Strange Z moves when touching off

[stepper]

Hello guys
I was hoping someone may offer a little help with my issue.
I have recently upgraded my setup to Mach 4 and installed a C25XP BOB with an integrated ESS Smooth stepper from CNC4PC, the X & Y axis are homing and setting the machine zero coordinates correctly, the Z zero is set using a floating head off the surface of the material which activates the homing switch and works fine.
I then move the torch to the work and zero the X & Y work coordinate at its starting point, the Z axis is then jogged down until the torch just touches the surface and I than zero the Z work coordinate.

My problem is that when I start the program (Generated in Sheetcam), the torch is dwelling for pierce at -3.8 mm instead of +3.8 mm which is what the switch offset is programmed in the Sheetcam post processor (MP1000-THC), coincidently this is the same measurement as the Hypertherm pierce height.

X & Y axis moves are positive when moving away from the home switches, the Z axis is Negative when moving to the work surface and positive when moving away from the work surface no THC is being used.
Thanks
Andy

[stepper]

Program used for the above is as follows: -

N0010 (Filename: 25mm circle.tap)
N0020 (Post processor: MP1000-THC.scpost)
N0030 (Date: 03/05/2021)
N0040 G21 (Units: Metric)
N0050 G53 G90 G40
N0060 F1
N0070 (Part: New part)
N0080 (Operation: Outside Offset, 0, T3: 4mm Mild Steel Cut)
N0090 M06 T3 F2800 (4mm Mild Steel Cut)
N0100 G00 Z20.0000
N0110 X3.1308 Y-1.3946
N0120 Z3.8000
N0130 G28.1 Z3.00
N0140 G92 Z0.0
N0150 G00 Z3.8000
N0160 G92 Z0.0
N0170 G00 Z3.8000
N0180 M03
N0190 G04 P0.4
N0200 G01 Z1.5000 F1000.0
N0210 G03 Y3.1308 I-2.2627 J2.2627 F2800.0
N0220 G02 I9.3692 J9.3692
N0230 X1.2667 Y5.4732 I9.3692 J9.3692
N0240 G03 X-3.1433 Y6.4891 I-2.7129 J-1.6970
N0250 M05
N0260 G00 Z20.0000
N0270 X0.0000 Y0.0000
N0280 M05 M30

[weldguy]

Has it done this since you upgraded to Mach 4 or has it worked on Mach 4 and this problem just started?

[stepper]

Worked on Mach 3 but only started doing this following the change to mach 4.
Strangely, if I single block through the program the movements are okay.

[robertspark]

it's because g28.1 does not exist in mach4.

g28.1 will be skipped / ignored as mach4 does not know what you want the machine to do.

you need
a) a mach4 post processor
or
b) edit the post processor to change g28.1 to tell the machine to do what you want it to do instead


https://www.google.com/url?sa=t&source= ... _gZ7kW5Ecm


from memory g28.1 z

tells the machine to re-home g28.1 / reference the z axis.

I don't think there is an inbuilt macro in mach4 that does the same..... but I don't use mach4..... suggest you ask on the Mach forum....

or switch to g31 probe routine which is the correct way to do it as it is a probing routine and you set a temporary offset with g92

[stepper]

Hi robertspark
I thought that may be the situation, thank you for confirming this.
I will add another switch at the top of the Z axis to home to and use a g31 probing cycle to set the work height. Can you recommend a proven post processor that utilises the G31 cycle, I do plan on adding a THC very soon but do not have one as yet.
Hypertherm 45XP with CPC and machine torch
ESS Smoothstepper V3
C25XP BOB.

Regards
Andy

[robertspark]

send / post the post processor as a text file and I will edit it for you and repost

easier to do than talk / write about

[stepper]

function OnAbout(event)
ctrl = event:GetTextCtrl()
ctrl:AppendText("plasma MP1000-THC post processor\n")
ctrl:AppendText("\n")
ctrl:AppendText("Modal G-codes and coordinates\n")
ctrl:AppendText("Comments enclosed with ( and )\n")
ctrl:AppendText("M03/M05 turn the torch on/off\n")
ctrl:AppendText("Incremental IJ - set in mach2\n")
ctrl:AppendText("The torch is referenced at cut start and every 500mm of movement thereafter\n")
ctrl:AppendText("Designed for use with Mach3 and CandCNC MP1000-THC and Floating head Touch-n-Go\n")
ctrl:AppendText("Post variables:\n")
ctrl:AppendText("refdistance - set the distance between each reference\n")
ctrl:AppendText("switchoffset - set your net switch offset amount \n")
end


--post.SetOptions(post.ARC_SEGMENTS)


-- created 1/1/06
-- Based on plasma1.post



function OnInit()

post.SetCommentChars ("()", "[]") --make sure ( and ) characters do not appear in system text
post.Text (" (Filename: ", fileName, ")\n")
post.Text (" (Post processor: ", postName, ")\n")
post.Text (" (Date: ", date, ")\n")
if(scale == metric) then
post.Text (" G21 (Units: Metric)\n") --metric mode
else
post.Text (" G20 (Units: Inches)\n") --inch mode
end
post.Text (" G53 G90 G40\n F1\n")
minArcSize = 0.2 --arcs smaller than this are converted to moves

dist = 9999999
refdistance = 10* scale
--Put your switch offset value here
switchoffset =3.8
lastz = 0
end

function OnNewLine()
post.Text ("N")
post.Number (lineNumber, "0000")
lineNumber = lineNumber + 10
end


function OnFinish()
endZ = safeZ
OnRapid()
endX = 0
endY = 0
OnRapid()
post.Text (" M05 M30\n")
end

function OnRapid()
dist = dist + math.hypot(endX-currentX , endY-currentY)
post.ModalText (" G00")
post.ModalNumber (" X", endX * scale, "0.0000")
post.ModalNumber (" Y", endY * scale, "0.0000")
post.ModalNumber (" Z", endZ * scale, "0.0000")
post.Eol()
end

function OnMove()
dist = dist + math.hypot(endX-currentX , endY-currentY)
post.ModalText (" G01")
post.ModalNumber (" X", endX * scale, "0.0000")
post.ModalNumber (" Y", endY * scale, "0.0000")
post.ModalNumber (" Z", endZ * scale, "0.0000")
post.ModalNumber (" F", feedRate * scale, "0.0###")
post.Eol()
end

function OnArc()
dist = dist + math.hypot(endX-currentX , endY-currentY)
if(arcAngle <0) then
post.ModalText (" G03")
else
post.ModalText (" G02")
end
post.ModalNumber (" X", endX * scale, "0.0000")
post.ModalNumber (" Y", endY * scale, "0.0000")
post.ModalNumber (" Z", endZ * scale, "0.0000")
post.Text (" I")
post.Number ((arcCentreX - currentX) * scale, "0.0000")
post.Text (" J")
post.Number ((arcCentreY - currentY) * scale, "0.0000")
post.ModalNumber (" F", feedRate * scale, "0.0###")
post.Eol()
end


function OnPenDown()
if(dist >= (refdistance/scale)) then
dist = 0
-- modaltext (" G00")
-- text(" Z")
-- number (pierceheight * scale, "0.0000")
-- eol()
post.ModalText(" G28.1 Z")
post.Number(3 * scale, "0.00")
post.Eol()
post.ModalText(" G92 Z0.0\n")
post.ModalText (" G00")
post.Text(" Z")
post.Number (switchoffset, "0.0000")
post.Eol()
post.ModalText(" G92 Z0.0\n")
post.ModalText (" G00")
post.Text(" Z")
post.Number (pierceHeight * scale, "0.0000")
post.Eol()
else
post.ModalText (" G00")
post.Text(" Z")
post.Number (pierceHeight * scale, "0.0000")
post.Eol()
end
if (preheat > 0) then
post.Text ("\n G04 P")
post.Number (preheat,"0.###")
post.Eol()
end
post.Text ("\n M03\n")
if (pierceDelay > 0) then
post.Text (" G04 P")
post.Number (pierceDelay,"0.###")
post.Eol()
end
end


function OnPenUp()
post.Text (" M05\n")
if (endDelay > 0) then
post.Text (" G04 P")
post.Number (endDelay,"0.###")
post.Eol()
end
end


function OnNewOperation()
post.Text (" (Operation: ", operationName, ")\n")
end

function OnToolChange()
post.Text (" M06 T")
post.Number (tool, "0")
post.ModalNumber(" F",feedRate * scale,"0.#")
post.Text (" (", toolName, ")\n")
end

function OnNewPart()
post.Text(" (Part: ",partName,")\n");
end

function OnDrill()
OnRapid()
OnPenDown()
endZ = drillZ
OnMove()
OnPenUp()
endZ = safeZ
OnRapid()
end

[robertspark]

what feedrate do you home at?

[robertspark]

Just Change Line 43 to your probing / homing feedrate and it should work just fine.

I edited the probing sequence to make it a little quicker (less steps)

Code: Select all

function OnAbout(event)
ctrl = event:GetTextCtrl()
ctrl:AppendText("plasma MP1000-THC post processor\n")
ctrl:AppendText("\n")
ctrl:AppendText("Modal G-codes and coordinates\n")
ctrl:AppendText("Comments enclosed with ( and )\n")
ctrl:AppendText("M03/M05 turn the torch on/off\n")
ctrl:AppendText("Incremental IJ - set in mach2\n")
ctrl:AppendText("The torch is referenced at cut start and every 500mm of movement thereafter\n")
ctrl:AppendText("Designed for use with Mach3 and CandCNC MP1000-THC and Floating head Touch-n-Go\n")
ctrl:AppendText("Post variables:\n")
ctrl:AppendText("refdistance - set the distance between each reference\n")
ctrl:AppendText("switchoffset - set your net switch offset amount \n")
end


--post.SetOptions(post.ARC_SEGMENTS)

-- edited 04/05/2021 Robertspark
-- created 1/1/06
-- Based on plasma1.post


function OnInit()

post.SetCommentChars ("()", "[]") --make sure ( and ) characters do not appear in system text
post.Text (" (Filename: ", fileName, ")\n")
post.Text (" (Post processor: ", postName, ")\n")
post.Text (" (Date: ", date, ")\n")
if(scale == metric) then
post.Text (" G21 (Units: Metric)\n") --metric mode
else
post.Text (" G20 (Units: Inches)\n") --inch mode
end
post.Text (" G53 G90 G40\n F1\n")
minArcSize = 0.2 --arcs smaller than this are converted to moves

dist = 9999999
refdistance = 10* scale
--Put your switch offset value here
switchoffset =3.8 -- distance in milimeters
lastz = 0
probingfeedrate = 600 -- feedrate in mm/min
end

function OnNewLine()
post.Text ("N")
post.Number (lineNumber, "0000")
lineNumber = lineNumber + 10
end


function OnFinish()
endZ = safeZ
OnRapid()
endX = 0
endY = 0
OnRapid()
post.Text (" M05 M30\n")
end

function OnRapid()
dist = dist + math.hypot(endX-currentX , endY-currentY)
post.ModalText (" G00")
post.ModalNumber (" X", endX * scale, "0.0000")
post.ModalNumber (" Y", endY * scale, "0.0000")
post.ModalNumber (" Z", endZ * scale, "0.0000")
post.Eol()
end

function OnMove()
dist = dist + math.hypot(endX-currentX , endY-currentY)
post.ModalText (" G01")
post.ModalNumber (" X", endX * scale, "0.0000")
post.ModalNumber (" Y", endY * scale, "0.0000")
post.ModalNumber (" Z", endZ * scale, "0.0000")
post.ModalNumber (" F", feedRate * scale, "0.0###")
post.Eol()
end

function OnArc()
dist = dist + math.hypot(endX-currentX , endY-currentY)
if(arcAngle <0) then
post.ModalText (" G03")
else
post.ModalText (" G02")
end
post.ModalNumber (" X", endX * scale, "0.0000")
post.ModalNumber (" Y", endY * scale, "0.0000")
post.ModalNumber (" Z", endZ * scale, "0.0000")
post.Text (" I")
post.Number ((arcCentreX - currentX) * scale, "0.0000")
post.Text (" J")
post.Number ((arcCentreY - currentY) * scale, "0.0000")
post.ModalNumber (" F", feedRate * scale, "0.0###")
post.Eol()
end


function OnPenDown()
if(dist >= (refdistance/scale)) then
dist = 0
post.ModalText(" G31 Z-")
post.Number(probingfeedrate * scale, "0.00")
post.Eol()
post.ModalText (" G92")
post.Text(" Z-")
post.Number (switchoffset, "0.0000")
post.Eol()
post.ModalText (" G00")
post.Text(" Z")
post.Number (pierceHeight * scale, "0.0000")
post.Eol()
else
post.ModalText (" G00")
post.Text(" Z")
post.Number (pierceHeight * scale, "0.0000")
post.Eol()
end
if (preheat > 0) then
post.Text ("\n G04 P")
post.Number (preheat,"0.###")
post.Eol()
end
post.Text ("\n M03\n")
if (pierceDelay > 0) then
post.Text (" G04 P")
post.Number (pierceDelay,"0.###")
post.Eol()
end
end


function OnPenUp()
post.Text (" M05\n")
if (endDelay > 0) then
post.Text (" G04 P")
post.Number (endDelay,"0.###")
post.Eol()
end
end


function OnNewOperation()
post.Text (" (Operation: ", operationName, ")\n")
end

function OnToolChange()
post.Text (" M06 T")
post.Number (tool, "0")
post.ModalNumber(" F",feedRate * scale,"0.#")
post.Text (" (", toolName, ")\n")
end

function OnNewPart()
post.Text(" (Part: ",partName,")\n");
end

function OnDrill()
OnRapid()
OnPenDown()
endZ = drillZ
OnMove()
OnPenUp()
endZ = safeZ
OnRapid()
end

[stepper]

Thank you so much, I will give this a go in the morning

[stepper]

Hi robertspark
There was a slight error in your edit where the G31 Z move was referenced to the feed rate.
"post.ModalText(" G31 Z-")
post.Number(probingfeedrate * scale, "0.00")"
I have added the appropriate line to set a Z depth followed by the F command to use your probing feedrate, works great now so thanks again.
Andy

[robertspark]

oops.... good you worked it out and it now does what you want....

[adbuch]

Just Change Line 43 to your probing / homing feedrate and it should work just fine.