Re: [CAD_CAM_EDM_DRO] Re: G76 format?

Hi Donald and Dave,

Here is the definition of G76.

G76P(m)(r)(a) Q(d min) R(d);
G76X_ Z_ R(i) P(k) Q(dd) F(l);

m = Number of finishing cuts
r = Chamfering amount
a = Angle of tool tip
d min = Minimum cutting depth (specified in radius value)
d = Finishing allowance (in radius value)

X = X axis destination
Z = Z axis destination
i = Taper value (in radius value)
k = Height of thread (in radius value)
dd= Depth of first cut (in radius value)
l = Lead of thread

For example:
G76 P010060 Q100 R200;
G76 X60.64 Z-25. P3680 Q1800 F6.;

This code cuts a thread with one finishing cut, no chamfer on the exit of
the tool, with a tool tip angle of 60deg. It will have a minimim depth of
cut of .1mm and will have a finishing allowance of .2mm. The minor diameter
of the thread is 60.64mm and it will cut a thread 25mm long in the Z minus
direction. The height of the thread is 3.68mm and the depth of the fist cut
is 1.8mm and the thread has a lead of 6mm. This thread is a straight thread
with no taper.
As a general rule of thumb, on a 1.5mm pitch thread I would have approx 12
passes to complete the thread with a full form insert and I run about 250
meters/minute cutting speed. At this speed I get VERY good tool life.

Hope this helps.

Regards
Andrew


-----Original Message-----
From: Donald Brock <don.pat.brock@...> <don.pat.brock@...>
To: CAD_CAM_EDM_DRO@yahoogroups.com <CAD_CAM_EDM_DRO@yahoogroups.com>
Date: Monday, December 30, 2002 8:46 AM
Subject: [CAD_CAM_EDM_DRO] Re: G76 format?

>Dave,
>
>I'd like to help with this also. I'll post another responce to this
>monday evening when I have my manuals/notebooks in hand. Let me know
>if you prefer a group or off line responce.
>
>I'm totally in favor of the fanuc method which does the g-76 (canned
>cycle) multipass threading (both tapered and straight)with a single
>line of code versus the the two line command canned cycle as used on
>the mitsubishi and others. They are basically the same just different
>methods of entering the varibles for the macros.
>
>I may have a print out of the mitsubishi g-76 macro somewhere. I'm in
>the middle of changing isp's so my e-mail address may not be valid if
>you try to respond off line.
>
>Donald Brock
>
>> Anyone know what the defacto-standard is for G76 canned cycle
>> threading these days? I'd like to implement this in my control,
>and
>> as you all know, we're not exactly short of variety in G codes.
>>
>> Thanks.
>>
>> Dave Kowalczyk
>> Everett WA
>> Author of TurboCNC --> http://www.dakeng.com/turbo.html
>
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