Floating Head problem

[professor]

I am setting up a floating head on my plasma table and using the following code in Mach3 to set the material height.
N5 G28.1 Z.0
N6 G92 Z0
N7 G00 Z.73
N8 G92 Z0
N9 G00 Z-.2
N10 M03

When I manually home the machine the head travels down untill the head is pushed up and the switch is made. But when I run the code listed above the Z-axis moves up. Am I missing a setting setting somewere to cause the z-axis to move up instead of down to the torch switch?

[Mike 1948]

Originally Posted by professor I am setting up a floating head on my plasma table and using the following code in Mach3 to set the material height. N5 G28.1 Z.0 N6 G92 Z0 N7 G00 Z.73 N8 G92 Z0 N9 G00 Z-.2 N10 M03 When I manually home the machine the head travels down untill the head is pushed up and the switch is made. But when I run the code listed above the Z-axis moves up. Am I missing a setting setting somewere to cause the z-axis to move up instead of down to the torch switch?

You could try posting in the mach3 website forum:Machsupport Forum - Index
There are alot of knowledgeable people there. Its probably just a switch in Mach3

Mike

[Torchhead]

Originally Posted by professor I am setting up a floating head on my plasma table and using the following code in Mach3 to set the material height. N5 G28.1 Z.0 N6 G92 Z0 N7 G00 Z.73 N8 G92 Z0 N9 G00 Z-.2 N10 M03 N5 says home the Z (move down to the swtich) N6 then zeros the Z DRO N7 then raises the Z up .73 inches (?) N8 Zeros it again so unless your swtich offset is also 3/4" the head is way up in the air at this point N9 Moves the torch .2 inches BELOW the point you established at Z zero When I manually home the machine the head travels down until the head is pushed up and the switch is made. But when I run the code listed above the Z-axis moves up. Am I missing a setting setting somewere to cause the z-axis to move up instead of down to the torch switch?

If a manual REF on Z does not work right then:
1. Make sure the Z is actually moving the right direction. Give it a Z command in the MDI window and see if it moves the direction (absolute) you tell it. The motor has to move the direction the G-code tells it. The hit keys are aribitrary and should be set after you get motion to agree with code. You can reverse motor direction in MACH by using the Ports&Pins/Motor Outouts and the DIR Active low setting.

2. After you get the direction to match the code (DRO increases when the Z is going up and decreases when it's going down) then open the Homing and Limits config and you can define the Direction the axis moves to move towards the home switch.

3. Since you are setting the switch offset in the code you should not apply any offsets in Homing and Limits.

No negative numbers in plasma cutting! a neg number means move BELOW the Z (top of material) I don't think you want to drive the torch through the metal and cut below it (:_)

All the numbers on the machine are absolute meaning they are all referenced to a known zero. Z zero is typically the top of material. For routing and milling where you are cutting below the top of the material the Z moves are negative. If you are below the material with plasma you have some real problems! A negative number is not subtracted from where you current are but is a location in relation to Zero on that axis.


there are some examples of the correct touch off sequence in our DTHC users manual http://www.candcnc.com/PDF/DTHC_Setup-Config-Rev4.pdf
It's written to work with MACH, the floating torch holder for IHS and optionally using SheetCAM (which has all of the touch off stuff in the POSTS)

TOM caudle
www.Candcnc.com