[topline]

pulling hair out...

here is what happen:

1- I decrease the feed rate -- not solved
2- I change the PC to a new one -- not solved
3- I ground everything -- not solved

what can I do ?

still the second pass is 5 mm toward x and y and it happen with each pass.

please give me any idea before I finish my hair

thank you

[farmertom]

pulling hair out...

here is what happen:

1- I decrease the feed rate -- not solved
2- I change the PC to a new one -- not solved
3- I ground everything -- not solved

what can I do ?

still the second pass is 5 mm toward x and y and it happen with each pass.

please give me any idea before I finish my hair

thank you

Sorry you are having problems.
Questions:
1) Is the offset in x and y on each pass or just the second pass and the rest are OK?

2) Can you post some pictures of the bad cut part?

3) Have you tried cutting something different? Does this happen on each part you cut or just the "Z" part.

Just a few things to check:
1) Is you Z axis perpendicular to your table? If not, at each pass it will be in a different place as far as X & Y location.

2) Did you verify that you are not lossing steps?

3) Is you gantry hitting any stops, clamps etc while it is carving? This will lose steps.

post a picture of your machine and setup.

Sometimes it is the obvious you overlook.

good luck!

[Senna]

Let me ask a simple question that I probably should of asked previous to this... is this the first project ever attempted on your machine...? In other words... is it ONLY this file that is giving you problems... OR have you had success machining other projects on your CNC...?

I went through your gcode again and on ALL 5 passes the pocket cycle starting point is X-10.077 Y-45.258. I ran it through Mach 3 and virtually cut the pocket. NO issues with a second pass offset... nor on a third pass, nor forth, nor fifth...!

farmertom has suggested some other areas to investigate... and photos of the problematic offset and even a pic of your machine would be helpful also...

Senna

[topline]

Here is some photos of my work and the CNC

Thank you for your support

[topline]

I discovered that X-axis is losing steps, I use the homing and limit to set the table limits and zero all axis

after finishing the milling process and I want to return back to machine zero limit every axis is OK to zero except X-axis it losing steps?

any solution?

[farmertom]

I discovered that X-axis is losing steps, I use the homing and limit to set the table limits and zero all axis

after finishing the milling process and I want to return back to machine zero limit every axis is OK to zero except X-axis it losing steps?

any solution?

Looks like you are making some progress!
Check to make sure that the coupler to motor shaft is tight and the coupler to lead screw is tight.

[Senna]

You have a nice solid looking machine so I wouldn't expect it to have a 5mm backlash issue. If it isn't a loose coupler in the X axis... then the loss of steps may be due to too much friction in the X bearings. Since you are seeing the offset after each pass and the gcode is telling it to return to exactly the same pocket start location... I'm still of the opinion that the rapid move from the end of the pocket pass to the beginning of the 2nd pocket operation pass is where the step loss is occurring. There might be too much resistance in your X axis bearings for the stepper to overcome at a higher RPM where a stepper has less torque than at the lower RPM when machining.

Uncouple your X axis and see if the Z assembly has free travel and is not binding while traveling the length of the X axis rails.

Also... your machined pocket of the letter Z does not appear the same as what the gcode should machine. It looks like you are using too large an end mill to successfully machine that design. Did you generate the gcode using one sized bit and are machining it using another? OR did you scale the design smaller after generating the gcode and not recalibrate the toolpath? I'm at a loss trying to figure why your machining attempt looks so different from mine...???

Senna

[topline]

Looks like you are making some progress!
Check to make sure that the coupler to motor shaft is tight and the coupler to lead screw is tight.

it is tight and fixed I mark it with a marker and it look OK.

Is it needed to change the stepper motor to solve that? and how can I test It?

farmertom, Can you teach me how to verify because when I click verify nothing
happen?

THank you

[topline]

You have a nice solid looking machine so I wouldn't expect it to have a 5mm backlash issue. If it isn't a loose coupler in the X axis... then the loss of steps may be due to too much friction in the X bearings. Since you are seeing the offset after each pass and the gcode is telling it to return to exactly the same pocket start location... I'm still of the opinion that the rapid move from the end of the pocket pass to the beginning of the 2nd pocket operation pass is where the step loss is occurring. There might be too much resistance in your X axis bearings for the stepper to overcome at a higher RPM where a stepper has less torque than at the lower RPM when machining.

Uncouple your X axis and see if the Z assembly has free travel and is not binding while traveling the length of the X axis rails.

Also... your machined pocket of the letter Z does not appear the same as what the gcode should machine. It looks like you are using too large an end mill to successfully machine that design. Did you generate the gcode using one sized bit and are machining it using another? OR did you scale the design smaller after generating the gcode and not recalibrate the toolpath? I'm at a loss trying to figure why your machining attempt looks so different from mine...???

Senna

Hi,

The Z sign is the same what you had but I just do redesigning and use another font try to see if I can success but still no progress

but your thoughts is excellent and it logic to check your points.

I will see that and give you the feedback.

thank you

[Senna]

Ah... OK... that's actually a good approach to attempt another design. If you are having issues with multiple files of differing designs and you also said you swapped computers, that confirms it's a machine problem. Most likely lost steps due to a mechanical alignment issue.

I hope you can pinpoint the problem and it's an easy fix...!

Senna

[farmertom]

it is tight and fixed I mark it with a marker and it look OK.

Is it needed to change the stepper motor to solve that? and how can I test It?

farmertom, Can you teach me how to verify because when I click verify nothing
happen?

THank you

The Mach3 Users manual is located here http://www.machsupport.com/docs/Mach3Mill_1.84.pdf

Here is the entire section of Verify from the Mach3
6.2.2.6 Verify
The Verify button, which is only applicable if you have home switches, will move to them
to verify if any steps might have been lost during preceding machining operations. (does not give a lot of details!)

Somewhere in the Mach3 configuration is a check box to state you are using home switches.

After you run a part (do not close the gcode file), click the button and it should run back to home and then back to the part. It then displays how many steps you have lost.

I have only used this once and am not an expert at it. Maybe someone on this forum can add more information. I am sure if you ask in the Mach3 section of this forum you will get an expert answer. Hopes this helps and you get your problem solved.

[Markovic Slavol]

Cimco simulation