# What is this mysterious 4th axis?



## joe_m (Sep 17, 2012)

I was surfing for tool-porn today and while drooling over 250K CNC lathes the size of an 18-wheeler (I can put one in the living room if I move the couch just a skosh) I saw an ad for 4-axis CNC router, which kind of threw me for a loop.

If the X-Axis is left-right, and the Y axis is front-back, and the Z-axis is Up/down, what is left for the fourth axis? 

And just for grins, I then googled 5-axis cnc and it seems that they exist too. Huh?? Where are these additional dimensional planes coming from?

Joe


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## DMS (Sep 17, 2012)

Usually (not always) axes in excess of 3 are rotational axes. For a router I suppose it would let you do columns, kinda like this:

[video=youtube_share;HTBex99IFQ0]http://youtu.be/HTBex99IFQ0[/video]

As far as 5 axis on a router.. not sure what you would do with that.


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## Tom Griffin (Sep 17, 2012)

Hey Joe,

A fourth axis will allow you to rotate the work. Additional axes will allow you to rotate the axis of the tool and keep it perpendicular to a curved surface. Machines with five axes or more are used in mold work for milling complex three dimensional surfaces.

Tom


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## Tony Wells (Sep 17, 2012)

Normally, the X axis represents the diameter of the work, the Z axis represents the work, or depth. The B axis usually is the rotational axis of the main spindle. On a mill, it's akin to what is called the 4th axis. There can be many more axis designations, depending on what other equipment the machining center has. If there is live tooling on one or more turrets, they have independent movement and receive axis designations. I've watched a 7 axis Emco, and it is quite impressive. The axis count is run up more when there is a sub-spindle where the regular tailstock would be. The part can be handed off from the main chuck or collet for finishing the other end, all while primary operations continue. It takes sophisticated software, and pretty sharp programmers to get the most out of multi-axis machines, but they are very impressive when they are running right.

One of the coolest, but really the simplest operations was one that turned a hex on a small diameter part _while spinning at 3000 RPM_. The mill cutter in a live station on the turret was timed so that the inserts swept the hex as it whizzed by. The guys we sent to school on the programming software all got to make themselves a stainless pen, complete with cap. I got to see part of how it was done. The hex pen won't roll off your desk at least!


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## jumps4 (Sep 18, 2012)

it's as simple as placing a rotary index or rotary table on your mill thats the 4th axis a 5th could be placing that rotary table on a trunion table. a sixth could be rotating the head left or right and a seventh....
http://www.bing.com/videos/search?q...B2696A20BC0C04D82DFEB2696A20BC0C0&first=0hope 
they are really fun to watch making turbine impellers and such. but like tony was saying it is probably a team of people writing the software. every micron of motion is calculated for jet engine parts
steve


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## Bill Gruby (Sep 18, 2012)

If you got bogged down with the 4th axis this will be mind blowing for you.

 "Billy G"

http://www.youtube.com/watch?v=LzJHPWimizg


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## Mid Day Machining (Sep 22, 2012)

Here's some 6 or 7 axis machining for you.

http://www.youtube.com/watch?v=kddPuLSaOjQ

And then here's a machine everyone should have in his living room, right next to the TV.

http://www.youtube.com/watch?v=AV6m5_DZ-tk


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