Author Topic: PCs for CNC  (Read 3183 times)

Offline Roger B

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PCs for CNC
« on: August 28, 2018, 10:16:11 AM »
I don't want to further hijack Mike's thread so I will start a new one.

I would like to start experimenting with CNC. I can buy a kit to convert my Proxxon Micromill which gets me to a parallel interface. That's ok.

I have looked at my selection of old PCs but none have a parallel port. Reading up a bit it seems that for CNC you need a real port not an emulator as it has direct access to the interrupts. USB to parallel converters will work with printers but not in applications that require time sensitive bi directional communications.

What do others do?
Best regards

Roger

Offline kvom

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Re: PCs for CNC
« Reply #1 on: August 28, 2018, 12:26:38 PM »
After using Mach3 with parallel port for years. I made the switch to PathPilot from Tormach.  Here the pulse generation is handled by a hardware card from Mesa.  PP itself is a version of LinuxCNC;  I had a computer built using the least expensive components possible, since the software uses relatively little CPU capacity.  The computer cost about $350, Mesa card was $125, and the PP software was $100.  I was able to reuse my existing BoB and driver card.

Biggest improvement was faster rapids since pulse rate is not dependent on CPU interrupts.  The PP UI is also superior to Mach3 in my opinion.


Offline Admiral_dk

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Re: PCs for CNC
« Reply #2 on: August 28, 2018, 12:40:14 PM »
Most never (and older) compact and full size PC's has one or more expansions slots that will accept a true Parallel Port plug-in board - just beware that you get the right expansion interface + size version for that particular PC or even better check that you still can get what fits the one you will like to buy, before you commit.

Offline Dave Otto

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Re: PCs for CNC
« Reply #3 on: August 28, 2018, 01:27:39 PM »
I'm using a Smoothstepper USB motion control board on my system.
https://warp9td.com/index.php/products

Someday I would like to switch to better machine control software but I haven't had time to dive into it. I get by with Mach3 ok for the time being.

Dave 

Online Vixen

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Re: PCs for CNC
« Reply #4 on: August 28, 2018, 01:45:46 PM »
Roger,

Most laptops do not have a paraport these days. If you have an old desktop box, you should be able to buy a PCI card with a paraport and slot that in. That would be adequate for your Proxxon micro mill. If you can get that to work, then you probably do not need the added expense and complication of an external motion control board, like a Smoothstepper or the Mesa card for a LinuxCNC installation.

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline jadge

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Re: PCs for CNC
« Reply #5 on: August 28, 2018, 02:48:46 PM »
I started by running a custom version of Mach3 on a clean install of XP on an old computer (with parallel port) with my Tormach CNC mill. I had some issues with the software and computer. As in sometimes it went AWOL during a "toolchange". I eventually discovered it was going into relative mode for some unknown reason. I "fixed" it by adding an absolute command in the post-processor code at a toolchange. Eventually I upgraded to a proper Tormach controller, still running Mach3. Personally I didn't particularly like Mach3. The screens were messy and inconsistent. And the 4th axis stuff, especially feedrates, plain didn't work. Ultimately I upgraded to PathPilot, and also had to upgrade the controller as well. Generally so far so good. PathPilot is much easier to use, with more logical screens. The only caveat is that it isn't quite as user friendly if you use metric rather than imperial. A jog step of 10mm could be quite exciting!

Andrew

Online Vixen

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Re: PCs for CNC
« Reply #6 on: August 28, 2018, 03:15:46 PM »
Roger,

Mach3 needs Windoze to run. LinuxCNC and Pathpilot are both fresh installations of Linux.

I am with Andrew in disliking Mach 3

Pathpilot needs a fast modern processor, whereas LinuxCNC will run a 3 axis mill happily on and older (XP vintage) PC.

Pathpilot was developed by Tormach (from LinuxCNC) specifically for Tormach machines but can be successfully adapted to others (expect no help from Tormach if you do this).

LinuxCNC is good for any machine and works well in both Inch and Metric units.

LinuxCNC does not need and external motion control card if you have a paraport

You may gather I like LinuxCNC, I have it driving three mills and a lathe via the paraport, no motion cards. Each machine has it's own mini PC, laptops can be problematic.

Mike
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline fumopuc

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Re: PCs for CNC
« Reply #7 on: August 28, 2018, 07:29:16 PM »
Kind Regards
Achim

Offline Stuart

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Re: PCs for CNC
« Reply #8 on: August 28, 2018, 07:53:54 PM »
That’s the Same one as I use for mach4

Got mine as a refurb from micro dream in the UK

Works fine one year warranty for £300 not to bad deal but it what they have in stock
My aim is for a accurate part with a good finish

Offline Roger B

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Re: PCs for CNC
« Reply #9 on: August 29, 2018, 09:04:43 AM »
Thank you all for your thoughts  :)  :ThumbsUp:

I see two problems:

1) I am starting out in something new to me. Do I want to base it on an obsolete interface? I know from my day job that PC technology evolves much quicker than machine technology.

2) My workshop space is extremely limited. It will be difficult to find a place for a desktop PC that is out of range of high speed swarf.

I will have to buy something. It could be a parallel card for an existing PC, it could be a PC with a parallel port or it could be some sort of motion controller. I am tending towards Linux CNC on my netbook with a USB link to a motion controller. Is this feasible?
Best regards

Roger

Online Vixen

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Re: PCs for CNC
« Reply #10 on: August 29, 2018, 10:31:19 AM »
Hello Roger,

I have never considered a Netbook with a USB link to a motion controller. I do not know if it is feasible. LinuxCNC do not recommend laptop type PC's

I would be inclined to run LinuxCNC on a small form PC, similar to the one identified by Achim. You could mount the PC out of the way on a remote shelf or under the workbench or protected by a perspex screen. You only need access to press the ON button. The cost of that PC is minimal and once set-up will last forever.

You may need to do some research into the interface for the mill. Mach3, Pathpilot, LinuxCNC with or without a motion controller, will all give three pairs of 'step and direction' signals for the three axes. You will need to check what the Proxxon interface needs or expects.

Mike
« Last Edit: August 29, 2018, 11:24:53 AM by Vixen »
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline nj111

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Re: PCs for CNC
« Reply #11 on: August 29, 2018, 11:27:57 AM »
I don't know if this is helpful but a friend of mine is getting great results converting large industrial heavy duty CNC routers to run UCCNC  - a Mach 3 competitor.  The nature of his work requires fast 3D profiling - at high feedrates  (compared to what we need) and in his testing he found this totally outperforms Mach3 that was previously installed.  he calls himself automateanything on you tube -  Most Recently he's converted a Denford Mill to run this software whilst still using it's original Fanuc Servo motors - complete with rigid tapping cylces etc.
Search on youtube  "Uccnc overview of screens- quick talk through"  "Rigid tap - done!"  and also "uccnc vcarving on old rye mg cnc rebuild"    Nick
Nick

Offline Roger B

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Re: PCs for CNC
« Reply #12 on: August 30, 2018, 03:07:06 PM »
The GoCNC kit for the Proxxon micro mill includes a version of Linux CNC,

https://gocnc.de/shop/en/cnc-acessories/cnc-software/273/linuxcnc-dvd

A parallel interface card for one of my old PCs will cost 20-30 so I can put it all together and see what happens  :headscratch:

I think that one PC is Win 7 and the other is Win 10. If I put in the Linux CNC DVD will it install Linux (and deinstall/deactivate Windows)?

How do people protect their keyboards?

Will I also need some form of CAM software?

https://gocnc.de/shop/en/cnc-acessories/cnc-software/450/estlcam-software-vers.11

Best regards

Roger

Online Vixen

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Re: PCs for CNC
« Reply #13 on: August 30, 2018, 03:18:34 PM »
Hello Roger,

The LinuxCNC disc will overwrite everything on the PC's hard drive. Make sure you have removed or backed up anything of importance first. It will overwrite whatever windoze already installed. You will get a stand alone LinuxCNC controller. Best to disable the internet.

CamBam is a very popular CAM you get a free trial period before you need to pay for it. Never heard of the one in your link so cannot comment.

You will also need a 2D CAD package capable of outputting your drawing as a DFX file. The CAM program converts the DXF file into the G-code file, which controls the CNC mill.


Mike
« Last Edit: August 30, 2018, 03:25:25 PM by Vixen »
It is the journey that matters, not the destination

Sometimes, it can be a long and winding road

Offline Roger B

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Re: PCs for CNC
« Reply #14 on: August 30, 2018, 03:44:13 PM »
Hello Mike,

I think I understand how this goes together now  :headscratch:

I use DraftSight 2D CAD. The CAM package will go on the same PC as the CAD package and will allow me to create 'G code'. I then transfer this G code file to the Linux CNC PC (via a USB stick?) The Linux CNC PC then outputs step and direction signals (via the parallel port) to the stepper motor driver that is in this case installed in the milling machine.
Best regards

Roger

 

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