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On most machines (lathes, typically) the G76 is a compound infeed angle threading cycle, not a boring cycle.......................
............................That's my explanation for G76, there will be other opinions.
he is quite particular about details
Hello Cuda:
That is a really unusual way to do multiple threads, in fact, I have never seen it before.
What control do you have on the Mori?
The normal way to do a 2 lead multiple lead thread is to move the startpoint back in Z by 1 lead and then repeat the G76.
Heinz.
www.doccnc.com
WOW that part looks just like a part that we make here in our shop.
Except that the Larger diameter behind the large nose sticking out forward, gets a Bolt Circle drilled into it with large counter bores.
But its nice looking either way.
This is just another explanation of the cycle. Maybe it'll help...
A copy n paste from my manual.
G76 – THREADING CYCLE – TWO LINE FORMAT*(FS 0,16,18,21T,31i,32i, -FORMAT)
(Applicable with Fanuc Controls, T series, systems 0,16,18,21,31i,32i.
Also: Mitsubishi 500L, 50, 64)
FIRST COMMAND LINE:
G76 P021060 Q05 R10 (See detailed explanation, below)
P 02 10 60 Specify “P”, followed by a six digit number. Translation is shown, here:
02 =Number of finish passes at the bottom of the thread (02 means 2 Passes) (Sets PAR 5142– see note 1)
10 =Chamfer-width or pullout-width at the “Z” end position of the thread. Chamfer size is expressed in1/10th fractions of the lead.
10: means the chamfer-width equals one lead.
05: means the chamfer width equals ½ of lead.
00: means no chamfer.*See note 3, below.(Sets PAR 5130)
60 =The included angle between the thread flanks. ½ of the angle as
Specified is applied for the in-feed angle. Normally, 60°*is used for standard threads.
Other angles, such as: 80°, 60°, 55°, 30°, 29°or 0°*can be specified (Sets PAR 5143)
Q05 =Minimum cutting depth (depth of cut becomes progressively smaller, after each pass.
Remainder, smaller than “Q” is discarded (Sets PAR 5140).
R10 =Material allowance for finishing passes at bottom of thread (Sets PAR 5141)
SECOND COMMAND LINE:
G76 X__ Z__ P100 Q200 R300 F0.038461 (See detailed explanation, below)
X =Diameter of the thread. For an external Thread – specify the minor diameter.
For an internal Thread - specify the major diameter.
In case of taper threads, specify the diameter at the opposite end from the start point.
Z =End position of the thread.
P =Height of the thread. Calculation: Major diameter minus minor diameter, divided by 2
(Radius value, without decimal point) See note 2, below.
Q =Depth of the first cut. If “P” and “Q” are the same, then the
Thread is `cut in a single pass. (Radius value without decimal point) See note 2, below
R =Taper. (Radial height difference of taper slope, per side)
Specify a negative value for OD taper thread.
Specify a positive value for ID taper thread.
F = Lead: distance between two threads. (1 divided by the pitch), six digits allowed after the decimal point.
NOTES:
1.) Upon execution of the G76-cycle all data contained on the first
G76-command line is automatically stored in the parameter tables.
2.) Values for “P” and “Q” to be specified without decimal point for all Fanuc Controls.
For example:
0.0001” =1
0.001”** =10
0.01”**** =100
0.1”****** =1000
1.0”****** =10000
3.) Specifying a chamfer (pullout distance) reduces possible damage to the last thread lead near the Z-end position.
*
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