CNC Machinist Calculator UltraG87 Back boring cycle / Side drilling cycle, live tool
Fanuc G-code · Mill, Lathe
On mills: Back boring cycle
Orients the spindle, shifts off center by Q, rapids down through the hole to R below the part, shifts back, and feeds up to Z to bore the back side. Then orients, shifts and rapids out.
Format
Addresses
| Address | What it does |
|---|---|
X Y | Hole position |
Z | Top of the back bore, end of the upward feed |
R | Start point below the part, bottom of the cycle |
Q | Shift amount, always positive |
P | Dwell at top, milliseconds |
F | Feed rate |
K | Number of repeats |
How it works
Modal, group 09. Cancel with G80 or any group 01 code. Only G98 return is allowed.
Example program
G90 G54 G00 X2. Y1.5 S800 M03 (HOLE CENTER)
G43 H09 Z1. M08 (CLEARANCE)
G98 G87 Z-.75 R-1.1 Q.1 F4. (BACK BORE FROM Z-1.1 UP TO Z-.75)
…
The full 5-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- R is below Z in this cycle. Check the values twice.
- The shift direction is a parameter, same as G76. The bar must pass through the hole with the shift applied.
- Use G98. The tool cannot return to R because R is under the part.
On lathes: Side drilling cycle, live tool
Drills along X into the side of the part with a radial live tool. Q gives peck drilling.
Verify on your machine. This entry could not be fully checked against the maker manual. Check your machine manual before you run it.
Format
Addresses
| Address | What it does |
|---|---|
Z C | Hole position along the part and angle |
X | Hole bottom as a diameter |
R | R point |
Q | Peck depth, no decimal point |
P | Dwell at the bottom |
F | Feed |
K | Repeat count |
How it works
Modal, group 10. Cancel with G80.
Example program
G98 (FEED PER MINUTE)
G00 Z-.5 C0 X2.2 M08 (FIRST HOLE)
G87 X1.2 R-.1 Q1000 F5. (PECK .1 TO 1.2 DIA)
…
The full 6-line example is in the app. Example is in inch. Check offsets and clearances first.
Watch out for
- X is a diameter, so the hole bottom is the diameter at the hole bottom.
- R is often the distance from the start point to the R point, not an absolute Z. Check on your machine.
- Cancel with G80 when done.
Related codes
G87 on other controls
The same number can mean something different on another control.
| Control | Meaning |
|---|---|
| Haas NGC | Boring cycle, stop and manual retract |
| Mazak (EIA) | Side drilling cycle, live tool |
| Okuma OSP | Back boring cycle |
| Mitsubishi M70 M80 | Back boring cycle |
| Brother Speedio | Back boring cycle |
| Fagor 8055 8065 | Rectangular pocket canned cycle |
| LinuxCNC Tormach | Back boring cycle, not implemented |
| Mach3 Mach4 | Back boring |
| Hurco WinMax (NC) | Back bore (ISNC) or chip breaker (BNC) |
| Fadal | Bore in and out, Fadal G87 |
| Swiss (Citizen Star) | Side drilling cycle |
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