CNC milling with open source software • Hacker News Board

Re: CNC milling with open source software

#31

Post by rmu09 » Fri, Jan 18, 2019, 5:42 PM UTC

nickpinkston wrote: post #25

th0ma5 wrote: post #23

Earlier quoted context omitted.

Is there no way to test? Or there is, just not everything?

The best shops use simulation tools, but you need the 3D models / configurations of everything to make them work, and then the machinist still needs to load everything correctly. It's very easy to make a mistake. Check out a simulator here: https://www.ncsimul.com/

There are machines that are "self-aware" in the sense that they run a simulation parallel to the NC control, slightly advanded in time, to catch catastrophic crashes and ESTOP the machine. Cutting into the machine bed can be _very_ expensive.

Re: CNC milling with open source software

#32

Post by syntaxing » Fri, Jan 18, 2019, 5:43 PM UTC

I owned a 3020 and own a Shapeoko 2. Unfortunately, I rarely use them. The biggest problem with CNC is that the overhead is so expensive. There's very little room for mistakes and material cost (stock and bits) can get very expensive. Holding a part can get tricky and the wrong feedrate can ruin your part. I end up using my 3D printers to do most of my parts nowadays. Though I do use my CNC for "food grade" stuff around the house.

Re: CNC milling with open source software

#33

Post by lvh » Fri, Jan 18, 2019, 5:50 PM UTC

tlarkworthy wrote: post #27

G-code is the most hilariously bad language. Keywords are G + a number, e.g. G01, with wildly different effects, varying arg lists and no standard. E.g. G01 move to position, G20 set the machine units to inches. Its often stateful. Obviously its coz its old and works, but i chuckle everytime i have to look up the codes at how comically awful it is compared to anything else i see https://en.m.wikipedia.org/wiki/G-code

What would a good G-Code variant look like? For all its flaws, it's pretty good at encoding the exact thing you want the CNC machine to do and while there certainly are different post-processors for different machines and in most cases they're not optional, it's also not like they're entirely different.

I think of G-code as ASM. For high-performance work you might write code differently for different (related) machines, but it's still a pretty OK compilation target.

Re: CNC milling with open source software

#34

Post by grawprog » Fri, Jan 18, 2019, 5:54 PM UTC

tlarkworthy wrote: post #27

G-code is the most hilariously bad language. Keywords are G + a number, e.g. G01, with wildly different effects, varying arg lists and no standard. E.g. G01 move to position, G20 set the machine units to inches. Its often stateful. Obviously its coz its old and works, but i chuckle everytime i have to look up the codes at how comically awful it is compared to anything else i see https://en.m.wikipedia.org/wiki/G-code

The g-code variant my machines use contains most of the control structures of modern programming languages. It has variables, comparisons, loops, subroutines, the codes are all fairly straight forward and honestly a lot of g-code is produced automatically with CAM software rather than being written manually these days.

It's a simple language, you don't have to memorize the codes and you end up memorizing the few you use most often anyway.

Honestly the actual math and figuring out the toolpaths for your machine ia far harder than writing the g-code for it.

Re: CNC milling with open source software

#35

Post by grawprog » Fri, Jan 18, 2019, 5:56 PM UTC

opwieurposiu wrote: post #18

CNC is programming "for keeps". Any tiny little error in your gcode has a chance to crash the machine. Unlike a computer crash, a CNC crash results in broken metal flying across the room and anywhere from $5- to $5000 in damage. I programmed for a heavy machine shop for a year before I gave up and went back to making websites. Hobby CNC is fun though, it is amazing what you can make out of wood when you can shape it…

Spindle crashes are terrifying. I've had a few. I've destroyed tools and pieces. Cost thousands of dollars in damage from a single misplaced tool path or lead in/out.

There's also this very transitive nature to the programs. Unless you make a whole bunch of the same pieces your programs tend to be one time use. 99% of the things we make in our shop are fully custom meaning brand new programs for every single table.

Re: CNC milling with open source software

#36

Post by dylan604 » Fri, Jan 18, 2019, 6:14 PM UTC

gangstead wrote: post #21

nadavami wrote: post #8

Earlier quoted context omitted.

I've been using a 3018 CNC with pretty good results. They're fairly inexpensive machines (about $300 I believe) and are decently accurate. I still order boards from China, but for a quick breakout board it's incredibly handy! I also decided to get a 5W laser which is also pretty fun to engrave with. I'm planning on writing a series of blog posts about it if you're interested! As a last note, if you like tinkering, th…

I'm definitely interested. I got into 3D printers and CNC machines at about the same time last year. I figured out the 3D printer right away and quickly went from printing out things on thingiverse to doing my own designs and outgrowing my printer and getting a fancier one. While I've done about 250 print jobs in just under a year on my 3D printers after 8 months with the CNC I've cut two things. I got an entry level…

There's a big difference between an additive process vs subtractive process. To me, additive is much easier as it starts at the bottom and build up. Nothing is ever in the way of the next step. Subtractive is much more difficult as you have to figure out how to get to places that needs tooling, how to hold the piece to do the work on it (especially as the piece changes shape in the process). Most projects I work on requires more work in setup than actual milling/cutting/etc. It's one of those things that most people just don't realize until they actually attempt it.

Re: CNC milling with open source software

#37

Post by NegativeK » Fri, Jan 18, 2019, 6:15 PM UTC

syntaxing wrote: post #32

I owned a 3020 and own a Shapeoko 2. Unfortunately, I rarely use them. The biggest problem with CNC is that the overhead is so expensive. There's very little room for mistakes and material cost (stock and bits) can get very expensive. Holding a part can get tricky and the wrong feedrate can ruin your part. I end up using my 3D printers to do most of my parts nowadays. Though I do use my CNC for "food grade" stuff aro…

This is largely the difference between hardware projects (not just electronics -- metal and wood as well) and software. Decent quality physical things and materials can't be downloaded and reused indefinitely.

Re: CNC milling with open source software

#38

Post by joshu » Fri, Jan 18, 2019, 6:18 PM UTC

th0ma5 wrote: post #23

opwieurposiu wrote: post #18

CNC is programming "for keeps". Any tiny little error in your gcode has a chance to crash the machine. Unlike a computer crash, a CNC crash results in broken metal flying across the room and anywhere from $5- to $5000 in damage. I programmed for a heavy machine shop for a year before I gave up and went back to making websites. Hobby CNC is fun though, it is amazing what you can make out of wood when you can shape it…

Is there no way to test? Or there is, just not everything?

https://camotics.org/

Re: CNC milling with open source software

#39

Post by CapitalistCartr » Fri, Jan 18, 2019, 6:22 PM UTC

opwieurposiu wrote: post #18

CNC is programming "for keeps". Any tiny little error in your gcode has a chance to crash the machine. Unlike a computer crash, a CNC crash results in broken metal flying across the room and anywhere from $5- to $5000 in damage. I programmed for a heavy machine shop for a year before I gave up and went back to making websites. Hobby CNC is fun though, it is amazing what you can make out of wood when you can shape it…

I program non-ferrous CNCs. Someone-who-wasn't-me crashed the head (router motor). $35k. Instantly. Breaking $160 bits is trivially easy.

Re: CNC milling with open source software

#40

Post by dsfyu404ed » Fri, Jan 18, 2019, 6:23 PM UTC

opwieurposiu wrote: post #18

CNC is programming "for keeps". Any tiny little error in your gcode has a chance to crash the machine. Unlike a computer crash, a CNC crash results in broken metal flying across the room and anywhere from $5- to $5000 in damage. I programmed for a heavy machine shop for a year before I gave up and went back to making websites. Hobby CNC is fun though, it is amazing what you can make out of wood when you can shape it…

>I programmed for a heavy machine shop for a year before I gave up and went back to making websites.

Yeah, very few people seem to be able to transition from "ship it now, fix it later" tech to programming for industrial purposes where you can't test everything without risking physical hardware. The other way around seems to be a much easier transition.