Drawback

I work with EMC2 over 1 year. I like this programm.
But i don`t know how realize drawback.
Example.
I have the machine of oxygen cutting.
If you are running the program and goes off oxygen,
operator must stop programm. But the tool is moved on the program.
If he again kindle flame and continue to cut, then we get the detail
of the unerupted.
The operator must stop the program. Run it with the last frame.
Pause it in point where the oxygen go out. Burn up and
resume programm.
it was easier to return the program to the point where oxygen go out.

P.S. I'm sorry for my english.

Hello,

Are you using the Run from selected line (run from here)? With this you select the line you want to start with. See User manual for caution as the machine will move the tool to the expected position before the line first.

Rick G

I know how to use "Run from selected line".
But for large part (detail) this is not good.
Example.
Velocity = 100 mm/min
line = 5 000 mm.
Max time = S/V = 5000/100 = 50 min

If use Drawback Max time < 1 min.

I wont do negative velocity.
For this
in custompanel.xml file

<number>
<halpin>"my-number"</halpin>
<font>("Helvetica",20)</font>
<format>"+4.4f"</format>
</number>
<button>
<halpin>"OverPl"</halpin>
<text>"Plas"</text>
</button>
<button>
<halpin>"OverMn"</halpin>
<text>"Minus"</text>
</button>

in custom_postgui.hal file

net speed-scale => halui.feed-override.scale
net my-speed-incr pyvcp.OverPl => halui.feed-override.increase
net my-speed-decr pyvcp.OverMn => halui.feed-override.decrease
net my-speed pyvcp.my-number <= halui.feed-override.value

in emc2-2.3.3/src/emc/usr_intf/halui.cc

static int sendMaxVelocity(double velocity)
{
EMC_TRAJ_SET_MAX_VELOCITY mv;

// if (velocity < 0.0) {
// velocity = 0.0;
// }

if (velocity > maxMaxVelocity) {
velocity = maxMaxVelocity;
}

mv.serial_number = ++emcCommandSerialNumber;
mv.velocity = velocity;
emcCommandBuffer->write(mv);
return emcCommandWaitReceived(emcCommandSerialNumber);
}

and Terminal

make
sudo make install

But FeedOverride >= 0.

I have 2 questions.
1. how to make a negative FeedOverride?
2. acceptable if the negative rate in one frame?

O.K. now I think I understand what you want to do. If I understand correctly you want to stop the machine, set a negative feed rate to in fact reverse the machine travel to where the oxygen ran out. Then restart and continue on. I do not know enough about EMC to say for sure but I expect EMC will not be able to do this. There may have been some talk of this kind of move with EDM machines. I think the theory was to store the last known good position then make a move toward it, then go back to the rest of the program. I suspect the trajectory planner in EMC only looks forward.

Perhaps someone with a better understanding of EMC will jump in.

A few ideas come to mind but I am sure you already have thought of them.

Can you break the long moves into several short moves? Easier to find your spot and less wasted time.
Can you issue a MDI command to rapid back to the last good position, then enter a MDI command to rapid to the problem area, stop then run from there?

Rick G

Thanks.
When I have more free time. I write subprogram, for realize this function.

Could we ask for this feature to be added to EMC? I know the Mach3 has this option. It could be added at the same time as the move under feedhold capability that has been requested for so long.