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Perhaps should change the subject line now, since my hardware has changed...

We have now installed a 7i97T/7i74/7i84U combo and have the machine up
and running. I would still like to use the mesa modbus component to
talk to our several modbus I/O boards and the spindle.

To enable this, I'd be grateful if you would make a firmware for this
combination:

7i97T with pktuart/modbus on the TB4's RS485 port, and a 7i74 on the
P2 expansion connector with pktuart/modbus on channel 7 and 7x SSERIAL
ports on channels 0-6

if possible?

Ethercat components are now very inexpensive to purchase. The servo kits at Stepperonline cost less than €200, including customs duties and taxes. Fieldbus modules are available at low prices on eBay.
Why Ethercat?
Step/dir: has limited frequency/encoder resolution and is only suitable for small tools. High demands on the PC.
Analog: I tried this, but unfortunately it was very disappointing.
Ethercat: Real-time capable, motion control, position feedback, extremely high speeds possible.

 

The forum decided to ban my IP because of its distorted view of the world during outages.
Thankfully, Andy rescued me back from the dead after a message to the developers mailing list!

Ihave a new component in progress that is designed to address many if the things you raise home jump, pv mode etc. be patient as i had to put it aside for a while

The mindset should be that the drive decides.
The component can only ask the drive to do things like switch op-mode, start homing, etc
for the rest the drive must react to every status condition that comes from the drive.

There are other circumstances when the position feedback can be out of sync with linuxcnc joint commanded position.
A spindle running in PV mode as a spindle motor, switching to csp mode as an axle comes to mind.
The component handles and offset in such a case.

thanks, indeed that doesnt work therfore jsut as
URL: github.com/LukasOtis/LinuxCNCEthercat
and link  link
 

It's Bridgeport Series 1 CNC milling machine.
My home switches locations are randomly placed but min/max are measured home to hard limit switch and then backed a little.

My X and Y axes home switches are cheap China proximity switches but Z axis switch are good mechanical. Thought maybe they are not accurate but DRO will show that machine have run over soft limit and next time soft limit is working.

Credit where credit is due: I built it but didn't design it, the credit goes to Mike Bax, who builds and sells the high voltage pulse generator used in his EDM machine design. Anyway, it's running and working fine; my questions are about using linuxCNC in general.

I'm having a heck of a time wrapping my head around how to properly set up a workpiece in linuxCNC so that it starts cutting at the expected point.  There are three markers in the Preview window, a large circle with crosshairs, and two smaller "X"s. I understand that the large marker is Machine Home but don't understand its usefulness in the display. The two small "X" figures move around when offsets are changed, but they don't always seem related to where the cut starts. My usual steps are:

Load an .nc job into linuxCNC, which appears in the Preview tab.

"Home All" is selected.

Bax supplies software with his power supply, including extensions to linuxCNC that provide utilities such as Edge Find. I run that, and the respective axis value changes to some value denoting the edge. So far, so good.

The first issue is that I don't know how the resulting value relates to the overall workpiece. The value changed somewhat during the Edge Find, so is offset by some amount. For this example when the cut starts right at the edge of the workpiece, I don't know if Touch Off is necessary, since the cutter is already immediately adjacent to the work piece. If a Touch Off value is required, I don't know what to enter.

The first photo shows a typical preview display with the large target and the two X's. My "guess" is that the two X's represent the start and end of the cutting path. Correct? The large target doesn't seem useful, but it's probably because I don't know what it represents.

The second photo really confused me. Here, the cut "started" at the free end of the red diagonal line, moving toward the upper left corner of the workpiece (note that this is inside the workpiece). Also note that neither of the X markers is at the start of the red line. While the red diagonal line was extending, the physical cutter was Not moving. The red line continued until it reached one of the X's and then began following the contour of the cut. The crazy thing is that the physical cutter Still wasn't moving and didn't until the red track came down even with its start. Only then did the physical cutter contact the work. As a result, the entire workpiece ended up missing everything above that point.

I'm fairly convinced that I'm not understanding and using Touch Off values correctly and am hoping that someone can explain it to me as someone would explain to a small child... Thanks.

Just what I needed. The rotary screw extruder is centered on the mounting plate and it can probably push filament faster than any NEMA17 motor could.

hackaday.com/2021/12/05/rolling-screw-extruder-goes-brushless/

Did you confirm the parport address is 0x378?

If not, post the output of
sudo lspci -v

The nozzle will be heated with induction heat. It will be interesting to find out whether the stainless steel tube 3mm od x 2mm id x 25mm long between the extruder and nozzle will have low enough heat conductivity to avoid overheating the extruder drive without additional cooling.

i responded to your git issue. the probe routines are correct, your issue is your machine setup. many new folks get things a bit twisted as they view motion from the perspective of the table when whats actually happening is motion relative to the spindle.

gantry machines (head moves around) DOES actually follow expect cartesian motion because the spindle is what is moving in all 3 axes. however when you have a machine where the table moves, everything is opposite to the motion of the table because the spindle is still in the x and y axis. so we are moving the work and not the spindle.

in a traditional mill where the table is what moves:

table moving rearward = Y minus
table moving forward = Y plus
table move right = X minus
table moving left = X plus

because the spindle motion relative to the work is what is moving.

Z axis is also tricky. on a knee mill it is also opposite, where the knee moves up it is Z minus

on a VMC, Head Moving up is Z plus, Head moving down is Z minu. this is because the tool is actually moving with expected cartesian coordinate system.

Hope this helps!

Here is a problem. The arms will catch the drive motor, no matter which way I rotate it. I probably have to lengthen the arms of the 'center piece' that holds the extruder. Mounting the extruder drive farther away from the nozzle is not an option. Unfortunately the filament path is not centered to the extruder.

The plan is to have multiple extruders living inside the upper part of the 3D printer, with some method of automatically swapping extruder heads. The nozzle is attached to the extruder head, the high frequency induction heater is attached to the 'center piece'.

There will be spring contacts between the motor and the 'center piece', to make the motor's and thermocouple's electrical connection.

I might use strong magnets to hold the extruder to the 'center piece'.

The linear carriage blocks will have the gearbelt sandwitched between the carriage block and the arm bracket, teeth out. The return path for the belt is between the arms. HDT5M x 20mm wide gearbelt not shown.