Hi all,

I would like some advice on how you would program an 'incline off center' using a turning tool. When I first looked at the video I thought it could only have been done using some sort of software, but after looking at the spindle rotating it looks to me there is a definite synchronisation between the turning tool and spindle rotation that at first seemed easy enough to do which set off the challenger inside me to find out how to do it! On the link of the star video, it is described as 'helical interpolation turning', which I had never heard of before. it seemed easy but once I started to think how to do it I just confused myself silly!

(done on an St-38 star)

https://www.youtube.com/watch?v=r_LcY7Q8X0w - (done on an M32)


I've had ago myself at how I think the program/macro should look but would like someone who knows how or a better understanding of the principles of offset turning to have a look through my attempt first. this is would be a macro program to suit a star sliding head machine and wont do an off-centre taper like the videos. (haven't tried it on a machine)

T200 (OFFSET TURN)
M5
M8
G0 X32.75 Z-1.0 C0.0 T2
G1 X31.75 Z-0.4 F0.2

(INPUT THESE VARIABLES TO SUIT)

#100 = -0.4 (COUNTER) (Z START POSITION)
#101 = 10.0 (Z LENGTH REQUIRED)
#102 = 25.4 (OFFSET TURNED DIAMETER)
#103 = 5.0 (OFF-CENTER AMOUNT)
#104 = [#102 + #103] (HYPTOTHETICAL BAR DIAMETER)
#105 = 0.2 (INCREMENTAL Z MOVE)
#106 = 0.0 (OPTIONAL C-AXIS START POSITION)


G28 H0.0
G0 C#106
G50 C0.0

G1 G98 F400

G112 (POLAR ON)

WHILE [#100 LT #101] DO 1
G3 X-#102 C0.0 R[#102/2] W#105
G3 X#104 C0.0 R[#102/2] W#105
#100 = [#100 + [#105 + #105]] (CALCULATE CURRENT Z DISTANCE)
IF [#101 - #100] LE [#105 + #105] THEN #105 = [[#101-#100]/2] (CALCULATE FINAL PASSES)
END 1

(CLEAN FACE AT DEPTH REQUIRED)

G3 X-#102 C0.0 R[#102/2]
G3 X#104 C0.0 R[#102/2]

G113 (CANCEL POLAR)

G1
G0 X40.0
G97
T0
M1

am I on the right track or miles apart?


thanks in advice guys, any input will be greatly appreciated