Plasma Cutting Workshop - March 25th
For our next maker event we are going to visit FastCut CNC to learn about CNC plasma cutting. I thought this was a good fit because there is a lot of interest in CNC and metal working in our community. During the workshop Jordan Adair and possibly some of my other coworkers will give a brief introduction to CNC plasma cutting and share some tips and tricks. We will show you how a 2D design is prepared and profiled for plasma cutting.
To make this tour/workshop even more special, I plan to cut your designs on a sheet of 14awg at the end of the workshop. Stay tuned for more details.
- When: Wednesday March 25th from 6pm to 8pm
- Where: FastCut CNC
- Cost: 5$
In order to cut a shape on the plasma cutter you need a 2D model, preferably in
dxfformat. I can also help you trace an image or convert an SVG image to dxf. For an example of how you can trace an image and prepare it for plasma checkout this post. If you have any questions or suggestions let us know here.
Aras works at FastCut CNC
@arasbm Did you want an event listing created?
20 spots. You can pay online or to you, or cash at Kamloops Innovation (with Amanda) or cash at the door, etc.
@amanda yes please! 20 spots sounds good. I have a feeling this will be sold out, so lets not advertise cash at the door. Thanks!
@arasbm okay sounds good!
Event page is live! https://www.picatic.com/fastcutcnc
You can pay online or drop by Kamloops Innovation with cash if you like. We’re open around 8:30-4:30, shoot me an email or here if you are going to come by.
There won’t be any tickets at the door, so please grab a ticket in advance!
Seem like most people are wanting to leave buying the ticket to last minute. But if you are planning to come dont forget to tell me here what you want to cut so I can help you get a 2D design prepared. During the actual workshop we wont have enough time to do a custom drawing or tracing. If you want a custom shape cut for you, get it to me in advance!
Everyone will get at least 1 sqft on a 14awg mild steel material which we will be cutting on the 25th.
In case you need some more inspiration here is a video of a sign I cut for Victoria Makerspace on Friday:
If you do not know where to start find or make (or find) a silhouette image of what you want to cut. Then we can trace that to get to a 2D model.
Hi Aras, I’m still sketching away on the piece I’m interested in trying out, should get them to you this week though. Could you clarify the thickness of the sheet we’ll be cutting out? You said 14AWG, but that’s a wire gauge, not normally applied to sheet metal. 14 AWG would be about 1.6mm thick, where 14G sheet steel would normally be closer to 1.9mm, and a lot sturdier. I’m looking to do some art-metal stuff this time and I suspect that the thickness involved will be more than I need, if anything, it might be a problem for the folding I’m looking to do. Might have to get out the torch and work hot.
I have a couple of parts I wouldn’t mind getting made.
I’d like to get 4 of these made:
https://www.dropbox.com/s/h66s5qstz6i38r1/5 Hole 90 Degree Joining Plate.dxf?dl=0
2nd choice (I think this puts me over a square foot, but I figured it can’t help to ask)
I’d like to get 2 of these made:
Both files are using millimeters as the units. I don’t know how small a detail the plasma can do, so if the holes are too small (for example) then I can always drill them out myself.
I’d also be interested in finding out what the cost would be if I were get these done as a paying customer (mostly just curious to get an idea for other stuff)
I was probably going to cut these out of aluminum once I get my OX going, but the plasma event seemed timely.
@pierre you are right, I used the AWG incorrectly. The sheet is as you said ~1.9mm thick. I can show you some samples and if you think it is too thick for your project, I can try to find an scrap piece of 16G and cut yours out of that.
@dhylands I am sure I can fit your 6 pieces in there, no problem. My only worry is some of the holes may be too small. I will do a test next week to see how small of a hole I can cut on the plasma on the 14G sheet and will take pictures. Generally, if the whole is too small, it would be better to leave it out of the design and cut it later. Pierces don’t work well as guides for drilling either since they harden the metal and actually make it much more difficult to drill. Other than that, your pieces should cut very nicely.
Just to double check the cross in the middle and the short lines around the circle are not actually meant to be cut, right?
Thanks for the updates Aras. I’m going to try altering my drawings to get a decent minimum bend radius on 16G. Should not be hard. I’m putting in dashed lines where I plan to bend, which should make it easy to fold on those lines, then I can weld up the folded corners and grind smooth. I think that if I make the dashed lines about the same thickness as the sheet, then the “web” between the dashes should fold easily and cleanly. This is the sort of thing I would not want to try with my hand-held plasma torch… I am not nearly precise enough to not make things worse instead of better here. I usually plasma out a bigger part than I need, then use a combination of nibbler/grinder to take it down to the lines.
You should be able to work around the hardened area on the steel with a torch. If you need to machine/drill in the heat affected zone, just anneal the affected area by bringing it back up to around the color of “boiled carrots” with the torch, then cool it slowly over the course of a minute or so. The steel will be soft again when you get it done. Come to think of it, I will probably have to do this to get folds on the dashed lines on my part anyway. If it is harder there, it’ll shift the bend over. If it is very hard there, it’ll crack when I go to bend it.
The quick and dirty way is heat it with the torch and then back the flame off and move the hot spot around to keep it from cooling too fast.
It’d be better to chuck a thick piece of scrap into a hot fire and get it good and hot, then back up the area where you are going to anneal with the block of hot steel. Bring it up to temperature with the torch and bury it in hot ashes from your fire. This will make it cool slowly and also produce a reducing environment to keep it from scaling too badly.
The professional way is to use a tempering oven to do it. A proper oven will have a hookup for an inert gas like argon to flood the part and keep oxygen away and a PID controller with a feedback system to bring the contents up to annealing temperature, hold them there to let the heat fully penetrate the parts, then slowly ramp back down, probably over the course of a couple of hours.
If I were annealing a large number of small parts, I’d use the modified toaster oven in my shop to get it done. No proper inert-gas flooding system, but I can put entirely inside one of my old aquariums and flood it with argon from the TIG welder tank. The gas is heavier than air, so it should stay in the aquarium, mostly. I have a SSR that will take the current, so if I just push the toaster to max, I can have a raspi or arduino use PWM to control the duty cycle and run a ramping program. Be better if I dig out one of the Type K thermocouples from when I was experimenting with DIY sous vide and get one of these boards https://www.adafruit.com/products/269 to implement feedback… but I’ve used both the torch and the toaster oven (without shield gas, and just by manually tweaking the dial every few minutes) in the past to anneal or temper parts to achieve desired results.
'Nother quick question: Will your controller interpolate curves? A lot of 2D vinyl-cutters will only work on the straight segments of a DXF file, so it becomes necessary to interpolate the nodes on a curve and then turn it into a bunch of approximate straight segments… Usually at that point, I’ll keep both an original drawing and the ouput version, because any editing I need to do is easier with the bezier curves.
@arasbm Yeah - I don’t know why those extra marks and stuff are there. I can remove them. It looks like they were intended to go into a different layer.
Will your controller interpolate curves?
Yes. Generally the less points you can have in the drawing the cleaner it is, less G-Code will be generated and it cuts nicer. So use curves as much as you like and try to remove any extra points.
Just a thought: if the computer file tells the plasma cutter to cut from that file, it would be handy to have that plasma cutter make a mark where a hole is to be drilled later. It would be more accurate than any other way those marks could be made. If the test piece had a few tiny lines on it, we could assess which size of line works best for drilling a hole.
@cam The absolute location of the holes on the plate isn’t so important, it’s the relative positions of the holes to each other that’s important.
I’m used to picking up an edge to locate where to put features when swapping back and forth between the lathe and mill, or even when flipping a part over on the mill to perform operations on the other side.
So even if I can only get the pieces cut, I won’t have any problems putting the holes in (they’ll either get drilled on my new OX or on my Sherline mill) - under CNC control in either case.
@arasbm Hi folks! I’d love to come along next Wed. Is there anything I need to do/bring other than $5 and perhaps send an drawing. I am totally new to the Makerspace after Dave H (@dhylands ) mentioned it.
@Andrew great! Looking forward to meeting you. There is a good chance this event will be sold out so I would recommend grabbing your ticket in advance.
If you like me to cut something for you during the workshop, send me the drawing here. I can allocate around 1sqft to each participant.
If you have shade 5 or 8 goggles bring them with you, we will have to take turns to look closely at the torch and for that you’ll need to use eye protection.
My ten mask is too dark? Is it useful to bring if someone has a lens for it?
@hdsheena ten would be to dark. 8 would be a little to dark to. A 6 shade would fit in your mask if anyone brings one. It is definitely overkill though
I created the following variations:
Hey Aras, I just signed up for the event! I was hoping to cut out something like the attached screenshots (I am still tweaking them, but I will have dxfs soon). It would include 4 pieces, about 6" x 4" for each. Do you need any specific stuff on the dxf file other than an outline for each piece? Also, should the interior holes be on a different layer? and finally would you like me to nest them myself in a small area or just leave each piece as an individual file?
Also, if anyone is trying to make dxf files or create a mechanical design I can help create a design in SolidWorks for you, just send me a message.