Originally Posted by
protrxrptr17
I need to cut some 2"- 4.5 TPI thread on 1018, 6.5 inches long. I'll be using a high speed tool for the first one and when the brown truck comes I'll be using an insertable carbide tool. I have a Fanuc 6-T control. What G-code should I use? An example would be great. The manual says G92 is the canned cycle for threading, but I can't understand how to write it. I could use G28, but that would take forever to write. What RPM and depth per pass should I use for each tool? I have only cut threads with a manual lathe. What infeed angle will this machine use? Thanks for any help or suggestions.
G92 is a good Canned Cycle but you may want to use G76 instead.
G28 is a Home Position Return example home X and Z
G28U0W0
G92 goes like this. It is a little long because the Material was Inconel X750
G0G40G80G97G99M5
G28U0W0M9
G50S2000M41
M1
N1(THD .5 20 UNJF-3A KENNAMETAL)
T0707 S1000 M13
G0 X.75 Z.08
X.62
G92 X.496 W.22 F.05
X.49
X.484
X.479
X.474
X.469
X.464
X.46
X.456
X.452
X.449
X.447
X.445
X.443
X.442
X.441
X.44
X.4395
X.4395
X.439
X.439
G0 X.52 Z-.0167 S2500
G1 U-.12 W.06 F.0008
G0G40G97Z.1M9
G28U0W0T0700
M1
----------------------------------------------------
G76
X= the minor diameter of the thread
Z= the length of the thread plus deceleration distance
I= taper from start to end radially {Tapered NTP Threads}
K= depth of the thread = D major - D minor / 2] D [depth of the cut on the first pass
F(E)= the thread lead {F has 4 place decimal programming}{E has 6 place decimal programming} EX. F.0001 E.000001
A [the angle of the thread normally 30,55, or 60 degrees]
G00 will cancel both G76 and G92 Threading Cycles.
Here is a good rule of thumb. Take the same Depth of Cut with your CNC that wou would on an Engine Lathe. That is a Nasty Large Thread that you have to cut in 1018. Speeds are going to be relative to the Setup Rigidity. The Feed will be the Thread Lead so that can't be changed. The Lead on that thread is F.2222
I would use E.222222
1018 CR is gummy and tears. It is difficult to get a good finish without using Cermet Inserts like Seco Carboloy FF1's
Toby D.
"Imagination and Memory are but one thing, but for divers considerations have divers names"
Schwarzwald
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
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