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  • Spring meet up in Ontario, Newmarket, April 6/2024. Discussion

CNC for combo machines.

jcdammeyer

John
Premium Member
A question came up on the Unimat forum. The initial question was which axis moves in which direction. That then morphed into the discussion of X verses Y for a DRO mounted to one of the combo mill/lathes. And how to do CNC.
1707082994832.jpeg
I posted a couple of screen shots in the MACH3 config dialog for Lathe verses Mill installations. How all it takes is assigning the pins to a different axis. Depending on which icon is clicked to run MACH the correct pins move the X for the cross slide and Z for the carriage in Lathe mode but in Mill mode the X becomes the Y and the Z becomes the X. A separate drive from the lathe runs the quill.

Also trivial in the LinuxCNC Hall file since those are different for lathe verses mill.

That brought up the question on how easy is it to set up the ACORN or other prefab mill/lathe systems so all that is required is to click on a desktop ICON to run Lathe or Mill CNC?
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
I posted a couple of screen shots

Very nice looking combo machine. Might be nice to hear what @mbond thinks about what axis is what. He is one of at least 2 members who have one.

Does anyone know the rule if there even is one?
 

jcdammeyer

John
Premium Member
Very nice looking combo machine. Might be nice to hear what @mbond thinks about what axis is what. He is one of at least 2 members who have one.

Does anyone know the rule if there even is one?
There is a general rule. When a lathe the Z axis moves the carriage towards the head stock and X moves the cross slide. When a mill The Z becomes X and the X becomes the Y axis and a third axis moves the quill.

I have two shortcuts set up:
1707087690363.png

Here's the Lathe from the MACH3 perspective.
1707087609239.png


And the mill.
1707087751015.png

Nothing mechanically is changed (nor electrical) but the pins used are moved to the correct logical axis.

My question was can this be done this easily with the ACORN and other types of CNC systems?

For example from the DRO perspective you need different firmware (and an overlay) not to mention moving the connectors.
1707087975214.png
 

mbond

Well-Known Member
Premium Member
I know nothing about ACORN, but axis assignment is always arbitrary.

If it were me, I would use X to always be the carriage travel between the head and tail stock, Y to always be the cross slide, and Z to always be the quill. For a DRO, that should work without needing to make setup changes when switching modes / tools. I don't think that this machine isn't really a good candidate for full CNC because of the feed configuration, so compatibility with standards used in CAD files etc. seems less important
 

Upnorth

Well-Known Member
I have 2 acorns of my own and have installed one other on another persons CNC project. They work great. They are very reliable and stable. Going from memory the axis assignment is not arbitrary. You have to follow their system. I had an issue during setup and that was the cause. I can't remember exactly what the issue was but read their install manual before buying one.
 

mbond

Well-Known Member
Premium Member
In my experience, this machine can't really be made into a CNC. There is too much slop in the feeds and there is only power feed in specific configurations. I have made a bunch of improvements to the machine that I have, but unless I want to take the bed & quill apart, and remake the gears, gibs etc. I don't think I can get it to do much more.

To me this implies that the only thing one could really want to do with this machine is to add a digital readout that improves the accuracy of the dials. If the digital readout is all you care about, then the choice of axis is always arbitrary. As long as the operator understands what the numbers mean, it's fine.

But if you do want to try a full CNC conversion on this machine, the next question is standards compliance. That's where you have to worry about what you call X is what the software calls X, if the software allows substitution, or it if can do coordinate transformations (automatic or manual) etc.
 

trevj

Ultra Member
Thanks for chiming in.
I think @mbond is wrong, about the ability to convert the machine (or "machines"), but really, the CNC "I" would want, really needs the ability to run the mill head under CNC control, along the lathe spindle centerline, so you could do fluting, flats, keyways, and the like. You then need to wrap your head around the 'other' axis sets that each is a pretty capable partner to the "XYZ" set. That would be the ABC, each rotating in turn around the XYZ axiis'. Plus you need to add in some linear movement for the mill head to move in relation to those. It becomes complicated! LOL! FWIW, the largest mill I have seen firsthand, was in the Canadair Plant in Montreal, and it had a bed 208 feet long. IIRC they had seven (nine?) axiis that they couple program in, and a crew of guys with snow shovels, clearing the chips into the conveyor. It took thousand pounds-plus ingots of aluminum, and carved out wing skin sections with integrated ribs, and other structural elements, from them. Typically about a one percent yield (ie: thousand pound ingot, into a ten pound part!). This was a bed fixed to the floor, with a large gantry that ran on tracks for the full length. It had two heads, each capable of a LOT of different movements!

IMO, this outlines maybe the largest problem with the way the 3-in-1 machines, and about any lathe with a milling column mounted upon it, lack, as they are not so much an integrated machine capable of doing ALL the functions of both machines, rather a pair of machines that utilize some of the same structural elements.
 
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