center pierce holes help?

Problems and questions
1

I would like to make some different parts and just use my plasma to center punch the holes for me so I can drill them out to the correct size…

I use Hycad for my CAD drawings and it as a feature to put a point in (or a dot), but when i load it into sheet cam, it doesnt come up… In order to make this happen i have to draw a tiny hole… like. .20 or so and then the plasma will cut that…problem with that is my machine doesnt cut small holes very round and when I drill them after, its sometimes off center,

any help would be great thank you

2

Draw the holes as circles but put them on a different layer to the outline. This stops SheetCam from trying to cut the holes. You can now use a drilling operation in SheetCam to select these holes and mark the centres. In the drilling operation you have options for min hole size and max hole size. Circles between these two sizes will be marked.

If drilling appears to work in simulation but doesn’t in your final code your post may need to be modified. I can explain how to do this if you need it.

3

Hi, we have been trying for a week or so to get this center punch to work. We have tried a few different ways and the machine goes over to the hole, but will not drop down and strike off. It just moves on to operation 2. What are the code modifications you are talking about?

4

What post processor are you using?

5

We are using Qcad to make the drawing, Sheetcam to process and CandCNC to cut. We have tried a drill operation with a rotary tool as the manual shows for CandCNC as well as a drill operation with a plasma tool. Both give the same results. Shows the hole in the the drawing window but does not show z codes in the cammand list.

6

CandCNC

7

This sounds like a post processor issue. Do you have the most recent CandCNC post?

8

I would assume so. The machine is only a couple months old now. How do i see what ours is?

9

Go to OPtions->machine->post processor. CandCNC usually add a version number to the name of the post. I’m afraid you will have to contact them to see if it is the most recent.

10

I am having the same problem.
Can draw the circle and get it all to work in sheetcam, but when actually doing the cutting, the punch operation is bypassed.
I am using UGCS to send the gcode, drawing are made in Corel Draw 12, the machine is running GRBL 1.1h and the post processor is a modified version of GRBL plasma.

GRBL plasma post processor

Generic plasma post for machines with or without THC

Modal G-codes and coordinates
No comments
M04/M05 turn the torch on/off
Incremental IJ

11

Take a look at your post and see if it has this code:

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

If it doesn’t that is probbly the problem. If it does post a job file here (File->save job) with everything set up ready to cut.

12

I just did this a few weeks ago on my CandCNC (CommandCNC) system, so I know it works. I did it with the CandCNC rev27 post. I use a HT45 Plasma cutter and turned down the amperage to 30 amps to mark the holes, then back to 45 amps to cut the part out. I put a pause in the job to turn the amps back up (don’t know if that was really necessary, but I did it anyway.) I took a couple of screenshots to show my settings. Hope this helps some.

Steve

SC2.png
SC2.png640×517 45.9 KB

SC1.png
SC1.png1592×877 111 KB

13

Yes I have that coding in the PP.
I have the original job file that I used (attached) and also have the DXF
centre punch test.job (6.26 KB)
centre punch test.job (6.26 KB)
centre punch tool.jpg

centre punch test.job.jpg
centre punch test.job.jpg1205×683 13.9 KB

14

I can’t see anything wrong with the job file. The center drilling looks correct. Could you let me have a copy of your post processor.

15

firstPierceTime = 0 --this is an extra delay added to the first pierce as needed by some machines




function OnAbout(event)
ctrl = event:GetTextCtrl()
ctrl:AppendText(“GRBL plasma post processor\n”)
ctrl:AppendText(“\n”)
ctrl:AppendText(“Generic plasma post for machines with or without THC\n”)
ctrl:AppendText(“\n”)
ctrl:AppendText(“Modal G-codes and coordinates\n”)
ctrl:AppendText(“No comments\n”)
ctrl:AppendText(“M04/M05 turn the torch on/off\n”)
ctrl:AppendText(“Incremental IJ\n”)
end




function OnInit()

post.SetCommentChars (“()”, “”) --make sure ( and ) characters do not appear in system text
if(scale == metric) then
post.Text (" G21\n") --metric mode
else
post.Text (" G20\n") --inch mode
end
bigArcs = 1 --stitch arc segments together
minArcSize = 0.05 --arcs smaller than this are converted to moves
firstPierce = firstPierceTime
end

function OnFinish()
post.Text (" M05 M9 M30\n")
end

function OnRapid()
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()
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()
if(arcAngle <0) then
post.ModalText (" G03")
else
post.ModalText (" G02")
end
post.NonModalNumber (" X", endX * scale, “0.0000”)
post.NonModalNumber (" 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 (preheat > 0.001) then
post.ModalText (" G00")
post.ModalNumber (" Z", cutHeight * scale, “0.0000”)
post.Text (“\n G04 P”)
post.Number (preheat,“0.###”)
post.Eol()
end
post.ModalText (" G00")
post.ModalNumber (" Z", pierceHeight * scale, “0.0000”)
post.Text (“\n M04 M8\n”)
if (pierceDelay + firstPierce > 0.001) then
post.Text (" G04 P")
post.Number (pierceDelay + firstPierce,“0.###”)
firstPierce = 0
post.Eol()
end
end


function OnPenUp()
post.Text (" M05 M9\n")
if (endDelay > 0) then
post.Text (" G04 P")
post.Number (endDelay,“0.###”)
post.Eol()
end
end


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

16

I just ran your job with that post and it appeared to work. One thing I noticed is that your ‘centre punch’ tool has a pierce delay of 0. If you have arc sensing this is fine but if you don’t, the torch probably won’t fire.

17

I probably don’t have arc sensing, so what should I do?
When I run the file, the torch goes through all the motions correctly, just doesn’t fire when it is supposed to do, then moves on to the next hole and misfires again and so on.

18

What cutter are you using? The arc sensing he is referring to would be an arc ok signal from the cutter to let the program know that the plasma arc has transferred and it is cutting. If you don’t have this signal you need to add time to your pierce delay to allow the arc to begin cutting before it begins movement. I would think a second would be a good start.

19

The cutter I am using is suppose to be for hand held use only, it has no special features except it has low frequency pilot arc.
Unimig Viper 30
It is only a 30 amp machine, but works very well for my purposes, I use mainly 3mm (1/8") thick mild steel for most jobs.
If I add pierce delay time, what amount should I try, I have no idea?

20

I would start with one second and test. If it doesn’t pierce, add 1/2 second and try again. It’s going to be trial & error until you figure out what works.