New video about the G71 roughing cycle on a Haas or a Fanuc control, also covers the G70 finishing cycle.
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G71 is sometimes known as a canned cycle when in fact it is a multi repetitive cycle. The G70 cycle goes with it and can pick up the same lines to finish.
The N numbers are important as the cycle uses these as the points of reference to jump to.
G71 cycle interprets the shape between these two N numbers and then breaks up the shape for roughing.
CNC lathe tool nose radius compensation, I think that sometimes in life we get off to a bad start with things. I know when I was at school I was convinced that I was useless at French, Physics and all sports.
I just got off to a bad start.
Getting stabbed with a javelin in the foot did not enthuse me with regards to sporting activities.
Oh and two of my close friends wanted to see if passing a high voltage though my body would give me special strengths a bit like Frankenstein. Needless to say it didn’t work and to this day I can’t watch those films.
So when you have a bad experience with something it just puts you off.
Maybe when you first tried to use G41 and G42 you got loads of ALARMS. Not to mention that nasty rash that you needed a three month course of antibiotics to clear.
We often find ways around our lack of knowledge or whatever.
I know when I was in France my mate always spoke English in a kind of French accent thinking they would know what he was on about. He would put an “a” at the end of each word.
He would say “doa youa knowa thea timea” and they would say “Va te faire foutre”
Here is the video (DON’T YOU DARE WATCH IT YET)
Sorry about the long intro but I have a record to sell as well.
If you liked this video, please don’t forget to subscribe to my YouTube channel by going to:CNC Training Centre
Anyway, Tool Nose Radius Compensation.
People find ways of programming without tool nose radius compensation.
It surprises me when people don’t use it and it is usually because they don’t understand the very simple rules.
Rules CNC Lathe tool nose radius Compensation
The daftest one being, don’t ask it to do the impossible.
So if you are machining a diameter of say 40mm and you move to a bigger diameter 40.5
If your tip radius is 0.8 the machine would alarms out.
You swear at the machine but unfortunately it’s you that’s being a prick. You can’t fit a .8 radius in that gap.
The same thing applies if you machine around a radius that is smaller than the tip radius.
The other common fault is knowing when and where to apply it. (A bit like lip gloss.)
Your shape needs to be one continuous path that does not go back on itself.
No reverse gear.
I always say “use it and get rid of it”.
You can’t just move on to another shape.
You need to cancel and then re apply.
If you don’t use compensation your parts are not really correct because you are frigging the figures. You naughty naughty boy.
CNC Lathe Tool Nose Radius Compensation
The other big problem is if you need to change the tip radius and you didn’t use tool nose radius compensation you would have to change the program.
Your program and part will simply be wrong without tool nose radius compensation that is unless you are only machining orthogonal lines. (Some of my readers will need to goggle that)
If your CAD system is not outputting tool nose radius compensation or cutter compensation in milling then you need to look at your post processor.
If you can’t do it get your software provider to help. Believe me they can all output this if they are set up correctly.
If you liked this video, please don’t forget to subscribe to my YouTube channel by going to:CNC Training Centre
This is a video explaining cutter compensation in CNC programming.
You will come across various terms to describe this such as:
Tool cutter comp.
CNC cutter comp.
G41 G42 cutter compensation.
Cutter diameter compensation.
Cutter radius compensation.
Heidenhain RL RR.
Cutter compensation is referred to as cutter diameter compensation and cutter radius compensation
Haas cutter compensation, Fanuc cutter compensation and Mazak cutter compensation all work in the same way.
Although Heidenhain cutter compensation or Heidenhain cutter comp looks different. In the programme it functions in exactly the same way.
In the parameters or settings of your control you can set up your system to use the radius or the diameter of your cutting tool.
This means that when you input the data for your cutting tool in your offset table you can use the diameter or the radius of the tool. This depends on your settings.
When people talk about cutter compensation G code they may say “cutter comp G code” it’s often shortened.
(Cutter compensation G code)
The G codes used in this video are:
G41 cutter compensation left
G42 cutter compensation right
G40 G code to cancel cutter compensation
This Video shows you :
How to program G41.
How to program G42.
CNC cutter compensation examples.
Cutter compensation Heidenhain style.
Heidenhain RL RR.
We always recommend that you climb mill so you will be using G41 most of the time.
Milling the outside of a square using G41.
Milling the inside of a square using G41.
Milling the inside of a square using G42 (should you want to conventional mill).
Milling the outside of a square using G42 (should you want to conventional mill)
The rules when using compensation on a CNC Milling machine.
This is simple on a square sided figure or a simple radius. Anything more complex and it’s a nightmare.
I just heard some smart arse say “Ah well my CAD system takes care of that”.
So it should my friend but, and there is a but:
What will you do when your cutter wears?
What if you want to use a different size cutter?
The cutter may not run true.
What if the cutter is not exactly size?
In the old days of paper tape and Corned Beef we as programmers would write several programmes.
This was so that we could re-grind the milling cutters in fixed increments. A different programme could be used each time the tool was changed.
Sorry I can’t talk about this much longer as I still have the nightmares (mainly about corned beef sandwiches).
Anyway enough of that. So when we machine our first profile we can add some on to the tool radius in the offset file. When we check the part we can adjust the offset and re-cut the profile to achieve an accurate result.
The Rules:
Shape must be continuous and consistent.
You can’t cut along a line and then go back along it.
It’s important to allow more than the tool radius when entering tool compensation. The same applies when you come out of tool compensation.
Internal corner radii and steps must be greater than the tool radius.
Always allow more than the radius because when you adjust it it may be larger than the actual tool you are using.
Don’t ask
For example if you have a 12mm endmill but you have .2mm in the wear compensation. The machine thinks that the tool is 12.4mm in diameter.
You can’t do this in cutter comp:
You would have to apply one cut in G41 and cancel with G40 then do another cut in G42 and cancel with G40:
