Manual lathe CNC conversion

[kong]

Hell, I haven't even bought my new lathe yet and I'm already considering a cnc conversion for it. My plan is to make R/C car alloy wheels from 6082 aluminium, these are average 2.5" dia x 2" length. I feel the cnc would give me much greater design opportunities than the manual lathe, such as cutting a curved face. I have quite a few spares left over from my router project, so would like some advice. I have one 360 oz/in peak servo motor, which I think would be suitable for the Z axis, maybe geared down, but what is a "good speed" to shoot for on these small lathes cutting aluminium? As for the x-axis, I have a xylotex stepper driver board knocking around, but the only steppers I have are 116 oz/in, which will not be powerful enough. The board will handle 2.5Amps/phase, at 36v max, so I'm thinking a stepper in the 200-300 oz/in range for this axis. Again, what is a decent speed to aim for?

Lastly, I have never even seen a cnc lathe "in the flesh" so to speak, so are there some good articles on the net to act as a primer - anything from cutter selection to g-codes.

Many thanks, Jason.

[Al_The_Man]

Jason, Chart of G-codes Turning & milling www.cncezpro.com/gcodes.cfm
Al

[InventIt]

I cut alum at .003 - .006 per revolution on my lathe. That would be for a fine finish. You could crank it up to .008 -.011 per pass for a rough cut. Depends how deep your cut is and what tooling you'll be using.

BTW, Most cross slides run 1/2 speed of the carrrage.

[kong]

Thanks guys, but that brings up another couple of questions! The tooling I am looking at is the "glanze" import indexable cutting tools like these on grizzly:
http://www.grizzly.com/products/item...emnumber=H5681
But, then I hear HSS tools will give a better finnish on ali. I have seen special inserts designed for aluminium, so I guess I'll have to suck it and see!
One other daft question - when setting up a part, where would you set the zero for each axis; edge of part with negative going towards centre, or centre of part? I think I need a good book!

[One of Many]

Originally Posted by kong One other daft question - when setting up a part, where would you set the zero for each axis; edge of part with negative going towards centre, or centre of part? I think I need a good book!

Z=Negative left of zero, Positive right of zero
X=Negative behind spindle center, Positive front of spindle center

The software you choose should handle this in its particular format. Primarily there is a tool library that defines the basic geometry of the tools. Once you set your X & Z references for tool #1. All your other tools will have an X & Z offset in relation to #1 stored in a tool length offset(TLO) table. It gets a bit more involved when defining ID and OD tools, but again that is handled by the controller software/hardware interface.

If you choose to re-invent the wheel and set up your own software, I would follow this as as the standard format at a minimum.

I have a 14" lathe that I would love to convert to a format like the EZ-Path or even SouthWest Industries Trak tool room lathes. The "do one" functions for tapers, radiuses, chamfers and roughing make life so much easier than form tools and tedious setups for minor cuts. The form pages with field settings make it a snap to program any thread, pitch, even at a taper to a shoulder. The full CNC option(less tool changes) is great too.

If anyone has seen this in the public DIY. I would sure like to get info on it.

DC

[kong]

Mach3 has somegreat wizards, I haven't used them in a while, but there may well be some good ones for turning now. I will have a look next time I am on the lathe!

[One of Many]

Hello Kong

Dho!, I didn't realize I was posting to an old thread. I thought it was current. Oh well, at least there is still interest in the thread you started!

The nice thing about the 2 tool room lathes that I mentioned was the ability to use them as a manual lathe, with very handy CNC features. The odd part is that the handwheels are rotary encoders, so no feedback it felt by the operator. Feeling the cut was part of the process as I was used to. I have been using an EZ-Path for about 6 years and have learned to live without it, but I miss it for some operations. Not enough to go back to an all manual lathe though!

It will spoil you when having to come home to use a totally manual lathe for hobby work and side jobs.

DC

[Geof]

Originally Posted by One of Many Z=Negative left of zero, Positive right of zero X=Negative behind spindle center, Positive front of spindle center DC

On a CNC converted manual lathe this is totally correct but if you ever move to a commercial CNC lathe the tool is normally upside down and behind the spindle from the operator's point of view so 'positive front of spindle center' appears to the operator as behind the spindle.

[One of Many]

Geof,

Correct.....

I had seriously contemplated putting that in as a matter of the differences between full CNC production lathes verses Manual retrofits. But, I didn't want to add confusion to cover non-issues or be out of context for the focus of this thread.

I suppose including coverage of x,y and z coordinate origins for commercial lathes with live tooling, dual chucks, indexing and Bar feeders should apply here as well?

It is all good info if anyone thinks they can go pushing buttons on equipment they are not yet really qualified to run.

DC

[Geof]

One of Many;

My philosophy is that it is better to mention the variations even if it does cause confusion. Somebody who is confused is less likely to go pressing buttons than the one who has an incomplete story but does not know that! And the confusion can occur at any time; I have just started using a Haas TL1, tool post at front like a manual machine; graphics on the machine controller show the tool coming in from the back like any of the bigger Haas machines; very confusing!

[One of Many]

Thanks for the clarification Geof,

I often leave things out that IMHO do not directly apply to my comprehension of the question within the realm of the given scenario at the time of the post response. A matter of perspective I suppose.

It sounds like Kong got his project done? Maybe there are more threads about his progress and learning curve he could give more details on? Things produced?


Sounds like you should view your Haas setups via a mirror above the work to compensate for the screen anomoly! You might suggest this to Haas a cheezy low tech option. LOL!

DC