Plasma Questions

So what does mean?

Well, I'd say somebody has cut and pasted some HTML code somewhere becasue it is HTML for Now it will make sense to you. See www.w3schools.com/html/html_entities.asp

And yes, I know long term Hypertherm is the way to go. I've got a Traffimet S75 machine torch. The table will be very stiff, probably with 100mm x 100mm SHS legs and frame

rodw

Thank you. The last time I did any real programming HTML was still inside CERN.

One other thing you should consider while still building is what you are going to do for fume control. Plasma cutting is a smokey dirty process. Water table or down draft both have their ups and downs. Water table is simpler but only gets about 95% of the crud. Down draft can cost a lot of of heat or AC if you don't filter and recycle. The filters get big and expensive for the size you need.

I have put in the scale, ddt and pid components and connected them up to the THCad encoder so I can see how they react with a real arc. Initially I will just watch them with Halmeters.

John

islander261 wrote: rodw
Thank you. The last time I did any real programming HTML was still inside CERN.

Your welcome. I've tried to avoid it too becasue I have a background in the printing industry where postscript rules supreme but we have smart software to do the dirty work whereas with HTML you eventually have to drop to source code.

islander261 wrote: rodw
Down draft can cost a lot of of heat or AC if you don't filter and recycle. The filters get big and expensive for the size you need.

Thats not really too much of an issue where I live. I have a mate who lives in my street who does some contract work for me. He was complaining a few days ago that it was 42 degrees C in his workshop while he was working on my parts. Thats 108 deg F...

Good luck with PID control. I think LCNC has a long way to go to catch up with commercial THC control. Despite having cheap, high quality hardware to read the voltage, we have not developed the software yet.

I just remembered that the external THC I have wires into the X & Y step pulses. It must do that so it can measure cutting velocity. Because we are embedded in the motion controller, we should be able to blitz the competition. LEt me know if you need help with the programming....

The measured arc voltage into a long straight cut @ .07" height is about 80V on my old Torchmate AVHC and confirmed using a DMM. So 80V / .07inch = 1142.857 Volts/inch *.005 inches = 5.7V voltage change for a .005" change in cutting height if all other parameters are fixed.

I do not think you will find this to be accurate.
A better test might be to make your cut at .07" as you did but then make another cut at say .075 and read that voltage.

I would suggest anyone using the Mesa THCAD try the THC.comp just the way it is before making any changes. It has worked great for me. The experimental version I am cutting with is the result of another member asking about the possibility of cutting corrugated steel. Will try to document and post right after Christmas as we are currently swamped.

By the way I am currently using a Cutmaster and the cutting heights are quite different from a Hypertherm.

Rick G

I really look forward to seeing how your revised THC handles Corrugated Iron as that is what will really put a THC through its paces as I followed that thread..

I'm certain the THC.comp will work fine for me as I doubt I'll often go below 2mm steel but I want the machine to do the thinking when different thickness material is used.

Hello

Thanks for the replies. I am now thinking about how to implement the needed torch touch off and start action. I will most likely post some pseudo code for comments next week.

rodw

I actually expect that the existing THC component will follow corrugated sheet steel just fine if the correction velocity is high enough. It is all the other niggley parts I don't know about.

Rick G

Ok, I just assumed the voltage change to be near linear near a given point. I will have to go out and check this today otherwise it will be several weeks before I will be cutting again. My present THC will only allow .01" resolution in setting height so the measurements will be with a .01" change in cut height. I intend on starting with the present THC component. I have a TD A60 power supply (a Cutmaster with CNC interface I think). I do use a Franken Torch that is the Duramax parts grafted a TD SL100 torch body. This allows me to use the Finecut consumables which last much longer and give good cut quality. Also in bulk packaging the Finecuts are cheaper than the TD parts.

John