Rusted steel and focal .250

[JeanFreli]

Hi

How rust affect the cut on mild steel? For the same parameters on others sheets no problems but today try a really rusty one and man I regretted putting that sheet on the table and start (on top of it) a full program (60X120 in).
I understand pretty good the focal on SS but a lot less the mild steel. I cut rarely that kind of materiel. I have a feeling they gona giva some more so...
If I put 2 for a focal ... how do I expect to see the cutting side of the piece? I mean there's a rule of the thumb for SS 2/3 of the thickness. On SS you can see realy good where the focal goes. I try an other piece after and vlang very good. The thing is cut so good and mirror that I can't figure if I put too much focal or not. I saw a 1/4 of fire coming out under the sheet. That's why I was wandering about the focal. First bubble on top.....had to slow down but anyhow the melting steel was bubbeling under the cut. Lucky to success to remove the pieces out. I was shy of the result. I hate grinder......

Well if somebody have the patience to explain a little bit the + focal, it will be very appreciate.

 

[JeanFreli]

Well found why I had so much problem.
Wasn't really the rust on the piece (but I not use materiel like that anymore)
Ihad a little opening in the ceramic, between the ceramic and yhe metal piece on the ceramic witch is use for the sensing.
Icannot control the gas properly so I was tring to adjust by changing my focal.
But anyhow going on internet to find out more on cutting steel.
Now the machine work back like a rocket.
I admit this Ermaksan machine is very good. I would like the 4kw one. Very fast