Hi Hood,

Have you made any more progress on your plasma table? If you've had some more time to get acquainted with it, what are your impressions of the MiniTHC? Would you recommend it? I also have a CSMIO controller and also agonised between using a MiniTHC (which I haven't bought - yet) and adapting a divider to my plasma cutter and using CSMIO's analog THC function.

Your thoughts on the matter will be greatly appreciated.

Afraid I have just been too busy to get this finished. Hoping to get some time in the next two or three weeks as I could really do with getting it running. Have 3 Cheetah Marine Cats to fit out nearer the end of the year which will need a load of Alu and Stainless cutting and it will be a good test.

Hood

Looking forward to your reports!

Had a lot on and also been a bit under the weather and not been having much luck with this
Got the plasma finished enough to start testing but having all sorts of issues which I am unsure whether are me or not due to me never having used a plasma before.

First problem I have is I am just ruining nozzles in short order, seem to be fine one run and then not another. What seems to be happening is the pilot arc starts and then the plasma arc, just as it should then sometimes it seems to go all soft on the arc and then it will come good again. Problem is the nozzles is now screwed
 Been doing some looking around and it seems it may be double arcing. I have tried quite a few things so far, increasing the pierce height, increasing/decreasing the air but still it happens every so often. Pics below of a nozzle that had done one or two cuts then had the problem and that was it screwed

 I have also been having a load of problems with the M31 macro, getting EPID errors at times, why I have no idea but CS Labs have all of my Mach folder and are having a look to see if they can find the issue.
The computer I am using is the Via Pico that was on the wee lathe so it is loaded with all sorts of crap, think I will do a fresh install of XP and a fresh Mach and set things up from scratch to get rid of all the junk, hopefully that will help.

Also having issues with the THC, again not sure why but it looks like the signals from the THC are fine going by the arrows on the display, they change up/down extremely fast but the Z axis seems to have a lot of lag in it when under THC control so it is looking like there is a problem between the THC and the IP-S, may even be computer related so the clean install may help that.

Here is a vid showing the cut with the soft arc which I think is Double Arcing, you will see it starts fine, goes kind of soft and spread out then goes fine again for the cut.
https://www.youtube.com/watch?v=QDTFbefEEi4

If anyone can suggest a fix for this I would be delighted to try it out. If I make it to the workshop tomorrow I will try reducing the current to see if that makes a difference.

Hood

Here is one that went fine. Obviously I had the travel a bit better than the earlier video but if I get that arc problem when doing this speed the axes have travelled half way round before the arc comes good again
https://www.youtube.com/watch?v=NhezLzf2wFw

Hood

Hiya Hood, welcome to the world of plasma - a world of pain

Apologies if i am preaching here but...

I am the opposite to you - I started in CNC plasma first then progressed to the luxury of CNC milling

Double-arcing will kill consumables fast, what torch/system are you using ?? I ask this because I wasted many hundreds of ££ and hours and hair by using poor plasma systems at the start because i thought i could save some £££ - I was wrong, I worked through three systems before i got it going, nearly made me give up and throw the towel in. The ONLY thing that saved me was splashing the cash on a Hypertherm 30XP which was later upgrade to a Hypertherm 45 - once you go Hypertherm you never go back Hypertherm torches do not double arc, at least i have never managed it.

Next is air supply - it must be dry, totally dry and oil free, I have a little refrigerated drier as well as the usual water traps in line.

Next is THC - the torch needs to find initial pierce height repeatably and accurately, then it must drop to cut height rapidly and accurately when the Arc-Ok signal is seen by the controller.

I won't mention motion as your table has servos so should be better than my stepper one.

Don't bother using the "book specs" for cut speed or voltage, just use pierce height and cut height, the rest is all measured on your table, let us know and i'll explain how its done if you want.

Once that lot is sorted out, the fun starts - plasma is never a cut and run system it seems - I still get bad days when it refuses to cut or blows a tip, but these days are between many days of good running now so i don't mind so much.

Dave,
 torch is a Trafimet S65P machine torch.
Machine is a TecArc Opticut 65.

Air supply seems ok, certainly no issues when I do the hand cutting. It uses a Trafimet S65 hand torch.
I have a few more things to try such as moving slowly whilst piercing but if I can't seem to get to the root of the problem I will make up a holder for the hand torch and see, in fact I may even set the machine torch up with the long consumables and drag nozzle that is on the hand torch just to see.

Height sensing, initial pierce and final cutting height are accurate so don't think that is the issues, have tried all sorts of different pierce and cut heights as well.

One thing though, you say

then it must drop to cut height rapidly and accurately when the Arc-Ok signal is seen by the controller

Are you meaning you drop as soon as the arc is started and don't have a pierce delay


Hood

I can't seem to find much as to how that torch strikes the arc - it says it does not use HF but does not say it is blow-back start (hypertherm) or something else.

Have you grounded the plasma to the sheet or the table - use direct to the sheet, at least to start with, this rules out poor return issues.

What thickness steel are you playing with? If its <12mm I would not bother moving the torch while piercing as it will not help, my little 45A will pierce 12mm without moving, just.

Have you any recommended settings for pierce and cut? There is no point in trying random settings here, there is usually only one setting for piercing a certain thickness of a certain type of metal.

Yes, my system has a built in lag (caused by THC, BOB, Mach3) of around 0.3s so until my book tells me i need more than 0.3 I set zero delay. Thinner (<3-4mm) metals need no extra delay. I think i used about 1s delay on 12mm.

What sort of dead-band do you have on the THC, mine is +/- 1v i think, so it does nothing in that area.

The best cut is achieved at the maximum setting for the nozzle in use so if i use a 45A set, i get the best cut at 45A although it will go down to 20A, if i use the 30A set i get the best cut at 30A although it will go much lower, all to do with arc energy density. Air pressure is a fixed setting and needs to be maintained without loss or it drops out.

How are you obtaining cut speed and voltage(height)??

To set mine up for a new material, I turn off THC, set my cut height as per book, then cut multiple straight lines maybe 150mm long with various speeds, looking at dross, cut quality, kerf etc, one of the lines will be better tan the rest - that one is the right speed. Then I cut one more line at that speed and this time monitor the arc voltage on screen (THC still off) - this now gives me the correct voltage.

Both these values are then plugged into the G-Code and the THC and away we go, sometimes a little tweaking is needed but it works. I tend to always have one eye on the screen where it shows Z height when cutting - i am watching for a sudden drop in z height immediately after the THC kicks in - this indicates my voltage wants tweaking a little as the Z gap cant physically change (sheet warp) in such a small distance therefore it must be consumable wear or just a wrong voltage.

It is Pilot Arc starting.

Yes, initially thought it was a grounding issue but it made no difference at all.

Never made it to the workshop today so never got a chance to test out with a lower current. The machine is 65Amp but nozzle  is 60Amp so maybe the extra few amps is the reason it happens sometimes and not others, kind of grasping at straws

Anyway may make it tomorrow and might get some time to try a few more things.

Oh alsmo meant to say I am not using the THC at the moment as it is not working correctly as mentioned previously so until I find the problem with it I have it disengaged.