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Hi all. I've been playing with a design for a board that will allow me to read arc voltage with a Raspberry Pi. I think I've got something that will plausibly work. I'd appreciate a review of the attached schematic because circuit design is not my core competency.

Here's a quick tour:
1. Inputs are expected to be connected to the arc volt port of a blowback-start plasma power supply. 
2. Input voltage is limited to 250V by a TVS diode
3. Voltage is divided 50:1
4. RCRC filter limits frequency to 14Hz
5. Raspberry Pi reads divided voltage via ADC

Thanks!
 

Hello All,

New to the forum and first of all would like to thank you for the valuable information you guys post, it has helped so much me moving ahead with my build. id appreciate your help with my issue where it cannot activate the thc even when all the settings (that i know of) have been properly adjusted. first my setup:
-LinuxCNC QTPlasmac table
-Rpi5 with image LinuxCNC 2.9.8 Raspberry Pi 4/5 OS based on Debian Trixie
-Mesa 7176s over ethernet
-THCAD2 + 3M resistor array enclosed near the plasma source, F+/F- routed to mesaboard encoder input A with shielded microphone cable grounded at control side, also used a more simple twisted pair for testing.
-Used Pnconf for setting thcad2 trimming and ratio
Tested for correct voltage measuring for example, hooked a power supply from 39 to 56 volts and Main screen voltage readings coincide very accurately to multimeter reading.
-Flaring 65 plasma source with no cnc interface. (HF piercing) voltage probing connected to torch (-) and clamp (+) leads.
-For testing im using a straight line of 100mm at full speed so thc is not affected by speed reduction  (tested from 400 to 1800 mm/min)
-THC is enabled
-Mode 0 is used so arc ok is derived from voltage readings
-setup plasmac.arc_lost_delay =.3 as was having some issues for getting it to start cutting due to initial spike/valley.

I took the follwing HALSCOPE trace where:

 

1)torch on triggers,
2)probe voltage goes to 260 for piercing, then falls, then recovers to around 94v
3)Arc OK signal goes to true
4)Pierce delay elapses
5)Movement starts
6)THC active never goes up and of course  no correction

as Far as I can see voltage is "stable" once cut starts and there is no variation that could lead to deactivation as the tresholds are LOW=39 HIGH 990 (for testing purposes), samples 10 and threshold voltage 10.

has anyone had this issue or any lead on what to look at?

 
Hi all,

I am developing a 4-axis foam cutter using a Bigtreetech Octopus Pro V1.0.1 F429 connected to a Raspberry PI5 via SPI.
I have amended the Config.txt file, the .hal and .ini, and named the axis as X, Y, A and U.

What happens is the following:
1- X and Y axis work fine.
2- If I try to move the A-axis, then both A and U move.
3- If I try to move just the U axis, then nothing happens.

What am I missing?

I have attached the board pin mapping, the Config.txt and my .hal and .ini files, which were modified from those in the remora "ConfigSamples"  directory.

Cheers
Pier


 

Hi i can get cheap a q6a with 8gb ram. I read that its more powerful then a raspberry pi 5.

But here i cant find Informations.

Is it useless for us?

Thanks

Hello everyone, I am working on an upgrade for my old lathe. In short, I want to replace the old main motor with its multiple belt stages as well as the change gear system for the lead screw with two servos (more detail below). I am wondering whether or not LinuxCNC is the right way to go about it. I am a mechanical engineer by trade, but have little to no experience with control systems or LinuxCNC, so I do apologize in advance for any potential stupid questions coming up. 

The long version:
I want to upgrade my lathes drive system. It's an old machine, build somewhere around 1945, and it uses an induction motor followed by two v-belt, one flat belt and an optional gear stage to set the spindle speed, giving me a grand total of 12 possible spindle speeds to select from. Changing speeds therefore also isn't the quickest process. Even worse is the feed gearing driving the lead screw; It's set up as a change gear type system, so to set the feed rate I have to disassemble and then reassemble the drive train, which makes for painfully slow changes in feed rate. While the machine is certainly mechanically beautiful, my shop is not a museum and my time is quite precious to me, so I want to change that. The plan is to replace the main spindle motor and drive train with a big servo, and the feed gearing with another, smaller, servo. That would allow for easy changes of my feeds and speeds, as I just need to set whatever value I want on the controller. The feed rate per revolution would then no longer be controlled mechanically through the feed gearing, but electrically, by the smaller servo acting as a virtual reduction gearing if you will.

I already sourced the servos, a 1kW for the spindle and a 400W for the lead screw. They use EtherCAT for communication. For the controller I was thinking about either a Raspberry Pi 4 or a Kunbus RevPi that I have lying around. To run the machine I want to use LinuxCNC and an open source EtherCAT master, as done by Marco Reps for example.

I am however unsure on how to go about it. I don't yet require the full CNC potential of LinuxCNC; That might come at a later point, but for now, all I need are the following two features:

• Set the spindle's rpm
• Set the feed rate

Both of those options I would like to have on an easy GUI, ideally with as little unused "clutter" as possible. Depending on how hard that is to pull off, I would not mind learning how to program/code/design that myself, it might however quite likely be far above my current skill level. I am a mechanical engineer after all, not a software wizard. 

For the actual servo control I would like the option of having soft start and stop options by controlling the acceleration and jerk, so that the servo doesn't just violently try to reach the set spindle rpm.
Ideally the feed servo would be set up as a slave, following the main spindles rpm precisely, i.e. perfectly mimicking a mechanical gear train. So if for example the main spindle bogs down during thread cutting, the feed servo should ideally not just run it's course and lose synchronization. That should certainly be possible via EtherCAT, I just don't know how hard that would be to set up with LinuxCNC. It would however also be acceptable to solve that via a maximum allowable tracking error for the servos, if full on synchronization doesn't work.

I have a lot of ideas and things I would at some point like to add/have, from motor load indicators, a DRO via linear encoders, small easily programmable cycles all the way up to full on CNCing the lathe. But for now its baby steps, i.e. getting the lathe functional with its new servo drive train.

Is what im having in mind possible with LinuxCNC? Does anyone have pointers to a similar project? Or any advice or resources on how to set this up in LinuxCNC? How do I go about setting up the big servo as a spindle motor? Can I actually use the smaller servo as a slave synchronized to the main spindle motor? Is it possible to create a simple custom GUI showing only spindle speed and feed rate? Or would you guys recommend an entirely different route to set this up?

Any advice is greatly appreciated. I apologize if the post became a bit "rambly" in places and for any stupid/basic questions contained in it.

Cheers,
Nik

Hi there!

my Raspberry Pi5 died so i needed to setup thing new, but I can´t get it working anymore. It worked before... 

I have two Ethercat modules which need "speical care"
1. its the external "EP1809-0021" this is identical to the EL1809, so just replicating the last line in the el1xxx.c with the correct PID, works
2. the EL2564, this is a dedicated "driver" which is copied into the linuxcnc-ethercat/src/devices which gets compiled, works... 

LinuxCNC runs in the SIM Modes... also with ProbeBasic
EtherCat works - ethercat master and slave commands...
but LinuxCNC with ProbeBasic and Ethercat doesn´t want to start.

Here you can see my terminal-log when starting LinuxCNC
 
here you see my Ethercat terminal Outputs...
the EP1809 wasn´t connected...

so what can it be? I followed the "EtherCat installation from repositories" from Rod... i tried multiple images, 2.94~2.98 on Bookworm and Trixie... 

thank you

miniwini

maruf1777 wrote:

DRO shows identical position at arc entry and exit — LinuxCNC believes the machine returned to the correct point. But probing a fixed reference shows X shifted +9.3mm and Y shifted -12.2mm. HLFB is configured at 20 counts and did NOT trigger. This means every commanded step was executed by the motor. The error is in the arc interpolation — the step path LinuxCNC generates to trace the circular arcs does not sum back to the correct physical position.
LinuxCNC version: Master (2.9), running on Raspberry Pi 5 (4GB), Debian Bookworm, Mesa 7i96s over ethernet (hm2_eth), SERVO_PERIOD = 1000000.
 

Linuxcnc doesn't generate a step signal. All planner calculations are based on position (float64 number) and velocity signals.These numbers (not steps or pulses) for each servo cycle are sent to the Mesa board, where "stepgens" converts them into pulses.

These are the connections in hal:
joint.N.pos-cmd -> hm2.N.stepgen.position-cmd;

Each cycle, Mesa sends back the counted number of generated pulses for reporting:
joint.N.pos-fb <- hm2.N.stepgen.position-fb;

The difference between the sent position and the feedback is tracked using the joint.N.f-error pin.The path planner (on the computer) and stepgen (inside the Mesa board) do not influence each other, but each performs its own role in the chain.

I hope you understand that, in this logic, the position can't simply shift in the planner. If there was an error, it would mean it was transmitting an incorrect coordinate to the mesa, and the same incorrect coordinate would be visible in your DRO (since it's also connected to the joint.N.pos-cmd == axis.N.pos-cmd signal). And the incorrect path would be drawn in the graphics window. The "live plot" draws either based on the pos-cmd or pos-fb numbers. there's a switch for this.

If "LinuxCNC believes the machine has returned to the correct point," then the planner has indeed returned to that point and is transmitting that exact position command to mesa.If the error occurred in stepgen inside mesa, then the position-fb counter would have returned an incorrect number of counts (as a float64 number, not pulses).

If your servos don't report their own following error, then there remains the possibility of an error between Mesa => Servo. Due to electrical interference/noise, not all pulses could have been received by your servo - it thinks it's following the path, but in fact, not all the pulses reached it.
This is confirmed by the fact that you saw a connection between the error and pulse timings.

I have been working with linuxcnc and fusion 360 for a long time as post programmer, so I can assure you - there is no connection between the post processor, pathplanner and your problem. Both work fine.

DRO shows identical position at arc entry and exit — LinuxCNC believes the machine returned to the correct point. But probing a fixed reference shows X shifted +9.3mm and Y shifted -12.2mm. HLFB is configured at 20 counts and did NOT trigger. This means every commanded step was executed by the motor. The error is in the arc interpolation — the step path LinuxCNC generates to trace the circular arcs does not sum back to the correct physical position.
LinuxCNC version: Master (2.9), running on Raspberry Pi 5 (4GB), Debian Bookworm, Mesa 7i96s over ethernet (hm2_eth), SERVO_PERIOD = 1000000.

Very nice, thank you, and also thank you for sharing the files on GitHub.

Hi,

Just wanted to share the control panel I've built for my VM32 CNC conversion project. The aim was to get away from a typical PC+Monitor setup and build an all-in-one control panel for LinuxCNC which can be mounted on the mill cabinet and control the mechanics through MESA board. I published the resulting models for this build in a Github repo:  github.com/belovictor/linuxcnc-control-panel
You can also find the panel build video on my YouTube: 

Best regards,
Victor Belov
 

Hi everyone,
 
I'm experiencing cumulative axis position shifts (mostly Y, some X) during helical boring operations generated by Fusion 360 Personal Use. The shift happens between passes, not during cutting. I've done extensive testing to isolate the cause and I'm stuck — hoping someone with trajectory planner experience can help.
HARDWARE:
- 3-axis mill, 1204 ballscrews
- Mesa 7i96s ethernet card
- Teknic ClearPath CPM-SDSK-2311S-RQN servos (step/dir mode)
- 75VDC PSU
- Raspberry Pi 5 running Debian Bookworm
- LinuxCNC Master (2.9)

THE PROBLEM:
When running a Fusion 360 helical bore operation (3 passes: rough, semi-finish, finish), the machine shifts position during the helical arc cutting itself. The first boring pass starts correctly, but position drifts during the operation. The shift is cumulative across passes — each subsequent pass is worse. I initially thought the shift was only happening between passes during repositioning, but after extensive testing I've confirmed it also occurs during the actual G3 helical arc execution.

WHAT I'VE RULED OUT:
1. NOT mechanical: Dial indicator shows <0.01mm backlash. Coupling and ballscrew are tight.
2. NOT motor faults: ClearPath LEDs stay green, no faults. (Note: HLFB is wired but not yet configured in HAL — this is on my to-do list.)
3. NOT lost steps during linear moves: I wrote a test program doing 20 cycles of G91 G1 Y50 F1000 / G1 Y-50 and Y returns perfectly. Zero shift.
4. NOT electrical noise / VFD: Shift occurs with VFD off, spindle off, no tool, air cutting only.
5. NOT step timing: Tested DIRSETUP/DIRHOLD at 2000, 5000, and 10000ns. 5000 was slightly better but didn't solve it.

WHAT I'VE FOUND:
The problem appears related to how the trajectory planner handles the G-code Fusion 360 Personal generates. Key factors:
A) Fusion 360 Personal Use converts ALL G0 rapids to G1 moves. This means repositioning between bore passes (retract, XY travel, approach) are G1 moves subject to G64 path blending. The machine blends through the repositioning corners instead of making exact stops.
The bore operation uses helical arcs (G3 in XY with simultaneous Z) — this is the exact pattern described in GitHub Issue #426 (Arc Blending Bug).
C) I tested ARC_BLEND tuning parameters:
ARC_BLEND_ENABLE = 1
ARC_BLEND_FALLBACK_ENABLE = 1
ARC_BLEND_OPTIMIZATION_DEPTH = 50
ARC_BLEND_GAP_CYCLES = 4
ARC_BLEND_RAMP_FREQ = 100
D) ARC_BLEND_ENABLE = 0 did NOT fix the second file either.

G-CODE STRUCTURE:
The problematic repositioning sequence between bore passes (02.ngc):
N635 G1 X-77.844 Y12.6 (exit move)
N645 Z5. (retract - G1, should be G0)
N650 Z15. (retract more - G1, should be G0)
N655 Z4. (approach - G1, should be G0)
N660 Z2. (approach to cut depth - G1)
N665 X-80.544 Y13.2 (XY reposition AT cut depth - G1, gets blended!)
N670 G3 X-81.144 Y12.6 ... (arc cutting begins)
My INI Snippet:
[EMCMOT]
EMCMOT = motmod
SERVO_PERIOD = 1000000
ARC_BLEND_ENABLE = 1
ARC_BLEND_FALLBACK_ENABLE = 1
ARC_BLEND_OPTIMIZATION_DEPTH = 50
ARC_BLEND_GAP_CYCLES = 4
ARC_BLEND_RAMP_FREQ = 100
 
[JOINT_0] (X)
MAX_VELOCITY = 50
MAX_ACCELERATION = 150
STEPGEN_MAXVEL = 62.5
STEPGEN_MAXACCEL = 250.0
DIRSETUP = 5000
DIRHOLD = 5000
STEP_SCALE = 200.100
 
[JOINT_1] (Y)
MAX_VELOCITY = 50
MAX_ACCELERATION = 150
STEPGEN_MAXVEL = 62.5
STEPGEN_MAXACCEL = 250.00
DIRSETUP = 5000
DIRHOLD = 5000
STEP_SCALE = 200.460
 
G-code preamble: G64 P0.005 Q0.005

QUESTIONS:
1. Is there a known interaction between Fusion 360 Personal's G1-only rapids and the trajectory planner's arc blending that could cause multi-millimeter position shifts?
2. Is there a recommended set of ARC_BLEND parameters for helical boring operations where G1 repositioning is mixed with G3 arcs?
3. Would modifying the linuxcnc.cps post processor to insert G61 before repositioning moves and G64 before cutting moves be the correct approach?
4. Should I be looking at something else entirely?
I can attach the G-code files if helpful. Any guidance appreciated — I've been chasing this for a while.
 
Thanks!

Marcos wrote:

@RODW,

Have you tried Ventoy?

I've tried a number of tools and the only one that has never let me down is balena etcher. It even works with raspberry pi images!

Hello everybody!
I am new to this forum, so first I want to thank everybody for all the information posted here.
I want to replace my old 32-bit computer running a 3-axis stepper cnc via a parallel port. 
What I succeeded in:

1. I bought a Raspberry Pi 4 and a Mesa 7i90 card.
2. I used my old computer with parallel port, connected to the 7i90 and programmed the 7i90_spi_svst4_8.bit firmware using mesaflash.
3. I downloaded the LinuxCNC disk image for the RPi 4 and installed it.
4. I connected the 7i90 to the Raspberry Pi (about 3 inch flat-cable, all ground lines connected). I can read the device configuration using mesaflash without problems (well after a new install of mesaflash from the git repository).

Now I want to start ``linuxcnc linuxcnc/configs/by_interface/mesa/hm2-stepper/7i90-rpi-spi.ini``. The GUI pops up and everything seems fine.
But when I press F1 to reset the estop latch nothing happens. Up to now I did not connect any drivers or switches to the 7i90.
I changed 'DEBUG = 0x7fffffff' in the ini-file and added a 'show' to the end of the ini-file. I attach the output when running the linuxcnc. I marked what happend when I pressed F1 by '******' in the text.
If you need more information (ini-file, hal-file) let me know.
Many thanks for any support, H. Hermes

masawee wrote:

but normal need use WHITOUT this expensive hat , only gpio pin out and shift level converter can use 3,3V gpio pin to out 5V and traight to driver step and dir and enable pin.
how this made if ewer newer not has understand anything code nd not understand what need doing code, understand only good all hardware how connect and build,
i have rpi4 and SD card have linuxcnc rpi4 image, working and boot ok, (whit HDMI display) but not boot whit pi hut mikro HDMI to vga cable.
how make this gpio pins can take out gpio pin to driver DM556. were can download setting hal and ini file or what need add to rpi4, normal peoples NOT can understand and write hard code to rpi, hal or ini or what possiple need doing, not know.
i just buy rpi4, paraller port BOB, cheap chinese 10$ board, encoder, rotary SW, shift level converter modules, 3,3V to 5V, all buttons, DM556 drivers, nema 23 470 OZ/3Nm motors, lot hardware but not can made code anything.

help need send to me files what need copy and paste to rpi4 linuxcnc and were folder need add. not know were and what and how.

I have not tried connecting a BOB to a Raspberry pi. I think it could work but it will not be easy. You will have to write the hal and ini files.

How will you connect BOB to the Raspberry pi? The connectors are quite different.

If you could use your BOB connected to a pc that has a parallel port that will be a lot easier. I might be able to help. Then you could use stepconf to create your configuration.

but normal need use WHITOUT this expensive hat , only gpio pin out and shift level converter can use 3,3V gpio pin to out 5V and traight to driver step and dir and enable pin.
how this made if ewer newer not has understand anything code nd not understand what need doing code, understand only good all hardware how connect and build,
i have rpi4 and SD card have linuxcnc rpi4 image, working and boot ok, (whit HDMI display) but not boot whit pi hut mikro HDMI to vga cable.
how make this gpio pins can take out gpio pin to driver DM556. were can download setting hal and ini file or what need add to rpi4, normal peoples NOT can understand and write hard code to rpi, hal or ini or what possiple need doing, not know.
i just buy rpi4, paraller port BOB, cheap chinese 10$ board, encoder, rotary SW, shift level converter modules, 3,3V to 5V, all buttons, DM556 drivers, nema 23 470 OZ/3Nm motors, lot hardware but not can made code anything.

help need send to me files what need copy and paste to rpi4 linuxcnc and were folder need add. not know were and what and how.