Siemens CNC Mixing MM with Inches

Siemens CNC Inches and Millimeters (Do you switch?)

CNC Training Call David: 07834 858 407

30 five star ratings on Google (Just saying)

I remember a long time ago we used to run metric programs and imperial (inch programs). So if the drawing was in inches then that’s how we programmed it. Seemed like a good idea at the time no converting figures and no need for writing on drawings.

You had an inch drawing, inch micrometer so why not have a program that’s in inches too?

One day someone (not me, honest) changed an X figure by 1 inch thinking it was a 1 mm.

The difference between one inch and 1 mm is what we call a country mile or a shit load. Anyway the part flew out the chuck on the impact of hitting the tool.

G20 was assigned to our history book. Oh and the boss shoved the broken tool up my arse.

I often work in Scotland where there are a lot of engineering companies specialising in Oil and Gas type work. As a result most of them work exclusively in inches. To be honest to me it’s a pain in the arse and I never quite get used to it. Although when I did my apprenticeship at Rolls Royce in 1971 things were just changing over so in theory I should have a brain measured in inches (it wouldn’t be many by the way).

Metrification (it’s not a new sexual identity)

I need to be careful here, because I’m now at that age where you can bang on for hours about all this kind of innocuous shit (it’s what old men do apart from pissing themselves if there’s not a toilet nearby).

If You Must

To change to inches on a Fanuc control select MDI and go to your setting screen, press the offset/settings button.

Just change from 0 to 1.

Shut your machine off and back on again then zero return it if required. Everything will change to inches (you’ll now have four decimal places)

Siemens Program Training Cool Siemens Stuff

CNC Training Call David: 07834 858 407

This Article is About TOFFR

TOFFR….  No it’s not some kind of vegan substitute for cheese.

It’s a programming command on a Siemens 828 or 840 Sinumerik Control.

Now everyone who reads this crap knows that I usually start the articles about Siemens Program Training by saying how versatile they are.

Well today I’m not going to. Instead I’m going to show you a picture of the fly I bought from a local pet shop.

Her name is Tinkerbell.

“I want to buy a pet fly” I asked. “We don’t sell them” said the shopkeeper.

“Well there are quite a few in the window” was my reply.

I then forced him to sell me one for £25 (that taught him a lesson, I think he was afraid I’d call in trading standards)

Siemens Programme Training TOFFR

I could talk about Tinkerbell all day, but I’m not going to, Iv’e written this amazing article all about TOFFR it’s the Siemens vegan option.

Let’s imagine you want to machine around the outside of a shape. You want to rough it and leave material on. So what do you do?

Two Programs?

Do you have two programs one bigger shape for roughing and one that is the correct finished shape?

No you use TOFFR

What TOFFR does is modify you tool radius in your offset file.

Firstly you add some to it.

TOFFR=1. (Add 1mm)

Run your program which will leave 1mm on the size.

Then…

TOFFR=0 (Sets it back to it’s original amount)

Run your program again this time the tool is back to it’s correct radius and will therefore finish the part.

Take a look at the code below.

WORKPIECE(,””,,”BOX”,48,0,10,-80,-52,-52,52,52)
G40 G94 G64 G90

T=”CUTTER 12″
M6
D01
G54 G94

G0 X58. Y0 S1500 M3

Z-10.5
M8

TOFFR=1.;Add 1mm to radius

SHAPE:
G1 G41 X48.Y0 F1500.
Y-48.RND=10.
X-48.RND=10.
Y48.RND=10
X48.RND=10.
Y0
G40 X58. Y0
ENDLABEL:

TOFFR=0;Reset Radius

REPEAT SHAPE

G0 Z50
M17

Let me explain what’s going on here.

This line:

TOFFR=1.;Add 1mm to radius

Will add 1mm to the active tool radius so you mill around the part leaving 1mm of extra material.

Then this line:

TOFFR=0;Reset Radius

Takes the 1mm back off so when you repeat the section of code with this line.

REPEAT SHAPE

It finishes the shape.

Here is a nice video I made.

Oh and if you want to know about repeating sections of program  and subprograms read this.

Thanks

If you feel you have been affected by any of the issues raised in this post or need CNC Counselling then contact me.

If you want to learn to program CNC Milling Machines

Siemens 840D Sinumerik training

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