[bohica]

Recently I saw several YouTube videos of guys who figured out how to use their CNC mill as
a lathe with gang tooling. I have an IH CNC mill (now Charter Oak) so I quickly got very interested in this, since the price of
a CNC Lathe was totally out of the question. It was fascinating to watch, but they did not provide enough information on just
how they did it. One guy said he did this using Mach3 and had to write macros to make it work.
Some of them wrote the Gcode by hand. There was never enough information in these videos. Sounded way to complicated.

I spent a lot of time on Google searching for information. I quickly learned that the CAM software starts
and $1000. Then there was the problem of figuring out just how these guys got Mach3 Turn to work since it
does not have a Y axis. I found two posts with critical clues. Fusion360 by Autodesk appears to be the best bet for the
CADCam software for my needs. The second software is MSM Mill Turn by Calypsoventures. This becomes the interface
with Mach3 with the ability to set Y axis offsets very easily. The only other mill turn software I found was
MasterCam Mill Turn. Prices start at $4000. I will be testing both MSM Mill Turn and Fusion360 software within the next week or two.

Having selected the potential software for this project, I just completed the preliminary design for the tooling
to make this all work. Attached is CNC Lathe.pdf that will show the setup. This is version 1.0. I hope to get some
feedback to make this even better in version 1.1.

With the impressive 22" Z travel axis on the IH mill, I will have the capability to have a usable 9" of material length to work with.
I will be using an 1" ER collet for the material holding. The gang tooling is set up to be able to turn up to 3" in
diameter. With a 3" 3 jaw chuck with an r8 spindle, I will also be able to turn up to 3" pipe as well.

Here are the cost estimates for this project.

Fusion360 $0.00
MSM Mill Turn $0.00
(both software packages allow free use to hobbyists)
7 piece lathe turning tools $100.00
3" 3 jaw Chuck with R8 $100.00
3 1/2" Jacobs Chucks $30.00
Materials $50.00
Total $280.00

Not a bad price for a CNC Lathe!
Feedback?

[Ron Thompson]

I have successfully used two different mills to do turning. On the first, a Taig cnc mill, I hand wrote the G-code and used Mach 3 mill. The limitation there was the Z column rigidity. It was very easy to push the column out of tram, but it did work. The advantage was I could interchange the lathe chuck to the mill.
Single point gear cutter.
Single point gear cutter in use.

More recently, I used my 30 taper Trionics CNC knee mill using Mach3 mill for setup (to get the Y axis on center) and then switching to Mach3 turn using Fusion 360 to generate the G-code. I used traditional lathe tooling held in the mill vise. I cut a pulley mounted on a 3/4" arbor held in a collet.

I have recently bought a Taig turn cnc lathe that uses gang tooling on a mill table. Gang tooling would lend itself to mill turning. You could use boring bars instead of traditional lathe tools for easier mounting, maybe using ER collet chucks as many lathes do.

The limitation, IMHO, is the spindle bearings. Keep the speed reasonable and watch the bearing temperature. In case you don't know already, Mach3 turn only uses diameter mode. Once I figured that out, the rest was easy. You may need to reverse the axis directions in Mach3 turn, but that's not hard. Good luck.

[bohica]

Thanks for the reply. The IH mill is much more rigid than a Taig, so I'm not worried about pushing the Z axis out of tram. In addition, I will probably limit my DOC to .010, especially on long stock up to 9".

Regarding Mach3, I will not be using Mach3 Turn directly, but will be using MSM Mill Turn, which integrates wit Mach3 and makes it much easier to do the offsets, and no axis direction changes are required.

[Ron Thompson]

MSM mill turn looks like a screen set for mach3, right?

[bohica]

Similar, but different. When I get MSM Turn, I will post a screen shot of it. Or, you can go to calypsoventures.com for all of the info on this product

[bohica]

Yes, MSM Mill Turn is a screen set for Mach3. But it is a little bit more. Mach3 Turn has no Y axis, so all it can do is control X and Z. MSM Mill Turn controls the Y axis, independent of Mach3. Attached is a screen shot of this. This is loaded on my drafting system for testing. I will be shortly loading this on my CNC system and run some
simple tests with a single cutter, just straight cutting. I hope to get Fusion360 loaded this week so I can do more complex lathe work.