Messages

1

General Mach Discussion / Re: Where are the plasma THC settings

« on: May 04, 2014, 01:33:02 PM »

 Ok. So THC Min Speed % = Anti Dive? I will play with that and see what i get.

2

General Mach Discussion / Re: Where are the plasma THC settings

« on: May 04, 2014, 11:44:40 AM »

 Ok, i am feeling dumber by the minute. I entered a value in the box and hit ENTER and whaola, it took it. I swear i tried that 5 times and it didnt work but i guess i was mistaken.

 I have no box labelled anti-dive.

 Also there is a box which has "THC speed" and a second box which has "THC Min Speed %". I can change the THC speed and the THC will react at the changed speed. But what is the Min speed used for?

 When cutting with my THC speed set to 20 the Z axis would move up so fast it ended up about 1" above the part and would not come back down to where it belonged during the cut. When i changed the speed to 5 the Z axis moved up and down perfectly when cutting at 30" per minute. But im afraid when i start cutting much faster the THC Z axis speed will have to change to match. So i guess this is a setting that must be adjusted manually depending on the XY cutting speed you will be using?

 Also when cutting small holes in diameter of .5" the Z axis was dropping down and dragging the nozzle around on the part. Is there any way to turn the THC on and off in the post processor to inhibit it during small cuts?

3

General Mach Discussion / Where are the plasma THC settings

« on: May 04, 2014, 09:24:21 AM »

 For the life of me i cant seem to find the plasma THC settings such as the anti-dive that everyone talks about and others. I have the screen that does have the THC on button and also shows the THC speed and up and down limits but it doesnt allow me to change those settings. Any one want to help out a rookie?

4

General Mach Discussion / Re: Plasma Z home speed homing in rapid

« on: May 03, 2014, 09:49:47 PM »

 Got it. That explains it perfectly and easily understood.

 I did a search on the manual and there is only one single reference to G28.1 that i found and it doesnt explain anything about how it should be used.

 Thanks for the help im sure that is my problem.

Ive spent half my lifetime operating and programming CNC controls and im half embarrassed to admit i havent came across this before. All machines ive ran before you home the machine using the controls home sequence and after that if you want to return to the machines 0 coordinate (1st reference point) you give it a G28 Z0 or a G30 for second reference point.

5

General Mach Discussion / Re: Plasma Z home speed homing in rapid

« on: May 03, 2014, 08:14:12 PM »

 How does the G-code control the slow down for homing? The code simply gives a G28.1 Z0 command. I assume the control (mach3) simply executes that command. I also assume mach3 would over ride any feedrate commands during a homing sequence and use its feedrate parameters for homing.

6

General Mach Discussion / Re: Plasma Z home speed homing in rapid

« on: May 03, 2014, 05:31:55 PM »

 I have the homing speed set to 20% of rapid and slow down position set to 1.0", rapid speed is 100"/minute. It ignores this for whatever reason.

 I will try giving a z position other than Z0 when calling up the g28.1 command and see what happens.

 I thought of adding some code to my post script to make it origin to 0 and then home from there as it slows down when it gets to 0. Something like this -

 G92 Z0
 G28.1 Z0

 But i would rather have it work properly in the first case.

7

General Mach Discussion / Plasma Z home speed homing in rapid

« on: May 03, 2014, 05:07:53 PM »

 This is my first experience with Mach3. Like the software, but more detailed instructions would be very helpful. I am setting up a plasma table with THC that has a floating head and a limit switch on the head for using as probe. Instead of connecting the switch to the "probe" under ports and pins i have the switch connected to the "Z home" pin.

 Here is my latest dilemma. When the machine homes Z axis it runs in rapid speed until the limit switch activates which many times ends up overrunning the switch and jamming the floating head. Under configure limit/home switches i can set the slow zone to whatever i want and mach3 just ignores this value and still homes in rapid speed. However if i run the axis way up and give a G92 Z.5 in MDI and origin the Z position to above the part and then home Z axis it will slow down to the homing speed after it reaches 0.0000 inches and continue down homing as it should. While running a program the torch head slams into the part when it homes and things go bad from there. I can slow down the Z motor max speed to allow for this problem but im afraid that will affect the speed at which my THC will adjust the Z axis.

 So what am i missing?