4th axis support?

Another great X-carve feature I can think of for woodworking is support for a fourth, rotational axis. This could effectively turn the machine into a CNC lathe as well as a CNC mill. Imagine being able to turn table legs, make small cylindrical boxes with threaded lids, etc.

My vision would be an accessory consisting of a headstock, driven by a motor and having a small 3 or 4 jaw chuck (NOVA, etc.) to hold the piece, and a tailstock to support the stock at the other end. These would be bolted to the table, parallel to the X axis. The motor rotation would be controlled by the fourth axis. The current Z axis cutting area of 65mm would be plenty, but we would just need taller rails to raise the gantry up higher above the bed, see this thread

Any plans for supporting a fourth axis?

sounds great, but that will mean X-Carve needs new electronics for 4th axis
so i don’t think that will be coming from inventables anytime soon.
also i cant see myself working it out. There are some 4th axis kits on ebay ,but how to get them setup and with what software i just dont know.
proxxen do a fantastic cnc metal lathe but at a crazy price.In time other manufacturers will do hobby versions no doubt . CNC is just short of going mainstream, so i’m sure in a few years this whole area will explode. I have the same feeling about CNC and 3D printers that I had when i first started typing code into my 8 bit computer from a magazine in the early 80’s.

Yeah, the gshield controller that comes as part of the pre configured kit will not support a 4th (rotary) axis. But the tinyg controler will. :smile:

So you have the option of ordering the x-carve kit without the Motion Controller and ordering the tinyg controller board separately. (though you will have to come up with your own case / fan / power supply setup) So you can then add your own 4th axis setup.

My plan is to get the standard kit (fully loaded) to have something that I know work “out of the box”. (I am tired of having to constantly “tinker, tweak and repair” every time I want to try to use my current MaxNC mill. I just want something that works.)

Then after I have used it for a while I can upgrade the control board and reconfigure the mechanicals for a 4th axis. (Especially as I have yet to source a 4th axis spindle and mount.)

And who knows, by the time I am ready to upgrade maybe someone will have come up with a upgrade kit (or at least a nice project write up) and save me having to do it all from scratch. :wink:



Ditto to most all of that.

I’ll be doing the same. I work on a lot of Jewelry design and plan on cutting 3D stuff by working with the stock “it just works” machine and just doing 2 sided milling, but will eventually add a 4th rotary axis and a new board like the TinyG to control said axis. Possibly even use the TB6600 and driver shield when it comes out… Inventables announced it here: http://blog.inventables.com/2015/01/tb6600-stepper-driver-shield.html?m=1

@AaronMatthews, @sketch42

This is pretty much my plan as well.

I am new to the whole CNC world, so my initial goal is to get the “works” machine up and running. I do woodworking in my shop and, although it has a dust collection system, it is still messy, crowded, disorganized, and has a lot of small projects in flight - just not a good place for a PC or laptop to live - although I do have ethernet in the shop. So, I am going to go the “headless Raspberry Pi” route, using a wired network connection, and a cheapie Android tablet as a pendant.

On the software size, I am currently transitioning over from the Windows world to the Mac [as a long-time professional Microsoft software developer I can’t believe I am writing this] and am still exploring the CAM software side of things, but have some experience with Sketchup for the CAD piece. The plan is to generate the g-code on the iMac, and copy it over to the Pi either over Ethernet or even by memory stick.

Once the machine is up and running, and I have a few simple projects under my belt, then I’ll think about a fourth axis. Although I may initially pursue a simpler lathe configuration where the fourth axis is uncontrolled - maybe a fractional HP three-phase electric motor controlled by a VFD (my current lathe setup) - so I could do simple “2D” turning work that doesn’t require the rotation of the piece and the movement of the bit to be synchronized …

Complete utter noob here so don’t throw (big) rocks.

It doesn’t look like a 4th axis is needed for rotary cnc. Use the x (or y) axis to rotate the spindle, leaving the y and z to work as typical for a 3 axis xyz cnc router. Right? The trick, this non-EE would think, is “connecting” the rotary spindle to the electronics that once drove the X stepper motor. You don’t need to move the spindle in both X and Y directions AND turn a spindle.

Adapt something like http://www.amazon.com/Engraving-Machine-Router-Rotational-tailstock/dp/B00QSX5YCM/ref=sr_1_4?ie=UTF8&qid=1432229607&sr=8-4&keywords=4+axis+cnc+router to X-Carve? Humanly possible for those folks with EE skills?

Thanks. Enjoying reading about X-Carve and considering how to use in in woodworking.


That is one way of doing rotary carving (I am not sure what this is called) . It is still 3 axis, just Y, Z and A. Some software only support this option.

4th Axis cnc still has the X, Y, Z and A. This lets the bit get in at angles that are not normally possible, carving undercuts and such. The down side is not a lot of software support this. (Often an expensive “pro” version feature.

Ah, sure, that makes sense. Thanks for the explanation.

Perhaps some clever person could create a 3-axis, X-Y-A setup with X-Carve. Not as desirable as 4-axis, but more flexible than X-Y-Z in some cases.

I know I’ve seen another one on a better machine, but I like the general idea behind this project. rack and pinion 4th axis I think you could probably get more accurate with a dedicated stepper motor for the head stock, but I love the idea of using linear motion to make the rotational motion, and always being in the correct location to mill. Software may be a bit of an issue, but I’m sure it could be worked out.


Wow, that is really clever! Such an easy mod and no rewiring needed.
You would just need to tweak the settings in the software to get the right rotary values.
adding to the project wish list

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Damn, that’s slick! I like it, too.

Agreed; this is very clever. Thanks for the great ideas here …

From my perspective, I think I would rather go for rotational motion for the A-axis, instead of one that relies on the linear movement of the gantry along the rails. Also, the diameter of the part you could turn is limited by the Z-axis travel. The design I have in mind would limit the radius of the piece by the Z-axis travel.

Not sure if this is feasible (haven’t received my machine yet) but imagine that the A-axis is a rotational axis located approximately at height of the wasteboard surface. There would be a “gap” in the wasteboard at one end. (Or, imagine the rails hanging off one end of the table.) You would move the gantry all the way to one end, so that the A-axis is co-planar and above the gantry. To turn a piece, the router spindle would move in the X and Z directions, and the piece would be rotated about the A-axis. You could then turn a piece having a max diameter of twice the Z travel of the machine.

For the case of the X-Carve, this would mean about a 5" max diameter, vs. 2.5" in the “rack and pinion” configuration.

So, basically, you could work from one end of the machine to do lathe work, and from the other end to do router work. You’d still have a 3-axis controller, but four motors (five, if you count the 2 Y-axis motors). Maybe have a toggle switch that would connect the correct motors / axes for “lathe mode” vs “router mode”.


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George what you describe is a much more traditional 4th axis, and is very viable. You are also correct about the size of material that can be used in a standard configuration. If needed I think some modifications could be made, to get bigger stock in place. But for serious 4th axis work, the way you describe seems to be best.

I finally found the videos I was originally thinking of they are this guys Kenneth Barry’s Video’s. I found the post on another forum, and he did base it off of of the original post I mentioned. He also talks about the article Rotary Machining with Vectric Software as a good description of how to “wrap” your head around the setup of designs for doing this sort of work, no matter what software you use. Pun intended.


Great info here; thanks!

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shut up and take my money

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Do you work with sterling silver? I hand-stamp sterling silver with metal stamps would like to gain a little bit more of creative freedom and cleaner look so I’m researching the X-Carve in hopes it will allow me the leeway I’m looking for. Any opinions on the X-Carve for sterling silver?

I don’t currently work in silver, though I have in the past. I am hoping that because of the X-Carve, I am able to work in silver again.

My plan for silver though is to do casting where I mill machinable wax and then use it to make molds.

For one-offs though, I don’t see why you couldn’t mill it, but the first thought I have about milling silver is that there will be more waste if you don’t work carefully to recover the chips.

4th axis work can be very complicated and one of the biggest problems that you will run into is CAM program that handles 4th axis.
I have 4th axis on my Tormach 770 CNC mill and the CAM software that supports it . The software is $1500.00 all by it’s self.

Is 4th axis doable on an X-Carve yes is it going to be easy and not cost much I don’t think so.


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Also Fusion 360 is looking to add 4th axis support.

But here’s the thing… If you plan to work in prescious metals and can’t justify spending a few thousand for software that you plan to make money with by milling said prescious metals, then a rethink might be needed.

Entry to 4axis carving will come down in the future, but until then, Deskproto and others do have free trials to at least test the software out.

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Great post George - The idea I had in mind is actually not a fourth axis and accomplishes what you describe with a worm gear attached to a stepper, driving a pinion gear attached to the spindle of a small lathe or two facing headstock pieces and a stepper driven worm gear. You could probably use an acme screw in a pinch but the tolerance and wear wouldn’t be optimal. You could also use two sync’d steppers driving the worm gears on both ends but that’s probably overkill. I’m shopping for a small used lathe this weekend to start this project and once I get that piece I’ll look at which carver (still not certain the X-Carve is the best option, but I’m really leaning that way since I’m used to programming sketches in arduino and working with arduino shields). I really like the open source aspect and the Easel/GRBL combo look sufficient at first glance. I’m not trying for true four axes right now as I can’t afford the software that can handle it. I’m fairly confident I can work something out to dynamically adjust the step for a rotary axis based on radius given the GRBL source. I have an ATMega and an Uno that aren’t dedicated right now so I’m going to play this weekend. If I get it I’ll update this post and then look at mating the lathe system with a carver (again looking at the fully loaded X-Carve as my first choice - I even have one configured and loaded in my cart :wink: ). The difficult part actually seems to be finding the right worm/pinion gear combo and attaching it to the headstock. This is a great thread! Thanks everyone!