Speaker To-Dirt wrote:
> Hi All:
>
>    My Bridgeport Series 1 is popping fuses on axies. I'm making a mount plate 
> and drilling a scad of holes. 160 to be exact. I have a stepping machine with 
> no glass encoder feedback. So it just counts steps and assumes the stepper 
> makes the step. I was lucky tonight in that the Z axis konked out on me 
> ~0.050 above the work.
>
>    Anyone out there with this experience. That when you use an axis a lot you 
> pop a fuse. I'm guessing since I'm using the orig old boards the transistors 
> might be going into thermal runaway and popping the fuse. I'll blow a fan on 
> them next time. Any other ideas out there?
>   
The original Bridgeport drivers used a saturable reactor to limit motor 
current when not moving.  At some speed the reactor was switched off to 
send full voltage to the motor drive.  Are you controlling this?  It is 
an extra transistor on the driver board, so you need to drive 5 wires 
for each axis, 4 for the phases and one for the reactor control.  If you 
are controlling the reactor transistor, you may be turning the reactor 
off at too low a speed, causing excessive current in the motor.  You 
probably are moving Z very slowly (a couple IPM max) when drilling, and 
if your reactor control is set to turn it off on any movement at all, 
that may be the problem.

If your transistors were going into thermal runaway, then it is very 
unlikely the drive would work after you replaced the fuse.
>    But my real question is this. How do I tell EMC2 where to start the the 
> g-code program. So for my board I use two nested loops. The outer loop sets 
> the number of rows and the inner loop sets the number of columns. I have the 
> machine set in X and Y, so I can easily rstart the program and be indexed, 
> but I sure would hate to have to wait another ~30 min or so to return to 
> where I was. I'd like to just tell the g-code parser that I'm in this line 
> and the outer loop has cycled two times (I've completed 2 full rows) already. 
> Is there a way to do this?
>   
You can't easily restart a program with loops.  Just starting at a 
specific line won't do it, you need to set the loop counter variables to 
the right value first before restarting.  There is a pull-down menu that 
allows you to select "run from line" that will start the program at the 
highlighted program line on the screen.  You'd need to do MDI entries 
first to set up the loop variables.

Jon

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