Considering building a small hobby CNC Plasma

like this www.expondo.co.uk/stamos-power-2-plasma-...-50-a-230-v-10020153

I am also looking at 50A Plasma to my upcoming build. Now on hold due to seller promising too much. Bought a combined AC/DC 200A TIG with plasma but unfortunately the well needed foot pedal does not work on this unit.

So I am on a lookout for another combined unit 200A AC/DC Tig, pulse, foot pedal, 50A plasma as I don´t have a lot of space. So either UK or DE is my choices.

3-phase is always the best but as I am having issues with my feed to my shop and had a 120A plasma that I sold due to power issues so it could not be used.

I think the suggestion to use the cheaper plasma machines with obsolete HF torch designs is bad advice. In fact, its the first time, I've seen a post anywhere recommending them. Most posts I've read about them have a common theme about problems.

In my (costly) experience, they don't last long. Pay attention to what Tommy has said about criteria when selecting a machine. Also consider a machine with a shielded tip to allow you to use ohmic sensing. A float switch is OK, but for 2mm or less, they do not probe accurately due to flexing in the material. I struggled with 2mm until I could do ohmic sensing. If you are cutting thin material you need this!

At the entry level you have Everlast which is sold in the UK as R-Tech:
Everlast USA
Everlast Australai
R-Tech in the UK
I would follow Rtech's advice on plasmaspider and get the Tecmo PM70 torch as this will allow ohmic sensing.

Look at their 50 amp single phase or 60 amp three phase machines. R-Tech in the UK becomes a no brainer for this machine as they are the only one I know who have put the hard yards in to get it profiled with cut charts for plasma cutting. Everlast hasn't.

Stepping up from there, you could consider the Hypertherm 30 amp machine and bring raw arc voltage out of the case via a resistor on each leg that sum to a 200v range as per the THCAD-10 manual but you won't have an ArcOK signal. A couple of members are doing this now.

So the last three brands standing with blowback torch and CNC port options, become Hypertherm or Esab who also own Thermal Dynamics these days.

As an alternative to Hypertherm, you could also look at the Esab/Thermal Dynamics 60i

If you go with Esab/Thermal Dynamics, make sure you get the optional full automation interface with AcOK and torch voltage signals as the basic machine does not bring these signals out to the interface port.

So in summary, I would say for the US, Australia and the UK, Everlast/R-Tech is the minimum entry level.
In Europe if you can't source from R-tech, see if you can screw a good deal out of forum member Grotius on a 60i. He is a Hypertherm and Thermal Dynamics dealer based in the Nteherlands.

I might just mention that Hypertherm is often touted as being superior over Thermal Dynamics but in my experience since purchasing a Thermal Dynamics A120 120 amp machine and comparing notes with the next door shop running Hypertherm, the real difference is Thermal Dynamics have many more tips for different amperage (about 7) so you need to be more particular matching consumables with the material to be cut where as my Hypertherm neighbour can get away with just 3 sets of consumables. For a small hobby machine, this will be less of an issue.

And don't forget plasma cutters need clean dry air. Some people try to use filters but in a humid climate, factor in a refrigerated dryer which might cost more than the entry level machine.

Thanks Rod, but re

Look at their 50 amp single phase or 60 amp three phase machines. R-Tech in the UK becomes a no brainer for this machine as they are the only one I know who have put the hard yards in to get it profiled with cut charts for plasma cutting. Everlast hasn't.

I phoned R-Tech today I asked them if they had cutting charts for the 50A www.r-techwelding.co.uk/plasma-cutter-r-tech-p50hf/ and they said no they don't have any.

I am confused though in the type of start as the one linked to has
"HF pilot arc for easy starting even on painted surfaces and HF pilot re-start - ideal for cutting mesh etc."
and the 30A machine has "HF arc starting enables easy starting of cut"

So re

I think the suggestion to use the cheaper plasma machines with obsolete HF torch designs is bad advice

what is a obsolete HF torch designs

I realise I have to get a 50A 230V machine but not sure of the specs required (this is for hobby use only)

Clive wrote:

"HF pilot arc for easy starting even on painted surfaces and HF pilot re-start - ideal for cutting mesh etc."
and the 30A machine has "HF arc starting enables easy starting of cut"

Hmm, it looks like there is a new plasma cutter in the lineup. This is not the same as the Everlast 50s I had. Just look at the front panel differences. Sounds like they are keeping the better one with CNC port for their Plasma table.

Clive wrote:

I think the suggestion to use the cheaper plasma machines with obsolete HF torch designs is bad advice

what is a obsolete HF torch designs

Any of the PT- torches as used on CUT-40's etc ex China. They are based on a 30+ year old design

Ok the plot thickens .

R-tech don't sell plasma tables but they do supply a machine called a Plasma 50 (non HF) to another company. www.ebay.co.uk/itm/132946307639?ul_noapp=true

They have these machine built specially for them.

But R-Tech won't sell these machine to anybody else. They also tell me they don,t have any machines suitable for cnc because of the HF.

So do I need a machine with Pilot arc or just HF start?

IN this forum post Jim Colt from HYpertherm outlines the difference
forum.weldingtipsandtricks.com/viewtopic.php?t=10923

You can use a HF pilot arc start but the additional RFI/electrical noise makes it harder and you will probably need to put earth stakes through the slab plus implement other defensive methods to build a reliable system. The THCAD is designed to cope with this environment but I'd suggest the THCAD board needs to be located at the plasma cutter as the frequency output is designed to be more immune to noise. Remember that every wire feeding back to your control panel becomes a radio antenna that feeds that RFI back into your control panel and it could see you chasing intermittent faults for a long time...

Jim speaks about HF start on bigger high end systems and I know from an associate's experience that even the commercial table manufacturer's get it wrong with electrical noise which results in annoying intermittent faults.

Very informative thanks.

So.

use a moving electrode inside the torch. The main DC power is activated in the plasma torch, then moments later the gas flow starts in the torch. The gas flow causes the spring loaded electrode to slide back away from the nozzle, which creates a short circuit spark that ionizes the gas flow through the torch.

The magic is in the torch. Is this the type of torch you have? I know that this is a cheap torch www.ebay.de/itm/P80-CNC-Brenner-Schneidb...AHLWERK/372335022023

but is this the type I require. or can you link me to something that is reasonable for hobby use.