Rods "Spaceship" Scratch built Plasma Cutter build

For Tomy's bennefit, here is the GUI I've been using to tune my THC


Hardly a work of art, but it does make me wonder why we need all of the controls we plasma nerds insist on adding to our GUI's

Rod

I think you've hit the nail on the head. My GUI and PP have every possible adjustment available to the operator. In routine production cutting I make no adjustments. I only make sure that the torch is enabled (I intentionally made this a required user setting) and that I choose to use cutting parameters from the cut file or the GUI. I know that if I was running a job shop that cut many different thicknesses and materials every day that this wouldn't be the case. I think this is because we all have such unique systems that we don't know the cutting parameters until we actually start using them. If you look at some of the attempts by commercial offerings to simplify things by using many tools in the PP to cover all possible combinations of materials and thicknesses you will see how plasma cutting needs a wide range of settings that need to be set some place.

John

Well I got my remap in place so now we know the desired cut speed set with the F Command and revised the Sheetam generated cut file so I can retire to airconditioned comfort to work on the post processor.

John, I think you are really on the money. Sampling the torch voltage is a major factor in creating a predictable environment.Here is the last cut today sampled at 120.544 volts. Now if it was worked of the book settings of 130mm, there would be an immediate attempt to adjust the torch height by about a mm.

EDIT: I was a bit wrong there. Looking at the cut chart again, the book setting is 120 volts so the actual volts was only out by 0.45%.


So I'll grab a photo of the parts I''ve cut and you guys can be the judge. but I am happy with the result.

Well, its not every day you have access to a photo studio in your plasma workshop



Anyway, the one I cut this afternoon is on top. with the underside showing after I gave it a few hits with a hammer to knock the dross off.

There is a couple of the same part I cut on Friday below it to show what each side looks like before knocking the dross off. There is very little in the way of striations in the cut so I think these are pretty good but I have any experience to judge it with.

I did find out that a 10mm hole in 8mm steel is asking too much. I'd like to slow the speed down on holes if I can make it happen in sheetcam automagically. The marked holes to drill are way deeper than what I got from my old plasma cutter from turning off the arc as soon as I got an ArcOK.

This is 80 amps at 1775mm per minute. Once the post processor is cleaned up, I'll try at some other amperage setting as I finished the soul destroying job of entering the mild steel cut charts into sheetcam yesterday...

Thnx Rod, i saw the GUI and i am pretty sure i have bumped into it somewhere somehow before, that should be the EO testing stuff right ?
Those cuts look nice.

Rod

I would consider the TD cut charts as starting places for your cut parameters. Myself and other have found they are not nearly as good as the ones HT supplies.

No striations is a good indication that the THC isn't working too hard. The dross looks like normal low speed type which shouldn't be too tightly bound to the work piece. I would check actual cut height and adjust volts as needed. Check air pressure and current setting, I know the frustration of the TD pots and knobs. I put a pencil mark on the dial face so I can set at the same spot every time. Then try increasing speed in about 5% steps until the dross goes away. Cutting over air you should be able to achieve dross free cuts on rectilinear parts on 8mm HR steel. If you get to the point of having lagging cuts in the corners slow back down a bit. You may want to use a lower cut current for 8mm. Usually when production isn't an issue the lowest cut current that will work yields the best cut quality.

The arcok signal from the TD power supply is really slow to come on. I use no pierce delay on 2mm and still get a start divot.

Small inside circles (holes) will need a speed reduction between 40% and 70% to get good straight sides and adjust the kerf width used or hole size to get the required diameter spot on. Yes there will be dross. You are going to have to cut a bunch of holes to find the correct settings for your system. Lots of discussion about this over on plasmaspider. You can either use SC cut rules for holes or do as I do and just have another tool defined.

John