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Mach 3 and Controlling a CNC via USB
« on: August 15, 2022, 05:38:09 AM »
Hi Everyone,

I work as CNC Machinist and I am looking at purchasing a small CNC mill for at home use. The machine I am considering buying is this one...
https://www.aliexpress.com/i/32706031866.html

Now I have no experience with Mach 3 so I have a few questions...

The guys over at Linux CNC mention that there may be latency issues with running a cnc via usb. Presumably that wont be as much of a problem with this machine because the motion control hardware is on the machine?

Will I need a plugin to run the motion control?

I am a bit confused as to the system requirements regarding 32 bit vs 64 bit computers. Does it matter either way for this application. If I understand it correctly both will work.

As someone who has never needed to hook up a cnc before... what can I expect connecting to Chinese motion controllers, what sort of work is involved. Once I buy the machine will I be able to look in the back and figure out the best post processor to work with the components?

Sorry for asking stupid beginner questions BTW
Thanks,
Matt.
Re: Mach 3 and Controlling a CNC via USB
« Reply #1 on: August 15, 2022, 11:20:35 AM »
Well in principle that looks quite a nice little machine.  USB motion controllers can work well with M3, I use one on a small mill and another on my lathe, no issues with latency.  Mine are made by CNCDrive, type UC100, EU made and well supported.  Chinese USB equivalents (some of them direct rip-offs) have a dodgy reputation on here. 

You have to have a Mach3 software plugin to allow it to drive the USB controller rather than parallel port, and the Chinese ones are apparently of dubious quality and support isn't good.  Now, if the machine internally has a conventional parallel port into which the USB controller plugs, like the UC100, then if it doesn't work you could always junk the supplied controller and fit a UC100.  In the limit, just replace the electronics in the machine with better ones, at least you get the basic mechanics at a reasonable price.
Re: Mach 3 and Controlling a CNC via USB
« Reply #2 on: August 15, 2022, 03:38:09 PM »
Hi,
all Windows PC CNC software solutions including Mach3, UCCNC, PlanetCNC are 'buffered control' solutions, that is to say the the numeric trajectory data
from the CNC software goes into a motion buffer before being executed by the motion controller. The motion buffer will typically be 100ms or longer.

LinuxCNC however is realtime, that is to say the the numeric trajectory data is executed as it is generated.

Thus the LinuxCNC brigade are correct that all Windows solutions do have latency, and in certain situations that is important, however mostly you can't even tell
that there is a motion buffer and you can make perfectly excellent parts just as fast and accurately as LinuxCNC.

If you are trying to decide between LinuxCNC or Mach then the 'latency issue' is somewhat of a red herring. The real and distinct advantage that LinuxCNC
has comes ONLY if you intend using the PC to close a motion feedback loop where its being realtime is REQUIRED. Most hobbyists never ever come
close to that requirement.

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: Mach 3 and Controlling a CNC via USB
« Reply #3 on: August 15, 2022, 11:14:28 PM »
Hi,
if you are new to hobby CNC then I'd recommend Mach4 rather than Mach3. Mach3 certainly works and tens of thousands still use it but all development ceased seven plus years ago.

I suspect the machine you have linked to, and it looks like a pretty fair machine for the price, will work with Mach3 rather than Mach4. Not a deal breaker but Chinese electronics tend
to be pretty shoddy and have not kept up with Mach.

In the early days of Mach the pulse streams to the motors came from the PCs parallel port. Such a machine HAD to be 32 bit, and Windows 7 or XP.

Since that time we now use external motion control boards connected to a the PC by USB or better Ethernet. A PC used is this manner can be basically anything, 32 OR 64 bit, a laptop
OR a desktop, up to Windows 11. When using an external motion controller the PC does not need to be powerful, one of the kids cast-off PCs will be fine.

I have very little regard for Chinese motion controllers and I think it reasonable for you to consider that when you purchase your machine that you will in the short to medium term
upgrade to a US or European motion controller like an Ethernet SmoothStepper or a UC300. I personally have an Ethernet SmoothStepper and have used it extensively for eight years,
best $180 I've ever spent. It has a Mach4 plugin and a Mach3 plugin so you can use either, Mach4 preferred.

Per my previous post LinuxCNC is another very worthy choice, but are you up to play with Linux? If your more comfortable with Windows then Mach is entirely reasonable as are UCCNC or Planet CNC.


Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: Mach 3 and Controlling a CNC via USB
« Reply #4 on: August 16, 2022, 04:24:28 AM »
Mach3 is not compatible with  USB breakout boards, so  Planet CNC is required instead.https://www.mcdvoicecom.info/
Re: Mach 3 and Controlling a CNC via USB
« Reply #5 on: August 16, 2022, 06:30:18 AM »
Mach3 is not compatible with  USB breakout boards, so  Planet CNC is required instead.https://www.mcdvoicecom.info/

This is not correct.  For example the UC100 from CNCDrive works fine over USB from Mach3 provided the corresponding plugin is installed.  It also works with Mach4 and UCCNC..
Re: Mach 3 and Controlling a CNC via USB
« Reply #6 on: August 22, 2022, 04:17:30 AM »
Thanks for all the replies the information is appreciated. I have emailed the factory for a copy of the English user manual, fingers crossed is has some information regarding electronics and hooking it up to a computer.