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Belts do wear and stretch.

Make sure you grease ballscrews, bearings, etc. so they don't wear down over time, which will mess with accuracy.

Grease also makes the machine move more smoothly.

Hi All,I’d like your input on my planned setup.
As I mentioned in my previous post, the latency on my new machine was so high that I had to switch from the parallel port to a Mesa card. Earlier this week, I received a Mesa 7i76EU board. It looks awesome—if a bit overwhelming at first glance!My plan:

• Motors:
  I’m using 3x Longs DM542A stepper drivers, which I plan to connect to Stepper 0/1/2 outputs on the Mesa board, using what I believe is called a “single-ended” wiring configuration. My plan is to connect +5V to the ENA+, DIR+, and STEP+ on each driver, and wire the ENA (5V), DIR-, and STEP- of each driver directly to the corresponding outputs on the Mesa card.
• Spindle:
  I have a Huanyang VFD 1.5KW for spindle control. For now, I’ll keep my Modbus-over-USB setup, which seems to work well enough. I’ve read that getting Modbus running directly on the Mesa board requires a bit more advanced configuration, so I’ll save that for later.
• Homing Sensors (Capacitive, 3x):
  My plan is to connect the +24V supply to the positive (brown) wire, and field ground to the negative (blue) wire of each sensor. I intend to connect the sensor output (black) wires to Input 1, 2, and 3 on the Mesa card.

Questions:

1. Current-limiting resistor for home sensors:
   For the capacitive homing sensors, do I need to add a resistor between the output pin of the sensor and the Mesa input to protect against overcurrent? In the past, I’ve blown a few sensors and started using resistors to protect them, but those were cheap sensors—the Mesa card isn’t!
2. 2-wire touch probe:
   For my two-wire touch-off probe, I plan to connect one side to +24V field power and the signal wire to Input 4. Here too, should I add a resistor to avoid potential shorts or overcurrent situations?

Bonus questions:

• Any recommendations for best practices when wiring sensors and stepper drivers to the Mesa 7i76EU?
• Are there things I should definitely avoid to protect my Mesa card or improve reliability?
• For those who have set up Modbus on the Mesa board, how steep is the learning curve compared to using Modbus over USB?

Thanks for your advice and experiences!

The code (at least the code in your first post), works fine on 2.10.008.064.  I realize you are on some version of 2.9, just was easy for me to test on that. 

Can you state the specific version of 2.9 you are on (like above, as taken from the window title with QtPlasmaC open)?

Back when, there was a commit that temporarily broke feed reductions, but it was fixed. I honestly can’t remember if it was in 2.9 or master or both, but perhaps you have an older version that has the bug.

the best way to do this is to use the provided usertab, this way your edits remain with your config folder and do not get overwritten during updates (which a couple big ones are getting ready to drop). what you definitely do not want to do is edit the main probe basic because then you become the developer for any and all future updates which is not ideal for an end user.

to edit a user tab, open a terminal, type in:
editvcp

a dialog will pop up, in the dialog, find your machine config directory, typically it will be
/home/(your_pc_name)/linuxcnc/configs/(whatever_you_named_your_machine)/user_tabs/template_main/template_main.ui

in the file type drop down at the bottom of the dialog, make sure the type is set to VCP UI Files (*.ui)

this will show you the file :

template_main.ui

select it and click the open button.

Here you can add and edit it as you desire. when done, click save.

check your ini file and make sure that user tabs path is active under the display section:

[DISPLAY]
USER_TABS_PATH = user_tabs/

this activates the user tab and loads on probe basic start up.

enjoy!

If it was working and then changed I would expect that's more likely
to be a mechanical issue (loose coupling etc).

Two PCs were used in those machines.
NEC 9801UF / NEC 9801UV11
Thank you

Realistically speaking, the chances of someone else here having replaced the exact same computer is not high.

Could you post pics?

Belts and gearboxes do introduce backlash.

No encoder is exactly precise.

Be aware that vibrations can trigger sensitive switches like those used in most mechanical keyboards.

My Logitech G413 carbon mechanical keyboard turns on my iMac if I bonk the table it rests on.

But it uses romer-g switches.

(And it was scavenged from garbage)

'comp' is listed twice. The first entry is correct:

 

The second is the wrong one.

I need an aluminum clamping table like that!

Where'd you get that anyways?

Looks great!

FUN FACT: most CNC machines are CNC-machined, most 3D-printers are 3D-printed.

Kinda weird, eh?

Since that's a list of hal components, the link is correct
but the description is not.

OK, That's entertaining...

It should be possible to home by using a component that
measures the distance between index's and only arms
the actual index logic by simulating home switch detection
when the correct inter-index distance is measured.

Hello,

I tested the S-curve feature on the following system:
PC: HP with Intel i3 3rd Gen, 2x4GB RAM (latency < 20k)
OS: Debian 12
LinuxCNC: 2.10 pre-release
I created an XYZ mill configuration using StepConf and ran the same G-code with and without tpmod_scurve.
The results can be seen in the attached videos.
Observations:
Without the S-curve, the feed rate remains continuous.
With the S-curve enabled, the feed fluctuates significantly—at times dropping to 1/10 of the programmed feed rate.
It also noticeably increases the overall program execution time (2,5x slower with scurve in this situation).
I tried increasing VECTOR_BUFFER_SIZE to 100, but it didn’t help much. (Just for testing, I also set VECTOR_BUFFER_SIZE = 2, which made the behavior even worse.)
Maximum velocity and acceleration settings are visible in the video (they’re not particularly high, and are the same in both cases).
Question:
Do you think it's possible to achieve a continuous feed rate using the S-curve?

Files: 
drive.google.com/drive/folders/1uR1LfCv_...4-w6Daf8?usp=sharing