Newbie- Creating a Curve

[n1bpd]

I have a Chinese Mill that I converted to CNC from plans a few months ago. I'm very much at the bottom of a steep (to me) learning curve....

I want to create a toolpath that looks like this (the red line). Each square is .25" and each arc is essentially 1/4 of a circle.



(Center of the drawing is my 0,0 and each square represents .25 of a unit)

I am using Mach3 with the "Cut Arc" wizard to create 4 arc's and then combine the 4 to create one curve.

When I made each arc in the wizard they looked ok, and I ended up with this -

G3 X-0.125 Y0 I0 J0.375 F2
G2 X0 Y0.375 I0.375 J0 F2
G2 X0.375 Y0 I0 J-0.375 F2
G3 X0.5 Y-0.375 I0.375 J0 F2

Which unfortunatly leads to this in mach3 -



I have double checked my number's in the wizard and started over several times. I'm not familiar with g-code at all, but I know G3 does a CCW arc and G2 is CW the coordinate figures are not the same coordinates I entered into the wizard and I'm not at all familiar with I or J g-codes.

If someone could please explain what I'm doing wrong and point me in the right direction for how to do this correctly, or of a better method I'd greatly appreciate it.

Thanks

[tfisher]

if you start at zero zero x and y this should work

G3 X0.25 Y.25 I0 J0.25 F2
G2 X.5 Y0.5 I0.25 J0 F2
G2 X0.75 Y.25 I0 J-0.25 F2
G3 X1 Y0 I0.25 J0 F2

hope this helps.

[jimalb]

Before you can cut the G2 or G3 arc you first have to move the tool to the start point.
By your numbers looks like a .250 tool

(this is cutting the top of the curve)
G00 X-0.500 Y-0.125 Z(tool clearance)
G01 Z-0.(Tool Depth of cut) F(Plung Rate)
(Now tool is at start point)
(Rest of your code follow)
G03 X-0.3750 Y0.0000 I0.0000 J0.1250
G02 X0.0000 Y0.3750 I0.3750 J0.0000
G02 X0.3750 Y0.0000 I0.0000 J-0.3750
G03 X0.5000 Y-0.1250 I0.1250 J0.0000
G00 Z0.(Clearance plane)

(this is cutting the bottom of the curve)
G00 X-0.5000 Y-0.3750 Z(Tool Clearance)
G01 Z -0.(cutting depth) F(Plung Rate)
G03 X-0.1250 Y0.0000 I0.0000 J0.3750
G02 X0.0000 Y0.1250 I0.1250 J0.0000
G02 X0.1250 Y0.0000 I0.0000 J-0.1250
G03 X0.5000 Y-0.3750 I0.3750 J0.0000
G00 Z0.(clearance plane)

I drew your evample out to double check and my numbers came out different than yours. for some reason you are cuting the bottom of the first curve and the top of the next curve.

G3 X-0.125 Y0 I0 J0.375 F2
G2 X0 Y0.375 I0.375 J0 F2
G2 X0.375 Y0 I0 J-0.375 F2
G3 X0.5 Y-0.375 I0.375 J0 F2

HTH
Jimmy

[n1bpd]

Thanks Jimmy - I appreciate the annotations !