Plasma cutter, automation project

tomrscott · Feb 27, 2005

Somewhere I had read that there is a risk of getting a build-up of hydrogen trapped underneath your work when you cut in water. The place I was reading had a suggestiion for evacuating the hydrogen, but the trouble is I can't remember what they said or where I read that.

I know that is not much help. I may be able to find it again. I've been scouring so many things lately.

sierrabob · Feb 27, 2005

I've been cutting in water for the last 6 years and have experienced no problems. Although by keeping the water level just below metal I'm probably not setting myself up for this problem. Tommorro I'm going to call the tech support for Hypotherm, they have always been very helpful and can probably answer this question. Thanks for the info!

sierrabob · Feb 27, 2005

You're right! on the last page of my Hypertherm Operators Manual there is a discusion on aluminum cutting and the problem with creating free hydrogen. They also tell you how to build a PVC Aeration Manifold to add oxygen back into the water. I really never cut aluminum so have not incounted this problem. Once again thanks for the info!!!

jimgerken · Feb 28, 2005

Software I use to create almost all my mechanical parts is Catia. It is a 3D solid modeling software with sheetmetal package. The sheetmetal package puts in the material bends and reliefs automatically. There is a one-button flat pattern, and then it will produce a 2D DXF file output of the finished part. Catia is pretty expensive. I am actually using an old "try it" version from a few years ago. Couldnt remember where I got it.
Master5 does not allow Torch Height Control (THC). The same author does offer a slightly more advanced software that does THC. I have not yet upgraded. It hasnt really been all that bad doing the height manually. Lately I have been thinking I will at least motorize the Z rack, and run it from a handheld wired remote, so I can stand back and do it from any side, even when the torch is out in the middle or hard to reach.
Water is a good idea, I want to try that, the air quality could certainly benefit!
My racks are 20 degree, 24 pitch, from memory.

Rgillard · Mar 30, 2005

Jim,

Could ya tell me what stepper motor controller board you are using? Was looking at one there on www.stepperworld.com they have a good deal on the SP-3/HT. any info would be appreciated.

Ronan

jimgerken · Mar 31, 2005

I used a Brewington Tech board. Go here and find the link to Brewington:
http://www.kellyware.com/links/links.shtml
I went to the link but it wasnt much of a site. Try calling or emailing them from the "ordering" link. The board type is a "chopper" which allows the current to be set and the voltage to be WAY over-driven. That is how a person gets performance from steppers. Give them 5-6 times their rated voltage but limit the current. Current limiting can also be done with resistors in-line, large ones which will get hot. But the most efficient solution is to use the chopper driver. The power supply you add to a Brewington chopper is simply a transformer (of about 30-35 volts output). the board does the rectification as part of the circuit (steppers use DC). My board is a three channel unit and cost me about $110 from memory. It has worked in the most hostile environment I can imagine for electronics, from the standpoint of conductive dust and Electromagnetic radiation, stray voltage, etc, for two full years now. I have cut many many parts with it. Hope you can find a way to contact Brewington, they sold me a good product. BTW, NEMA 23 motors sell for about $20 each, all over the internet and on EBAY.
I looked at the Stepperworld stuff, they do at least one "chopper" board (or kit), the MS-1. I think it is only a single channel, and might be in kit form. From everything I read when I did this, the chopper is the way to go, BUT the kit you have your eye on does give great value and it is nice and complete, even some documentation. You will appreciate the "help" the complete kit will give. There were LOADS of unanswered questions for me to dig up when I did this. GOOD LUCK and WELCOME TO THE AUTOMATED WORLD! /forums/images/graemlins/grin.gif

Rgillard · Aug 17, 2005

do you think this project would be achievable using an oxy propane cutting torch rather than a plasma cutter

frederic · Aug 18, 2005

Weird. I posted this twice so far, maybe this third time it will work properly.

Here is a picture of my "in progress" CNC Plasma cutter table thingy.

here you can see a 2mb video of how nicely it slides around too: Sliding CNC trucks

I've chosen to use CNC pro for the software, and I downloaded the free, limited use version just to test my homemade stepper drivers. I built the stepper drivers mostly out of junk Iv'e collected in baby food jars over the years. Transistors from this jar, resistors from that jar, CMOS chips from that jar... heh-heh.

I was going to buy the "Gecko" controllers, but at over $100 each, needing three, that got expensive quickly. Since I recycled parts I had lying around, my cost so far has been zero, for the electronics.

I took a PC104 form factor PC motherboard I had lying around and put DOS on that, it it drives my controller just fine. I have to weld together a little box/case for it, and mount it on the cutter table at the back next to the power supply. The power supply also was a no-cost option, also built of collected parts.

The table is very simple as you can see in the pictures, and no, it's not done. That's jsut as far as I've gotten so far, I've been engrossed in other projects and haven't gotten back to it.

Got four Nema23 180oz unipolar steppers too for a mere $150. Was a price I couldn't argue with.

Anyway, a DIY plasma cutter is not that difficult to make... I'm an amatuer and mine's starting to look okay. And to whomever asked - you are not obliged to mount a plasma cutter gun there - you can also mount dremels, routers, rotozips, a cutting torch, pretty much whatever you like. I intend to make the "Z" axis in such a way that with four allen-head machine screws, I can change the "head" mount, so I can eventually use this thing for many different types of material. Though, my design is gravity based, which is just fine for any type of cutting tool that does not touch the material, such as a plasma cutter or an cutting torch. For a dremel, rotozip or router, my table design is not appropriate. You'd need to make the tracks in such a way that vertical movement is not possible, to prevent the router from getting snagged in the material, and the "truck" to keep going, tilting the router.

There is a yahoo group called "DIY CNC" if you guys are interested, there is a ton of good people there are take this hobby fairly seriously, and share what they know.

Also, I'd be happy to answer emails about making your own, if you like. YOu can post here too, but I don't get to check this forum as often as I like. I have too many projects going, and a newborn.