The second part of the Multiplaz 3500 review is about cutting.
The cutting torch is exactly the same as the welding torch. The only difference is the fuel you put in the torch - water, just water. There are two modes MODE I - indirect arc mode and MODE II - direct arc mode. Both modes use the water to create steam around the electric arc, compressing the arc and ionising the steam. This results in a huge amount of energy released in a very small space. Each mode has six different voltage levels that regulates the amount of energy released. It's worth having a bit of a play around with the different levels and see how it affects the cut.
Mode I
In this mode the arc is formed within the torch between the cathode and the nozzle. The energy is transferred along the plasma jet to the work piece. This mode allows you to cut anything that is non flammable (trying to cut flammable material will just burn it up with the 8000C arc!).
Mode I cuts up to about 10mm. Thicker than that the slag doesn't leave the cut before it solidifies stopping the cut going all the way through.
I've tried cutting steels of different thicknesses with varied results. Thin stuff is no problem in Mode I, but thicker steel >10mm needs Mode II. I have practiced cutting bricks and abrasive cut off wheels with surprisingly good results. I melted part of one brick as I tried to cut a hole in it, but the other seems ok. You are limited by the depth of cut. Tiles would be good to cut fiddly shapes into. The abrasive cut off wheel cut very cleanly. Not sure why I would need to cut one, but I had an old one around when I was practicing. The ability to cut non flammable could be really useful in a workshop. Just for that random problem, where other tools don't cut it (bad pun I know).
Mode II
Mode II - direct mode is more powerful because the arc forms between the cathode and the work piece. But it does require the workpiece to be conductive of electricity i.e. metal. When the arc activates you notice a increase in the cutting power and depth of cut. This will cut steel, stainless, brass, copper and other metals. It's important with this mode to keep the piece dry as there is electricity around. Mode I can be used to cut wet material.
Refilling the "Fuel"
When the torch is switched off and the tip immersed in a container of water to cool, it sucks up water to refill the tank. Alternatively you can refill it when it runs out with the syringe provided. I get around 15 minutes from a 60ml refill of water. Which is pretty good. I can't remember how many hours I got out of the old Oxy-Acetylene bottles, but it was definately more expensive than 1/4 a cup of water.
Results
Part of the challenge in cutting is holding your hand steady so the cut is smooth. Using some form of guide does make it easier, and the Multiplaz come with a circle cutting attachment (for small circles) and a guide with a ball bearing on the end to help maintain a constant distance. I think I'll make an adaptor for my large circle cutter from my old plasma torch. Like any new tool, you quality of results improves with some practice and trial and error. The final cut is at least as good as my plasma torch (a nice little Cebora) and much better than my Henrob/Dillian III I used with my Oxy-Acetylene rig. The unit is only 9kg and draws 9.8A so can easily run of domestic power supplies (240V). I'm not sure how it runs on 110V for our overseas friends. It's an added bonus to cut non flammable non conductive material in Mode I. But the biggest advantage is the fuel costs - water.
Next in the review - welding and heating
