New Build

[wes709]

Hey Guys

In the works of building a new 5x10 plasma table ...

Here's what I got.

CNC electronics components using nema 23 steppers geared.
Rack and pinion drive.
Cheap THC (https://www.amazon.ca/ToAuTo-Automat...ght+controller)
Hyptherm 45xp (https://store.weldersource.com/p-426...ge-088123.aspx)
...


Im sure ill have some questions when it comes to slapping everything together just trying to see if i missed anything or if someone has had bad experience with any of the products above.

Cheers!

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[Torchhead]

I like the term "slapping everything together" as if its going to be a weekend project. Better brace yourself. The "slapping" may be your hand on your forehead. Not sure I would call $476 Canadian cheap for a THC even though it does have the lifter part (You still need a Z ) . Did you find anybody that uses that for plasma before you pulled the trigger?. That uses capacitance for measuring the arc gap. It's a big old ring that hangs down around the torch. The 45XP is a great machine, but it cuts at .063 above the material and a variation of more than + or - .01" will result in some poor cuts. The predominate method of torch height control is to sample the arc volts and adjust via that number. I suspect that at the higher cut rates for thinner material the response of that THC will be pretty slow . Its probably a fair height control for really think material that is pretty flat or for oxy-fuel cutting where there is no feedback voltage from an arc and you have a much wider gap and tolerance .

No mention of software or how you are going to generate cut files. How does it do the IHS (Touch off) . What about pierce height and cut height? Does it have any form of anti-dive? Is it automatic or something controlled by software and by which software?

Not sure you will get much help with that mix of parts.

Outside that its darn near perfect!

[wes709]

Hey thanks for the input! Are you trying to say that THC is cheap or expensive? I was looking at another one for approx 1000 usd on cncrouterparts.com ,,, i see that the one i chose goes up and down and i intend on having a z on my machine. I have built a CNC router in the past and i know its not a weekend project :P i have 2 weeks vacation so i hope to get the bed done and more if possible. The machine i plan on buying is made for the cnc machine with a machine torch so should it not mesh with the THC nicely ? not sure about the technical stuff you speak of yet but i will look into it. Also i plan on using sheetcam or another software that i can get my hands on ... any prefrences ? im really looking for information here! i have been doing wood cnc router for a few years now so that part should be a cakewalk

[wes709]

Also no triggers have been pulled yet aside from all the material i need to build the 5x10 table with the 3 axis

[wes709]

Here is the manual for that thc let me know please ! CHEERS

- - - Updated - - -

https://issuu.com/apexcnctech/docs/start_sh-hc30_height_controller_sys

[wes709]

LOL well looks like im gonna have some fun....

[rodw]

What Torchhead is saying is that the capacitance sensing method is not ideal for plasma cutting torch height control. It is more used for oxy/flame cutting.

If you want a budget THC, consider the Proma. I've never used it and there are mixed reports but I do know somebody who makes plasma tables for a living and swears by it and LinuxCNC. The other budget alternative would be to look at using LinuxCNC and some of the Mesa hardware and let LinuxCNC manage the torch height control. Thats the approach I've taken and its been about 12 months now since I started and I'm still not cutting... so plasma is not a trivial build.

[asuratman]

On Mesa Electronics, is that plug n go kits enough to run stepper cnc system ?
So the system consist of plug n go kits + ethernet cards, THC, stepper motor, stepper driver ... ?

[rodw]

On Mesa Electronics, is that plug n go kits enough to run stepper cnc system ?
So the system consist of plug n go kits + ethernet cards, THC, stepper motor, stepper driver ... ?

This page explains how to put stuff together diagramatically. Mesa Electronics US
Its also the best place to buy mesa hardware. Mesa themselves are not really geared up to sell single cards so they can be slow to ship... but their support is first class.

For steppers, there are 2 schools of thought:
1. Buy a motherboard and treat it as just another component in your control box. (use 5125/7i76 for PCI or 6125/7i76 for PCIe)
2. Buy a 7i76e ethernet board and only have a single ethernet cable between the PC and the control box. Great for noisy environments like plasma.

I'm building a plasma machine so it is a high noise environment so the 7i76e is a more logical choice.

For clarification, the 7i76e ethernet card is basically a 5i25 and 7i76 rolled into one card.

For plasma torch voltage reading they make the THCAD card. There are 2 versions. THCAD-10 0-10 volt sensing range which you can scale to whatever you want with a resistor. and THCAD-300 which is 300v version that takes raw arc voltage. I am using the THCAD-10.

The THCAD is a voltage to frequency converter optimised for high noise environments. You send the frequency count to LinuxCNC's spindle speed input where it can be easily read. There is a new experimental branch of LinuxCNC that supports external offsets. This allows you to apply an offset to the commanded position for an axis. This means that a Torch height offset can be applied and fed into the trajectory planner so LInuxcnc does not even know the height has been adjusted and we can use PID control to control torch height. Very exciting stuff if it actually works. I'm not sure if anyone has installed it on a real machine yet but I am close!

This is a better forum to explore LinuxCNC and there is a new plasma section
https://forum.linuxcnc.org/

[rodw]

Sorry, did not answer one of your questions. Steppers always need a stepper controller. One side of the controller is attached to the stepper motor and say 48 volt power. The other side of the controller is attached to 5 volt logic for step and direction signals which you would connect to the Mesa 7i76e step generator outputs. You would power the 7i76e and all of your sensors with 24v power. The 7i76e has an onboard regulator that steps down to 5 volt for the step generators, MPGs and the THCAD. I'm using Longs Motor DM542a stepper controllers. I am impressed with them.

[Torchhead]

LinuxCNC based alternative: (saves doing any LINUXCNC programming). CommandCNC(tm) is a custom user interface/driver for the hardware and its free with the purchase of the hardware.

https://www.candcnc.com/product-cate...mp3000-series/

This is a complete front end solution with the PC preloaded with LINUX and RTK (Real Time Kernel). PC loaded with utilities , CAD , Drawing (Inkscape) and unlicensed SheetCAM for LINUX. Has GUI configuration app for motor tuning and axis setup and all I/O. Has isolated remote digital pickup (PWM MOdule) for Hypertherm Powermax units. Works with 50:1; 20:1 and 7:1 divided volts input.
MAT150 interface card controls up to 5 independent axis. Hookup to motor drivers via screw terminals (Step & Dir) or use the on-board 25 pin connector to plug directly to the popular G540 4 axis motor driver module
Comes with POST processor for SheetCAM TNG for either LINUX or Windows. Ethernet from PC to controller for motion. USB via RS485 (hub required) for software to manage the modules.

The DTHCIV is a high speed THC with PID loop control, that is integrated with the toolpath (so it can do things like automatically turn off on corners or sharp turns, and not dive on the slowdowns..) and handles touch-off via a probe input. Uses the existing Z for both G-Code and THC moves so switching back and forth is a simple process of changing the tool holder (plasma or router ) and switch to another stored CONFIG . System comes with two default Configs: one for plasma, one for router.

Options for Ohmic Sensor , 48 function Hand Controller, Hypertherm RS485 Serial Port hardware/software, 5th axis rotary , and Rotary Plasma Pipe cutting.

Best part is you have a 2 year warranty , a phone number with humans that answer, and two online dedicated support forums to get answers. Designed, manufactured and supported in the USA.

TOMcaudle
www.CandCNC.com

[rodw]

And you have a very good option too Torchhead, but I did not see it as being feasible on my side of the world. Few people have the skillset, time or patience to build a plasma machine with LinuxCNC. When I first started my project, I thought all the pieces were there but boy was I wrong! Purchasing a prebuilt system is definitely a good option if you just want to get cutting given I spent a good 3-4 months just working on the software.

I think though the message for CandCNC is to stay ahead of the game. Every feature you have in your hardware solution can be quite easily replicated in the LinuxCNC software so if you are not careful, one day you will wake up to find the world no longer needs you.

[Torchhead]

Oh, we ARE careful. Not many shops have the expertise to do even the basic integration you need to stick build a plasma table using LCNC. You should spend some time on our support phones!

Everything can be done in software. First self-driving cars, then self-cutting CNC machines. You just "think" of a project and the machine cuts it for you !

TOM C

[rodw]

[QUOTE=Torchhead;2062248} You should spend some time on our support phones!
TOM C[/QUOTE]

No thanks! I've seen enough on this forum. Even someone blaming you for him not turning the machine on in the right order.