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Anyone ever convert a CO2 cutting laser to plasma?

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
I have a 1KW Mazak CO2 laser 50 x 100. Rarely do I have anything that I can cut at a lower cost than my surrounding laser cutters. It sits a lot and now it needs some work on the beam path seals and the chiller that I really can't justify.

These machines are worth more in parts than whole. Parts are not going for much either.

It's about an 18k lb cast iron bathtub. Chip/dross conveyor, good motion system and control, fully enclosed with exhaust system. My machine is in nice shape, looks like new.

The footprint is kinda dumb for a plasma since the sheet moves in the long direction the machine is 18ft long. I'm OK with that, but I would be thrilled to be rid of the fridge sized chiller that doesn't fit nice anywhere. I could see modifying it so I could cut 16' long sheets. That would be cool.

Upcoming product is going to be made from 3/16" T1. Laser cutters around me are not competitive at lower quantities of T1. I can cut it cheaper myself and I really need to make quick changes during the proto phase. This will be formed/drawn into a shape and there will be experimenting with blank size and tooling to get it just right.

I could also use the plasma to cut other stuff I make, mostly 3/8" and 1/2" thick A36. I would still tend to farm this out to laser cutters, but it would give me better options when I forget to order something in time, somebody wants a custom part or the laser cutters are all 2 months out .

Any reasons why it wouldn't work? I have very little experience with plasma. I'm sure there are things I'm overlooking.
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
THC...no not pot

Torch Height Control is the biggest hurtle I can see, along with back and forth communication
from torch (ohmic sensor,) voltage divider, and plasma power supply "OK to Move" signals.

Look on ebay, they sell the slide, and the THC controllers. I think these seperate controllers allow
your motion control to give the "go" signal, and then the box handles most of the rest.

IIRC Jim colt has posted that the THC needs to maintain height to within .004 for accurate cutting.
The plasma "Jet" is cone shaped, so up/down movement affects the kerf width.
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
The Mazak has 4" Z travel. The laser lens has to be controlled super precise as well. Focal length is critical. I might be able to keep the exact same system? .004" seems like it would be feasible with the setup it has, but I need to figure out how it works.

Looking at how this thing is built I think the mechanical aspect of the conversion would be real simple to make it cut 4x8 sheets. Remove laser shit, defeat safeties for vacuum, gas, resonator systems.

Don't know what would entail to make a Mazak T-Plus control talk to a Plasma power supply.
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
The Mazak has 4" Z travel. The laser lens has to be controlled super precise as well. Focal length is critical. I might be able to keep the exact same system? .004" seems like it would be feasible with the setup it has, but I need to figure out how it works.

Looking at how this thing is built I think the mechanical aspect of the conversion would be real simple to make it cut 4x8 sheets. Remove laser shit, defeat safeties for vacuum, gas, resonator systems.

Don't know what would entail to make a Mazak T-Plus control talk to a Plasma power supply.

I always wondered how the laser keep the focal point where it should be.

Some kind of surface sensing ?
 

Strostkovy

Stainless
Joined
Oct 29, 2017
Lasers have capacitive sensors at the tip. They will not work with an arc nearby. They can be fickle just from building ground noise and typically specify a dedicated grounding rod.

That being said, you could feed the DTHC value into the control loop, however you will need to change programming such that height control us unused until piercing is completed, and it knows the data is invalid below a minimum value to prevent crashing. Plasmas like to dip when set up wrong, so a breakaway mount for the torch is a must in my opinion. A floating head will handle your touchoff for setting your material height and should be easy enough to add to the controls.

I built a plasma once, including the DTHC and worked a *lot* on operating, repairing, and tuning in an arclight table, as well as lasers and can help you with the interaction between the plasma and laser controls and coding things properly.

I am definitely happy to pay for shipping on any optics you are dumping, by the way.
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
This is a 1998 Super Turbo-X48 Mazak. I started looking at the Z height sensing and it's well hidden, but appears it may be electromechanical? The nozzle has a brass ring mounted to a snap-off shaft that rides on the surface being cut. This moves a linkage up/down and something inside a black box senses that position. I haven't time to get into this at the moment, but I'm thinking this old laser might make a real nice plasma.
 








 
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