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Per Westermark
04/30/12 16:05
Read: 1032 times
Sweden


 
#187275 - Need not be exactly in middle.
Responding to: Mahmood Elnasser's previous message
If you have two position pins in a straigt vertical or horisontal line, then you just flip the board. The CAD program will not care if the two pins are a bit away from the center of the board. So in theory, the two holes could be top-left and bottom-left and after you flip board they are top-right/bottom-right. Just that the CAD program produces data relative to the holes so the machine in that case on one pass do most work to the right of the pins, and after flip have most work to do to the left of the pins.

The issue is that you need to align the pins so that you can flip the board while maintaining exact relative position. With two pins in diagonal corners, you can't flip the board because the board must then have four holes - it will be the two opposite diagonal holes that would be used after board is flipped. No such issue with the two holes in vertical or horisontal line on board.

+--------------------+
|                    |
|                    |
| o                o | <= not symmetrically placed
|                    |
+--------------------+

+--------------------+
|                    |
| o                o | <= but still ok after flip
|                    |
|                    |
+--------------------+


So as you see from above - having the holes symmetrically just means that you can make maximum size PCB in relation to table size of machine. As long as board is smaller, it doesn't matter if you have an assymetry. Just that by minimizing the longest distance from hole to side of board, you get board better held down.

One interesting thing with very narrow traces is that the bit can "push" the trace sideways, if bit isn't sharp enough and movement speed suitable.

List of 74 messages in thread
TopicAuthorDate
CNC      Mahmood Elnasser      04/14/12 10:43      
   Enjoy :)      Oliver Sedlacek      04/16/12 04:14      
      Having fun      Mahmood Elnasser      04/17/12 13:53      
   Congratulations      Joseph Hebert      04/16/12 09:42      
      We looked at buying one of those      Jez Smith      04/16/12 14:09      
         Me Either!      Joseph Hebert      04/16/12 14:17      
            We use a variety      Jez Smith      04/17/12 00:50      
               do not be lazy,Mr.Smith      Stefan KAnev      04/17/12 11:28      
               prototype cost and turnaround      Joseph Hebert      04/17/12 13:31      
                  I'll find the ads      Erik Malund      04/17/12 14:14      
                     googled      Erik Malund      04/17/12 14:22      
                        Ebay deal      Steve M. Taylor      04/17/12 15:08      
                           What about this one then...        Robert Revens      04/25/12 12:59      
                              Follow up on prototype board shops      Joseph Hebert      06/22/12 08:41      
                                 international pcb houses      Mahmood Elnasser      06/22/12 14:13      
                                    PCB Houses      Joseph Hebert      06/22/12 16:55      
            working out of town      Erik Malund      04/17/12 07:20      
      CNC bits      Mahmood Elnasser      04/25/12 06:37      
         answering      Joseph Hebert      04/25/12 11:38      
            it happens      Mahmood Elnasser      04/25/12 14:51      
               what other tools required?      Mahmood Elnasser      04/25/12 15:00      
                  a new trick zeroing Z axis      Mahmood Elnasser      04/26/12 12:26      
                     Z ref      Steve M. Taylor      04/26/12 13:10      
                        Collet type      Mahmood Elnasser      06/22/12 14:27      
                        Z axis reference      Mahmood Elnasser      07/02/12 01:40      
                           Vacuum      Per Westermark      07/02/12 02:35      
               this sort of thing happens often, from my experience      Richard Erlacher      05/01/12 07:38      
                  ctrl+A, crtl+C, submit      David Brown      09/19/12 01:34      
         tools      Joseph Hebert      04/26/12 14:11      
            holding the PCB      Mahmood Elnasser      04/27/12 00:27      
               Holding the PCB      Joseph Hebert      04/27/12 14:06      
                  Carbon steel?      Per Westermark      04/27/12 20:16      
                     Not tungsten carbide      Joseph Hebert      04/28/12 16:37      
                        Just carbide is a bit lazy slang for tungsten carbide      Per Westermark      04/28/12 21:41      
                           If you say so.      Joseph Hebert      04/28/12 22:30      
                  Plate through holes      Mahmood Elnasser      04/28/12 11:05      
                     plating holes      Joseph Hebert      04/28/12 16:46      
                     plated through holes cont.      Joseph Hebert      04/28/12 22:37      
                  2 point registration system      Mahmood Elnasser      04/30/12 14:27      
                     Need not be exactly in middle.      Per Westermark      04/30/12 16:05      
                        is it that simple?      Mahmood Elnasser      05/01/12 00:27      
                     2-pin registration      Joseph Hebert      04/30/12 23:40      
                     Fine pitch milling      Joseph Hebert      05/01/12 23:54      
                        Solder Mask      Mahmood Elnasser      05/02/12 10:28      
                           solder mask and legend      Joseph Hebert      05/02/12 11:47      
                              too much work      Mahmood Elnasser      05/02/12 15:54      
                                 Much work      Joseph Hebert      05/06/12 15:50      
                                    My CNC      Steve M. Taylor      05/07/12 06:57      
                                       Is That...      Michael Karas      05/07/12 10:30      
                                       which cad did you use?      Mahmood Elnasser      05/07/12 15:58      
                                          Limit Switches      Michael Karas      05/08/12 00:22      
                                             Will do      Mahmood Elnasser      05/08/12 10:55      
                                                Little Plates      Michael Karas      05/08/12 16:40      
                                             MEchanical limit switches      Steve M. Taylor      05/11/12 12:50      
                                       Your project      Joseph Hebert      05/10/12 06:18      
                                          This:      Steve M. Taylor      05/11/12 12:38      
                                             very cool!      Joseph Hebert      05/11/12 13:29      
                                             Funnel      Michael Karas      05/12/12 12:37      
                                                Funnel !      Steve M. Taylor      05/13/12 13:04      
                                                   Lawyer or Solicitor - Not ! !      Michael Karas      05/13/12 15:43      
                                                      RIght      Steve M. Taylor      05/14/12 12:16      
                                    vacuum pick and place tool      David Brown      09/19/12 01:29      
            90 degrees bits      Mahmood Elnasser      09/14/12 04:22      
               Z-axis depth control      Joseph Hebert      09/15/12 22:53      
                  stepper       Mahmood Elnasser      09/16/12 06:34      
                     z-axis control      Joseph Hebert      09/16/12 15:37      
   oiling      Mahmood Elnasser      09/29/12 14:49      
      lubrication      Joseph Hebert      10/01/12 10:41      
      Lube      Steve M. Taylor      10/05/12 14:47      
         ballscrews      Mahmood Elnasser      10/06/12 00:21      
            Ballscrews      Steve M. Taylor      10/06/12 14:00      
               Sometimes it's useful for controlling dynamics      Richard Erlacher      10/06/12 14:08      
            ballscrews & table slides      Joseph Hebert      10/06/12 15:15      
   LINUXCNC      Mahmood Elnasser      10/19/12 02:08      

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