5 Axis Machinist What Is 3 Plus 2???
Category : 5 Axis
5 Axis Machinist What Is 3 Plus 2?
Here is a question. Does three plus two equal five?
“Of course it does you twat” I hear you say.
Well when you are talking about five axis machining three plus two does not make five. Sorry I’m starting to talk in riddles here.
Honestly I fuckin hate riddles, you know those stupid things you sometimes find on Facebook.
Before you know what’s happened you find yourself sucked in and actually trying to do the bloody things.
I mean maybe it beats the shit out of filling in your tax return but still a complete waste of brain power.
Three Plus Two as Opposed to Five
Anyway you have simultaneous five axis machining and you have three plus two. Lets deal with simultaneous five axis machining first.
This is all that clever shit you see on YouTube.
This is a SWARF cut Side Wall Axial Relief Feed (There’s one to impress your mates)
You really should get out more.
Anyway what you see above can only be done on a simultaneous five axis machine. This means that all the axis have to move together as if they were locked in a gear train.
5 Axis Machinist Three Plus Two
Now some machines have five axis but they can’t actually run the axis simultaneously. Now it’s not that they don’t have their shit together, it’s just that some mean bastard didn’t spend enough cash when they bought your machine.
Let’s get this clear they can all move together but they are not synchronized, kind of random. A bit like Strictly Come Dancing where they have some fat old celebrity that you know will get dumped after everybody’s took the piss out of them for a couple of weeks.
There are the normal XYZ boring axis, plus you have two more which are rotary axis.
Now the XYZ (three axis) are simultaneous, but the other two (known as the teenage axis because they do what the fuck they want and take no notice of anyone).
This means you can only send them to a position, lock them up and then do some machining.
In itself this is really, really useful because you can machine a part all in one setup. You just index the two rotary axis to each position.
This is probably the most common use of a five axis machine.
Types of Five Axis Machines
This is the machine above. It has a two rotary axis mounted on the table. The trunnion which is the big bit swinging from side to side and the round table that rotates on top it.
This is a head that swivels in two directions.
Sorry I haven’t got one of these to show you. This is where the head swivels and the table rotates.
When you are programming a five axis machine, which is usually on a CAM system, the CNC code is still the same no matter what configuration you have. (Head head, table table, head table)
5 Axis Machinist, Retro Fit
Retro, don’t even go there. What’s all this buying new stuff that looks like it’s old?
I mean if you are buying something new surely you want it to look new?
I mean how do you ever show off to the neighbors. They think you are buying second hand shit. Really, you just paid a small fortune for a fuckin TV that look’s forty years old before you even took it out of the box.
I mean do you get a warranty on this stuff? Or do they say “sorry mate it ran out in 1963”
Listen I remember some of this shit when it was new, it was crap then, so why would you want it now?
My mother used to have to beat the livin shit out of our telly just to make it change channels.
Let’s get back to some 5 axis stuff.
What I’m on about, before you side tracked me, is you can fit a fourth and fifth axis as an afterthought. You just nail them to your machine table and send out a few M codes and away you go.
They don’t actually do anything very exciting but you can do all the three plus two stuff shown above.
You can even pay out a kings’ ransom and get these fully simultaneous. Can’t say I would recommend that unless it’s a real high value machine you are going to keep forever.
Haas do some great add on 4th and 5th axis at a great price too (tell them David Garner said to buy them and I’ll get a massive commission).
It’s All Done With Smoke & Mirrors
Not really it’s just a shitty old M code.
Retro fitted axis can be fully interfaced with your control or the control can be made to output an M code to activate your axis.
Now the machine hasn’t got a clue what this M code does and it doesn’t give a flying shit. The machine just waits to get a reply saying it can carry on.
The 4th axis has a program and it will output a move each time it gets one of these signals from the machine. When it has done this move it will tell the machine to carry on by sending a signal back.
Why So Many 5 Axis Configurations
- Designers get bored
- Strength and rigidity.
- Weight. Imagine trying to swing round a massive engine block. It would be far better static on the table with the machine dancing around it.
Centre Of Rotation
I’m not going to go deep into this in this article. Mainly because I have to feed the cat and I’m having the name of my favorite celebrity tattooed on my arse later this afternoon.
I’ll be brief.
- It matters.
- It really matters
- It really really matters.
If the center of rotation on each axis is wrong then none of your positions will be correct.
With three plus two you can use a different work offset for each presentation. Each one can then be adjusted independently.
With simultaneous 5 axis you have to work around the centre of rotation. Fortunately if you have a touch probe a lot of machines have a built in routine to automatically set this using a ball bearing.
This is my video about all of the above, I saved it till last otherwise my lazy followers and the ones that can’t read, would just go straight to it.
5 Axis Machinist What Is 3 Plus 2?