[lostit]

hi everyone, im new to cnc'ing. i bought a machine a few days ago and have an stl file that i want to cut as a test to mess with settings and learn how to do this.

my problem is that when meshcam generates the g code and i run it in mach 3 the first thing it does is smashes my spindle down on the z axis, through the backing board into the t slot table and jams it up.

i have tried to run the code from the top and the bottom of stock and get the same result each time.

what i am doing is:

1) start machine and open mach 3
2) ref all home
3) auto zero tool
4) move the spindle along y/x to where i want to start
5) hit go
6) spindle fires up and then bam! its trying to destroy my machine by driving straight down.

can anyone look at my file and g code and tell me what i am doing wrong before i bust this machine?

thanks

[ger21]

6) spindle fires up and then bam! its trying to destroy my machine by driving straight down.

What does the Mach3 Z axis DRO say when it's going down?
The g-code is telling it to go down .063" and start cutting. Are you setting your Z zero to the top of your stock?

[lostit]

What does the Mach3 Z axis DRO say when it's going down?
The g-code is telling it to go down .063" and start cutting. Are you setting your Z zero to the top of your stock?

in meshcam i set it to the top of stock, i have also tried to set it to bottom of stock, i get the same result each time.

as for zero...i have a metal thing that plugs into the router then i hit auto zero tool, it goes down and touches it the backs off 5mm. the metal thing is 10mm, the readout at zero in mach3 is 15.0016mm

the person i bought the machine off used fusion 360 for a cam program, and he sent me a test file a .tap file and it cuts without issues. could it be that this machine can only run fusion g code? i have no idea really, but its going to break if i keep trying meshcam i think.

i cannot run fusion 360 because my stl files are all in solidworks and they show up as blanks in fusion 360 (apparently a common issue)

[stevensturgis]

It sounds like your g code and mach3 set ups are not both in mm or in inches.The cnc must be set up to one or the other at the start of loading mach3 for the motor travel set up. you cant change g code by using select native units. under configuration tab. That is for setting motor controls for the cnc only.
In mesh cam set zero to top of stock. use the real thickness of the stock you will use. set the mm or inches in the mesh cam tab marked define stock this should be set to what you what to work in mm or inches. mesh cam will set the g code to mm or inches by g code commands for mach3.automatically

The tool zero must also match the units your working in i think this is the problem. you can edit the tool zero text in windows note pad the thickness of your plate is set in this code change it to the thickness of your zero plate.

also. g70 is inches and g71 is mm. g 20 or g21 will set mach3 to the working units.look at the g code and see what mesh cam is using

. if you zero the tool and then hit go to zero in mach3 the tool should go to the top of your stock. if it dosent the tool zero code is wrong. or there is a tool offset being used tool offsets are set in the native units you picked when loading mach3. to view hit config tab then tool table.

In mach3 hit the tab operator than edit text bottom the screen will blink then hit tool zero button this will bring up the code its using so you can compare them. there is also a tool retract height in this code.

sample code only for reference or comparing to yours.

CurrentFeed = GetOemDRO(818) 'Get the current feedrate to return to later
CurrentAbsInc = GetOemLED(48) 'Get the current G90/G91 state
CurrentGmode = GetOemDRO(819) 'Get the current G0/G1 state


If GetOemLed (825)=0 Then 'Check to see if the probe is already grounded or faulty
DoOEMButton (1010) 'zero the Z axis so the probe move will start from here
Code "G4 P3" ' this delay gives me time to get from computer to hold probe in place
Code "G90 G31Z-4. F4" 'probing move, can set the feed rate here as well as how far to move
While IsMoving() 'wait while it happens
Wend
ZProbePos = GetVar(2002) 'get the exact point the probe was hit
Code "G0 Z" &ZProbePos 'go back to that point, always a very small amount of overrun
While IsMoving ()
Wend
Call SetDro (2, .246) ' change .060 to your plate thickness and then adjust for final accuracy
Sleep 200 'Pause for Dro to update.
Code "G1 Z1. F50" 'put the Z retract height you want here, must be greater than the touch plate thickness
While IsMoving ()
Wend
Code "(Z axis is now zeroed)" 'puts this message in the status bar
Code "F" &CurrentFeed 'Returns to prior feed rate
Else
Code "(Z-Plate is grounded, check connection and try again)" 'this goes in the status bar if applicable
End If
If CurrentAbsInc = 0 Then 'if G91 was in effect before then return to it
Code "G91"
End If
If CurrentGMode = 0 Then 'if G0 was in effect before then return to it
Code "G0"
End If

[stevensturgis]

g 54 can be found on the offset tab in mach3 it will start at what ever location is in this setup hit save tool offset and see whats there if the z is set to a certain height the tool will go there to start.

[lostit]

It sounds like your g code and mach3 set ups are not both in mm or in inches.The cnc must be set up to one or the other at the start of loading mach3 for the motor travel set up. you cant change g code by using select native units. under configuration tab. That is for setting motor controls for the cnc only.
In mesh cam set zero to top of stock. use the real thickness of the stock you will use. set the mm or inches in the mesh cam tab marked define stock this should be set to what you what to work in mm or inches. mesh cam will set the g code to mm or inches by g code commands for mach3.automatically

The tool zero must also match the units your working in i think this is the problem. you can edit the tool zero text in windows note pad the thickness of your plate is set in this code change it to the thickness of your zero plate.

also. g70 is inches and g71 is mm. g 20 or g21 will set mach3 to the working units.look at the g code and see what mesh cam is using

. if you zero the tool and then hit go to zero in mach3 the tool should go to the top of your stock. if it dosent the tool zero code is wrong. or there is a tool offset being used tool offsets are set in the native units you picked when loading mach3. to view hit config tab then tool table.

In mach3 hit the tab operator than edit text bottom the screen will blink then hit tool zero button this will bring up the code its using so you can compare them. there is also a tool retract height in this code.

sample code only for reference or comparing to yours.

CurrentFeed = GetOemDRO(818) 'Get the current feedrate to return to later
CurrentAbsInc = GetOemLED(48) 'Get the current G90/G91 state
CurrentGmode = GetOemDRO(819) 'Get the current G0/G1 state


If GetOemLed (825)=0 Then 'Check to see if the probe is already grounded or faulty
DoOEMButton (1010) 'zero the Z axis so the probe move will start from here
Code "G4 P3" ' this delay gives me time to get from computer to hold probe in place
Code "G90 G31Z-4. F4" 'probing move, can set the feed rate here as well as how far to move
While IsMoving() 'wait while it happens
Wend
ZProbePos = GetVar(2002) 'get the exact point the probe was hit
Code "G0 Z" &ZProbePos 'go back to that point, always a very small amount of overrun
While IsMoving ()
Wend
Call SetDro (2, .246) ' change .060 to your plate thickness and then adjust for final accuracy
Sleep 200 'Pause for Dro to update.
Code "G1 Z1. F50" 'put the Z retract height you want here, must be greater than the touch plate thickness
While IsMoving ()
Wend
Code "(Z axis is now zeroed)" 'puts this message in the status bar
Code "F" &CurrentFeed 'Returns to prior feed rate
Else
Code "(Z-Plate is grounded, check connection and try again)" 'this goes in the status bar if applicable
End If
If CurrentAbsInc = 0 Then 'if G91 was in effect before then return to it
Code "G91"
End If
If CurrentGMode = 0 Then 'if G0 was in effect before then return to it
Code "G0"
End If

this is a problem, im trying to cut it out of mdf as a practice but if i set the mdf thickness in 'define stock' which is 36mm, then i go to 'program zero' and hit 'top of stock' it says z 18.813 mm

so it wants to start half way through my material?

[ger21]

You'r g-code is in inches, and it sounds like you're machine is setup in mm's?

But that shouldn't really matter, as Mach3 will convert the code to mm's.

So, the .063 depth should actually be cutting a 1.6mm deep.

Bottom line, there's nothing wrong with the code, and nothing in it is telling it to plunge seep into your part.

My guess is that something is wrong with your Mach3 setup, or the process you are using.

[lostit]

You'r g-code is in inches, and it sounds like you're machine is setup in mm's?

But that shouldn't really matter, as Mach3 will convert the code to mm's.

So, the .063 depth should actually be cutting a 1.6mm deep.

Bottom line, there's nothing wrong with the code, and nothing in it is telling it to plunge seep into your part.

My guess is that something is wrong with your Mach3 setup, or the process you are using.

it cuts fine with the test .tap file though, so it only has a fault when i use meshcam gcode.

i tried cutting this from my metal sheet but destroyed a few hundred dollars worth of sheet so i tried cutting it into mdf board. that mdf is 36mm thick...should i set the stock size to 36mm thick? i dont think it should make a difference because i only want it to cut down 0.63 and it should know where zero is? but im out of ideas...it will break my spindle if it keeps doing it

[ger21]

Do a test run in air. Set Z0 high off the table, and watch the Z axis DRO, and see where it moves to.

[lostit]

no, i have not. do i change this line

G0X0.0000Y0.0000Z0.1000 to G0X0.0000Y0.0000Z0.0000

or this line

G1A0.0000Z-0.0630F0.1 to G1A0.0000Z-0.0000F0.1

[lostit]

if i set stock to 36mm it wants to cut through 18mm and then start the part there

[stevensturgis]

it looks like your cnc is set to work in g21 MM set the stock dimensions in mesh cam to MM then it should work. the machine is trying to move in inchis in the mesh cam code but the cnc is using MM. the difference between them is 25.4 units

[lostit]

the machine / mach 3 runs in mm. im using meshcam in mm...still i need to work out how it can start at the top of the stock

[ger21]

It's not the g-code telling it to cut that deep.

The deepest your g-code cuts is .063 deep.

[lostit]

ok well that doesnt help at all...i have no idea, i know nothing about cnc but it seems like a big confusing patchwork of crap...cad/cam/machine software/hardware full of errors or incompatible, i wish i never bought it tbh

[ger21]

Without physically having access to your machine, I can't tell you why it's doing what it's doing.

All I can tell you is that the code from MeshCAM is not causing the issue that you are seeing. It's either operator error, or some type of issue with Mach3.

[lostit]

what does "regen toolpath" do in mach3? does it rewrite gcode? should i try that?

[arminzendgani]

,مدل های سه بعدی دستگاه سی ان سی رایگان,free download model cnc ,free 3d,free art cnc


http://cnc3art.mihanblog.com/

[arminzendgani]

,مدل های سه بعدی دستگاه سی ان سی رایگان,free download model cnc ,free 3d,free art cnc


http://cnc3art.mihanblog.com/

[ger21]

It just redraws the toolpath display. It has no affect on any motion.