Plasma Cutter, Expensive vs El Cheapo

[Ohio Mike]

Have two Langmuir tables at work (well used Pro and an XR still mostly in the crate that just arrived) and an Everlast 45A plasma with their CNC torch head. The plasma has been OK but not as nice as the 15+ year older hypertherm aside from consumables costs. I chuck the tips and electrodes at the first sign of misbehavior. Solenoid went out and we replaced it with an equivalent but better Norgren I had laying around.

Not a fan of the old Langmuir. Drive design is unreliable and the ways jam up with dust. Many scrapped parts from lost motion. Have medium-low expectations for the XR.

Regardless of make, go spend the money on air preparation. Wet or oily air makes for crap cuts.

My plasma CNC is actually a Langmuir Crossfire Pro. Its an awesome table at its price point. Despite is "pro" moniker is not a table I'd want to run in business where employees are using it. I make sure the wipe the rails down each time its run and I'm careful not to crash it (the Pro doesn't have limit switches). If I had to spend more than $3000 on the table I wouldn't have purchased one. There at lots of other nice tables out there but anything better than it is twice the money.

[Ohio Mike]

What function does the z-axis serve on a cnc plasma machine? Is it adjusted dynamically as the cut is made or it is simply to dial in the best height for a particular material or whatever? If it is adjusted dynamically, what is used to determine the optimum height?

The Z function on the Plasma table is commonly called Torch Height Control (THC). It will touch off on the work piece in an operation known as initial height sensing. It will then back off a preset distance to the pierce height programed. The table control then fires the arc for the programed pierce time delay then starts to move per the G code. The THC then monitors the arc voltage moving the Z axis up and down as necessary to maintain the desired arc voltage which translates into standoff distance. Typical torch to work distance is just .06 inches (1.5mm). A good plasma cutter like the Powermax has complete tables for optimal settings for cutting various thicknesses of aluminum, mild steel and stainless.

[john hobdeclipe]

Does anyone have any firsthand experience with the various plasma cutters that places like Lowes Depot sell in the $400.00 - $600.00 range?

[Teachu2]

I bought a Lotos Cut50 about ten years ago. I don't use it much, but it works fine.

[Teachu2]

Mine is red, but this seems to be the current model: https://www.amazon.com/Lotos-LTP5000.../dp/B0052OX876

[Baz]

Last time this was discussed I recall 'pilot arc' featured - ??? think it added 30% cost. I'm seeing adverts for cut50 not mentioning it and "50a" that do.

[Teachu2]

Mine has pilot arc. Comes in very handy when cutting expanded.

[Tmate]

If you think you are ever going to upgrade to even a low end CNC plasma table, I recommend that you get a plasma cutter that can be fitted with a vertical machine torch. I have used various Hypertherm models for 25 years, almost exclusively on CNC machines. Right now I have a Hypertherm 45X with a machine torch, and it is great. You don't want to get half way through cutting a shape out of a $50 steel plate and have it fizzle out, ruining the plate.

$2,500 for a plasma cutter is a lot of money, as is the price of a low end CNC set-up. The average hobbyist has a hard time justifying it. That said, many of the same folks think nothing of spending that kind of money or more for a snowmobile, jet ski, or motorcycle for recreational use. The kind of work possible with a CNC plasma cutter can't be performed with any other type of equipment other than another more expensive CNC machine.

A few examples done with my 2' x 2' home-made CNC plasma table and Hypertherm:

[Ohio Mike]

If you think you are ever going to upgrade to even a low end CNC plasma table, I recommend that you get a plasma cutter that can be fitted with a vertical machine torch. I have used various Hypertherm models for 25 years, almost exclusively on CNC machines. Right now I have a Hypertherm 45X with a machine torch, and it is great. You don't want to get half way through cutting a shape out of a $50 steel plate and have it fizzle out, ruining the plate.

$2,500 for a plasma cutter is a lot of money, as is the price of a low end CNC set-up. The average hobbyist has a hard time justifying it. That said, many of the same folks think nothing of spending that kind of money or more for a snowmobile, jet ski, or motorcycle for recreational use. The kind of work possible with a CNC plasma cutter can't be performed with any other type of equipment other than another more expensive CNC machine.

A few examples done with my 2' x 2' home-made CNC plasma table and Hypertherm:

Also to add to this, if you are thinking of going CNC later many of the cheaper plasma cutters can't be used on the CNC tables because of the noise they generate. It causes control systems to completely freak out. Plasma's sound expensive but price out the steel you'll be cutting 😮

[Bob La Londe]

I have an El Cheapo, and while I can make "cleaner" cuts with it in some materials I am much much faster with a torch. I rarely use either for breaking down stock. I use the horizontal bandsaw unless I need to cut complex shapes. Then I only breaking out the torch or plasm if I can't do it on the mill.

When I first got the plasma my son and I took turns with both the torch and the plasma on upto 3/8 hot rolled flat bar. On average we got less slag with the torch, but the slag from the plasma knocked off easier and cleaner with a chipping hammer. Its a wash for me. The plasma might have won out on 3/16 and thinner, but the torch eats the plasma for lunch on 1/4 and thicker. The plasma is nice in that I can use it to free hand aluminum sheet. Something not practical (not possible?) with the torch. Of course I can cut thicker and thicker with the torch just by changing the tip.

On steel I have a lot of ways to cut it. I'm more likely to use the circular saw (metal cutting) or a zip disc than the torch or plasma cutter, but sometimes they are the best tool for the job. For the most part I consider them in the better to have it and not need it category then need it and not have it.

[DS_park]

Been looking into one of these myself. Do post what you end up with. I find the 4 and 3 star reviews to be more realistic when dealing with Amazon.

[Ohio Mike]

Below is an example of the kind of cuts you can get with a Hypertherm Powermax. This is 1/4" plate and the settings were 65 amps @ 88 inches per minute on the CNC table. Pictures are top, side and bottom. Notice the lack of dross other than pierce points, this part was not cleaned up nor did I tune the cut settings. This was the first time I cut 1/4 plate and those are Hypertherm book values.

[Ironbearmarine]

What function does the z-axis serve on a cnc plasma machine? Is it adjusted dynamically as the cut is made or it is simply to dial in the best height for a particular material or whatever? If it is adjusted dynamically, what is used to determine the optimum height?

I have used a hand held plasma cutter, I have never worked with one on a cnc table. A plasma cutter is on my wish list though. It is far more of a "want" than a "need" so there is not a lot of priority at the moment. I am still waffling on what I want to get.

The z axis control insures that the tip is at optimal distance from the material. This is done by maintain a constant voltage. A longer or shorter arc is detected by the increase or decrease of the voltage and the controller will adjust the z until the proper voltage of the arc is achieved. This means cleaner cuts, but more importantly is not having to level your target material, you get automatic height adjustment for warped or untrue plate, or sheet metal that warps during the cutting. Also you can pre program clearance jumps for multiple objects that may tip up, causing collisions with the head. Also i have noticed that i get better mileage out of my consumables

[psomero]

My plasma CNC is actually a Langmuir Crossfire Pro. Its an awesome table at its price point. Despite is "pro" moniker is not a table I'd want to run in business where employees are using it. I make sure the wipe the rails down each time its run and I'm careful not to crash it (the Pro doesn't have limit switches). If I had to spend more than $3000 on the table I wouldn't have purchased one. There at lots of other nice tables out there but anything better than it is twice the money.

Agreed. It predates me at this current company and got us into doing steel fab in house, so it has paid for itself.

I have enough experience with CNC stuff and I notice the naggy little things that can lead to failures that the other guys are too green to pick up on quite yet, unless the thing scraps a part.

Since I posted this, our torch height signal blew out on our Everlast and we bought the 80A unit to replace it. Guess we have a spare hand-torch-only machine now.

[alanganes]

The z axis control insures that the tip is at optimal distance from the material. This is done by maintain a constant voltage. A longer or shorter arc is detected by the increase or decrease of the voltage and the controller will adjust the z until the proper voltage of the arc is achieved. This means cleaner cuts, but more importantly is not having to level your target material, you get automatic height adjustment for warped or untrue plate, or sheet metal that warps during the cutting. Also you can pre program clearance jumps for multiple objects that may tip up, causing collisions with the head. Also i have noticed that i get better mileage out of my consumables

Thanks for that, that makes sense. All interesting stuff. Something to keep in mind when I get to the point of buying one of these.