Inside a 150 euro plasma cutter... - Page 1
Forum section: electronics / general

author: nctnico
author_rank: Super Contributor
timestamp: December 12, 2022, 10:10:50 pm
content: For one of my projects I needed to cut a hole in a sheet of metal that doesn't fit on my mill. There are several ways to do that but my father suggested to use a plasma cutter. Turns out these aren't very expensive and didn't need a huge investment in protective gear as well (shaded safety glasses seem to be enough. I bought 3M 2845 safety glasses; not something unspecified from Amazon). OTOH a plasma cutter needs a beefy compressor. I have a 230l/min compressor and it kind of keeps up with the cutting pressure set to 4 bar.I found a Güde 20092 plasma cutter GPS-E 40 A.2 on Amazon that could be deliverd quickly. Güde is one of the many brands that labels cheap Chinese equipment under their own brand. But they do have an office in Germany that sells spare parts. I also have a mitre saw from Güde and when something broke off, I could order a replacement part (not cheap though but less than a new saw). Not that I'm happy with the mitre saw; wouldn't recommend it.The torch is pretty standard for Chinese plasmacutters and parts are readily available. I bought some nickel plated electrodes and nozzles. According to a Youtube review the nickel plated nozzles are nicer to work with. The difference I noticed is that the copper nozzles are flat at the business end while the nickel plated ones are round.One problem I discovered while testing it was that the air pressure regulator valve was too small (500l/min) and not very precise (pressure dropped a lot during cutting). I bought a bigger pressure regulator valve (2000l/min) for around 25 euro from Aliexpress (the same ones are sold for around 75 euro / dollar on 'local' websites). I needed to take the cover off to fit the new regulator valve so I snapped some pictures of the electronics inside:From bottom to op: input filter, air valve, low voltage power supply and control board. To my surprise the boards have a conformal coating to that should make them resillient to moist environments like being stored in an unheated shed. Not bad for this price level.Look at how the components are placed on the control board. Could this board be fully autorouted / auto placed? I can't remember ever seeing a board with SMD parts being layout with a fixed distance between all components.The power electronics. At the top there is a HF injection board to start the arc. It seems to be fed by the main transformer (big toroid which also provides the isolation between mains and the secundairy side. The output of the HF board is injected into an inductor in the output. It looks like a relay on the control board switched the HF injection on/off. The big blue block attached to the heatsink looks like a Hall effect DC current sensor.All in all there is quite a bit of electronics inside this machine. Amazing how they can sell it for this price (even with the pressure regulator upgrade).And ofcourse I didn't buy it for one project. Every now and then I mill holes in aluminium plate material which is quite tedious to do. And the plasma cutter can also cut steel so it would enable me to use steel as well. I already made a steel bracket to hold a lamp on my mill.

author: thm_w
author_rank: Super Contributor
timestamp: December 12, 2022, 10:54:27 pm
content: What kind of cut quality are you getting?There are also sheet metal nibblers, probably much more limited in thickness though.https://www.youtube.com/watch?v=G4DoSOj9czIedit: would be super impressed if that were auto-routed, but, some parts are closer and some are further apart. Probably a very meticulous designer. Maybe working on large grid.

author: nctnico
author_rank: Super Contributor
timestamp: December 12, 2022, 10:59:22 pm
content: Quote from: thm_w on December 12, 2022, 10:54:27 pmFor thin (1mm / 2mm) aluminium sheet it is pretty good once you get the settings right. Like with a hand saw but straight if you drag the torch along a guide. In 4mm steel the cut gets rougher but then again I didn't optimise the settings that much.

author: coppercone2
author_rank: Super Contributor
timestamp: December 18, 2022, 03:50:41 pm
content: lol is that auto router ?

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 18, 2022, 06:55:04 pm
content: Quote from: coppercone2 on December 18, 2022, 03:50:41 pmIf it was, did a real nice job.I've done some autorouter/placer attempts in the past, either the settings or the software were crap, but the output was terrible, just like steel scourers, everything wrapping around in very messy patterns.