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Cylindrical Interpolation Guidance

Coadster32

Aluminum
Joined
May 4, 2011
Location
Milford, Ct
Hi all,

Having a bit of trouble wrapping my head around circular interpolation within cylindrical interpolation. I have scanned though the four pages of Practical Machinist posts on this subject here, and didn't quite see what I am looking for. I understand the yellow fanuc book version of it, but having a time getting it to do the same thing in inches instead of MM. For a 5mm quadrant radius, you move 5mm in C and Z axis respectively, and the R value would be 5. When I do this in inches, it doesn't come out proper. I've attached my program below for viewing. This is a Takisawa TS-4000YS lathe, Fanuc 32i control. Parameter 1022 C-is set at 5, and I call up G18. I've tried a circle, and a rectangle with radius corners. The feedrate all calculates out to be proper, so I would understand the C-value to be right in the G07.1 line. I get no errors, and the C and Z moves come out right. The radius' do not. I have tried increasing the value for C, but to no avail. The machine came with sample programs, but they are in MM as well, and those numbers don't quite seem to add up either. I'm hopeful someone else came across this as well, and it's a simple thing to get right.


O0444( CYLINDRICAL INTERPOLATION)
(1.750 ALUM STOCK)
G28U0V0A0(HOME ALL AXIS)
M141(COORD SYSTM#1)
M76(MILL MODE)
G00Z8.T0700(1/8 SNG FLT ENGRAVE TOOL)
(BTTM DBL-Y OD MILL BLCK)
G97S2500P12M71
G00X1.850Y0Z0C0.T08(START AT C0 ABOVE PART)
Z-.280
G98G01Z-.300F10.(FEEDRATE MODE)
G07.1C.875(CYLD INTERP ON--.875 RAD OF PART)

(ENGRAVE CIRCLE)
(FAILED ATTEMPT)
G01X1.740F3.
G18G3Z-.200C.100R.100
G3Z-.100C0R.100
G3Z-.200C-.100R.100
G3Z-.300C0R.100
GOTO1000(END PRG)


(ENGRAVE RECTANGLE SHAPE)
(FAILED ATTEMPT)
G01X1.740F3.
C20.
G03Z-.250C20.05R.05
G01Z-.150
G03Z-.100C20.R.05
G1C-20.
G03Z-.150C-20.05R.05
G1Z-.250
G03Z-.300C-20.R.050
G01C0
G01X1.760H10.(FADE OFF PART)

N1000G1X1.850F10.(ABOVE PART)
G07.1C0(CYLD INTERP CANCEL)
G00Z8.M72
G28U0V0
M30
%
 

angelw

Diamond
Joined
Sep 10, 2010
Location
Victoria Australia
Hello Coadster32
For starters, this Block in your program
G07.1C.875(CYLD INTERP ON--.875 RAD OF PART)

should be

G07.1 H8750(CYLD INTERP ON--.875 RAD OF PART)

Regards,

Bill
 

Coadster32

Aluminum
Joined
May 4, 2011
Location
Milford, Ct
I appreciate the reply. I finally got it figured out. I needed to convert the length of an arc to degrees of rotation. This is certainly not explained in the yellow facuc book. (They don't even mention the diameter of bar that they are using either). A train wreck for anyone getting their feet wet into this. I found the formulas pertaining to such, and all works as it should now.
 

angelw

Diamond
Joined
Sep 10, 2010
Location
Victoria Australia
I appreciate the reply. I finally got it figured out. I needed to convert the length of an arc to degrees of rotation. This is certainly not explained in the yellow facuc book. (They don't even mention the diameter of bar that they are using either). A train wreck for anyone getting their feet wet into this. I found the formulas pertaining to such, and all works as it should now.

Hello Coadster32,
In all Fanuc Manuals I've seen, the area pertaining to Cylindrical Interpolation does make reference to the diameter of the cylinder (bar size), by way of the cylinder radius that must be specified in the Cylindrical Interpolation Start Block. Following is a direct extract from a Fanuc Lathe Operators Manual showing the Syntax of the Start Block where "r" specifies the radius of the cylinder.

G07.1 IP r ; Starts the cylindrical interpolation mode
(enables cylindrical interpolation).

G07.1 IP 0 ; The cylindrical interpolation mode is cancelled.

IP : An address for the rotation axis
r : The radius of the cylinder

Specify G07.1 IP r ; and G07.1 IP 0; in separate blocks.
G107 can be used instead of G07.1.


In the example given in the same manual, an extract from which follows showing the Cylindrical Start Blocks, H57299 gives the radius of the cylinder as 57.299mm; a diameter of 114.590.

O0001 (CYLINDRICAL INTERPOLATION );
N01 G00 Z100.0 C0 ;
N02 G01 G18 W0 H0 ;
N03 G07.1 H57299 ;

Regards,

Bill
 

Coadster32

Aluminum
Joined
May 4, 2011
Location
Milford, Ct
Thank you for the replies Bill. I have read all of your responses to others in regards to Cylin. Interp. posts, and appreciate the help you have lent to others as well. Perhaps I should rephrase/restate what I meant about the Fanuc example.

Yes…I do agree with you that the C57299 callout does indeed mean the radius of the cylinder to be cut. The intent of the cylinder cut seems to be very vague. (I feel that a more defined blueprint with dimensions would have been a little more helpful). They map it out for you, but without a print, it quickly becomes misleading. The example lends itself to get you thinking that a quadrant of a radius, (90deg), would be the same value in C motion, as in Z motion. This is simply not true, (unless specified on the blueprint, which is not supplied). You need to convert the mapping from linear motion, to arc degrees of motion for the C-axis. Is it pure coincidence that the diameter happens to be the almost exact calculation as a Radiant? This may lend itself to being accurate in regards to 30MM motion in both axis’ to be true, but I didn’t calculate that out.
 








 
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