# Pm 1228 Fireworks (literally)



## jdell42 (Nov 21, 2016)

So I was parting off from some 1.75" 4130 and my 1228 starts to chatter a bit.  I was hand feeding and I was not too concerned as its a reasonable diameter.  I start to fiddle with RPM and adding some additional oil.  I started to get a little vibration then..... BOOM!

A large pop and visible flash from the back of the head stock area.  I about hit the ceiling as it scared the poop out of me.  After a few seconds to regain my composure I noticed the machine was still running.  I quickly hit the e-stop to assess the situation.

After investigating I notice no burnt areas, no smoke, no smell nothing out of the ordinary.  So I backed the tool out of the part and built up the courage to turn the lathe back on. 

It started up with no issues.  I ran through the entire RPM range and found nothing out of the ordinary.  As I had 6 more parts to make I went back to work.  After about 5 more parts and 5 additional parting operations ~40 min I was again taking a parting cut.  Again the machine started chatter a bit and the same scenario occurred... BOOM, Flash and skid marks.

I took some time to dig deeper.  I explored the back of the headstock where the boom and flash came from.  I noticed a ~.250" gap between the top plate and the rear of the unit  (See pic).  I took off the top plate and found the location for the motor driver board.  

My working theory is that some chips had vibrated themselves into this gap, fallen into the driver board area and created a short of some sort... why this did not trip a circuit or fuse I have no idea.  I have temporarily taped up this gap but I am clearly a bit concerned.

Anyone else have a similar experience?  or suggestions?


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## keithvi (Nov 21, 2016)

"Depends"
Sorry, I couldn't miss this opportunity.


I would look very hard at the capacitors on the circuit board.  They often fail with a pop and a flash.

Good luck to you Sir!


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## wrmiller (Nov 21, 2016)

This is one I've not heard before. Kinda gives new meaning to 'fuseable link'. 

I too hope no permanent damage was done. To the machine. Your shorts I don't want to know about. LOL...


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## tmarks11 (Nov 21, 2016)

I would think that any short circuit that could make a "flash and boom" would do permanent damage to a printed circuit board. 

I would investigate more.  Sure it is not coming out of the motor itself and not from the controller?


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## jdell42 (Nov 22, 2016)

Tim,

I have no idea to be honest.  

I did look into the electronics cavity and I did not notice any blown caps.. nor did I see any caps that could make that loud a bang.  In my experience when a cap fails at best its a small pop.. more likely a hiss and typically with a distinct smell.

It could be motor related but I have never seen a motor go boom like that.. much less go boom and keep running.


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## markba633csi (Nov 22, 2016)

Probably, and you are lucky if this is the case, some chips fell across a couple of live points on the controller and vaporized without causing any failure of the circuitry. Me, I would open it up and find the burned areas then do the proper insulation/shielding.  
Mark S.


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