Using my 4 axis for wood turning.

#1
I have a manufacturing company where we make wooden handles for our swords.

Over the last year I have been experimenting with using the 4 axis mill (Bridgeport, full servo all custom controls with Mach3)

The 4th axis on this machine was built from a 5C indexer on a hand built chassis (not by me). It is a pretty nice thing for homemade.

The quill is locked on this machine and the Z axis is the knee feed, rebuilt with the main ball screw from a fadal.

On the programs I am using right now the A axis is set up as 80" of motion equals 360 deg. No idea why he set it up like this. I will change it in the future but I wanted anyone ready to make better sense if I post a program.

This work is pretty simple. I use a wood lathe drive in the a axis and a copper insert in the wood because I have a dead center for a tail stock.

These are all turned on a 1/4 center hole which we then later burn the internal form with a red hot master.

I am using the Bridgeport spindle with a BT30 collet holder. My max rpm is 5000 so there is a little tearing in the wood. We do a bit of sanding and fitting by hand but these give us very good starting forms.

Most of the work is 6" long

Im not much of a programer. Im just hand coding this stuff in the G-code as I go.
 

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#3
Swords look great! What kind of a cutter are you using? End mill? Fly cutter? It would seem that if the end mill were big enough, and sharp, that your SFM at 5000 RPM would be great enough to avoid tearing. I've done some milling at 2000 RPM, 1/2 inch end mill, in admittedly some very hard woods without tearing. It would be interesting to see your setup. Are A and X moving simultaneously giving you your spiral?

Cheers,
Rich
 
#4
Hi Rich. I am using both a 4 flute standard end mill and a long carbide 2 straight flute router cutter. Both seem to work about the same but I assume if I mount a router on the mill head and turn 10k it will be much better. This work was done with a 1/2 cutter.

Since my Z axis is moving my knee rather then the quill I can mount anything I want on the head and still have full 4 axis. The guy who build this machine sourced a very large ball screw for the knee Z.

Yes I am moving a and x together for the spirals and it works great. I am also cutting on the side rather then the face with most of this work just because it is easier for me to see and program.

Motion to create a straight flute would be fairly simple

X 0.000 Y-0.500 Z-1.000 would be a starting location for cuts given the center of A being my 0,0,0,0

if I wanted straight flutes something like

X5.000 Y-0.5000 Z-1.000
A45 (angle offset for 8 flutes so 0,45,90,135,180,225,270,315 then back to 0 for each pass)

It is easy to make that an arc by adding a radius to the X motion ( the handle example has 2 arcs in 2 motions)

To make it a spiral just place the A axis into the same line/motion!

X5.000 Y-0.5000 Z-1.000 A45

It really is that simple.
 
#5
I am just starting with rough off the saw rectangles that we have drilled and turn on center.

Being able to just put any rough stock right on the machine really works great for us. Our dealers give us huge leeway in what we are making so I can use any wood I want.

I have a friend with a molding business and he supplies me with unlimited turning squares 6-10 ft long in ash, oak, mahogany and walnut.
 
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