New to Linux-LinuxCNC.... have questions

I currently own a CNC burning table (Ox/Fuel) operating on WinXP & Mach3. so Building a CNC machine isn't all new to me.
Wanting to build a 2nd. table using plasma Want to get away from Windows & their constant built in obsolescence....

It has been 11+ years since I built 1st. table. so I'm quite out of touch with what is out there.

Would like to use Ethernet to breakout board as opposed to Parallel port or USB of course need Home switches & a good THC Will be using a Hypertherm 1250 plasma

Would like recommendations on where to source the electronic parts I need

Already have a good power supply, Gecko 203V drives & robust NEMA-34 steppers.

Ethernet is a good choice for a plasma build as it has good noise tolerance.

There is a thread here discussing plasma:

forum.linuxcnc.org/plasma-laser/35349-op...ea-and-a-lot-of-info

The most popular ethernet control card with LinuxCNC is probably the 7i76E but that is a bit excessive (and expensive) for a plasma table.
The 7i96 is probably more appropriate and still has screw-terminals for convenient wiring. There are cheaper options still, such as the 7i92 and 7i93 but those do not have screw terminals so you would need to source and wire connectors. (of course, that can also be an advantage)

andypugh wrote: The most popular ethernet control card with LinuxCNC is probably the 7i76E but that is a bit excessive (and expensive) for a plasma table.

Personally, I disagree with Andy here. Plasma needs a lot more Inputs than most other machines so the 7i76e is a very good choice. I found it was possible to use all of the inputs.

rodw wrote:

andypugh wrote: The most popular ethernet control card with LinuxCNC is probably the 7i76E but that is a bit excessive (and expensive) for a plasma table.

Personally, I disagree with Andy here. Plasma needs a lot more Inputs than most other machines so the 7i76e is a very good choice. I found it was possible to use all of the inputs.

Plasma needs as a minimum 4 inputs to work properly WITH THC,
- Probe or floating switch
- ARCOK signal from plasma or THC ( Proma THC 150 provides that from analysing the voltage )
- UP from THC
- DOWN from THC
That is with no limit switches or home switches. For that even the parallel port has enough inputs.
Some parallel ports can be configured for IN or OUT or X mode so the number of inputs and outputs can be changed as needed. Adding another parallel port PCI or PCI-express card is always a cheap option for more I/O.
7i96 from Mesa has 11 inputs so that will provide for the above and as below
- E-STOP
- 3x Home switches for all three axis that should also be used as limits for their respective axis
- 3x Limit switches for the negative side of their respective axis.
That should complete a normal machine.
On machines that use DC servo motors i use always another set of limit switches ( 2 for each axis ) as extreme limit switches that are wired to a relay that will cut the power to the machine in case one of them is triggered. This is in case the drives fail, usually they will short one of the outputs and send all the power to the motor so even stopping the enable signal will not work in some cases.
Adding some physical switches to the control panel is also very useful so that would require more inputs or a Mesa 7i73 that has also encoder inputs for MPG and can control a small display and some keyboards. All this is still cheaper than a touch screen monitor.

Plus:
extra home switch to use Master Joint Axis to square entry
I prefer seperate home and limit switches as you can get larger usable area
torch breakaway switch
Scale select for 7i76e MPG (2 min)
Axis select for 7i76e MPG (2 min)
Warning lights (I have 3)
Run/Step button
Pause/Resume button
Drive disable output
motion.digital-in.00 for M66
Pendant e-stop
Pendant features (4)

I've not listed all I've used. What about downdraft zoning?
We are talking a large machine so a few extra inputs and outputs gives a much better user experience.

Thank you, Rod.
Will add that info to the plasma thread so we can have all the information gathered in one place.

Thanks to everyone for the input !
When looking at the THCAD-10 & the THCAD-300

Can someone thee me which is the better choice for a Hypertherm 1250?

The HT 1250 I have was purchased as a hand held torch. I did purchase a machine torch to fit the machine.

hyperterm 1250 is a great machine .. I would take thcad10 without a doubt, since your plasma has a 50: 1 internal divider available on the 14-pin socket on the back.

I purchased the HT1250 planning to add it to an existing Ox/Fuel table I built a few year before. Then didn't add it because of no water table or good way to remove most of the airborne dust & smoke from the shop environment. It's still in the box!! Wad purchased shortly before thr Powermax 30,40 etc. series hit the market

billykid wrote: hyperterm 1250 is a great machine .. I would take thcad10 without a doubt, since your plasma has a 50: 1 internal divider available on the 14-pin socket on the back.

In your case that is the choice .