to the cutting end of the spindle to see if is a physical problem first before troubleshooting electronics.

 

[george wilson]

Did you remember to turn the power,or circuit breaker back on? Silly question,but it happens.

 

[TIGL]

LMS has always been real helpful for me. I'd give them a call first thing and see what they say. Can't see why a light cut after hogging it open would kill it. Is it jammed up with something where it doesn't belong? I would peek at everything from the motor to the cutting end of the spindle to see if is a physical problem first before troubleshooting electronics.

I'm hesitant to start unscrewing panels and poking around when it doesn't even sound like the motor is trying to run but I may have to. That's been my experience with Chris as well. He sent me a pair of new vice mounting studs for free after one sheared under only moderate torque (bad heat treat I would guess). I'll email of call him first thing in the am and see what he says

Did you remember to turn the power,or circuit breaker back on? Silly question,but it happens.

I'm not aware of any breakers or buttons other than than the green power button and the Estop. The manual didn't say and I couldn't find any looking over the machine. Zeroing the variable speed knob reset the fault last time so I assume it just be that.

Also, the green power button lights up so it appears to have power but the knob does nothing.

 

[george wilson]

O.K.,green light must mean it has power. Sometimes when people get frazzled,they forget to check the obvious.

 

[TIGL]

Mill wouldn't start this morning so I emailed Chris and will see what he says.

:bitingnails:

 

[Fabrickator]

You have power to the unit (green light) but the motor doesn't respond to the variable speed control knob. I have an LMS High Torque mill but I've never had it go into the overload mode. I've been into both of the control boxes at one time or another and I haven't seen any obvious resets.

Chis @ LMS is your best bet.

 

[TIGL]

Emailed Chris and got a lightning quick response with a trouble shooting guide for the motor. The fuse (I had forgotten it had one) was burned out so I put in the spare. I plugged the mill back in and pressed the green power button. I immediately heard the buzzing sound again so I hit the Estop, unplugged and pulled out the fuse plug assuming it had fried again. Strangely it had not. So I replaced the fuse plug and tried the green button again - no sound. I tried the speed knob and the spindle hesitated then started. It rattled without the drawbar screwed into anything so I stopped the mill, and screwed in the drill chuck. I tried the speed knob and the spindle hesitated and the fault light turned on. I tried again and this repeated. I then removed the drill chuck and tried again with nothing on the spindle and it hesitated and started as before. I emailed Chris with this new information and he recommended that I open up both electrical boxes and check the connections. This is what I saw...

The top two heat sinks were mashed out of position by the power cord/wires and there was noticeable heat damage to the main circuit board around the base of the two sinks. It also smelled like the magic blue smoke might have escaped D:


I don't believe I was over stressing the machine when this happened so I'm not sure what would cause this. In any case I don't like where this is going...
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[hman]

The top two heat sinks were mashed out of position by the power cord/wires and there was noticeable heat damage to the main circuit board around the base of the two sinks. It also smelled like the magic blue smoke might have escaped D:

I don't believe I was over stressing the machine when this happened so I'm not sure what would cause this. In any case I don't like where this is going...​

It looks very like you'll have to replace that board ... multiple component failures! Hopefully, this will be under warranty. In any case, ain't it nice that at least SOME failures announce themselves plainly? :lmao:

And just to be complete, be sure to check one other thing ... that the "collision" between the heat sink and the cord didn't cut through the cord's insulation. If that's the case, you'll have to replace the cord as well. Shorts are no fun!

Best wishes!

 

[wrmiller]

I was going to say that it sounds like you popped a FET, but after looking at your board, I'd say that was obvious.

Not knowing how long the machine was running, what cutter size, DOC, etc., I don't know if you overheated the board or not. But it kinda looks like it.

The duty cycle on these little machines is probably very low. For prolonged usage I would add airflow over the control board/heat sinks to better handle the extra power dissipation requirements. Maybe even larger heat sinks on the FETs.

Bill