CNC Plasma cutters, DIY, building info and guide

The_wolf_of_walmart wrote: So as someone that has mill/turn capabilities- Is it a ridiculous notion to take the guts out of the OE torch and make something sturdier and more machine-torch like in shape.

A different torch to yours but a good example.
forum.linuxcnc.org/plasma-laser/36730-30...ch-conversion#135766

Ok so it sounds like there is a difference?

After a little more digging I did find what appears to be a 3rd party(?) machine torch on Ebay that fits the Lotos power supply I linked earlier. I totally understand value of paying for quality up front, but with the reviews, price point, and option of expanding to a machine torch, it does seem to be a high-value low cost of entry option.

That being said, I have not decided on how I'll be doing initial height sensing. Reading your recent post on THCAD with ohmic sensing is the only exposure I've had to that method so I'm not sure if the Lotos route will obviate that option for me, though I am planning on using THCAD for height control. Any advice on that in the meantime will be appreciated

If you plan on cutting thin material up to 3 or 4mm, Ohmic sensing is better, anything thicker and floating head is the way to go.

Take care with your torch selection. The plasma cutter you shared does not have a central connector as shown on your ebay torch so the two are not compatiible out of the box.

And yes, you might be able to do ohmic sensing using the hypersensing circuit. It will at least be be electrically safe.
forum.linuxcnc.org/plasma-laser/37311-hy...-to-do-ohmic-sensing

But the blowback mechanism will probably short the tip to the material while not cutting becasue the arc is established this way before the mechanism :"Blows back" to separate the dead short.

If you plan on cutting thin material up to 3 or 4mm, Ohmic sensing is better, anything thicker and floating head is the way to go.

I would imagine I'd be cutting thicker than that MOST of the time, but I'd hate to sacrifice the ability to cut one over the other. How difficult is it to cut <4mm with floating head and vice versa, >4mm with ohmic?

Take care with your torch selection. The plasma cutter you shared does not have a central connector as shown on your ebay torch so the two are not compatiible out of the box.

And yes, you might be able to do ohmic sensing using the hypersensing circuit. It will at least be be electrically safe.
forum.linuxcnc.org/plasma-laser/37311-hy...-to-do-ohmic-sensing

But the blowback mechanism will probably short the tip to the material while not cutting becasue the arc is established this way before the mechanism :"Blows back" to separate the dead short.

Ah my mistake- Wrong link; They do make that torch with the correct connection as well.

I'm finding a lot of general description on blowback start but I can't find anything that illustrates what is actually happening in the torch. Under what circumstances would the piston be energized, the torch not cutting, and low enough to short to my material? I would assume the arc starting height is taller than the piston before it blows back?

The_wolf_of_walmart wrote: How difficult is it to cut <4mm with floating head and vice versa, >4mm with ohmic?

It can be a big pain the the ass.

I have done a bit recently with 1.6mm black hot rolled sheet and if the material is warped the torch will come down for a touch off - push the sheet down until the limit switch trips - moves up to pierce height then lowers to cut height but the material will push back up and cut height will be lower than the top of material. Then the torch drags and destroys the part.

Only way around this is to baby sit the machine and keep the material flat by pushing it down with a length of rod or RHS until the cut has started and the THC will take care of the warped sections and maintain the correct arc length.