Comment by DannyBee | Hacker News Reader

Comment by DannyBee | Hacker News Reader

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(I have built and worked on a lot of CNC mills, routers, etc)

In some cases, it is.

There are integrated CAM + Machines depending on industry and price point. (see woodwop, etc, which are the interface to the machine)

The motion planning aspects can be taken care of (despite other comments), beckhoff, for example, does real time plc on windows machines by isolating cpus away from windows. i have no problem using it as a plc. They also support CNC control.

Outside of software like that, it's usually being taken care of by an FPGA card and that's a pain in the butt. Assume you can solve this.

You still have the next problem: Actually driving the machine.

First, the low level

Most of the servos in these machines are using pulse train inputs of some sort. That's what the FPGA cards are doing, generating the pulse outputs, etc.

It's only in the past 5 years that things like "drive my servo over ethercat instead" became viable.

They use simple relays, etc to control safety/limit switches/you name it.

Now i could use an ethernet based field-io. So i'd say they are actually now there (in the past 5 years) for the low level. I can run all my field io/spindles/servos off ethercat now, for example. I do, in fact, outside of servos (my cnc software can't drive them over ethercat yet)!

5 years ago i couldn't do this.

Okay, so that's one level up. Now i can at least drive it from the CAM software in some standardized way if i knew what was what. Which is your next problem - knowing what anything does. Which io's are the limit switches. How do you home the machine or execute a tool change? How do i turn on the vacuum? Which drives go with what axes?

There is no standardized way of describing this, such that a piece of CAM software could actually do anything.

We'll get there, mind you, but it'll be a while.

Low-level control your machine from your CAM workstation in the office building will never make much sense (where the CAM software directly talks to servos).

I would prefer my (probably expensive) machine to kind of "know" what it's physical limits are and guarantee that executed commands adhere to them.

It depends on what you are talking about here. CNC is used for a lot.

The assumption that there is a cam workstation, and that it's in an office building, is certainly not one i would make. I wouldn't also say "will never make much sense".

You seem to have some particular set of users in mind for which you believe it wouldn't make sense. Okay - i'm not sure that changes that there are plenty of sets of users for which it will?

I even gave you examples of high end wood machines that have CAM directly integrated. There are many.

(They can also be programmed offline, but)

As for "knowing" the physical limits.

That's not actually possible since it there is no way to self-configure it even if everything did talk to each other. They don't know their own physical orientations (and it would be very expensive/hard to do that, and you'd still be guessing in the end)

Most of the non-safety/accessory programming is essentially explaining enough of the physical orientation and placement of things to the motion control that it can do something.

English is not my first language, so forgive me if I'm a bit ambiguous, it's not the intention.

CAM workstation (running some "generic" CAM package with machine specific configuration) in some office building was the precondition, in that case it will never make much sense to control a machine's servos from that workstation, in my opinion.

Integrating the CAM within the machine itself is something else, and yes, stuff like that existed for very long time, but that is something completely different IMHO.

The machine controller "knows" the physical limits because somebody configured it (and "locked" it). It would be hard to guarantee the integrity of this configuration if you put it on an arbitrary workstation to run CAM and machine control.

There will always be some sort of interface between CAM and other design tools and the physical apparatus to execute assembly. I think we're all just being pedantic in this thread; is it likely you're going to hook your workstation directly to the multi-axis mill? No. Is it more likely we're going to have some sort of queue and bus that'll allow you to send more complex instruction sets to assembly systems? I think so (based on my interaction with a firm who is doing this for high precision additive manufacturing). What that looks like is going to depend on the complexity of your shop floor, and manufacturing demands.

> They don't know their own physical orientations...

Wait, so even the really high-end gear in high-end names like DMG Mori don't use something like millimeter radar, ultrasound or machine vision to confirm that real-world orientations at least correspond to within a few orders magnitude accuracy of what is expected? If so, then mad props to you machining guys working with such expensive kit without continuous closed loop monitoring conditions; you re-e-a-a-ally like to live on the wild side.

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