[deejayspinz]

Hi all,

I am new to CNC and have been learning the ropes over the last few months. I am starting with a MyDIYCNC and using CamBam along with Mach3 to cut the part. I have successfully modeled my part, created the milling operations in CamBam and am using the eval version of CutViewer and everything looks good - at least to me.

My issue is when I take the gcode to Mach3 and start milling my part, the spindle seems to go to a Z point that is higher than my stock/part and starts milling there. It proceeds to mill all the way down to the actual stock surface (which seems to be the bottom of the part).

My stock size is 120mm x 56mm x 9mm. In CamBam and CutViewer my part sits nicely within the stock and it all looks good when simulated - it cuts down into the stock and reveals the part. I have the stock surface set to 9mm. In Mach3, I zero the spindle at the top of the stock surface (z=0).

When I run the gcode in Mach3, the spindle rises up above the stock to about what appears to be the same Z value (~9mm) as the stock height and then starts to follow the toolpaths to cut the part - but it's in the air above the part. After letting it run to see what it would do, it appears that it cuts down to the actual top of the stock surface and that appears to be the lowest cut (Z=0). The paths that the cutter is following seem to be correct, they are just in the air above the actual stock.

I 'believe' I have set Mach3 up correctly and am unsure if my issue is in Mach3 setup (table def, etc) or in the part milling operations in CamBam. Edit: I managed to to get the machine coordinates setup correct. Also, when I am in stock coordinates and click 'go to z' it goes right back to the top of the stock part and lower left corner - where I expect it to.

Forgive me if I am not making much sense - I trying to describe it based on what I observed. I think what I am doing wrong is probably simple and I am missing something that I don't know what / where to look for. I tried to set the stock surface to 0, but it moved the stock below the Z axis and the milling operations were all messed up (the part was +Z and stock -Z), so I think I have the stock setup correctly. Any help would be appreciated.

I've attached the gcode here.

Thx

[deejayspinz]

Anyone?

[deejayspinz]

Hey guys, I'm stumped and would really appreciate any thoughts that might help me figure out what I am missing.

[mactec54]

deejayspinz

Save the program G code as text & post it here

[deejayspinz]

deejayspinz

Save the program G code as text & post it here

Confused... It's attached as a zip in the OP which can be opened in a text editor? I've attached again as a text file.

[mactec54]

deejayspinz

All your Z axes moves are positive, they need to be negitive moves, has your Z axes been set up correct as well, Positive to home, all moves from home are negitive, in your program all your Z moves for cutting are G1Z-6F3. & G0Z10 for clearance

[deejayspinz]

deejayspinz

All your Z axes moves are positive, they need to be negitive moves, has your Z axes been set up correct as well, Positive to home, all moves from home are negitive, in your program all your Z moves for cutting are G1Z-6F3. & G0Z10 for clearance

Hmm.. Not sure how that can be the case. I ran the code and it was only the very beginning that messed up. When started, it went to the correct X/Y location, then went up 9 units and started to mill from there (in the air though). However, it did as expected and milled downward. It was the initial rise of 9 units above the stock surface that is messing up. Also note that I had Z zero'd at the top of the stock surface.


This time, I zero'd Z at the base of the stock. Then, we starting the code, it sort of worked. I say sort of because it tried to path over to the center of the cut without raising the spindle, (which would have broken the bit had I not stopped it in time).

I followed this in the g-code and saw the problem. In the original code segment, the GO F300.0 Z9.0 happens after it paths to the center of the cut area (G0 X31.1818 Y29.3222). So, I moved F300.0 Z9.0 below it and it proceeded correctly. Any idea why it would have been put in the wrong place?

I ran through a good portion of the code on MDF and it sort of worked. However, there were a few times when the spindle was moving to another cut and it did not raise the spindle but rather cut across the part - which looked (and sounded) wrong. I'm sure I would have broken a bit if this were aluminum. I think I'm missing something in CamBam and the g-code is not generating with the correct instructions to raise the spindle out of the part (or not enough) during these transitions. When I ran it through CutViewer, it showed all sorts of these red line cuts and looked like I would have had a lot of broken bits if I ignored them... Any ideas what sort of setting I should look for in CamBam to do this? I thought it would figure it out once it new the stock and drill bit info (which are all in there).

Original:

( 3DSurface1 - rough )
G17
M3 S1000
G0 X31.1818 Y29.3222
G1 F300.0 Z9.0
G3 F200.0 X30.5146 Y29.7158 Z8.9594 I-7.9521 J-12.7187
.....

Revised:

( 3DSurface1 - rough )
G17
M3 S1000
G1 F300.0 Z9.0
G0 X31.1818 Y29.3222
G3 F200.0 X30.5146 Y29.7158 Z8.9594 I-7.9521 J-12.7187
.....

[ger21]

Hmm.. Not sure how that can be the case.

Look at the g-code. All the Z moves are between Z=0 and Z=+9.

Can't help you with CamBam, but you have something set wrong. You might want to try the CamBam forum.

[deejayspinz]

Look at the g-code. All the Z moves are between Z=0 and Z=+9.

Can't help you with CamBam, but you have something set wrong. You might want to try the CamBam forum.

I think I follow, but I re-zero'd Z at the base of the stock so the top is now 9 and, as described above it sort of worked. The sample below shows the Z value tracking down into the stock (which it did when cutting).

So, I can make it work when I zero Z at the base of the stock, but is this the right (or should I say common) way to do it? Or should my goal be to zero the spindle at the top of the stock and then look at CamBam to make Z go negative?

Also, any thoughts on my note above about the spindle tracking through the material to get to other areas (it is like it is not raising the spindle up out of the material). Could this be related to my above issue?

Thanks for your input BTW. Much appreciated.


0 X31.1818 Y29.3222
G1 F300.0 Z9.0
G3 F200.0 X30.5146 Y29.7158 Z8.9594 I-7.9521 J-12.7187
G3 X31.7979 Y30.5069 Z8.8804 I-7.2205 J13.1478
G1 X36.7092 Z8.623
G1 Y28.8469 Z8.536
G1 X31.8958 Z8.2837
G3 X30.5146 Y29.7158 Z8.1982 I-8.666 J-12.2433
G3 X31.7979 Y30.5069 Z8.1191 I-7.2205 J13.1478
G1 X36.7092 Z7.8617
G1 Y28.8469 Z7.7747
G1 X31.8958 Z7.5225
G3 X30.5146 Y29.7158 Z7.4369 I-8.666 J-12.2433
G3 X31.7979 Y30.5069 Z7.3579 I-7.2205 J13.1478
G1 X36.7092 Z7.1005
G1 Y28.8469 Z7.0135
G1 X31.8958 Z6.7612
G3 X30.5146 Y29.7158 Z6.6757 I-8.666 J-12.2433
G3 X31.7979 Y30.5069 Z6.5966 I-7.2205 J13.1478
G1 X36.7092 Z6.3393
G1 Y28.8469 Z6.2523
G1 X31.8958 Z6.0

[mactec54]

deejayspinz

You can not set the Z to the bottom of the stock, you will have a crash, your program is very wrong, you have to set the
Z0 to the top of the part, all the Z cut moves need to be Z- The clearance moves need to be Z10 to clear your part

You have a program problem

[deejayspinz]

deejayspinz

You can not set the Z to the bottom of the stock, you will have a crash, your program is very wrong, you have to set the
Z0 to the top of the part, all the Z cut moves need to be Z- The clearance moves need to be Z10 to clear your part

You have a program problem

Thanks. I'm now wondering if I have the Z direction set wrong in Mach3. When I home Z, it goes to the top, and when I click the up arrow to move the spindle - it goes up and vise versa. Is that not correct?

Also, I'm a newbie and don't follow the Z10 for the part clearing. Does this mean I should be looking to add Z10 moves for the areas I see these problems in the gcode? There are many when I watch it in CutViewer.

[mactec54]

deejayspinz

That is what I said to check, that the spindle is moving the correct way minus- for down

Why I said 10mm I don't know how you have this set up, But for a clearance move you only have to move the tool in a Z move to just above the stock could be 2mm if that clears everything

This does not change how your program is it needs to be changed to Z- for your cut moves & just Z--- for the clearance moves

[deejayspinz]

deejayspinz

That is what I said to check, that the spindle is moving the correct way minus- for down

Why I said 10mm I don't know how you have this set up, But for a clearance move you only have to move the tool in a Z move to just above the stock could be 2mm if that clears everything

This does not change how your program is it needs to be changed to Z- for your cut moves & just Z--- for the clearance moves

I follow now. Thx! I will have a look tomorrow. As for the clearance moves, is it normal to have to add these to gcode? Ithought it would be automatic in CamBam?

[deejayspinz]

Thx for the tips guys. Think I figured it out - was placing the part/stock in the wrong place (above Z plane) in CamBam. Needed to set stock surface to 0 and transform the part down below the Z plane. The part originally imported with its bottom at Z=0.
Details: Mach3 cutting in the air above the stock.