Workholding is generally not a problem on a big CNC plasma cutter.; gravity does a pretty good job of keeping heavy sheet steel in place on the bed. But what if your CNC table isn’t a table? The answer: magnets — lots of magnets.
The backstory on this is a bit involved, but the condensed version is that [Lucas] needed a CNC plasma cutter big enough to cut full-sized sheets of steel, but lacked the floor space in his shop for such a beast. His solution was to build a custom CNC machine that stands more or less vertically, allowing him to cut full sheets in a mere fraction of the floor space. It’s a fantastic idea, one that he put a lot of effort into, but it’s not without its problems. Chief among them is the tendency for the sheet metal to buckle and bulge during cutting since gravity isn’t working for him, along with the pesky problem of offcuts slipping away.
To help hold things in place, [Lucas] decided to magnetize the bed of his cutter. That required winding a bunch of magnets, which is covered in the video below. Mass production of magnets turns out not to be as easy as you’d think. Also unexpected was the need to turn off magnets when the cutting torch is nearby, lest the magnetic field bork the cutting plasma. [Lucas] grabbed some code from the LinuxCNC forum that streams the gantry coordinates over serial and used an Arduino to parse those messages. When the torch is getting close to one of the magnets, a relay board cuts power to just that magnet. You can see it in action in the video below; at around the 18:15 mark, you can see the sheet bulging up a bit when the torch comes by, and sucking back down when it moves on.
The amount of work [Lucas] put into this project is impressive, and the results are fantastic. This isn’t the first time he’s relied on the power of magnets to deal with sheet steel, and it probably won’t be the last.
The magnets messing up the plasma cutter is definitely the most interesting part. Pretty smart to just cram a cnc machine in vertically if you don’t have the shop space
Ladies and gentlemen I present… the Maslow.
I want to know how often the torch cuts a slot through a magnet… :-/
That was my thought also.
He shows a few magnets that clearly got hit. They seem fine, at least for now, although I’d imagine they’ll need replacement at some point.
If the magnet locations can be marked on GUI preview, it would be possible to adjust the work offset to avoid them.
The cool thing about a plasma cutter and steel sheets is one can cut and stack plates to make fine-pole electromagnetic chucks where the actual magnet is oriented sideways when you accidentally cut into it, you only cut into the pole plate stacks, which are cheap to make and can be made replaceable.
For example, 4mm thick stock gets you 5+5 poles across an 80×80 mm area, which is nicer for thin stock than a single magnet.
Longtime follower of his. I’ve learned to be less of a perfectionist from watching videos like his. He gets stuff done. I have no problem getting my hands dirty, but I can’t image spending all my waking hours with hands as dirty as his.
Have you seen his vid where he builds an automated hand washing statement as a gag after he got so many comments about his dirty hands?
Not only did he build a vertical cnc plasma from scratch. He built the shed to house it almost completely from free material. This guys great, and he deserves more subs!