Thoughts about improving cut in 1/2 inch steel

[sdavilla]

cut60dn hynade with PTM 80 machine torch head.

topside:

bottom side:

I started (left) at 20 ipm, 45A. Far right is 1st “good” cut. 4 ipm, 60A. Air pressure was 60 all the time…

2 ipm is too slow, almost cut the table bottom

Top side looks good as far as dross is concerned, Cut slot curved until I replaced the tip. That was about two back from right. I also switched to THC instead of manual.

One interesting thing I noted, typically earth grounding a plasma table is fine. Ground strap to outside ground rod. I lost torch voltage measurement and had to remove the earth ground.

The nice cut dross popped off with pliers. What you see in picture might take more effort. No luck with pliers.

I did get a hang near end of run, FireControl hung and I had to manually power off the crossfire controller to get the plasma off. You guys ever hear of a watchdog process ? Now FireControl just bounces and stops responding when launched. I’m 10.15.7 with FC 21.1.5. But that’s a different problem.

So what to diddle or is this typical ? Speed seems really slow, I stared at 20 ipm and just made a mess across. Next was 10 ipm.

[ChelanJim]

I don’t have Cut60 but I just looked at a chart elsewhere on Langmuir site. Your air pressure seems really low. I would try 70 or 80 psi and see if that helps. Here is the chart I saw.

And that is with 12 gauge. Since you are cutting so long, you may be starving for air pressure. (I have Hypertherm 45XP so I just put 100 psi to the back of the cutter.) But, I have not cut anything more than 1/4 inch.

[ChelanJim]

Just ran across this post while reading about something else:

Shielded torch?

If you are having trouble piercing !/2" mild steel with the Primeweld 60 you have your setting wrong, air not set right, torch height not set right, etc. With a 1.1mm/60 amp tip set at 60 amps and 75psi flow pressure in will pierce 1/2" instantly. When setting voltage it has to be set with the torch set at the right torch height .060" from tip to metal for 40 to 60 amps, less for 20 and 30 amps. Just putting a voltage setting in does not mean it will hold the TH at .060" with out manually chec…

[72Pony]

The bottom side dross is due to speeds that are way to slow. I would guess 60 amps 24 inches per min. 70-75 psi air pressure .

The torch freezing in the on position is likely due to EMI.

Post some pics of your setup.

[Jemejia]

Good recommendations above. Attached is the cut chart that George sent me back when he was support for the Primeweld Cut 60 (probably similar guts as your Hynade). I no longer use that cutter or the PT60 torch, but I do recall that the torch was pretty sensitive to air pressure. I assume the pt80, which also calls for 65-75psi (in book specs) will be similar. Increasing pressure to 75psi should clear the molten metal from the kerf and reduce dross.

[mechanic416]

There are a few factors here that will cause some trouble with cutting.

First you have a 60 amp plasma cutter with a 80 amp torch. The air line in the 60 amp torch is 6mm and 8mm for the 80 amp torch. So setting the air PSI will off from any charts.

Next is the size of the cutting tip being used. A 60 amp tip is 1.1mm/60 amp with a .044" orifice hole. If you are using a larger tip say 1.2mm/70 amp or 1.3mm/80 amp it will not cut right. The smallest cutting tip I sell for the 80 amp torch is 1.0mm/50 amp/.040" orifice hole.

Also make sure your torch height is .060" from metal to cutting tip.

[sdavilla]

Good things to think about. More info.

IPT65: Hole diameter: 0.9mm
PTM80: Hole diameter: 1.0mm

They are both Hynade labeled. The PTM80 is recommended for used with the CUT60DN. In fact in the pictures on amazon, the PTM80 is shown together with the CUT60DN.

I did find this. “200mm/min at 20mm thick metal 70PSI (Air Pressure)”. Or about 7.87 inches per minute. Close to eight. Looking back at practice cuts, the eight might have worked if there was more uuhmp behind it. All the dross did chip off clean with some well placed wacks.

Here’s the CUT60DN air pressure. 56’ish. I’ll have to re-test but I don’t remember it changing over a 40A to 55-60A change so it’s fixed. I’ll also add a gauge on entry side of CUT60DN for sanity.

8 gallon reserve air tank under table. 3/8 hose through out. Pretty sure the compressor kicked on near end of that last, 2 ipm cut.

This is feeds here.

I had thought I might be connected to the regulated out but nothing on it. Line goes up about five feet then into a 1 inch PEX distribution line. Around short wall side (24 foot) , and down to compressor.

The compressor. Porter Cable PXCM201 Type 3. 20 gallon tank, Cast iron V-twin pump delivers CFM @ 40 PSI: 6.2 and CFM @ 90 PSI: 5.3

I don’t think I have a cfm problem. Looks more like internal air regulator in CUT60DN is just set too low. Some more tests and then we open it up and peek inside.

Also solved the FireControl problem. Mr GoldFish remembered that he had this same issue when 1st setting up. Delete App, Install app, works now.

The EMI is something I need to solve. As you can see in 1st picture, I’m running cable drag chains. Active USB cable (15 foot) with ferrites on both ends. Have a USB B - Ethernet - USB A on order. The earth ground should have worked too and not pulled down the THC voltage. I’ve read around and most references don’t mention if using same electrical rod is good or bad. I’m leaning to bad. $20 at HomeDepot.

[sdavilla]

Here’s better view of cable drag chains.

[sdavilla]

Simple setup, input, regulator/water separator with push-to-connnect drain and a hole, split to gauge and into torch cable connector.

A little twist and

I’ll start there.

[72Pony]

Here is a guide from Hypertherm on how to troubleshoot dross.

How to troubleshoot cut quality problems – too much dross (slag) (hypertherm.com)

I think speed is a big contributor to your issues but there are likely multiple factors at play.

Have you verified your cut height? There are a couple programs out there from guys like @ds960 and @Phillipw that will establish the actual cut height.

What type of climate do you live in?

What type of air-drying equipment are you using?

I haven’t been able to find a good source for the specs for your cutter. I’m sure someone out there can find it. They don’t have the output voltage listed on their website. Without that any cut speed is a just a guess.

I also wasn’t able to find the suggested compressor CFM but for hand cutting I would imagine it would be a min of 5 CFM. With that in mind you are right on the border for hand cutting and about half of what you will need for CNC cutting. Most recommend 2x the hand cutting value. Can you cut with the smaller compressor. YES, but your cut quality and consumable life will suffer. With your short test cuts the lack of CFM isn’t what is causing your poor cuts, but it is something to think about for the future.

As I said your low CFM isnt the cause of your poor cut quality in the pics but air flow through your lines may be a contributor.

In my opinion all the 3/8 lines, fittings and quick connects are introducing losses into an already borderline system. Try to eliminate as many of the quick connects as possible and where you can use larger lines.

As far as the EMI issues.

Are you running a laptop or desktop?
You may consider adding more chokes to your USB cable going from the computer to the control box(I ended up adding an additional choke to each end - 4 total - and haven’t had a problem since) and try to separate the torch lead and the cables for the Z axis along the boom.
Keep your computer as far from the control box as possible.

[ChelanJim]

@sdavilla

I’ve read around and most references don’t mention if using same electrical rod is good or bad. I’m leaning to bad.

Your instincts are good on this matter. Since the plasma work lead is actually positive (+) you do not want to hook the table up to your house grounding rod! When the work lead in connected to your metal, the table is charged positively.

If you want to ground the table, it needs to be to a different (separate) grounding rod, that is what people are usually referring to.

If you did put in a separate grounding rod for the table, it might be wise to check to see if you are getting continuity between that ground and your house ground. If you are, that will not work.

Program Cancels In Middle Of Cut (SOLVED)

Make sure you also connect the ground rod to the back of the plasma cutter earth ground connection. If it is EMI, it is coming from the plasma cutter. By connecting the housing to earth ground you are creating a Faraday cage.

[TomWS]

ISTM, that the polarity of the the Work Lead is irrelevant. What is vital to understand is that the Work Lead is used by the Plasma cutter to measure the ACTUAL current going into the circuit. It is a sensing lead.

Grounding it, or otherwise diverting the current away from the Work Lead will introduce errors and noise into that Sense loop.

To my mind, the BEST thing you can do is ensure that the Work Lead and Torch are completely isolated from any other electrical paths. And that means no grounding the table IF the table is in intimate contact with the workpiece.

[ChelanJim]

Thanks Tom for your clarification on this. I am totally good with that because I don’t want another wire to worry about.

My point was mainly to say “don’t ground the table to your house ground.”

[sdavilla]

Just noticed something. If you look at the picture of the CUT60DN, there are two markings on dial, one for 110v (30-50 psi), the other for 220v (30-70 psi). The factory setting was for 110v, just a little higher than 50 psi. It needed to be increased for 220v operation or one can never reach 70 psi. I run 220v.

Have you verified your cut height?
Yes, several different ways.

What type of climate do you live in?
NC, normally hot and humid Right now, shop is at 52%.

What type of air-drying equipment are you using?
None yet. I have parts, just have not assembled it yet. But not seeing any signs of water in air problems. I check drains every few months, not much.

Here’s spec page of manual.

The manual says, 45 lpm or 1.59 cfm. I should be fine. The min restriction in air plumbing will be the quick connects of course. It’s the min restriction that is the limiting factor as to how much air you can push through for a given psi. Waving hands at friction and turbulence from walls, the torch tip is the real air limiting orifice. Many times smaller than the quick connects. Basic fluid dynamics.

Are you running a laptop or desktop?
Laptop, and no, I’m not going to pull power just to run FireControl None of my MacMinis are new enough to run FireControl and I’m stalling on replacing my MacBook Pro (uptime 471 days). Plus I hate when the chokes come out. Chokes are real voodoo. Played many games with those chasing femtoamp measurements. If one or a pair on ends does not solve the issue, more are useless and one has to look elsewhere for the real issue. I have a pair on each end. Helps a lot but not 100 percent. I’ll see what the ethernet based USB extender does for EMI.

Yes, I know work lead is positive. But the circuit is floating (mine measures as floating). You just want the electrons to flow in the correct direction. The deta V provides the voltage potential and the sign sets the electron direction. Grounding one side of the circuit just bias the voltage, electrons flow the same direction as before. The THC voltage measurement should be a differential input which ignores any voltage bias. The torch did fire and cut (manually with THC off), I just lost THC voltage measurement. If the earth ground was stealing electrons, the circuit in the cutter should have increased the output or safety clamped. Maybe voltage, maybe current, depends on actual design and I don’t have schematics. I need more info…

In my electrical setup, I’m a shop about 250 feet away from meter/main breaker. Shop side, earth ground (rod) and neutral are NOT bonded and four big lines run to house, two hots, neutral and earth ground. At house meter/main breaker is where earth and neutral are bonded.

As for separate earth ground, how far away from real (rod) electrical ground is effective? There will be some conductivity between the two, dependent on distance and ground moisture. Seems this would matter a lot if a direct connect to electrical earth ground is bad. Smells like more voodoo and I don’t like to play voodoo games.

I think Tom has the correct approach if you are going to ground the table, then electrically float the water tray. That makes much more sense, keep the table metal from picking up and radiating the EMI. Not near a faraday cage but the next best thing. Let the hot leads do what they want.

[mechanic416]

Air pressure and voltage has nothing to do with each other. The 80 amp torch you have will not work properly below 60 psi and will work best at around 70 psi in most cases. The best thing to do is put a 60 amp torch on your plasma cutter and I bet you will get better results. You will also have a lot more options on consumables from 20 amp to 60 amp.

[sdavilla]

@mechanic416

Air pressure and voltage has nothing to do with each other.

Sorry if I implied that. Of course air pressure and voltage are independent. Never thought they were dependent, I’ve got a few issues going on. 1) Occasional EMI lockup, 2) Bad earth ground, 3) High dross on backside and slow cutting.

The culprit for 3) seems to be psi related because the internal air regulator is set too low for 220v operation. To reach higher output amps, one needs to run the cutter at 220v as you cannot supply the required current on 110v. Need the higher output amps to cut 1/2 steel plate. According to the manual page above, max thickness on 110v is 38 amps for 10mm @50-60 psi. For 220v, max thickness is 60 amps for 16mm @65-70 psi. I’m running 220v and cutting 1/2 inch steel, so I need more air pressure.

I cranked up the internal regulator to 75 and that should solve the problem. But I just cross-checked the internal gauge. It’s reading low, 55 for 60 coming in (on regulated wall connection now). I took another air gauge and checked before entering cutter. 60 there. From what I saw of the internals, there’s nothing between the input/regulator and gauge. So reading 55 is really 60. This jives with their 110v is 38 amps for 10mm @50-60 psi. Their default factory setup is for 110v usage.

So 70 is max now, unless I pop the top and re-adjust the internal air regulator.

As for the PTM80, I’d rather get it working. It’s rated to work with this cutter and consumables are not that bad with amazon. The only issue might be cfm. The PTM80 specs 120-130 lpm or 4.24-4.59 cfm and I’m a little better than 5.3. Might need a bigger tank(s). The compressor is new, replaced an old sausage that maxed at 2cfm. I’ll address that problem if it becomes an issue.

USB-Ethernet came in (yea), USB 1…0/1.1 rated (boo). I’ll have to check the crossfire controller to see what it’s using. I bet USB 2.0 speeds

[toolboy]

one thing to keep in mind when talking about air pressure…volume and pressure are very odd.

As the pressure on a gas increases, the volume of the gas decreases because the gas particles are forced closer together . Conversely, as the pressure on a gas decreases, the gas volume increases because the gas particles can now move farther apart.

[Knick]

If your going to get this deep into it, you should explain how this effects the average guy cutting with a plasma cutter in his garage? I feel like I understand compressed air systems pretty well and I have no clue as to how this effects my air system.

[TinWhisperer]

@toolboy

As the pressure on a gas increases, the volume of the gas decreases because the gas particles are forced closer together . Conversely, as the pressure on a gas decreases, the gas volume increases because the gas particles can now move farther apart.

That is a good description of Boyle’s law.

@Knick

you should explain how this effects the average guy cutting with a plasma cutter in his garage?

I think how this would affect the average homeowner would be how it affects your feet per minute at any given place in the piping system. If you have a lower feet per second there’s way more of a chance that water that has condensed will not travel along the pipe through entrainment.

[Knick]

@TinWhisperer

I think how this would affect the average homeowner would be how it affects your feet per minute at any given place in the piping system. If you have a lower feet per second there’s way more of a chance that water that has condensed will not travel along the pipe through entrainment

Now that’s something I can understand. So it sounds like this also holds true in a dust collection system. If there is not enough velocity for a given diameter duct, you will have dust falling out of the air stream.