Parts not cutting in the right place

[Onebat]

Hi

I am having problems with my router cutting parts in the wrong place
I use Vcarve Pro 9 and the mach2/3 Arcs (MM) (*.txt) post processor (Cant find one for mach4)
I am using Mach4 Hobby build 3233
I have the WiXHC USB Motion Card MK3-M4 V5.10

i have set the start at the center of the material (6mm MDF) and have zeroed the Y X and Z axis at this point

it starts cutting in the right place but after 3 parts are cut it starts cutting parts in the wrong place (like it has forgotten where zero was) this has happened every time

is this a G Code Problem or hardware ? in mach4 while cutting it is showing that it is in the right place but on the router it is not photo uploaded to show what is happening

Thanks
Karl

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[ger21]

Most likely, your steppers are stalling and losing position. This could be caused by binding, or mechanical issues, or motors set up to run faster than they are capable of.

[Onebat]

Hi Gerry

i have checked the manufacturers specs for motors and they are set as per the manufacturers specs

i have done a random shape test cut and it was exactly as should be but when i go to cut a real project it keeps failing ?

very strange

Thanks

Karl

[ger21]

Are the feedrates the same? Does the sample use rapid (G0) moves?

[Onebat]

Hi Gerry

The feed rate for test shapes is 3600mm per min and for the full parts cut i slowed it down too 1800mm per min

i have added the g code files for both

Thanks

Karl

[mactec54]

Hi Gerry

The feed rate for test shapes is 3600mm per min and for the full parts cut i slowed it down too 1800mm per min

i have added the g code files for both

Thanks

Karl

This could be your problem, you have it programed in incremental, and should be programed in absolute

[Onebat]

Hi Mactec54

Will i need to change the setting in mach configuration ?
Distance Mode is set to Absolute
Arc Center Mode is set to Incremental is this the one i should change ?

Thanks
Karl

[ger21]

None of it is programmed in incremental. That's not the issue.

Try decreasing your acceleration by 50% in Mach4, and see if it helps.

[mactec54]

Hi Mactec54

Will i need to change the setting in mach configuration ?
Distance Mode is set to Absolute
Arc Center Mode is set to Incremental is this the one i should change ?

Thanks
Karl

No your settings are as they should be, this is all the G91.1 means

G90.1/G91.1 – Absolute/Incremental Arc Center Mode: This setting affects arcs when programmed in the I, J, K format. In absolute arc center mode the I, J, K values designate the position of the arc center in the user coordinate system. In incremental arc center mode the I, J, K values designate the distance and direction to the arc center from the start point

I have never used G91.1 so don't know if this could affect the positioning of each cut or not, remove it from the program and see what it does, it is not needed

You could Jog your machine to the start points in your program of each part, and see if the Dro matches

[Onebat]

Hi Mactec54 Gerry

I reduced the acceleration by 50% and it cut 10 parts before it cut 11th part in wrong place

The Line in the G code said X-413 DRO said X-406 The X Y and Z have been Zeroed on the home switch's and they change to Zero with machine coordinates button on then
with the machine coordinates button off i set the X Y Z zeros on the martial

and from there it starts cutting great then cuts in wrong place

i have removed the G91.1 and had same result

This part of the g code has some G codes i am not sure should be there G71 G43 H5 is the T5M06 needed as there is just 1 bit for this cut ?

N100G00G21G17G90G40G49G80
N110G71G91.1
N120T5M06
N130 (End Mill {3.175 mm})
N140G00G43Z6.000H5
N150S18000M03
N160(Toolpath:- Snow White Castle Full Cut)
N170()
N180G94

Thanks
Karl

[ger21]

Leave the g-codes as they are, they are not causing your issue. The problem is that the machine is losing position. This could be cause for a variety of reasons. Most commonly, it's due to trying to go too fast. If there is any binding in the motion of the machine, it can easily cause the motors to stall.

It could ba an issue with your motion controller, and stepper drives, if the quality of the step/dir signals is not good. Unfortunately, it's a difficult problem to troubleshoot on a forum. The easy fix would be to reduce the acceleration even more, and or reduce the Velocity settings as well.I'd try reducing the Velocity by 25% first.

[mactec54]

Hi Mactec54 Gerry

I reduced the acceleration by 50% and it cut 10 parts before it cut 11th part in wrong place

The Line in the G code said X-413 DRO said X-406 The X Y and Z have been Zeroed on the home switch's and they change to Zero with machine coordinates button on then
with the machine coordinates button off i set the X Y Z zeros on the martial

and from there it starts cutting great then cuts in wrong place

i have removed the G91.1 and had same result

This part of the g code has some G codes i am not sure should be there G71 G43 H5 is the T5M06 needed as there is just 1 bit for this cut ?

N100G00G21G17G90G40G49G80
N110G71G91.1
N120T5M06
N130 (End Mill {3.175 mm})
N140G00G43Z6.000H5
N150S18000M03
N160(Toolpath:- Snow White Castle Full Cut)
N170()
N180G94

Thanks
Karl

As Jerry said the program should run without any problems, but there are things in the program that don't need to be there G0G43H5Z6.0 is normal T5M06 is normal

You have by the dro a 4th axes running as well, turn this off, when not using it, yes the G71 is a rough turning cycle and has no place in your program, G94 also is not being used, G91.1 is also not needed, when you have the control setup correct, which you have

I'm sure you have the Mach4 manual, but here it is, they give you the ideal G-Code format for the different operations, you don't want lathe operations in your mill programs, this is all coming from how the post processor you are using has been setup

[ger21]

I would go from this:

N100G00G21G17G90G40G49G80
N110G71G91.1

To this:

N100 G00G21G17G90G40G49G80
N110 G91.1

And I'd remove the G43 line.

Imo, the G91.1 should be there, as it will make sure the code always runs correctly, if Mach4's IJ mode inadvertently gets changed.

[Onebat]

Hi Gerry Mactec54

the changes you suggested have not worked not really sure what to do
maybe i will have to get someone who can come on site and have a look

Thank you very much for your time with this problem it is very much appreciated

Do you know anyone in Melbourne that could help i am happy to pay someone for their time ?

Thanks
Karl

[ger21]

So you lowered both acceleration and velocity, and it didn't make any difference?
It may be an issue with your electronics.

Chinese motion controllers have always been problematic when used with Mach3.
You are the first person I've seen using one with Mach4.

Imo, your g-code is 100% not the issue here. It's either a mechanical, or electrical issue.

[Onebat]

Hi Gerry

Yes i lowered both acceleration and velocity and still cutting in the wrong place the parts have cut perfect strait lines and arcs and circles i have measured with calipers

the settings were set up remotely so i am just not sure they are right i don't have a 4th axis
i have added some more photos
The machine is 3 phase and can move from one point to another very fast and goes where i want it too when jogging
if there was binding backlash or motor stalls would the parts cut incorrectly ? however while they cut in the wrong place the parts are cut perfect

Thanks
Karl

[mactec54]

Hi Gerry

Yes i lowered both acceleration and velocity and still cutting in the wrong place the parts have cut perfect strait lines and arcs and circles i have measured with calipers

the settings were set up remotely so i am just not sure they are right i don't have a 4th axis
i have added some more photos
The machine is 3 phase and can move from one point to another very fast and goes where i want it too when jogging
if there was binding backlash or motor stalls would the parts cut incorrectly ? however while they cut in the wrong place the parts are cut perfect

Thanks
Karl

Are you using a USB cable, to the motion card, if so it may be picking up some noise, If using a USB cable it needs to be high quality shielded with Ferrite Chokes at each end

They also have the transformer very close to the motion card, also could be a source for noise

[Onebat]

Hi Mactec54

Yes i am using a shielded usb cable with ferrite chokes
i could move the transformer to the right a little bit or i could shield the motion card ?

Thanks
Karl

[mactec54]

Hi Mactec54

Yes i am using a shielded usb cable with ferrite chokes
i could move the transformer to the right a little bit or i could shield the motion card ?

Thanks
Karl

Looks good, is the VFD to spindle wiring using a shielded cable and the shield terminated at each end, Spindle Ground / Earth wires also connected correctly, these are just things to check to element any possible noise interference

[Onebat]

Hi Mactec54

I am not 100% sure the VFD to spindle is a shielded cable it is a orange 3 phase cable dose not look shielded all connections are good tho at both ends

the machine was made in china and here in Australia the 3 phase is 415v +- 5% and could be as high as 435v the sticker on the power input has 380V could this be a problem ?

Thanks
Karl