Tap/Feed calculations

[Josh Kinney -Elite Engineering]

I have my post setup to double check the correct feeds/speeds are output for the tap. This works great for inch taps but metric I'm getting rounding errors.

 

Here's the post line

 

if n_tap_thds$ > 0,
     [
     if feed <> (speed/n_tap_thds$), [if mprint(stapfeed, 1) = 1, exitpost$] #Tap Feedrate check
     ]

 

So basically I convert my metric taps to inch in the tool definition.

 

M5x0.8

To get TPI I type into the field

0.8/25.4=0.031496(pitch)

1/0.031496=31.750064(TPI)

 

Now if I type 200RPM I get a feedrate of 6.3IPM

 

Now when the post does its calculation:

 

200/6.3=31.74603175

 

This alarms out.

 

How can I simplify this so it has a percentage or rounding effect in the equation?

 

Thanks,

 

Josh-

[K2csq7]

What's the format statement for "n_tap_thds$"

Not sure but if you format it to only 2 decimal places it might do the rounding for you....

Also,

I have never used it but I saw this in the V9 post ref guide...

fmtrnd

Formula Type Advanced Math Functions

Description Returns the rounded value of the argument. The format statement (fs)

for the variable is used for rounding. If no format assignment was

given, the format statement one (fs 1) is used. This does not modify the

internal state of the argument value.

Form function argument

Argument numeric variable, value (scalar)

Return Type numeric variable (scalar)

Formula Code Ex. real_result = fmtrnd(x)

Boolean Code Ex. if fmtrnd(x) <> prv_x, “CURRENT VALUE DOES NOT EQUAL PREVIOUS”

Notes Nested return values are stored internally to the post executable. This

formula is normally used to compare rounded values (updated variable)

to un-rounded values

 

The fmtrnd function may be what you are looking for.

 

HTH

[Josh Kinney -Elite Engineering]

I couldn't get this working, I'll have to come back to it later....