After many delays my new shop building is coming close to completion and I am exploring some new equipment options. Plasma has interested me for a while as a better way to process sheet metals but I have some questions about managing fumes and emissions. I am curious what others in similar circumstances have done.
I do a mix of machine shop, electronics, and woodworking, and being able to do some welding and fabrication has always been an interest.
A small plasma table would be useful for some things I’d like to do, but I have heard that it generates a lot of smoke and airborne debris. I also have some uses for cutting stainless for food-contact applications, and my understanding is that plasma cutting stainless generates hexavalent chromium emissions which I definitely don’t want in my lungs or precipitating out of the air onto every surface.
Welding-wise I am planning on GTAW and will be buying some type of fume extractor/filter like the Fume Dog for that. The woodworking area will have a good strong dust extractor and dust collector setup as well as an overhead HEPA filter to limit that. If I was going to do extensive wood work, I will probably cover the VMC/lathe/bandsaw to reduce fallout on them.
As it is, I am finding that on many of my parts it is almost the same price to have SendCutSend laser the part for me as it is to buy the raw material and do it myself. Anything beyond that starts to stack up ($5-10 per bend or tapped hole) fast but since most of my projects can afford to wait 3-7 days I am not sure if the plasma adds enough value to justify a lot of mess/complexity.
I have a plymovement exhaust fan. I do want to get a teefor it and put in a arm for the welding area. For PPE I normally wear a GVS half mask and then I have a selstrom face shield which I converted in ad flow to dump fresh air into when I’m cutting.
I priced a project in stainless and it was basically $115 to buy the 304 sheet and do the rest myself or pay SCS $125 and have them laser the parts. Depending on the metal supplier, sometimes SCS was $5 less. So the factor I’m grappling with is, if I design most/all of my parts in CAD, and can wait a week to get them, does having plasma onsite actually yield a net benefit?
Where their costs go up a lot faster are the ops that involve handling. So the $20 part becomes a $30 one with four bends, and a $40 one with six tapped 10-32 holes.
As for metal costs, well, we’re all just a fly on the world’s windshield.
Is this like a PAPR setup? I know that’s the gold standard for really hostile conditions. I can do that if I need to, but was hoping to avoid the need as it would mean I’m essentially nuking the shop for however many hours after I do something nasty. I’d rather not have to wear that while running the VMC or lathe waiting for the air the clear out.
Does Cr6 contaminate surfaces too, or does it stay in the air until the air turns over?
So when you buy the raw material are you buying something cut or sheared or are you buying a full sheet and cutting it yourself?
Also you have to remember the more you buy the cheaper the steel gets.
Most times I can buy a full sheet of material for a piece of half that size sheared or cut.
As far as plasma, I do powder coating and I move my table in the booth when I cut. You are correct Plasma is a dirty nasty process.
You also have to remember laser and plasma are two different things. Before making your decision have some one here on the forum, cut you some samples of your parts so you can compare with Laser.
As far as welding I have Fume Extractor with a HEPA filter and it works well unless you moving around on a large fixture table. Due to that I am selling mine and will just go with a respirator.
Right now all of this is just research in advance of buying anything. I’ve cut some flat parts on my CNCs, which worked because they were small, but not ideal either. Plasma cut quality is acceptable for probably >90% of what I do.
I went and ran the numbers again and I see I got a little confused so my numbers weren’t quite right. This is a project I’m working on right now which I thought would be a good test case. It’s basically a firebox for a barbecue, about 8x17x12" and made out of a mix of 14 and 18 gauge 304. I could probably get away with thinner but it will get beat on so didn’t want to start out too stingy.
Pricing this through SCS I ended up almost exactly $150 shipped. That is just for lasering out the parts. Bends cost about $2.50 each, so if I have them do those the final bill is $215. I went to Metal Supermarket, and to buy two 304 sheets cut roughly to size to make these parts comes out to $142 + S&H.
Now, you are right that there is a cut-size premium in there that is quite large. A 48x96" sheet of each size comes out to $760, and would probably make 10-11 of these, for the cost of five from SCS. So there is leverage in there, but only if you’re buying full sheets. $600 of material (probably $750 in 30 days ) I don’t need is a decent amount of $ to tie up on the stock shelf unless you know you’re going to use it relatively soon.
What is interesting is how much cost bending adds for SCS. Like many here I’ve been eyeing the 25T since I saw the announcement, and this shopping has me taking a second look at that.
I’m sure I could find alternatives, but my experience buying aluminum (most of what I’ve done in the past) was that everybody was pretty close on price unless you were buying a LOT of material. Metal Supermarket opened a retail location near me not long after Admiral Metals closed their retail department.
) I don’t need is a decent amount of $ to tie up on the stock shelf unless you know you’re going to use it relatively soon.