Suggestions for a plasma table

[Welder Dave]

I wasn't referring to a downdraft table just a fume extractor like used for welding that sucks the fumes right from the source. With plasma you could have it pretty close unlike a welding application using shielding gas where'd you'd have to be careful it wasn't too close. They work really good. That's why I was wondering if a nozzle could be set up right at the torch that moves with the torch.

 

[Entropy1]

Maybe?

The biggest problem is that the fumes you need to extract are on the opposite side of the plate being cut. Thus you'd need a mirror set of CNC controls on the opposite side of the plate being cut - to maintain the fume extractor directly opposite of the torch at all times. It would probably be more cost effective to draw suction on the entire void.

 

[Entropy1]

The other thing to consider - plasma is hot, but short lived. The molten metal being introduced into the airstream however is over 2800 degrees F, and remains hot for quite a distance (potentially all the way up the suction tube & into the filtering element). I assume there's some sort of protection designed into weld-fume extractors, however sucking weld fumes is not comparable to sucking molten metal straight off the business-end of a plasma cutter. I don't know if the machines are rated for that type of service.

 

[Welder Dave]

It would suck the fumes up from the top. Obviously wouldn't get all of them but could get a lot of them so you're not breathing them. Welding fume extractors are designed for hot gases, molten metal fumes, sparks and are commonly used with manual plasma torches. Getting rid of a bulk of the fumes is better than not getting rid of any of them.

 

[Entropy1]

For the home hobbyist, a 1-hp dust-collector blower with 30 feet of 4" hose - sucking up the weld smoke & blowing it outside the shop works well - very useful for SMAW, which makes a lot of nasty smoke. The setup even works well when welding outside on a calm day - Sucking smoke and blowing it 30 feet away is 1000-times better than having it rise up around your weld-hood. Usually on a calm day there is still a somewhat detectable breeze (however slight). Watch the smoke & point the blower discharge downwind from where you're welding.

It's completely illegal if you're a business, as filtration is required prior to discharge.

 

[Welder Dave]

Self-shielded flux-core is especially bad. I worked in a shop that did automatic and some manual chromium carbide overlay with 7/64" open arc wire. Nasty nasty stuff but thankfully they had pretty good fume extraction. I was shocked when I suggested they could get fume extraction Mig guns, that they had never heard of them or any welding sales people had not suggested them. I think it would have been an easy sale. Chromium fumes are about the worst.

 

[ThatGuysFarm]

I had a 5'x10' down draft table which was my first plasma table. It was used and worked ok, but you needed the entire deck covered or the fan doesn't do jack. When we were cutting smaller sheets we would cover the rest of the deck with carboard. We traded it off on a larger 6'x12' water table and it is leaps and bounds cleaner, quicker, and easier. From a software point of view it is the same, and we kept the Hypertherm 85 from the other table. But cutting same parts is less mess and prep. Have you seen the Arc Droid machines? If I was going to get a table for my personal shop I might look there. They look pretty handy and they use your regular hand plaz. Now if you are cutting a bunch of parts for other people you shop would be a disaster, but if you are doing some fab for yourself and need a custom bracket or dash part they would be slick.

 

[Welder Dave]

I'm not familiar with the Arc Droid system but looking at them seems like a pretty economical way to get precision cut small parts and is really compact. Doesn't take up a lot space and can be easily moved if necessary.

 

[digger doug]

I find keeping the water at most 1/2" under the plate bottom works best for me.
No steam to speak of, no smoke, and the splash up from under keep the parts cool.
I've tried submerged, and you get a more tenacious slag from the extreme quench.

You get more steam (all over your machine's bridge) if the water level is lower.

 

[digger doug]

No. Not yet, at least. Floor space in my shop is more important right now and I really don't have the time to brush up on my CAD/CAM abilities. Cheaper to go without right now for the amount of work load that I currently have. Sure would be nice to have but only so much time in the day.

I would think the first thing you could do is get the CAD system up and running.
When you send a part out for cutting, sending the CAD file lowers the cost greatly.