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Author Topic: Cutting wrong dimensions in only one spot  (Read 2877 times)

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Re: Cutting wrong dimensions in only one spot
« Reply #10 on: October 27, 2019, 12:26:22 PM »
I just broke a belt tuning my X axis servo. Hopefully I had a bad spot on the belt causing this. Won't have parts for a few days.

Not bad code for a cam. Finger follower. Not direct acting

Offline BR549

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Re: Cutting wrong dimensions in only one spot
« Reply #11 on: October 30, 2019, 10:39:18 AM »
Can you post your Gcode for the lobe ?

(;-) TP
Re: Cutting wrong dimensions in only one spot
« Reply #12 on: October 31, 2019, 02:37:59 AM »
Belt was bad on my X axis... but still cut the same. Here is some gcode


G00 G49 G17 G80 G50 G90 G64 P0.05
(.25 4 FLUTE CARBIDE SLOW)
M6 T1
M8
M03 S2500
G17
G00 X0.438 Y-1.759 Z0.500
G00 Z0.000
G01 Z-0.270
G17 G03 X-0.044 Y-1.242 R0.500 F3
G17 G02 X-0.855 Y-0.901 R1.242
G17 G02 X-1.242 Y0.003 R1.242
G17 G02 X-1.185 Y0.404 R1.438
G17 G02 X-1.173 Y0.440 R0.692
G17 G02 X-1.089 Y0.647 R2.406
G17 G03 X-1.025 Y0.810 R3.070
G17 G02 X-0.797 Y1.198 R1.161
G01 X-0.792 Y1.203
G17 G02 X-0.310 Y1.502 R1.027
G01 X-0.305 Y1.503
G17 G02 X0.061 Y1.545 R1.197
G17 G02 X0.776 Y1.270 R1.197
G01 X0.787 Y1.260
G17 G02 X1.030 Y0.967 R1.164
G01 X1.035 Y0.958
G17 G02 X1.133 Y0.731 R1.161
G17 G02 X1.141 Y0.702 R0.692
G17 G02 X1.184 Y0.477 R1.752
G17 G03 X1.201 Y0.360 R4.175
G17 G02 X1.223 Y0.231 R8.824
G01 X1.225 Y0.222
G17 G02 X1.234 Y0.147 R1.412
G01 X1.237 Y0.114
G17 G02 X0.949 Y-0.802 R1.242
G17 G02 X0.068 Y-1.241 R1.242
G17 G02 X-0.030 Y-1.242 R1.190
G01 X-0.044 Y-1.242
G17 G03 X-0.561 Y-1.724 R0.500
G00 Z0.500
M5 M9
M30

Offline RICH

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Re: Cutting wrong dimensions in only one spot
« Reply #13 on: October 31, 2019, 06:06:50 AM »
Attached is a dxf drawing made from a backplot of the gcode you posted.
Suggest you print the cad file full size and trace your actual machines path on the print.

You can also compare original drawing to backplotted drawing.

RICH

Offline BR549

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Re: Cutting wrong dimensions in only one spot
« Reply #14 on: October 31, 2019, 10:23:09 AM »
OK that checks out now HOW did you derive teh Black line plot you used to compare to teh actual cut profile that you measured ?

(;-) TP

Offline Graham Waterworth

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Re: Cutting wrong dimensions in only one spot
« Reply #15 on: October 31, 2019, 10:40:29 AM »
That Gcode is producing the black line perfectly by the look of it.
Without engineers the world stops
Re: Cutting wrong dimensions in only one spot
« Reply #16 on: October 31, 2019, 11:05:17 AM »
Thanks Rich. I'll print it out later tonight. 

Both plots are measured on a CMM. Then imported into my CAD.

Offline BR549

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Re: Cutting wrong dimensions in only one spot
« Reply #17 on: October 31, 2019, 12:29:01 PM »
Seeing how teh Gcode is a centerline profile how could it match teh actual cut seeing how there is a .125" offset of teh cutting tool. A conversion had to be made to be able to plot teh cut profile based on teh Gcode.

Just a thought, (;-) TP

Offline BR549

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Re: Cutting wrong dimensions in only one spot
« Reply #18 on: October 31, 2019, 01:20:56 PM »
Try cutting it with CV turned off (G61). What is teh look ahead setting ?

I have drawn this in an XY plotter ran by Mach3 about 20 times now 20 different ways and each time Mach3 drew it exactly how it plotted it in teh toolpath.

But I am still looking for something that could case this OTHER than the hardware. What type machine cut this. Steppers or servos ?

(;-) TP
Re: Cutting wrong dimensions in only one spot
« Reply #19 on: October 31, 2019, 01:37:50 PM »
The code I shared is for an offset master.  But the error is the same, no matter what size the shape is.

Servos,  G0704 style mill. It's definitely not the frame or axis flexing.

The look a head was 600. I just changed it to 200. Same results.

I am using a ESS smoothstepper