Project of the Month built by Stefan-K
Home Model Engine Machinist > CNC > CNC Machines and Conversions > Some people build Models, others build CNC PLASMA machines

Reply
 
Thread Tools Display Modes
Old 01-13-2017, 10:32 AM   #31
rodw
 
Join Date: Dec 2012
Posts: 896
Liked 274 Times on 212 Posts
Likes Given: 134

Default

With Mesa, you have a choice of either an ethernet solution (my 7i76e for steppers or its cousin the 7i77e for servos) Or a PCI/PCIe solution. In that case, you plug a card PCI in your PC (probably a 5i25) and then you use a 7i76 or 7i77 daughter card which connects to the PCI card via a parallel port cable. The PCI interface has multiple DB25 connectors for the daughter cards.

The 7i76e is basically a 5i25 and 7i76 rolled into one card connected by ethernet. It supports 2 daughter cards so I could add another 2 x 7i76 cards which would let me control a total of 15 steppers. I think then I could add a RS485 interface board that would allow me to add another 4 I/O cards to increase the number of inputs and outputs if required.

Aside from loading a different driver, PCI vs ethernet is totally transparent when you use it.

Tommy my LCNC plasma mentor on the forum says that putting your PC in there with the electronics with plasma is a surefire recipe to spend countless hours troubleshooting recurring random problems due to noise.

Most Plasma system use a high frequency start that generates a high voltage, high frequency spark to kick the plasma off. Mine has a blowback torch where the arc is started in the torch and once established, the tip blows back or retracts and thus does not generate the noise or HF. That style is much preferred for CNC systems as few torch height systems can handle the HF stuff. Mesa's THCAD card can...


__________________
RodW
Brisbane, Australia
vehiclemods.net.au
rodw is offline  
 
Reply With Quote
Old 01-13-2017, 10:57 AM   #32
rodw
 
Join Date: Dec 2012
Posts: 896
Liked 274 Times on 212 Posts
Likes Given: 134

Default

Quote:
Originally Posted by joco-nz View Post
i.e. no extra card in the PC meaning you should be able to go to a really small form factor mini/micro style ITX board with the associated small case.

Cheers,
J.
Sorry. Did not address this. Yes, I'm using an ULTRA SMALL FORM FACTOR PC (USFF).

The only issue is that to get support for hardware, you need to run a later version of Unix than the LCNC distro. This for me meant compiling a newer kernal and then of course compiling LCNC from source.

The kernel upgrade can be reduced to a single script but LCNC compiling takes a bit of work due to the large number of dependencies that need to be installed.

The onboard wifi cards on these cards cause terrible latency so you need to use a USB wifi dongle to connect to the internet as the ethernet port is in use. IF I built another, I would find a USFF PC with a dual network interface.


__________________
RodW
Brisbane, Australia
vehiclemods.net.au
rodw is offline  
 
Reply With Quote
Old 01-13-2017, 06:58 PM   #33
joco-nz
 
joco-nz's Avatar
 
Join Date: Feb 2016
Location: Wellington, New Zealand
Posts: 276
Liked 64 Times on 47 Posts
Likes Given: 53

Default

Thanks Rod. When you get back to posting on build progress I, and perhaps others, would be just as interetsed in the software/electronics side of the build as the medhanical. E.g. Wiring diags, models/versions of MBs/CPUs used, performanc characteristics/jitter/etc, good suppliers you have discovered.

A lot of what you a working through on the LinuxCNC side and associated electronics and controls I'm very interetsted in as I can see its application to any router style CNC table and much that can apply to a LinuxCNCing of mills or lathes.

I just cant let the wife get a hint of another possible project fasination right at the minute.

Hanging out for more build posts.
__________________
James,
Wellington,
New Zealand
joco-nz is offline  
 
Reply With Quote
Old 01-14-2017, 10:07 AM   #34
rodw
 
Join Date: Dec 2012
Posts: 896
Liked 274 Times on 212 Posts
Likes Given: 134

Default

Quote:
Originally Posted by joco-nz View Post
I just cant let the wife get a hint of another possible project fasination right at the minute.

Hanging out for more build posts.
Sorry, but I'm writing this on a Chromebook that crashed and lost my post. Very Annoying!

My wife would die if she knew what I've spent on this project!

The detail is on the LCNC forum here
https://forum.linuxcnc.org/show-your...a-cutter-build

Make sure you follow the links I post as many of them refer to links where I ask a specific question in another sub-forum to make sure the right people see it and help me!

Anyway, today was 36.2 degrees according to my weather station just above my shed which means it would have been 46.2 degrees where I was working in a tiny corrugated iron shed.

I managed to fit the steppers to the 5:1 timing belt reduction drives before I expired in the tin sauna. I emerged in a lather of sweat and was able to plug them in to my control panel which meant for the first time, I had all 4 steppers functioning.





I can't really do much more until I get the gantry ends installed and the gantry up on the table as I need limit switches and homing switches so I can home it. Until I get that done, I can't run any gcode to tune it.

But at least all of the motors run in the right directions.

Off to ebay to order 6 more proximity switches. This time I will make sure I buy the right type (PNP)


__________________
RodW
Brisbane, Australia
vehiclemods.net.au
rodw is offline  
 
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gas Turbine build, pictorial build log. rythmnbls Photos and Videos 103 03-02-2016 09:39 PM
People that build from blueprints? rodm1 Questions and Answers 22 01-02-2014 12:36 AM
6" Copper HRT Boiler Build (warning, long build and lots of pictures) A310 Boilers 21 04-06-2013 08:03 PM
What to build..? DaveRC Questions and Answers 10 12-08-2010 10:16 AM
My first build John Rudd A Work In Progress 3 10-14-2010 10:03 PM





Newest Threads






- Top - Member List