Owner's manual

Skip, Gauge, and Probing Cycles
Chapter 27
27-8
The purpose of this cycle is to provide a means to measure the actual
radius and/or locate the center of a hole in a part or gauge using a touch
probe.
To use the G38 cycle, the currently active plane when the G38 is
programmed must be the same plane that the hole to be measured is in (see
chapter 13 for information on plane selection). For example, to measure a
hole that is cut in the XY plane, t he G38 code must be programmed with
the XY plane active.
Format for the G38 code is as follows:
G38 H__ R__ D__ E__ F__;
Where : Is :
H
The estimated or expecteddiameterofthehole. T his parameteris optional. IfHis
notprogrammed,thecontrol will generatean H valuethatis equalto2(R+D),
where Ris the approach distanceand Disthetolerance band. Note thatifR+D
isgreaterthanone halfH,the control will ignore the programmed Hvalueand use
2(R+D) as the newexpected diameter.
R
The incrementalunsigned approach distance. Enter the distancefromthe
start -- pointoftheprobingcycle to apointthatitis desirable forthefeedratetobe
slowed. Atthis point,the feedrate will slow fromthe approach feedrate (E)tothe
probing feedrate(F). Thisparameterisoptional. Ifnotentered,thecontrol will
defaulttothe value entered in th e probing cycle parameter table discussed in
section 27.5.
D
The tolerance band distance. The value entered forD definesa bandon eachside
ofthe expected diameterenteredwith the Hparameter. Entera value defining a
tolerancedistance on eithersideofthe expected probe triggering point. This
parameterisoptional. Ifnotentered,thecontrolwilldefaultto thevalue enteredin
theprobing cycle parameter table discussed in section 27.5.
E
The approach feedrate. Entera value for thisparameterthatdefinesthe feedrate
atwhichthe probeistoapproachtheposition specifiedby the Rparameter. This
parameterisoptional. Ifnotentered,thecontrolwilldefaultto thevalue enteredin
theprobing cycle parameter table discussed in section 27.5.
F
The probe feedrate. Entera value for thisparameterthatdefinesthefeedrateat
whichtheprobeistomoveafterpassingthepointdefined bytheR parameter.
The probe continueson atthis feedrate untilcontacthasbeenmade withthe
diameterofthe holeoruntilthe toleranceband isexceeded. This parameter is
optional. Ifnotentered,thecontrolwilldefaultto thevalue enteredin the probing
cycle parametertablediscussed insection 27.5.
Parameters R, D, E, and F can be entered in three ways:
The system installer may have entered them in AMP, in which case they
will always be available a nd need not be programmed in the G38 block.
Refer to the documentation provided by your system installer.
They may be entered or changed through the probing parameters table
described in section 27.5. If entered in the table, they need not be
programmed in the G38 block. The table value will supersede a ny
values entered in AMP.
27.4
Hole Probing (G38)