Wafersaw: Change of shutdown procedure

Elmer Enriquez eenriquez at snf.stanford.edu
Mon Jun 6 08:30:28 PDT 2005


Eric Perozziello wrote:

>It should be ok to push the Emergency Stop button,
>so if it's doing something funny, we need to find out why.
>
>When you disable, it has the same effect as pushing
>the emergency stop button, so I don't think changing the
>procedure is going to help.
>
>I've not seen it do anything strange since the servo repair,
>so if it is, we should find out what's causing it (procedures
>or hardware problem).
>
>-Eric
>
>
>
>On Fri, 3 Jun 2005, Jia Feng wrote:
>
>  
>
>>Hi, wafersaw users:
>>
>>I just noticed this important change of procedure on coral. I am copying it
>>FYI. The problem has been occurring repeatedly recently.
>>
>>Change of procedure:
>>
>>-- Do not press the "Emergency Stop" button when you're done with the tool.
>>This takes the x,y and z axis motors to their limit switches.
>>
>>-- When shutting down the tool;
>>
>>      - Push the "Stop" button
>>
>>      - Turn off the air supply
>>
>>      - Turn off the pump
>>
>>      - DO NOT press the "Emergency Stop" button
>>
>>
>>Jia
>>
>>
>>    
>>
Eric,
     The wafersaw has gone done 3- 4 times since the servo motor was 
replaced.   The z and y axis motors would drive pass their limit 
switches.  I had to replace the -28 volt fuse once and the +28 volt 
once.  As far as pressing the "emergency stop" button and the disabling 
the tool being the same thing; their not.  If you press the "emergency 
stop" button, the system would try to rehome (find the limits) upon 
start-up.  If you DO NOT press the "emergency stop" and just disable the 
tool,  the motors will start-up from their current position and will not 
try to find the limit switches.  TRY IT.
     As far as finding out why it's behaving funny, we believe its 
caused by defective limit switches.  We will replace them when the new 
ones arrive.  I've heard that Len has replaced the switches several 
times in the past.  Perhaps pressing the "emergency stop" every time the 
saw is used puts undue stress on them.

- Elmer




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