Usefulness Of Tilt And Nod In A Cnc Mill?

Baithog

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Some time ago I did a quick and very dirty conversion of my little X2 mill. It was useful enough and worked well enough that I desired a first class conversion. Acquisition of a mill drill to make parts while the X2 was apart enabled the reconversion. The table is together and I should have the standoffs for the X-axis motor done tonight or tomorrow. It is time to decide what I am going to do with the column and head.

I could have really used the nod capabilities of a knee mill when I was milling the X and Y axis. but is there enough use for that capability in a CNC mill to re-manufacture the X2 head? Would a rotary 4th axis be a better project to waste time with?

The other thing I was thinking about doing was modifying the spindle saddle so that I could rotate the head 90deg. I used that capability on the mill/drill to do horizontal boring of the base, but again, would I ever want to write a program that ran with the spindle at an angle? Tramming is a whole lot easier on the mill drill by rotating the head than on the X2 by tilting the column. It may be a worth while modification just for that.
 
I guess I am just a noob. I have, not once, used my Mill in any configuration other than 0deg rotation and 0deg nod. I would more likely build a fixture to hold a part at an angle if I needed do do something like that. I am not even sure if BobCad can generate GCode for a tilted head.
 
I sometimes nod or tilt, but not often. If my mill didn't have that capability already I don't think I would modify the machine to have it.

I do find the 4th axis handy on occasion and it's an interesting project to build.:)
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I have a friend with a Super X3 converted to CNC and he tilts the head often for milling angles or facing the end of long stock. My PM932 has the ability to tilt right and left but I have never had the need or desire to do so. I'd rather not be messing with the tram that much.
 
A rotary fourth axis is much more useful for me.
 
A rotary 4th axis (B axis) is always nice, very cool, my favorite, and it's opens up some options. But it can be pricey and heavy to incorporate one with any real size or capability.
If your machine already has the ways for tilt and nod (A and B axis, I assume), then powering them is not a bad idea. Home shop 5 axis is pretty darned sweet; allows for more cool stuff; and gives untold bragging rights ;-)
The Big Boys, however, people like Cincinnati Millicron made lots of 5 axis machines that were only +/- 30deg in any direction. None of this 'vertical to horizontal' transitioning, really. So when you think within those limitations, the job becomes easier to understand and implement.
It's worth it if you say it is. I would. But no everyone would be as impressed as me.
You could then still add a longitudinal rotary "4th axis" (U axis) later and have a machine that would reach about anywhere. But you'd always be running out of Z travel ;-)

Wrat
 
On further reflection, I only have 6" of Y travel. That doesn't give one much room to swing the head for the nod on my mill/drill. On a much bigger knee mill with its moveable head it would be fun. Rotation in the x plane is possible and I am building a model to see what really can be done with such a small work envelope. Thank you for your input.
 
I try to use my sine vise to get away from moving my head when I need angles (Bridgeport). On a big machine, 4th and 5th axis is very important, not sure I would spend the money/effort on a small machine.
 
Start with a good 4th axis, see what all new stuff you can do with it. I doubt you have the rigidity nor the room to start articulating the head. 4th axis will open up a huge new world.
 
I have tilted or nodded my 2 axis machine only cause it was what I was able to do for that job without a bunch of setup tooling, that way also when I swapped parts they'd be the same. I keep trying to think of a way to get rid of the nod for more stability, but I might as well just save the time and money and get a 3 axis vmc like I want
 
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