Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: chuck767 on September 14, 2018, 11:02:34 PM

Title: cutting a spiral
Post by: chuck767 on September 14, 2018, 11:02:34 PM

I'm trying to mill a spiral. anyone know the code? I found a G2.1 code but Mach3 doesn't like it.
Thanks,
Chuck

Title: Re: cutting a spiral
Post by: joeaverage on September 15, 2018, 12:07:35 AM

Hi,
codes G2 and G3 are circular arc/helical interpolation moves.
See for instance 'CNC Programming Handbook' by Peter Smid, its pretty much the Gcode bible.

They are fixed radius, you cannot to my knowledge use them as a spiral.

The way to do it is use CAD to draw the part including the spiral toolpath then use CAM to generate the Gcode.

Craig

Title: Re: cutting a spiral
Post by: ger21 on September 15, 2018, 07:59:00 AM

Quote

They are fixed radius, you cannot to my knowledge use them as a spiral.

In Mach3, you can cheat with G2/G3 to create a spiral, by specifying the end of the arc to be offset from where it should be.
Load this code into Mach3 and you'll see a spiral.

G40 G90
G91.1
S10000 M3
G0 Z0.1250
G0 X0.0000 Y-0.7400 Z0.1250
G1 X0.0000 Y0.1233 Z-0.1000 F75
G2 X0.0000 Y0.1233 Z-0.1000 I0.0000 J-0.1233 F100
G2 X0.0000 Y0.2467 Z-0.1000 I0.00 J-0.1233
G2 X0.0000 Y0.3700 Z-0.1000 I0.00 J-0.2467
G2 X0.0000 Y0.4933 Z-0.1000 I0.00 J-0.3700
G2 X0.0000 Y0.6167 Z-0.1000 I0.00 J-0.4933
G2 X0.0000 Y0.7400 Z-0.1000 I0.00 J-0.6167
G2 X0.0000 Y0.7400 Z-0.1000 I0.00 J-0.7400
G0 Z0.1250
G0 X0.0000 Y0.7500 Z0.1250
G1 X0.0000 Y0.7500 Z0.0000 F75
G2 X0.0000 Y0.7500 Z-0.1000 I0.0000 J-0.7500 F100
G2 X0.0000 Y0.7500 Z-0.1000 I0.0000 J-0.7500
G0 X0.0000 Y0.7500 Z0.1250
M30

Title: Re: cutting a spiral
Post by: chuck767 on September 16, 2018, 02:17:09 PM

 Thanks  Gerry,
That’s what I’m looking for I will give it a try.
Chuck

Title: Re: cutting a spiral
Post by: chuck767 on September 17, 2018, 11:09:52 AM

Worked great!!!
Did you do this manually or is there a program to create the code?
Chuck

Title: Re: cutting a spiral
Post by: ger21 on September 17, 2018, 11:25:09 AM

I use this AutoCAD macro that I wrote. It creates these "spirals" when pocketing circles.

http://www.thecncwoodworker.com/ac2gc.html

Title: Re: cutting a spiral
Post by: chuck767 on September 17, 2018, 11:49:13 AM

 Nice, I use solideorks.
 Maybe I can find a macro for it.

Title: Re: cutting a spiral
Post by: chuck767 on September 17, 2018, 03:22:02 PM

 As it turns out Brian wrote a wizard for cutting spirals in Mach3
Chuck

Title: Re: cutting a spiral
Post by: ger21 on September 17, 2018, 06:13:01 PM

Forgot all about that.

Title: Re: cutting a spiral
Post by: garyhlucas on September 18, 2018, 01:02:29 PM

CamBam does spirals too. I cut flange faces to mate to round tanks. I project the spiral onto a surface with the tank radius and spiral inwards from the outside edge. Very efficient tool path.