CNC Plasma cutters, DIY, building info and guide

Ok I can definitely see why floating head is bad for thinner materials. Why is ohmic bad for thicker materials?

Its not bad at all,

The problem I have been having with the ohmic sensor is false readings triggering a stop.

I cut all sorts of parts and one of them has a large slot in the center, When the air from the torch blows water from the center of the slot into the torch is causes a fault reading and stops the machine.

I have not had time yet to play with RodW's new hypersensing design but it should have some ability to tune the reading voltage to overcome some of the false readings.

thefabricator03 wrote: I have not had time yet to play with RodW's new hypersensing design but it should have some ability to tune the reading voltage to overcome some of the false readings.

I'm not sure if it will! I never had any probe errors until I added a water table. Sometimes I get a false trigger via a short on a water splash much higher than the material. But what I've found is that Plasmac recovers so perfectly I don't stress about it. I just hit resume and keep going. Pulsing the torch to get post flow going before the first pierce helps I think. And also pulsing the torch is helpful clearing water out of the torch before resuming. I also now park the torch in the middle of the table at the end of a sheetcam job so water does not go everywhere.

I actually tried cutting some 4mm at 40 amps for the first time last week. The first part was a failure as it was not cutting right through so I reduced the torch volts by 3 volts and nudged the amps up a little bit on the fly and by the time I was ready for the next cut, It was pretty much perfect. So I just need to reduce the cut height by 0.3 mm and see if the on the fly changes can be translated to final settings. The next cut was perfect and the dross just knocked off pretty easily.

The_wolf_of_walmart wrote: Ok I can definitely see why floating head is bad for thinner materials. Why is ohmic bad for thicker materials?

Floating head will work if you have finer slats under it, it will work anyway you look at it, but it will need some help from you with thin material.
Ohmic is better at sensing thin materials but it is less reliable than floating switch/head.
Personally i never use ohmic, usually we cut 3 to 6mm, and rarely 1.5mm and 8 and 10mm, so floating works perfectly.

tommylight wrote: Ohmic is better at sensing thin materials but it is less reliable than floating switch/head.

Having started with just a floating head, I have to say that the benefits of ohmic sensing is vastly superior to a floating head. Some say its not suitable on rusty steel or painted surfaces but its fairly unusual to cut this. Most of us are cutting new sheets of metal. IIts not tested but I think the hypersensing should allow probing on rusty material and possibly painted surfaces by setting a reduced threshold

rodw wrote: But what I've found is that Plasmac recovers so perfectly I don't stress about it.

My main problem with the false triggers is I need to walk back down to the machine and restart it. Gets old after the 8th or 9th time. But most hobbyist would not have a problem its production runs that it causes issues.