CNC 4th Axis at work

**Lee Roberts** · 30-07-2009

Hey,

Just found this video of a 4th axis in action, i liked the design he was cutting and also think its a good example of what you could do if you went for a 4th axis !

Is anyone looking to add a 4th axis or ?

Lee

**BillTodd** · 30-07-2009

Is that a 4th axis or merely a rotary X or Y?

**John S** · 30-07-2009

Originally Posted by BillTodd

Is that a 4th axis or merely a rotary X or Y?

?????? Sorry can you explain the difference ?

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**BillTodd** · 30-07-2009

Originally Posted by John S

?????? Sorry can you explain the difference ?

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I was expecting to see 4 axes in motion.

**John S** · 30-07-2009

Here's one I did earlier :dance:

Ignore the dancing about, the X3 was on a transport stand ready to go to the 2006 Harrorgate show and the castors were not locked down.

This is another gear but instead of being done on a rotary table or 4th axis this one is just done in X, Y and Z fixed in a chuck bolted to the table.

The model came out of a CAD parts file off the web as an STL file, programmed in Vectric's Cut3D and cut with a 2mm ball nose cutter.
The video shows the final clean up pass in the opposite direction to remove some of the cutter marks.

It could have been a lot better if I had reduced to stepover but as I'd not done one before I didn't want to waste a lot of cutting time if it didn't work.

Never got round to doing a finer pass gear and some bastard nicked that one anyway [ probably Kip :whistling: ]

Spiral helicals are one of the hardest type of gear to cut and a one off can take well over a day to cut in a home shop.

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**BillTodd** · 30-07-2009

Originally Posted by Kip

Yup that's a 4th axis alright...didn't think much to the "action"....it was cutting fresh air!

When is a 4th axis not a 4th axis...now that is the question :D

When there's only 3 axes moving! (else I'll claim by engraver is a 9 axis machine - 'cos I've yet to build the other 6! )

[edit] Just remembered it has a unused 4th axis already so only 5 to build ;)

**tribbles** · 30-07-2009

Out of interest, is there a general thread for CNC videos?

**Lee Roberts** · 31-07-2009

Originally Posted by tribbles

Out of interest, is there a general thread for CNC videos?

No not as such, we do have a Video Gallery but it hasnt been used that much. I add video's as i find them, your more then welcome.

**adscnc** · 31-07-2009

On the subject of axis'sss whats the diference between 2.5d and 3d ?

**John S** · 31-07-2009

Rough difference.
2.5 D is where the Z axis drops to a predetermined depth and the shape is produced in X and Y whilst at this depth. X and Y can work together like doing a circle and it's called interpolation.

Typical example is doing a pocket down to 10mm deep in stages of 2mm at a time.

3D is where the Z axis is changing all the time as the X and Y are moving, imagine machining the aerofoil section on a plane wing.

Virtually all machines with a powered Z can do 2.5D and 3D, the difference is in the CAM software to generate the code.

2.5D is relatively cheap but full 3D starts to get very expensive.

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