Lathe ID taper

Here is a sub based on John Thorton's lathe id.
This untested sub should allow you to cut an inside diameter taper on the lathe.
It assumes you...
Have an existing undersze bore.
You know the depth of the taper and the difference between the large and the small diameter of the taper, and you have checked to make sure there is adequate tool clearance.

Rick G

Here is an updated id taper sub for the lathe.
It works when you have an existing hole and you want to taper to a larger diameter and know the final diameter and the depth.
It uses a different method to calculate each pass to avoid excess Z air cutting movements.
Again not tested yet, only on a sim.

Rick G

Interesting.

In this case I was working on a custom throttle body bore that needed a taper, I had the small diameter, the length and the large diameter.
What I wanted to avoid was excess Z moves cutting air part of the moves.
Below is a screen shot of two examples, on the left is the way I was cutting with full Z moves, on the right the newer sub.
The left took about 3 1/4 minutes the right 2 1/4 minutes at the same F4 cutting speed.

I can see the benefit and advantage of having different subs for tapers, ones that accept dimensions and ones that accept angles.

Rick G

Morning John,

Looking at your od taper sub would your id taper look something like this?

(info: Taper OD, multi-pass)
o<taper-ida> sub
;#<diameter> = #1 (= 0.750 Stock Dia)
#<diameter> = #1 (= 0.750 Hole diam)
#<final-depth> = #2 (= 0.120 Taper Depth)
#<doc> = #3 (= 0.025 Depth of Cut)
#<angle> = #4 (= 45 Angle of Taper)
#<z-start> = #5 (= 0.000 Z Start)
#<feed> = #6 (= 2 Feed Rate)
#<tool> = #7 (= 1 Tool Number)
#<max-rpm> = #8 (= 2000 Max RPM)
#<sfm> = #9 (= 100 SFM)
#<coolant> = #10 (= 8 Flood=8, Off=9)

G7 G18 G40 G54 F#<feed>
G96 D#<max-rpm> S#<sfm>
T#<tool> M6 G43
G42 (start cutter comp)
M3 M#<coolant>
#<current-depth> = 0
o100 while [#<current-depth> LT #<final-depth>]
o110 if [[#<current-depth> + #<doc>]LT #<final-depth>]
#<current-depth> = [#<current-depth> + #<doc>]
o110 else
#<current-depth> = #<final-depth>
o110 endif
#<current-x> = [#<diameter> + [#<current-depth> * 2]]
G0 X#<current-x> Z[#<z-start> + .01]
G1 Z[#<z-start>]
;G1 X#<diameter> Z[#<z-start> + [#<current-depth> * TAN[90 - #<angle>]]]
G1 X#<diameter> Z[#<z-start> + [#<current-depth> * TAN[90 + #<angle>]]]
G1 X[#<diameter> - 0.01]
G0 Z[#<z-start> + .01]
o100 endwhile

M5 M9
G0 Z[#<z-start> + .1]
G40 G97
;G53 G0 X0.000 Z0.000

o<taper-ida> endsub

John,

That is pretty cool, I will add that to my sub directory if I need to work from the angle of the taper instead of the dimensions.

As I park my lathe at the tailstock end I need to comment out the ending G53 G0 move to avoid surprises.

Rick G