o<bore> sub
	; x, y, d, stepdown, zstart, zend
	G90
	G91.1

	G0 X#1 Y#2
	G0 Z#4
	G1 X[#1+#3/2-#<_td>/2] Y[#2]
	G17

	#<r> = [#3/2-#<_td>/2]

	#<z> = [#4-#6]
	o101 while [#<z> GT #5]
		G3 X[#1+#<r>] Y[#2] I[-#<r>] Z[#<z>] P1
		#<z> = [#<z> - #6]
	o101 endwhile

	o102 if [#4 GT #5]

		#<ang> = [[#<z>-#5]/#6*360]
		G3 X[#1+COS[#<ang>]*#<r>] Y[#2+SIN[#<ang>]*#<r>] I[-#<r>] Z[#5]
		G3 X[#1+COS[#<ang>]*#<r>] Y[#2+SIN[#<ang>]*#<r>] I[-COS[#<ang>]*#<r>] J[-SIN[#<ang>]*#<r>] Z[#5]

		;G3 X#1 Y[#2+#3/2-#<_td>/2] J[-#3/2+#<_td>/2]
	o102 endif

	G0 X#1 Y#2
	G0 Z0

o<bore> endsub

M2