How good can it get

[Branislav83]

Greetings to all of you guys.
I have recently finished my build on my cnc plasma cutter. It is completly based on the mechmate design, which i found to be a very good design and most of all it is scaleable to almost any needed dimension. So i made mine 4 m long and 2.1 m wide. I incoporated a waterpool into the design to get rid of the fumes and lowered the mechmates original height to be cca 500 mm high in order to make it easy to load heavy plates on the table with a forklifter.
Our company is located in croatia, and its basicly a job shop, but due to its location, know how, employee structure and a little bit of circumstances we find ourselves in everything related to steel. Basicly the need for a cnc plasmacutting system was obvious to me for a long time, but the prices for commercialy available machines here in croatia are really way to high, i mean really way to high, mostly if i take into account the these are mainly chinsese machines which every professional knows arent simply worth the money ( like this one http://www.njuskalo.hr/strojevi-obrada- ... as-5323508 which costs 10000 euro without the basetable, its basicly a portable cnc system... ). The other problem with commercial machines is their maintanance, by which i mean, if anything goes wrong, i have to stand still and wait for a "technician" which will charge his/hers services by the hour and so on.
This way i have built my own machine, i know every screw that was built into it, and i got myself a great learning process by the way where i understood by learning by doing what a breakout board is, how stepper motors work, how my thc controls the height, how to set up mach3, how to fine tune my machines movements and so on.

I cant tell you how happy i was after i got everything set up and after i ignited the torch for the first time from my pc.
But basicly the real learning process began after i had my machine setup.

I learned that i need good grounding of my table because of the rf transmision of the HF arc starts, i learned about the importance of clean and dry shop air, about the way i need to make my inside cutouts , and my outside cutouts etc.

Today i finished installing my airdryer and i basicly got all of my "problems" kinda sorted out, so i would ask you guys about your opinion on how good my cuts look, and if there is any way to make it better. Long story short here are my specs, and tommorow im gonna serve you some photos of my machine, and some cutouts i made.

Base table : 4m ? 2.1m - mechmate design
Plasma source: ESAB Powercut 1500 - 90 AMP
Torch: ESAB PT 21 AMX mechanized cutting torch
THC: Texas microcircuits THC 301d
Controll software : Mach 3
CAM software: Sheetcam
Cutting gas: Predried shop air

Here a few videos on my youtube channel , that were made this sommer after i got everything working ( more or less )....

http://www.youtube.com/user/branistar

My first question: Is there any benchmark (dxf) for testing how fine i can cut lets say 1.5 mm thick sheets, so i can cut it out tomorrow to make some photos to show you my cut quality so we can comment on it and maybe improve it.
Second question: What do you think about my setup

[Branislav]

Sorry for not updating my thread, but i was really busy the last few weeks.

So to get a better insight here are a few pics i have taken during the last few weeks.

The first part i would like to show you is a 25 mm thick cutout that i later machined.

I was satisfied with the cut quality, although i had a little bevel on the sides. The part has a long hole in it and one one photo it is visible that i have my problems with hole cutting. Although my hole turn out good, i always have a little too much material taken away by the torch due to lead in and lead out movement.





The next few photos show cuouts from 10 mm thick material
The hole in the piece of square is 18 mm, again, i have a problem where my torch takes of to much material at the lead in and lead out. The hole gets slimmer at the buttom , although i have noticed that cutting speed is here the most important factor to reduce this problem.




The last set of pics shoes our company logo in 2 mm and in 5 mm although the 5 mm part was cut at wrong settings due to messing around with the thcs sensitivity.



I can not say that i am 100% satisfied with the cutting performance on 2mm thick steel. Also i have noticed that i should always turn my thc of when cutting thin material, or small cutouts because it tends to turn the torch of during cutting letters for example.

I filmed a job in 2mm thick steel , its on this link
http://www.youtube.com/watch?v=1ZGeNo1MsQk
The settings are described in the video. Although i was satisfied with the end product it all ran without thc except the last cut and without the loop sharp corners setting in sheetcam because these tended to turned my torch of during the cutting of some letters.

Does anyone of you guys have these issues with your thc or should i try different settings. Please leave a comment, im gonna upload some more pictures of cutouts soon.

[Branislav]

Here you can see that my lead ins and lead outs are causing me problems with holes. The holes were predrilled with a 3 mm drill bit so i dont waste my electrode and consumabels while piercing 20mm thick plates.

Is thee any way to get my holes cleaner or should i maybe try to avoid lead outs or lead ins in such thick material ??

Thanks in advance

[larrycameron44]

Well I for one, think you have done a brilliant fob, the cuts look great to me on that thickness.!!!!
I was under the impression that we dont use lead outs in plasma cutting... I read it somewhere. And while some use a radius lead in apparently a 90 degree lead is is better in some situations as it decreases the "plasma cut working area" when the plasma comes around to finish the circle.

Hope something I have written helps

Larry
NZ