Mini-lathe + shapeoko?

Hi there,

it’s been a long time, but I have not given up on this project. Minor progress today, which I thought I would share.

I grabbed this 2017A aluminium plate I had,

run a little surfacing op,

then started cutting,

ended up with this,

and a whole lot of chips to clean-up,

I tapped the front hole (M5), drilled a hole from the side to insert a bolt+nut for tightening the piece…

… around the lip/recessed part at the bottom of my spindle,

(and by that I mean the “dustproof cover” below)

image

and finally I was able to attach the little turning tool holder that came with my proxxon mini-lathe:

which hopefully should allow me to do this (soon!)

Yes, I have a clearance issue with my 3D-printed frame (usually supports my dust shoe), I’ll have to remove it when turning stuff.

Next on my list: look into attaching the mini-lathe to the aluminium baseboard. And then start looking into generating 2D (XY) toolpath to have the shapeoko move the turning tool. It will either be fun or a total disaster, either way I can’t stop now :slight_smile:

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hahaah you wild. i like it.

does the chuck thread on? may want to run it fwd and flip the tool upside down to ensure it won’t back off - if threaded.

looking forward to seeing how well that holds up. i’m working on a solid mount to replace the compound on my lathe.

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That’s an excellent point !

Yeah I dug a trench in my garage, to hide there when I hit the “run” button for the first time :man_factory_worker:

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so you’re not considering using an endmill to carve patterns?
(sort of a round version of 3D carving)

I need to survive step1 first :slight_smile:
Joking aside, that would be an interesting possiblity, but I would then probably have a significant Z clearance issue to address.

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So, having cleared up my todo list a bit, I’m restarting this.

Nice surprise, the two fixing points on the mini-lathe are spaced by exactly 350mm, and my aluminium bed has holes every 50mm \o/

I needed short M5 bolts, and the only ones I had on hand were salvaged from my original stock Z axis, so it’s like it was meant to be.

Potential disaster ahead, take cover!..

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Well, it’s alive, and I’m still alive too.

(lousy quality because it was captured from behind my acrylic front window, I’m not taking any chances)

It’s a good thing I reread the thread before launching the job, because I had my tool facing up (oops…it must be flipped since I’m coming from “behind” and the rotation is counterclosewise) so @PaulAlfaro literally saved me from a very silly crash on first try with his comment above.

I have no idea what I’m doing yet, so I semi-randomly chose 2000 RPM, 350mm/min feedrate (13ipm), cutting 0.5mm (0.02")

Conclusion for today:

  • I feel like a newbie again, I need to go and learn about CNC turning feeds and speeds and the different kinds of cutters and when to use them, etc…does anybody have a recommendation about a specific site or book to learn turning basics ? (but which would be CNC-friendly, I have gone through a few videos already and the “you have to feel it” comments don’t help me much for a CNC lathe…)
  • I will add a new power switch for the lathe on my control panel outside the enclosure, it feels a lot safer to have the front door closed when I start this thing.
  • I need to look into what my CAM workflow should be. I can probably use CC and X/Y contour profiles with no Z depth as a hack, I think VCarve supports turning toolpaths to so I’ll check that, and there’s always Fusion360.
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I haven’t thought about how you were going to hold that milling cutter. I’m surprised that that is stiff enough without giving you a bunch of chatter. I guess that will show when you “overfeed” the cut.

Looks really neat! +1

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Ok, Fusion360 it is, for generating turning toolpaths.

Since Fusion insists on the rotary axis being “Z”, for now I’m cheating, opening the G-code file and replacing “X” by “Y” and “Z” by “X”.

which then gives me a nice toolpath in the X/Y plane

image

Now to take a peek inside the turning post-proc and see where to hack to do the X/Y swap

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I wonder if this is something where you want to just feed it an STL file and then make a flattened depthmap…

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I’m not sure I get how that would work? I still need the CAM to generate a toolpath that will remove only [depth per pass] at a time (in the XY plane)

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if Y is your rotation… then getting a rectangle in, say CC Pro, that you can rough out + finish… will basically wrap around the cylinder in your lathe

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Scorchworks has a tool which will map a flat XY set of G-Code coordinates around a cylinder.

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The lathe isn’t actually an axis being controlled by the machine though. It’s not a CNC router with a rotary axis. He’s got a CNC lathe. Awesome for making precision parts that can be made on a lathe.

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I am really excited to see the development on this! Thanks for sharing Julien!

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Exactly what @neilferreri said: this is not a 4th axis (that’s an adventure for another day), this is “just” a CNC lathe experiment, so I only need to be able to generate 2D toolpaths in the XY plane of the machine.
The Fusion360 turning support is great, I had my turning toolpath ready in minutes, I’ll just need to edit the post processor to use X/Y instead of radial/X and axial/Z.

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What post are you using?

Also, what are you going to make? I’m excited about this!

I duplicated the “FANUC Turning” post, I thought it would boil down to modifying those lines:

var xOutput = createVariable({prefix:"Y"}, xFormat);
var yOutput = createVariable({prefix:"!"}, yFormat);
var zOutput = createVariable({prefix:"X"}, zFormat);

but either I’m missing something or Fusion360 ignores my changes and keeps generating X and Z…or maybe it’s just late.

EDIT: well I just closed Fusion and restarted it, and it started using my modified post now…there must be a cache somewhere, or this was a plain bug. Anyway, yay, I have a suitable post to proceed with tests.

For now this is for me to learn about turning, the long term goal is to make rings to support my wife’s jewelry making hobby. I may make the obligatory pen somewhere along the way.

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Julien, I know you are in France but take a look at Craft Supply USA (https://www.woodturnerscatalog.com/). They have turning mandrels and other ring making gear for use on an analog lathe. The Ring core blanks and the mandrels may be useful for your set up.

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Thank you Guy, I have seen some of their videos, and indeed they have interesting ring core blanks that I will check.