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First plasma table build

I got a little cocky and tried this sign out of 3/8" plate for a grill at one of our shops.

Piercing 3/8" is a whole new game and the puddle is a mofo to deal with.
I don't have a breakaway torch on this z axis so it was a real struggle. I goobered up the tip pretty early on dragging it through the puddles and after several failed cut cycles I finally got through it but it wasn't pretty.

I slowed the feed rate down 30% from 35ipm using a 60 amp 1mm nozzle at 60 psi and at 60 amps. I never got this material really dialed in before trying to cut the sign and it shows.

It will work for this but definitely doesn't meet my standards...

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Anyone have any ideas on how to determine plasma arc voltage, the biggest downside of the Chinese plasma is the lack of accurate cut charts. It's not a deal breaker but it does leave my confused as hell sometimes.
 
CarterKraft said:
Anyone have any ideas on how to determine plasma arc voltage, the biggest downside of the Chinese plasma is the lack of accurate cut charts. It's not a deal breaker but it does leave my confused as hell sometimes.
Click to expand...

On my THC system I learned the hard way that the voltage gets left at zero. It then determines a voltage on its own based off of your preset height and works to maintain that voltage. Mine is a proma.
 
Hypertherm has decent charts. They'd at least be a starting point for your Chinese machine. On the thicker materials, the pierce height is higher and the delay is longer to let it get through the metal before moving and getting closer to the work. I've been running our machine at 88% to accommodate using Chinese consumables on the Hypertherm instead of the Hypertherm consumables, so you'll likely still have to play with it some.

CutChart.png
 
PAToyota said:
Hypertherm has decent charts. They'd at least be a starting point for your Chinese machine. On the thicker materials, the pierce height is higher and the delay is longer to let it get through the metal before moving and getting closer to the work. I've been running our machine at 88% to accommodate using Chinese consumables on the Hypertherm instead of the Hypertherm consumables, so you'll likely still have to play with it some.

CutChart.png
Click to expand...
I assume voltage is a function of current, run higher current to hit higher voltage target?

Which probably means on the china watt scale I need more current than stated to hit the voltage.

However do I really need to be trying to hit that voltage spec at all of the cut is good?


First try on a yard sign for my MIL.
I got lazy and ran one cut path for it all with no offset and that was kind of sketchy of think. It worked but this made it clear I really need to make sure all the nodes etc. are dialed before sending to Sheetcam then really try and dial in the paths, starts etc.

1mm sheet
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Bacho said:
On my THC system I learned the hard way that the voltage gets left at zero. It then determines a voltage on its own based off of your preset height and works to maintain that voltage. Mine is a proma.
Click to expand...
I don't think mine is like that but I do have a Auto bolts setting that I have checked that might be working that way.
 
The failed thing garden sign got built anyway, I will just redo it later.
The MIL was really happy with it 🤷‍♂️

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Moved the table over into the new spot after adding the cheap moving dolly casters.

Need a 1 3/8" wrench to adjust the feet easily for leveling so I drew one up in onshape real quick and cut it out of 1/4" plate.

It was good to keep the skills up.
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Working on my RV tongue jack conversion and needed a 3/8" plate cut.

Whipped it up in Linuxcnc conversational and then tried to use the same old 1.1mm tip I used before on this material.
I have no idea why because it worked so poorly before but possibly cause I'm dumb:lmao:

I finally after messing with cut volts, amperage and feed and re starting the cycle 6 or 7 times I finally got it cut out, terrible cut bevel and dross.

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I pulled that nozzle out because obviously it's fucked. I put a 1.0m nozzle in it and lowered the amps to 55, feed to 30 ipm and air to 70 psi with 105 cut volts. It cut it first time with a little bevel still but what id consider acceptable for 3/8 plate.
Lots to dial in still but maybe the problem was that barfed tip cause this is less power but cut better.



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I had to pump my air pressure up to 120psi plasma inlet to get it to cut well on 3/8" plate.
 
GLTHFJ60 said:
I had to pump my air pressure up to 120psi plasma inlet to get it to cut well on 3/8" plate.
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Interesting, I am really shooting in the dark on the thicker stuff but I did make some progress with the cut voltage by turning OFF the auto volts then making cuts and seeing what was going on. I think that messed up nozzle caused me a lot of grief...

What I thought I needed was more amps but stepping down to a smaller nozzle and amps, that was not the case.
 
I haven't tried a smaller nozzle. I need to look that up, I don't actually know what my current nozzle sizes are.

But with fresh consumables, 45a, about 30ipm and 120ish psi to the cutter gave me the best results so far. That's with THC on.
 
GLTHFJ60 said:
I haven't tried a smaller nozzle. I need to look that up, I don't actually know what my current nozzle sizes are.

But with fresh consumables, 45a, about 30ipm and 120ish psi to the cutter gave me the best results so far. That's with THC on.
Click to expand...
I posted some charts in the non HF plasma thread about rules of thumb.
I bought some small ones from plasmadyn on eBay and they are nice quality need to buy the whole set, up to 1.2mm, as is I can't really cut up to the rated output of the machine.
 
CarterKraft said:
I assume voltage is a function of current, run higher current to hit higher voltage target?
Click to expand...

This is backwards. Plasmas are constant current, you set the amperage and the power source varies voltage to maintain that amperage target. A longer arc requires more voltage to maintain the same amperage.

CarterKraft said:
However do I really need to be trying to hit that voltage spec at all of the cut is good?
Click to expand...

The voltage number is irrelevant unless you have a cut chart you're trying to follow. Torch height is the only thing that matters, which is controlled by voltage. At a constant cut speed more volts = higher torch, less volts = lower torch. If you keep voltage constant more speed = higher torch, less speed = lower torch. Since you're basically building your own cut chart you can use whatever number you want for 'voltage' it's just a matter of finding the right combination of voltage (torch height) and travel speed that works best, just keep in mind if you change one you have to change other.

Make sure you're on the right side of the cut, and they you just want to set the height so the 'hourglass' is centered on the part. This is from a Hypertherm document:

Screenshot 2024-03-01 113443.png


Screenshot 2024-03-01 113510.png


CarterKraft said:
I don't think mine is like that but I do have a Auto bolts setting that I have checked that might be working that way.
Click to expand...

Not familiar with linux cnc but this likely just grabs the arc voltage shortly after the pierce and maintains that height. Might be ok for thin stuff but as you get thicker you really want to pierce higher then drop down to cut height.
 
srf said:
This is backwards. Plasmas are constant current, you set the amperage and the power source varies voltage to maintain that amperage target. A longer arc requires more voltage to maintain the same amperage.



The voltage number is irrelevant unless you have a cut chart you're trying to follow. Torch height is the only thing that matters, which is controlled by voltage. At a constant cut speed more volts = higher torch, less volts = lower torch. If you keep voltage constant more speed = higher torch, less speed = lower torch. Since you're basically building your own cut chart you can use whatever number you want for 'voltage' it's just a matter of finding the right combination of voltage (torch height) and travel speed that works best, just keep in mind if you change one you have to change other.

Make sure you're on the right side of the cut, and they you just want to set the height so the 'hourglass' is centered on the part. This is from a Hypertherm document:

Screenshot 2024-03-01 113443.png


Screenshot 2024-03-01 113510.png




Not familiar with linux cnc but this likely just grabs the arc voltage shortly after the pierce and maintains that height. Might be ok for thin stuff but as you get thicker you really want to pierce higher then drop down to cut height.
Click to expand...
Ok this helps my mind...

As much as I've tried I still haven't made a chart to go off, I usually just try to get the thing in two pieces by the end of it.

In Linuxcnc I can set pierce height, piece delay, cut height,cut voltage, and "auto volts" among just the variables that are directly related.

Understanding which direction up/down = voltage up/down will be a great help.
I noticed cutting that 3/8 plate again on my tests that I was crashing the torch, likely cause my set voltage was too high for the amperage.

I'm gonna re-read a lot of this when I am sitting in front of of it again. :beer:
 
CarterKraft said:
Ok this helps my mind...

As much as I've tried I still haven't made a chart to go off, I usually just try to get the thing in two pieces by the end of it.

In Linuxcnc I can set pierce height, piece delay, cut height,cut voltage, and "auto volts" among just the variables that are directly related.

Understanding which direction up/down = voltage up/down will be a great help.
I noticed cutting that 3/8 plate again on my tests that I was crashing the torch, likely cause my set voltage was too high for the amperage.

I'm gonna re-read a lot of this when I am sitting in front of of it again. :beer:
Click to expand...
If you have Automatic Torch Height Control, I would disable it while you are getting tuned in
that is one less moving variable
once you get your Amp/Volt/Travel speeds right, you can reintroduce it

I have Height Control , and hardly ever use it, but I cut thick plate and warpage is minimal at my shop
 
SomeGuyFromOlympia said:
If you have Automatic Torch Height Control, I would disable it while you are getting tuned in
that is one less moving variable
once you get your Amp/Volt/Travel speeds right, you can reintroduce it

I have Height Control , and hardly ever use it, but I cut thick plate and warpage is minimal at my shop
Click to expand...
I started playing with it on/off on the last few cuts like you said to help slow the moving target.
Everything happens so fast when it's cutting it's hard to instantly see wtf is going on.

I need to use the HALscope tool more but that's more learning I just don't need at the moment.
 
CarterKraft said:
I started playing with it on/off on the last few cuts like you said to help slow the moving target.
Everything happens so fast when it's cutting it's hard to instantly see wtf is going on.

I need to use the HALscope tool more but that's more learning I just don't need at the moment.
Click to expand...
this is the part where we revisit those snarkey buy-a-HT comments again :grinpimp::stirthepot:


keep at it, you will get it :beer:
 
SomeGuyFromOlympia said:
this is the part where we revisit those snarkey buy-a-HT comments again :grinpimp::stirthepot:


keep at it, you will get it :beer:
Click to expand...
Trust me I realize the value in those charts but I'm still stuck at there is no way I should put a $4k-6k cutter on this $600 rig.

If I built a commercial duty unit or had a product to sell I'd be all about it.
 
I fell into some good settings for the 3/8 plate I scavenged (might be T1 or something not sure)

After being a little disappointed in the china cutter and the lack of working settings I finally hit a run.

55 amps, 1.0 mm nozzle, 70 psi, 30 ipm
THC on and auto volts on @ 102 volts

The square was the second attempt, just raised the voltage from 97 to 102 and turned the THC on and auto volts, cut like a charm so I loaded a bigger piece and cut these bumper mounts for a co-worker. My first cardboard template to cad to cut project. Worked perfectly, I cut a piece of sheet metal as a template and he moved one hole 1/8' down and forward on testing.


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That's really good. Nice work. Which plasma are you using? Based on this post Im guessing I'm just going to be limited in cut quality with 3/8" because I've only got a 45xp.
 
GLTHFJ60 said:
That's really good. Nice work. Which plasma are you using? Based on this post Im guessing I'm just going to be limited in cut quality with 3/8" because I've only got a 45xp.
Click to expand...
Its the Hynade CUT80NP based on what I am seeing now with the correct nozzle It should cut 3/4" (really slow)

 
GLTHFJ60 said:
That's really good. Nice work. Which plasma are you using? Based on this post Im guessing I'm just going to be limited in cut quality with 3/8" because I've only got a 45xp.
Click to expand...
I've seen some crazy results from guys using the HT cutters on really thick material so you might be surprised.
Its probably hard on consumables but can be done.


This is Jim Colt, HT Guru's comments
 
CarterKraft said:
I've seen some crazy results from guys using the HT cutters on really thick material so you might be surprised.
Its probably hard on consumables but can be done.
Click to expand...
I think air supply, and voltage are key features to pay attention to
with genuine HT consumables, I can get 6hrs or arc-on time cutting 1/4 plate before cuts quality starts going downhill
that is if everything goes well, no crashes or anything dorking things up on the business one of the plasma

and with time, you will learn how to cheat, and you can get a lot more out of your machine (thickness wise)
 
I realized I never bought the motor guard filter the other day...
I basically didn't do shit with my (poor) air supply.

I have plans to add a air to air cooler on the compressor outlet and an auto drain on the outlet.

Since the shop is "air conditioned" maybe I can by with out a dryer.
 
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