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Author Topic: G76 threading cycle bug ?  (Read 3597 times)

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G76 threading cycle bug ?
« on: March 05, 2017, 05:43:58 PM »
Hi to all
i'm new to mach4 hobby, but i have a strange thing about..

when i try to make a g76 threading cycle (using canned cycle wizard), and i try to set the K parameter to "0", mach4 give me an error .. k value is invalid
If i try to set K from 1 to 4 mach accept this, but the manual report:

Quote
Kā€“Cutting method
K = 0: Flank in-feed constant volume removal for each pass
K = 1: Alternate flank in-feed constant volume removal for each pass
K = 2: Flank in-feed constant depth removal for each pass (each pass same as first pass)
K = 3: Alternate flank in-feed constant depth removal for each pass (each pass same as first pass)

can someone try this and report me ?
Is a bug ?

Bye

Axel
Re: G76 threading cycle bug ?
« Reply #1 on: March 05, 2017, 08:49:08 PM »
I get the same error but I can not get my machine to do any threading G76 or G32 sorry I can not be any heip
Re: G76 threading cycle bug ?
« Reply #2 on: March 06, 2017, 03:16:36 AM »
Hi !
Many thanks wwente for your test..
If you have the same problem then it could be a MACH4 problem/bug ...

Now.. someone who uses the threading function can tell me if the "0" value of the manual corresponds to "1" , "1" to "2" ..... and "3" to "4"
(every value is shifted to 1 ?)

Can someone confirm ?

Offline smurph

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Re: G76 threading cycle bug ?
« Reply #3 on: March 06, 2017, 06:59:47 PM »
Please see the G76 documentation in the Lathe user's manual.  The K word (for 2 block style G76) takes 1 to 4.  The canned cycle wizard is most likely labeled wrong. 

Steve
Re: G76 threading cycle bug ?
« Reply #4 on: March 07, 2017, 03:41:51 AM »
Hi Steve..
excuse me, but i have read the lathe manual..
This :
http://www.machsupport.com/wp-content/uploads/2014/05/Lathe%20GCode%20Programming.pdf

And at page 29/30 i can read:

Quote
K: Infeed type. There are 4 possible infeed selections, 0 to 3. The 4 options are combinations of
two infeed types and two depth of cut types. The two infeed types are flank and alternate flank,
see figure 76-1. In the flank infeed mode each depth of cut moves down at the angle for the
thread, following the trailing flank of the tool. Alternate flank changes from leading to trailing
flank for each pass. The two depth of cut types are constant volume and constant depth. In
constant volume the depth of cut will get smaller (down to the minimum specified by Q) for
each pass to maintain a constant volume of material being removed. This is usually better for
tool life and thread quality. Constant depth is just that. Each depth of cut is the same down to
the finish allowance.
o 0 constant volume flank infeed
o 1 constant volume alternate flank infeed
o 2 constant depth flank infeed
o 3 constant depth alternate flank infeed.
[...]

What is the manual do you refer ?
Can you give me the link ?

Many thanks..
Re: G76 threading cycle bug ?
« Reply #5 on: March 07, 2017, 09:55:21 AM »
Under mach4hobby/docs there is a lathe GCode programming pdf automatically installed with mach4.  Your looking at mach3 turn manual.

Additionally with the Mach4 threading wizard you need to select the infeed each time you use it or you will get a 0 for the K value.

HTH

RT
Re: G76 threading cycle bug ?
« Reply #6 on: July 22, 2018, 08:03:09 AM »
http://www.hdknowledge.com/2018/07/g76-fanuc-threading-cycle-cnc-program-with-description.html
N10 M06 T01 01 ;
N20 M04 G97 S1000 ;
N30 G00 X45 Z5 ;
N40 G76 P020060 Q100 R50 ;
N50 G76 X38.7 Z-50 P1227 Q100 F2 ;
N60 G00 X45 Z5 ;
N70 M05 M09 M30 ;

DESCRIPTION OF MAIN PROGRAM :-

N10- Tool change command , select tool no. 1
N20- Spindle ON anti clockwise , constant spindle speed command , speed is 1000 rpm
N30- Rapid action command where X45 and Z5 .
N40- Threading cycle command , P020060
                                                    ( P02 = No. of finished path
                                                     00  = Chamfer amount at end
                                                     60 = Angle of tool tip ) ,
                                                     Q100 = Each cut is 0.1 mm ,
                                                      R20 = finishing allowance 0.02mm
N50- Threading cycle command , Minor dia X axis , threading along Z- axis up to -50 , Threading depth , Depth of finish cut 0.1 mm , pitch is 2 .

: M40X2   

Major diameter is 40
Pitch is 2
Thread depth calculation = Pitch x 0.61363
                                       =  2 x 0.61363
                                               =  1.227 mm in micron is 1227
       
Minor diameter =  40-1.23 = 38.7  mm       
                                             
N60- Rapid action command where X45 and Z5 .
N70- Spindle off , coolant off , main program end .


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