CAM software for CNC Lathes - With C axis and constrained live tool

Folk may have seen my posts on the CNC lathe I am trying to build - it progresses well, but the associated software is lagging somewhat.

The lathe has a spindle motor that is actually a high power high speed servo motor, driven by step and direction signals. (2.7kW/2700RPM).

The intention is to use it in 'motor' mode - fed a 270KHz pulse train it turns at 2700RPM as normal spindle drive and then as a Stepper/servo ( it is internally closed loop - with encoder etc) to create a C axis with 0.02deg resolution/0.008deg repeatability.

The I have an ER16 600watt spindle in the tool gang, holding end mills, etc. The mill can be set axially or radially WRT the lathe spindle( manualy..)

The key to using all this hardware , is software that can generate the G code to feed a suitable controller.

There is a LOT of CAM software doing 2D lathe work - X and Z axis only, threading, etc. - Very little doing a C axis - just the usual culprits - EZcam, Mastercam, Visi, the various options in Solidworks, etc

Most of these start at around $4000/seat. None of the usual 'affordable' packages - AlibreCAM, RhinoCAM, etc, do more than 2 Axis lathe work.

As this is definitely a hobby and the lathe won't be earning any money, $4000 for CAM is way over the top..

Is there anyone using 3 or 4 axis lathe CAM and if so, what CAM? Does anyone know of more hobby style CAM system that may be applicable?

The second problem is a machine controller to drive all the motors - The C axis being a special problem - When done using it as a normal spindle , and indexing/polar operation is required, it has to be zeroed/homed to start from zero. This is managed by the controller. not the CAM package, and there are few ( read - NO - ) controllers I have found that can do this - Anyone know of any? Maybe I missed some...

LinuxCNC seems to be able to handle this, but , and apologies to the LinuxCNC Luddites, LinuxCNC for a person totally green on that stuff, is a nighmare. I did spend about two weeks trying to get a system running, but just the Intro page, with the various LinuxCNC version downloads already confuses and depresses one - No simple way of knowing which version is the one to use...And you have to be a Linux fundy and a LinuxCNC fundy to be able to understand . The Wiki explaining the functions is hopelessly outdated, no manual that lists and describes all the functions, etc - so good luck trying to implement functional mods to implement a C axis...that was two weeks wasted - all my queries and questions resulted in folk referring me to other folks queries and 'solutions', etc, with a lot of 'geek speak' ( to a none LinuxCNC fundi..) LinuxCNC seems very promising , just such a pity one has to jump through so many hoops and be so humbled...

Joe

Joe;

As you may not (yet) know, Tormach PathPilot is basically LinuxCNC with a simple install and conversational programming -enabled GUI by default.

The potential issue is setting the correct ports/cards for your system; Tormach sells it configured for their machines. They have a new lathe on the market.

It used to be (have not looked at in a while) that it used MESA cards; I'd assume it is still the same.

Last I read, you can get it on a USB stick. Maybe worth a look, and a web search for others using it.

By the way, yes, LinuxCNC seems to have gone through a bit of a rough patch with documentation and install, but once you figure it out, the thing *just works*. Incredible piece of software. (I have 3 machines with SSD drives and dedicated computers; flick the power switch by the machine, the PC boots, and you are good to go)

One of my mills, with a two-step pulley system on the spindle; I have it automatically figure out what "gear" it is in, and adjust accordingly, thus if you ask for (say) 1,000 rpm, you get it, as close as the sensor, etc, can get it.

It’s not really an answer, Joe ... but have a look at GCoder

**LINK**

https://motionics.com/software/machining-and-other-tools/

... surely a sign of things to come

MichaelG.

Fusion 360 CAM might do it - maybe their business model wouldn't suit you though.

Ecam is set up for lathe C axis work. It can only drill, chamfer and tap radially, but can mill/drill almost any shape coaxially to the lathe main spindle. I can try a part if you give me an idea of what you may be doing.

PlanetCNC is as capable as LinuxCNC. It has a max step rate of 110 Khz, so that may limit spindle speed resolution, but there could be ways around that.

If you're going to reposition your milling spindle between axial and radial then it's a trivial matter to switch Profiles within PlanetCNC to reflect that change - it takes only a few seconds once they are set up.

Martin.

Hello John.

Yes, it is the PathPilot usage that rekindled my Mojo to try LinuxCNC again - I have only read/heard good things re Pathpilot, but requests to obtain Pathpilot for my Lathe were rejected...I was wondering how Tormach approach the use of Open source Software for commercial Profit use, without complying with the Open Source License? Wold have thought they need to maintain the spirit and plow back into the software there doings? However, I suppose I can understand they also don't want to get involved with the implementation issues every Hobby user will come up with on his unique situation...

I wonder if I have the energy to try LinuxCNC again...Just so difficult to even start! On the choice of PC they indicate a few option, 'this XXX may work, but drivers for this may be a problem, or that system YYY has worked for some user, with a path for this driver or that driver'...!!!! etc etc - what cant they suggest something hard and fast with the usual disclaimers?. Same goes for the install version - 'this version works with XXX Real time patchs, or install YYY and you can add the real time patch after, or this previous version with that version of Debian, but needs this kernel'...!!! WOW!! What a shambles for a poor newbie to that strange world...ANd I have searched the web for Boot CD's - lots available, but same issue with choices without useful guidelines, ditto distro's on USB sticks...

Frustrating!

Joe

Hi Martin,

I suppose none of the commercial Vendors business model would suite me - Since it is all really just a Hobby, a challenge to build such a machine, the fun of it, etc, and no money being made from it ( a lot being spent, mind you!)

However, as what I am doing is not in the simple norm, I would be willing to make whatever sacrifices needed, so Fusion would have to do if it would do, but from what I have found, the CAM part in the 'Free for Hobby' use does not do multi-axis lathe, and the subscription version multi-axis lathe CAM is lagging behind to be 'developed in time'...

Ecam - I spent some time with it - downloaded the full function demo - It can only import DXF/DWG, no 3d STL/STEP, etc. There is a 2 part tutorial showing how a piston is done, Part 2 shows how some flats are milled in the C axis, on the periphery of the piston. Except...The series was done in 2019, and still now Part 2 does not exist yet..!

Also, all clickable selections on the web site to show software features, functions, etc, have ALL references to the C axis and its use are greyed out - also just says ' Lathe C axis functions are available in the Mill software' and in the Mill software the C axis is not covered..!

So If I was to select purely from the vendor web site, I would not...

Are you using Ecam? It is implied in your offer to try a part? Could you tell me more about the software specifics WRT multi-axis lathe use?

Martin, please tel me more about PlanetCNC. I have tried hard to find more specific detail WRT its use in my setup, but that is not easy. I have done the same with Centroid - the Acorn - and ditto...

One cannot ask the designer/Manufacturer tech questions directly on these web sites - they all have a user forum where you register and then ask the question. Thats ok in theory - lots of users so lots of experience and lots of answers - except - but it works only for the basic setups! The Vendors seems to look very rarely at the forum - so many questions and comments that they just don't get involved. The 'users' are all experts, till it comes to the nitty-gritty detail! The PlanetCNC tech docs are very lacking in the setup and use with a C axis - in fact it is NOT described or explained anywhere I could find, neither the 4 axis nor the 9 axis boards.

(in fact, you responded my C axis CAM query on the PlanetCNC module on the PlanetCNC forum , 4 or 5 days ago..)

A member on that forum ( his member name is 'Planetcnc - is he therefore a Planetcnc employee??) answered me saying -

'I have a lathe that does everything that you describe and it works great.'

That was hugely promising, so I asked for more tech info, and he has never replied again..I know its Holidays, but he has responded a few dozen times to other folk in the meantime, so not on holiday...

So, you seem to be a PlanetCNC AND an Ecam user, WITH Lathe C Axis capability!

PLEASE tell me more!

Regards

Joe

Edited By Joseph Noci 1 on 30/12/2020 05:51:31

Apologies for any hijack.

Would also be interested to explore PlanetCNC for lathe work. Need to replace a Mach3 2axis lathe setup. My router is on PCNC and I am very happy with it. Anyone tried it from a Raspberry Pi 400 ?

Can I mention a couple of ideas on the periphery of your request?

Have a look on the Dolphin site, particularly among the documentation for the milling
module. That describes a way to 'unwrap' the A-axis so the machine treats it as a linear
axis. With a bit of thinking and post-post-processing, that could work for a C-axis. I
think there is a program called G-code unwrapper that does the same thing.

Have a look on the madmodder site for some posts by Andrew Mawson. He has a Beaver CNC
lathe with C-axis capability. He wanted to mill a hexagon onto the end of round stock with
a live tool. His solution might give you some things to think about.

Have a look at the K-Flop controller. That is very configurable.

Have a good think about what you want to use the C-axis for. For instance, if you are
making a cam, the cut surface is just a series of (X, C) coordinate pairs with a bit of tool
positioning before and after.

It is not too difficult to use (spit!) Excel to generate the meat of the geometry and then
hand write the intro. and outro. Much easier in something like python, with the benefit
that python interfaces easily to dxf so some automation of input geometry and sanity
checking of output is possible (see also a program called CNC simulator)

If you want to mill a polygon on the end of stock, you just have to work out the equations
for one side, do a turn at the vertex and repeat for the other n-1 sides.

Hole patterns in the face is a simple index, peck and retract and repeat.

So my suggestion is to hand code the C-axis stuff. Once you reach the limits of this, then
go looking for a commercial solution.

I am not sure why the spindle zeroing before starting C-axis operations is causing you
distress. Say you are holding square stock and you want to notch it at the midpoint of
each side after turning the end of it round. Once the turning is finished, you switch to
C-mode, jog the axis so that the stock is in a known position (use a square off the lathe
bed, for example) and then zero that axis in the controller. Then load and run your C-axis
code. If you watch the Edge Precision YouTube videos, that is what he seems to do on a
multi-thousand dollar Mazak machine.

If you think about what you are asking, the machine would need to keep track of the
spindle position from the moment it is switched on and you would need to load the stock
into the chuck in a specific orientation. You do not set the DRO on your mill to 2mm
and then push the stock around on the table until the edge finder jumps. You clamp it down
anywhere, touch off and then type 2mm into the DRO.

On the spindle control, the only servo with which I am familiar is the Mitsubishi one. On
this, the motor has three modes of operation: position, speed and torque. For position
control, you feed it step and direction. For speed control, it needs a 0-10v analogue
signal. To switch between modes, you change the logic level of a couple of input pins on
the servo brainbox. This is easy to do in something like Mach3 and is an exact copy of
what it does for flood or mist coolant on/off.

So you need to be looking at the servo controller documents to see how it wants to be
mode-switched and then build something that will do that (possibly with a break out board
if it is something strange). The 270kHz for maximum spindle speed is likely to be a big
stumbling block. Mach3 will not do a lot more than 10% of this. As someone says above,
LinuxCNC is 110kHz. So look very hard to see if there is a way of controlling the spindle
speed by analogue methods. If not, you might have to build a dedicated circuit.

A quick reply.

I have Ecam with Turn, Mill and C axis options. I have a 2 axis lathe and so have NOT used the C axis feature within Ecam as I don't have the hardwear to support it. I do have a 4 axis mill, but Ecam only supports 2.5 axis features. I use Deskproto for 3d work on the mill.

I have PlanetCNC on my lathe and will refit my mill with it too, when I get around to it.

PlanetCNC supports up to 9 axes, has very extensive toolchange features and seems (to me) to be just about one of the most configurable controllers available to the hobbiest market.

The PlanetCNC person who said they had a lathe with all the facilities you wanted is Mr PlanetCNC himself (Andrej, I think). He is a very, very capable individual, in that everything is created by him - both software & hardwear.

I'll try to make a video of Ecam creating a part under a C axis setup. It might be something we can both learn from. A quick play yesterday soon made a hexagon (internal or external) on some lathe barstock, as well as various hole patterns etc.

Martin.

Edited By blowlamp on 30/12/2020 13:08:28

Joe;

http://linuxcnc.org/downloads/

lists an ISO download.

I do know that there was an issue going from one real-time kernel to a newer one; this gave the LinuxCNC team a bit of an issue. Looks like it's solved.

Note that with "smart" cards like the MESA ones, perfect real-time is not required; with the old parallel port, servicing that port did require quick and timely response. (I use the MESA cards in all of my machines)

I can fully understand the frustration when LinuxCNC was going through that real-time transition, but with an ISO, maybe it'll install nicely. Knowing what I do from seeing your work here, I'd expect that once it is running, and you comprehend the flexibility, you'll be very happy.

Whatever you do, keep doing, and (especially) keep posting!

John.

Martin, thanks for your response. I agree re the PlanetCNC module - I think that the two main good modules are the PlanetCNC and Centroid Acorn boards. After extensive to a fro-ing on the Centroid site it finally came out that their CNC12 software ( sort of the equivalent to the PlanetCNC TNG software) cannot handle the C Axis currently, so that unfortunately broke that choice.

Martin, I would be greatly in your debt if you could do some trials and tests on your setup, to see how the C axis is handled.

In particular, I wish to be able to create a part in CAD, CAM it , and then use that Gcode with 'a' controller to drive the lathe. X,Z and C

So to give a test some direction and size, lets say something along these lines -

Machine a stock shaft to say 25mm diameter, 50mm long. Then mill an inscribed Hexagon 'head' onto the end of the shaft, say with flats 10mm long, with the milling cutter AXIAL to the lathe axis. This requires the system to work in polar mode as the X axis moves coupled with the C axis to cut a flat on the shaft...

( note the sequence of process is important here...)

Then with a grooving tool make a 25mm wide slot in the shaft, starting 20mm from the shaft end, leaving a 20mm diameter section of shaft in the groove.

Then with a 4mm milling cutter, Radially to the lathe axis , cut a spiral ( an Acme style tread maybe?) inside that groove, on the 20mm diameter shaft section, with the spiral start on the center of one of the hex flats... The milling cutter is 90deg to the lathe axis, and horizontal, on the lathe spindle centerline.

Does that make sense? I can make a small sketch if not, and of course you can modify the 'task' to simplify it, etc.

The key here is each task type, and the sequence.

The shaft machining to 25mm OD and facing is easy 2D stuff.

Then the C Axis must be zero'ed, and the Hexagon milled. Then the Groove is machined, BUT either the Zero of the C axis must now be maintained by the system, or the axis must be zeroed by the controller again later.

Then the 'thread' is milled, with the thread start referenced to one of the Hexagon flats.

The trick here is how the system manages the C axis reference - For example, LinuxCNC maintains a large counter that simply accumulates spindle encoder pulses relative the the first spindle motion index pulse. It increments and decrements this counter and computes the actual spindle angle relative to this...This counter accumulates even when doing normal 2D machining...claims the spindle can run for a few years at high speed before the counter will overrun...

Other systems will zero the C axis each time it is to be used ( index pulse, and then re-positions it to the required angle.

Interesting stuff - If you can see useful results I will be tempted to just procure the PlanetCNC board and Ecam and try it!

Regards

Joe

For now, here's an older turning video I made which shows the basics of Ecam.

Joe

Hi John, Thanks for the encouragement!

Yes, I was on that page, but that is what I found confusing ( for the un-initiated..)..

Assuming I have MESA cards, what must I choose?? Makes me feel all Wheezy..

Joe

Joe;

on all of my machines, I use the MESA 5i25 cards. I use the parallel ("printer" cable option.

On one machine (a small CNC lathe) I use a Gecko G540; on my older Seig KX1, the same.

On my larger mill, and ex-project CNC lathe, a MESA 7i76.

(I hate giving advice, so use your judgment )

I think for you, a MESA 5i25 and 7i76 combo. It gives you lots of stepper outputs, lots of signal outputs, inputs, spindle encoder, "0-10v isolated" spindle control, etc, etc. Way more i/o than you'll need, but better too much than too little. You've got the brains to figure out a) what you need i/o wise, and b) what else you can do once you have it running.

There is a "plug-n-go kit" for the combination:

http://store.mesanet.com/index.php?route=product/product&path=83_84&product_id=215

Anyway, my 0.02c - it's what I use and I find it well supported and incredibly reliable.

And, if it matters, my 3 machines are running an old Intel board, dual-core, obsolete from about 6 years ago; more than enough power to run the machines, with i/o, MPG controllers, touch probes, 4th axes, and so on.

John.

I'm just setting up an old Denford Orac on Linux CNC and it is twisting my mind somewhat.

I have a friend helping who has some experience with linux (but not CNC) so things are progressing.

We had the slides moving today but still have to sort the spindle out. Sadly we realised we needed a newer version and are now reinstalling.

I'm going to start with using a single parallel port before setting up the Mesa card (7i96).

This machine was bought to be a test bed for Linux and I was expecting trouble in the initial setup but hopefully will end up with a stable and usable machine.

For all its faults Mach 3 is a doddle to set up and customise.

David.

Ok John, Now you are pushing...I may still try this route - it does have a lot going for it - the learning curve scares me - I presume I will get to grips with it, but I had hoped to put the effort more into the machine as opposed to the software..

Could you explain a little the listed downloads on that page I included - There is the ISO you mentioned, but its definition differs ( a lot?) from the other available downloads - is that significant to me? Or do I just take the ISO and go for it?

I gather from your PC that the ISO is 32bit? That also confused me a little - in the system requirements on the wiki is is quite unclear what is needed - they mix 32 bit and 64 bit requirements somewhat haphazardly..

Joe

Joe - the Real Time package for Linux has changed; as LinuxCNC (especially if driving one of the inexpensive breakout boards) needs realtime so that signals come and go without varying latency. It seems like it's fairly settled now.

That first ISO, on the top of the page is one that I would use.

Just download the iso, burn it to a USB, and boot. You should be able (if it is as it was) to run LinuxCNC directly, without installing it, just to test drive it.

32 or 64 bit - don't worry about it. Try that ISO on the top of the page.

(Am I pushing? Well, Tormach went from Mach to LinuxCNC-based software, and paid $$ for work on the trajectory planner in LinuxCNC, so why not use what a successful company uses?? They also use MESA hardware, so you are following fairly closely a known, successful path)

John, Seems the 32bit/64bit thingy is important...I downloaded the ISO, created a USB boot drive, and stuck it in a Mini-ITX pc I have - 32 bit Intel Dual core - came back and told me I am an idiot trying to boot 64bit stuff on a x86 machine...Ok, stuck the USB drive in my Dell 64bit Win-10 laptop - it booted , into Linux, and for the life of me, I could not work out how to run Linuxcnc controller! After an hour digging in the LCNC forums, gave up, and found my Laptop would now no boot windows anymore..put it in its bag, packed away, and gave up!

Next year's problem! ( Oops..that's tomorrow..)

Won't give up just yet, but need some direction soon!

From Namibia, Happy new Year to all!

Joe