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



## TIGL (Apr 30, 2014)

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 (Apr 30, 2014)

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.


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## george wilson (Apr 30, 2014)

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


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## TIGL (Apr 30, 2014)

LEEQ said:


> 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 



george wilson said:


> 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.


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## george wilson (May 1, 2014)

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


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## TIGL (May 1, 2014)

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

:bitingnails:


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## Fabrickator (May 1, 2014)

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.


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## TIGL (May 1, 2014)

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 (May 1, 2014)

TIGL said:


> 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!


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## wrmiller (May 1, 2014)

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


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## TOOLMASTER (May 1, 2014)

looks like it went poooof


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## TIGL (May 2, 2014)

hman said:


> 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:
> Best wishes!



Heard back from Chris again, he's going to  send out another board under warranty. That dude is great. He really  stands behind his product and is helping me out even though this was  probably my fault. I will make sure i give him more of our business. 




wrmiller19 said:


> 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.
> 
> ...



This happened around 6-6:30 in the evening and I had  been making chips most of the day. It wasn't a real deep cut - 5/8" 2  flute end mill .06" DOC with about 50-60% engagement while I was  roughing out the slot. Nothing crazy but I had been doing similar work  for a least a couple hours. Duty cycle was not something I had  considered when I picked this mill, probably a critical oversight. I  will definitely look into adding an exhaust fan to the back housing to  keep the air moving in there.  


All that being said, I'm  starting to regret a little bit that I didn't go for the G0704/759 when i  was looking at mills. More machine is always mo' better, right?


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## wrmiller (May 2, 2014)

I've never gone larger than a 1/2" end mill in the LMS, and that was a rougher to keep loading on the machine down. Mostly I stayed with 3/8" and smaller. But that's just me. 

You're not alone in the 'larger is better' arena. Which is why my LMS machine is just sitting around looking forlorn while the PM25 gets all the work. The LMS was 'almost' big enough for what I need, but not quite. Unfortunately, I had to use it for a bit before I came to that conclusion. Such is life.

Bill


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## Fabrickator (May 2, 2014)

Glad you got it figured out and that LMS is standing behind their product. I remember pushing my duty cycle last year on a deep cut steel project and felt the motor to see if it was getting hot after an hour or so. It was starting to get pretty warm so I setup a room fan to provide additional airflow and it helped.

With this in mind, I recently picked up a surplus 3" 125v box fan ($5) like a computer uses to aid cooling, but it sounds like I should be using it to draw air through the control box instead of blowing it across the motor. I never even considered the temp of the control board components.

I run 3/4" bits once in a while, but my go to bits for hoggin are 5/8" 3 flute (alum) and 4 flute (steel) in both finish and roughing. A quality 3 flute roughing bit eats aluminum like butter @ .060" per pass with no problem.


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## John_Dennis (May 4, 2014)

If you add a fan to a control box, it might be a good idea to put some kind of air filter to keep out dust and other crud.

John


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## TIGL (May 4, 2014)

John_Dennis said:


> If you add a fan to a control box, it might be a good idea to put some kind of air filter to keep out dust and other crud.
> 
> John


The control box has filtered vents but no forced air so I think I would wire up a motor to blow air out of the box and have the makeup air come in through the existing filtered holes.


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## TIGL (May 5, 2014)

Fabrickator said:


> I run 3/4" bits once in a while, but my go to bits for hoggin are 5/8" 3 flute (alum) and 4 flute (steel) in both finish and roughing. A quality 3 flute roughing bit eats aluminum like butter @ .060" per pass with no problem.



Something like this maybe?


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## Fabrickator (May 5, 2014)

I just completed this mod to mine this past weekend and posted it this AM on the thread, My LMS Mill.  Check it out here.

http://www.hobby-machinist.com/showthread.php?t=22202

- - - Updated - - -



TIGL said:


> Something like this maybe?



Yep, they work great.  I buy most all of my tooling through Enco though.  They are always having sales and sending coupons that help with the prices.


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## John_Dennis (May 6, 2014)

believe it or not, sometimes you can replace the obviously scorched parts on a board and it will run again.  I have replaced the diode in my air conditioner control board a couple of times and gotten it fully functional.  There is no way for most people to check the chips, but resistors diodes and transistors ect can be checked with a good volt meter.

John


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## TIGL (May 8, 2014)

IT LIIIVEES!!!!

Got the board in today and carefully switched them out being mindful not to let the power cord mash the heat sink again. With this crisis averted, I'm going back to my original thread on the acquisition/project.

Thanks for the help!


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## wrmiller (May 8, 2014)

Glad you are up and running again.  

Bill


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