HF start plasma and CNC...

[Davek0974]

Grounding...

Having been informed about the risks of interference from a plasma cutter affecting the Pc controlling it, I am doing some work prior to the cutter arriving next week. There is an excellent thread here as well..General CNC Plasma And Oxy Fuel Cutting Machines > Grounding CNC Plasma Question

So far, I have fitted screening braid to the stepper motor leads up to the point where they connect to the (now) shielded 4-core cables, this shield is connected at one end only to machine ground. The motor cable shields are connected at one end only, inside the steel control cabinet directly to my cabinet star earth stud.

I have connected the Z-axis to the gantry carriage at the steel terminal box, this point is the run back to the cabinet star point with its own ground cable. Next I have connected the gantry back to the star point with it's own ground cable. The steel cabinet is bolted directly to the chassis so I can't see much point in connecting another ground lead there??

The travel limit, e-stop and probing switch circuits are all relay isolated from the BOB and run on a separate 24v PSU, cables are just standard 2-core flex.

The e-stop relay also kills the torch control signal in case the board locks up with the torch on.

I have fitted several ferrite clamp-ons to supply cables etc.

The case of the PC is connected back to the control star point with a ground lead.

The keyboard and mouse have ferrite clamp-ons fitted at the PC end.


Now for the unknown bits....

The case of the plasma PSU has a bolt lug for grounding, I intend to connect this to a ground spike, the chassis of the machine also, as well as the slat bed with its own ground lead. Is this a good idea or should I just connect the slat bed ??

The torch lead will be suspended from above and not run in the cable-track.

How long can the ground leads be to the earth spike??
Where the machine will likely be going is about 15' from the ground outside, I could drill through the concrete floor but I have no idea how far down actual 'soil' is underneath the shop.

I could possibly drill through the wall and sink the spike there, that would be about 4' away.

Is it best to remove the ground clamp from the plasma and bolt the lead directly to the slat bed or just clamp it on??

[Davek0974]

Just an update,

in the end I could not get the machine to work with the HF, total nightmare and spent weeks trying.

in the end I gave up and bought a hypertherm powermax 30xp cutter, since bolting that on, it has worked perfectly, I now have the plasma unit in the same socket as the PC and CNC unit, plus I have routed the torch cable along the gantry with the other cables so it's much tidier and it still works.

[JAZZCNC]

Just an update,

in the end I could not get the machine to work with the HF, total nightmare and spent weeks trying.

in the end I gave up and bought a hypertherm powermax 30xp cutter, since bolting that on, it has worked perfectly, I now have the plasma unit in the same socket as the PC and CNC unit, plus I have routed the torch cable along the gantry with the other cables so it's much tidier and it still works.

That's interesting and a surprise. Thanks for posting that Dave because in the not too distant future I'll be making a Plasma table for my self and chances are I would have turned to R-tech plasma unit.!

[Davek0974]

Yes, I really am not denigrating the wonderful r-tech units but it's like chalk and cheese in reality. I fail to see why they cannot integrate the blowback start torch into their units, it means less electronics so should be easy.

the table has not missed a beat since getting it and I was just about to give up. It's damn expensive though and I could only just afford the little 30xp unit but it gives me 3-1/2 mins of continuous cut and I can throw in a pause if I have long job to let it cool off.

[Boyan Silyavski]

Nice read. I am at the same situation now, as i want to fit plasma to my new machine, to cut this and that from time to time at the further side of the bed, as i have HF plasma. Its Stahlwerk Combo unit CT-520 PULS TIG/ MMA/ Plasma. Though rebranded it seems is not the typical crap, i opened it to make pictures when i was ordering THC and even the boards were branded. +the 5year warranty. I bought it for the Arc and the Tig. Which work flowlessly by the way. The plasma was added bonus, i thought at the time, not knowing about issues in cnc.

The AG60 torch and the same machine torch i bought recently seem like toys. Andrew who makes the Neuron THC gave me info that many people in Russia change the torch of similar plasmas with Binzel Abiplas Cut 70 MT, which seems very popular in Russia and around and at better price than here in Spain. So he said that torch gives excellent cut with HF machines.

I received a grounding scheme from him, also read around a lot the proper grounding. It seems some have no problem with HF machines others could not make it work. i will give it a try.

The good thing is that all my system will be at 24v , optoisolated and differential signals. Will see what happens and report here. Till now my garage looks like a cheese, cause i tried to drill for a rod but its rock bellow, fortunately just 1 meter outside i managed to find a spot where the rod goes deep. Now i am worried about lightnings and so, seems i have to read more.

[rJam]

Nice read. I am at the same situation now, as i want to fit plasma to my new machine, to cut this and that from time to time at the further side of the bed, as i have HF plasma. Its Stahlwerk Combo unit CT-520 PULS TIG/ MMA/ Plasma. Though rebranded it seems is not the typical crap, i opened it to make pictures when i was ordering THC and even the boards were branded. +the 5year warranty. I bought it for the Arc and the Tig. Which work flowlessly by the way. The plasma was added bonus, i thought at the time, not knowing about issues in cnc.

The AG60 torch and the same machine torch i bought recently seem like toys. Andrew who makes the Neuron THC gave me info that many people in Russia change the torch of similar plasmas with Binzel Abiplas Cut 70 MT, which seems very popular in Russia and around and at better price than here in Spain. So he said that torch gives excellent cut with HF machines.

I received a grounding scheme from him, also read around a lot the proper grounding. It seems some have no problem with HF machines others could not make it work. i will give it a try.

The good thing is that all my system will be at 24v , optoisolated and differential signals. Will see what happens and report here. Till now my garage looks like a cheese, cause i tried to drill for a rod but its rock bellow, fortunately just 1 meter outside i managed to find a spot where the rod goes deep. Now i am worried about lightnings and so, seems i have to read more.

I was just about to buy a Stahlwerk plasma for a cnc build simply because the 7 year guarantee these days seems unbeatable, even if a Chinese machine, Boyan did you ever get your HF machine to work? or end up getting a blowback style non HF to make it work?