Well, its been ages since I posted any updates here. I've had a few trials and tribulations along the way.
I found that I needed to use the preemptive kernel for Linux to get the Mesa Ethernet card working properly and this proved a major tasks. I installed the kernel on my 32 bit PC and the latency went out the window so I had to buy a new PC
Then a week of frustration followed and I finally installed Linux Mint 17.3, upgraded to the later 4.13 kernel, applied the preemptive patch to the kernel source code and compiled the LInux Kernel from scratch. Then I had to resolve all of the dependencies and compile LinuxCNC for the different flavour of Linux. As you can see, this is a massive PC. With the single Network interface reserved to talk to the Mesa card, the internal Wifi card introduced huge latency so I am running a USB wifi card to talk to the world from my garage.
While this was happening, I put a fair bit of work into the enclosure
I added green, amber and red indicator lights. While the machine is running it is green, if it is idle, it is amber and if in estop, its red.
A small blue LED on the far left indicates when the Plasma ArcOk signal comes on.
The red and green switches act as a run/stop and pause/resume switches.
I would like to make the green light flash when its in a pause state but I decided I had too much to do to get it functional.
I must take some photos of the electronics now its almost all wired in.
I got the gantry complete and running at about 21 metres per minute (well over 800 inches per minute for those that are metrically challenged)
The movement is spot on and there is no backlash. I let it loose for 20 metres up and down the gantry and it finished exactly where it started off on.
I decided I better tidy these bolts up
and ordered 20 M5 dome nuts from my bolt shop.
THe bill turned up and to my amazement, what you are looking at is AUD $158.60 worth of dome nuts! Well at least they were solid brass! After a terse email, the price dropped back to a more reasonable $7.60 or so. I was glad about that becasue I had ordered the wrong size and already had the correct M4 dome nuts to hand.
There is an insane number of sensors on the gantry (7 actually) so I decided to cheat and buy a 5 metre DB9 cable and build a breakout board. Using 2 wires for 24 volt power, I had just the right number of wires for the sensors I needed.
I made a bit of a mistake as I bought NPN proximity sensors only to find out that I should have used PNP sensors with the Mesa hardware so I had to add some pull up resistors which are also soldered onto my breakout board as you can see above. I also added a 24 volt LED indicator that pokes up throuh the top of the gantry to help with trouble shooting.
I have 3 proximity sensors in a row
The outer ones are limit switches and the inner one is the home switch.
These see the limit/home switches
The home sensor is a lot lower than the limit switch so it sees the edge of the mounting bracket. Once LCNC sees this, it backs off, approaches slowly to find the edge precisely and then there is a HOME_OFFSET setting that then lets me park the sensor wherever I want. I use it to park it as close to the end of physical travel as I can without th elimits being triggered.
The Torch breakaway sensor has been OR'ed with the external e-stop switch.
So if the torch falls off, the machine stops immediately.
Last week, the 25mm Hiwin linear rails and carriages arrived for the X axis and a day later the these NEMA 34 timing belt gear boxes arrived
They are about 4:1 ratio and they drive a 1.5 module helical pinion that engage with a 1400mm long rack you can see in the left of the photo above.
With all of this arriving, I spent the last few days working flat out on finalising the table design
And this morning I prepared 15 files to hand off to my laser cutters and I've emailed that off for quotes today. I hope it is cheaper than the dome nuts!
I've also ordered the NEMA34 stepper motors to suit the gear boxes so I hope to have the table together by the end of January. Its been a piece of cake sorting out the table and X axis in comparison with the gantry and Z axis. I always knew they would be the hardest bits.