When I was in high school (late 80’s) My Father picked up a large NC machining center from the junk yard. This was junked out of a local manufacturer because at the time - retrofitting said machine wasn’t worth it. Dad was trying to get a small machine shop running and already had some manual machines (mill, lathe, shaper , etc…)
Well - the new machining center (Kearney & Trecker IIIb from the 60’s) required a new building. So we added on to one of our pole buildings. The machine required 2f’t thick slab of concrete under it. After a bit we had the machine place and I spent my Junior summer splicing 1000’s of wires and hydraulic lines. We decided to use the original control. This was a GE germanium transistor 60’s vinitage control the size of a very large fridge. We got it working again and used it that way into the 2000’s.
At this point in time - computers started to become powerful enough to do machine control and a lot of machine control software started showing up. Some ran on dos some windows and one really cool one on linux. (mach, tubocnc, emc to name a few) We played with turbocnc for a bit but decided it was too basic for what we needed. Mach was not free and we were cheap…
Searching around we found emc (enhanced machine controller). It was actually a project that was created by NIST and put into the public domain. It initially ran on windows nt with a commercial realtime build. Once it went public domain - the linux community picked it up. Linux had some realtime kernel options that worked well. At the time it was based on redhat. they had a BDI cd. (brain dead install) to make installing linux+realtime+emc easy.
I got into it at a great time. A bunch of the developers were working on EMC2. This was quite a re-write that made it so you didn’t have to edit source code to make config changes. It was qutie a leap. They also created a livecd based on ubuntu (I think it was 6.04) This is when I first installed linux on my laptop to play with linuxcnc. I dual booted between windows xp and ubuntu.
I found out as time passed that I booted into xp less and less. The next laptop I didn’t install windows naively… I ended up using virtualbox initially the rare times I needed Microsoft then moved to QEMU/KVM when I wanted to do pass through… (I wanted to run fusion 360 with decent performance in the vm)
Here is one video when we first got the old K&T working…
Funny thing is - I thought every family fixed their own cars, equipment, electronics, electrical, plumbing… It wasn’t until I went to school that I found out that wasn’t the norm… I got a heck of a good schooling at home and at the time didn’t know it.
What are you using for servo drives and the interface between the linuxcnc computer and the servo drives?
I’ve really wanted to play with linuxcnc for quite a while but I haven’t had the time. Last I had looked into it, I was thinking about using some ethercat controlled drives and some beckhoff ethercat digital IO for control of accessories (coolant, safety switches, etc). I liked the idea of running it all through a nic and not using pci cards.
I am using a mesa ethernet solution. (7i92) This emulates 2 printer port (all be it - super high speed) and is expandable. I am using it as 2 printer ports in effect. 1 port runs the leadshine stepper drive - the other runs various encoders, serial and i/o. So - this is a stepper machine - but linuxcnc is just as good running closed loop servos.
I have not played with ethercat - partly because I don’t like the licencing of it.
I have been testing the rpi4 and so far it has been working well. (pc’s are easier and more rubust… but it is still cool what the Pi can do.)
Yeah I thought the vertical sounded like stepper drive, but the horizontal sounded like servo with a vfd driven spindle.
I’ll look into the mesa ethernet cards. I didn’t know they had anything that wasn’t pci/pcie based. Its been a couple years since I looked into it though.
The reason I like the idea of ethercat is that it is deterministic and didn’t require a full sized computer with pci/pcie slots. Maybe some magic between the linuxcnc kernel and the mesa ethernet cards makes them deterministic. I’ll do some reading on it if I get the chance.
Yes - linuxcnc needs a deterministic (realtime) connection with hardware. Linuxcnc uses rt_preempt for ethernet connected hardware. Depending on the hardware - you can run over 2khz or more. (although 1khz is usually more than enough unless you are running crazy acceleration.) The pi doesn’t seem to handle 1khz currently - so I am running it at 500hz. As you can see - it still is pretty darn good.
an FYI - the config I have been running doing the poly machining - is running 1khz… I had switched configs and didn’t notice. So it seems the rpi4 will run 1khz with an mesa ethernet interface.
