Machine cutting deeper than G code indicates

[kaetamer]

Hi guys, need a little help please.

Doing a roughing pass on a 3d terrain file and when the second pass started the machine was cutting deeper than the g code indicated. I've included screen shots of my setup and the Mach3 screen when I interrupted the cut as well as the actual material being cut. You can see the g code calls for Z-0.2 yet the display says it's cutting +2.28. Clearly I've got a parameter set incorrectly somewhere...




I tried restarting the computer, regenerating the g code (though the code appears correct), closing and restarting Mach3. I saw this one other time with a 3d terrain file and when I re-ran the file it worked correctly. Restarting this time just moved the place in the file where the error occurs.

Anyone seen this or know of a fix?

Thanks. Scott

Similar Threads:

• Z axis cutting deeper than expected
• New Product- Year of portable Tube Cutting Machine Welcomes SteelTailor TubeTailor Cutting Machine
• Cutting deeper than flute length
• Cutting deeper than cutting length

[ger21]

Is there a G43 in the code, and is their a tool length in the tool table for the tool being used?

[cncjack01]

you can do like this : let the z axis up or down 10mm(the screen show ),then use the ruler measure the real distance .compareed .

[nlancaster]

Also check to be sure you are not losing steps, and that the tool is not pulling out of the collet.

[kaetamer]

ger21 - no g45 code included and no way to indicate tool length in database.
cncjack01 - will try this tomorrow and report back
nlancaster - listened very carefully at 100% feedrate incrementally down to 10% feedrate - never heard anything - measuring as per cncjack01 should put that to rest - as far as tool pulling out of the collet - interesting thought though I'm not sure how it would pull out and get stuck out; I would think it would simply be pushed back in. I'll try tightening the collet sorme more.

Thanks for your input.

[CitizenOfDreams]

Even with tool length compensation on, lost steps and pulled out tool, "G1Z-0.2" should still go do -0.2 on the DRO. I'm confused.

[ger21]

when the second pass started the machine was cutting deeper than the g code indicated........You can see the g code calls for Z-0.2 yet the display says it's cutting +2.28

How deep was it actually cutting?
And did it say Z 2.28 when you stopped it, or did it move after you stopped it?

What are your Native Units set to, inches or mm's?

ger21 - no g45 code included and no way to indicate tool length in database.

It's G43, and I'm talking about the Mach3 tool table.

[kaetamer]

ger21 - my mistake, G43, and it also does not appear in the .txt file - all units are set to inches unless by native units you're referring to a Mach3 setting, will need guidance if you mean Mach3. Have not needed to address the Mach3 tool table since I started running the machine two years ago and don't know how but I'll try to be a quick study The depth of the second cut is to my best measurement .228 inches from the top - when I noticed the increased sound of the deeper cut I stopped the machine (e-stop) - the DRO is where the machine stopped.

CitizenOfDreams - the discordance between line 550 and the Z DRO IS confusing. Since there is a difference between the two values is it safe to assume there are no lost steps? Even with lost steps in the retraction between passes the DRO value should match the g code. The depth of cut would be wrong (too deep) but the DRO should be correct - or have I misunderstood what the DRO reports? It's as if steps are being added.

[ger21]

The g-code says Z -.2
The DRO says +2.28.
So, the DRO is saying the tool should be about 2-1/2" above where you say it was.
But the real issue is that the DRO should have said -.2, not 2.28

In Mach3, go to Config >Select Native Units, and make sure inches is selected.

[109jb]

Is the DRO showing machine coordinates, or the work offset?

[CitizenOfDreams]

Is the DRO showing machine coordinates, or the work offset?

The DRO shows work coordinates (otherwise there would be a red border around the button).

[kaetamer]

ger21 - units set to inches in Mach3 - I see your point about the MINUS .2 PLUS 2.28 discrepancy. On the pic of the Mach3 screen I uploaded I noticed the Z DRO has a green border around it while the X and Y DROs are bordered in red. Tried to reproduce that situation by re-running the program cutting air - can't figure how I managed it. After RefAllHome, all are now green while the program runs. BTW, I tried running the roughing pass again and it ran to completion without error while cutting air. I measured .1" of negative Z at the end of every pass. Will retry cutting wood in AM and report back.

Thanks for your help. Hope it was just "gremlins".

[Goonk]

I'm just a rookie here, but I had a weird situation similar to this and I figured out that somehow, I had chosen the wrong controller in VCarve.

Tony

[kaetamer]

Goonk - thanks for input - checked that as well.

FWIW I did a re-cut this AM and it ran normally. Not sure what happened but thanks for all the help and for allowing me to waste your time with "electrical gremlins" or, more likely, operator error.

Have a good day. Scott

[warrenb]

Could be a couple things.

As before check your G43 to make sure it's referencing the right tool number.
If not using g43 check that you don't have a z off set in your g54
If not using g54 check your homes again
If all looks good check your collets. The tool could be pulling out.

[kaetamer]

warrenb - thanks for your suggestions. I will check as you suggest. Scott