o<helical_plunge> sub
	; o<helical_plunge> call [x][y] [diameter] [zs][ze] [mode]
	;                        [1][2]    [3]     [4] [5]   [6]

	#<M_CONVENTIONAL> = [FIX[#9/1] MOD 2 EQ 1]
	#<M_BOTHWAYS>     = [FIX[#9/2] MOD 2 EQ 1]
	#<M_PLUNGE>       = [FIX[#9/4] MOD 2 EQ 1]
	#<M_OUTSIDE>      = [FIX[#9/8] MOD 2 EQ 1]
	#<M_CLIMB>        = [FIX[#9/1] MOD 2 EQ 0]
	#<M_ONEWAY>       = [FIX[#9/2] MOD 2 EQ 0]
	#<M_HELIX>        = [FIX[#9/4] MOD 2 EQ 0]
	#<M_INSIDE>       = [FIX[#9/8] MOD 2 EQ 0]

	G90	  ; absolute x,y,z
	G90.1 ; absolute i,j,k
	M101  ; enable Z-axis (M102 disables)
	G17   ; select XY plane for arcs

	#<td> = #5410
	o1 if [EXISTS[#<_z_clearance>]]
		#<z_clearance> = #<_z_clearance>
	o1 else
		#<z_clearance> = #4
	o1 endif
	o2 if [EXISTS[#<_rampang>]]
		#<rampang> = #<_rampang>
	o2 else
		#<rampang> = 5 ; degrees
	o2 endif
	o3 if [EXISTS[#<_stepover>]]
		#<stepover> = #<_stepover>
	o3 else
		#<stepover> = [#<td>*0.4]
	o3 endif

	#<r> = [#<td>*0.3]
	o115 if [[[#3-#<td>]/2] LE #<r>]
		#<r> = [[[#3-#<td>]/2]*0.8]
	o115 endif

	#<z_step>  = [#<r>*2*3.14*TAN[#<rampang>]]

	G0 Z#<z_clearance>

	#<z_total> = [#4-#5]
	#<turns>   = [#<z_total>/#<z_step>] ; subtract off an epsilon fixes some things...

	#<a> = [[#<turns> MOD 1.0]*360]

	o103 if [#<M_CLIMB>]
		G0 X[#1+COS[-#<a>]*#<r>] Y[#2+SIN[-#<a>]*#<r>]
		G0 Z#4
		G3 X[#1+#<r>] Y[#2] I[#1] J[#2] Z[#5] P[FUP[#<turns>]]

	o103 else
		G0 X[#1+COS[-#<a>]*#<r>] Y[#2-SIN[-#<a>]*#<r>]
		G0 Z#4
		G2 X[#1+#<r>] Y[#2] I[#1] J[#2] Z[#5] P[FUP[#<turns>]]
		
	o103 endif

o<helical_plunge> endsub