This post is just a convenient place to store links to some of my X-carve information.
Positioning Errors
One of the most asked about troubleshooting problems with a new X-carve is positioning errors. Almost all positioning errors are corrected by adjusting the various parts of the machine. Very few of the problems are actually due to failing components. The X-carve is a very flexible machine and so one answer cannot fit all situations. Each person will use their machine in a different way which makes it difficult to precisely quantify each adjustment.
Positioning errors are alm…
The potentiometers on the gShield are setting the Vref (Voltage Reference) level on the TI stepper motor driver chips. This determines the current limit for the driver.
You can measure this voltage at one of the potentiometer pins (see photo) and adjust it to obtain a given current limit. Use great care as the potentiometer pins are very close to other components and it is easy to short the pins together with your meter probe. Really bad things happen.
The gShield (version 5) uses a 0.1 ohm cu…
Looking at things from the grbl perspective, the term “limit switch” only applies for the X-carve if you use hard limits ($21=1) .
Looking at things from the grbl perspective, all other cases for the X-carve the switches are “homing switches”.
Homing switches allow soft limits ($20=1) to work. For this case the “limits” depend on having done the homing cycle and on the low end the limits are 0,0,0 and the limits on the high end are set by $130, $131, and $132. After the homing sequence the swi…
Direct access to grbl.
You can interact with grbl directly to isolate problems at the low level.
To do so, you need to use a terminal type program to issue commands and get responses from the serial port that has the Arduino attached.
Some of the programs are HyperTerminal, Putty, UGS (limited access), and the Serial Monitor in the Arduino IDE, among others.
Make sure that you have the correct settings for the program that you use.
The COM port where the Arduino is attached should have the …
If you are having difficulties with your homing switches you can do a quick test with Grbl to see what the state of the homing switches is from Grbl’s point of view. NOTE: In order to use this procedure you need to have grbl Version 0.9j or later installed on your Arduino.
To do so, you use the Grbl status immediate command ? (question mark). This command asks Grbl for its current value of some of its state information. For the purpose of this article we are interested in the homing switch stat…
Updates to grbl have changed status reporting in version 1.0c (used in the X-controller I believe). These changes affect the output from the “?” status command to grbl.
Information here is based on version 1.0c (edge fork).
The status report mask (grbl parameter $10) has two new control bits to select display of the probe pin and control pins’ status.
The bit assignments are as follows:
7 - Not used at this time
6 - display control pin status
5 - display probe pin status
4 - display homin…
Got a carve running and you need to make a quick change? Don’t want to start over, just stop for a while?
Grbl provides a method for pausing a G-code job without losing machine position.
The pause function is called “feed hold”. You can issue a software command to Grbl to invoke the feed hold function or you can use a hardware switch to invoke feed hold. Both methods are an immediate command to Grbl to execute a controlled stop without losing machine position. It is an immediate soft stop.
To…
Recent discussions of homing switches and various modifications in the homing switch technology used made me wonder just how accurate the lowly mechanical homing switch is. So I ran a test to see if I needed to consider an alternate technology.
Spoiler alert: I don’t see any reason to change.
My machine:
X-Carve 500mm x 500mm stock Inventables kit
Standard electronics (Arduino/gShield mounted on 24 volt power supply)
Mechanical homing switches (shielded wire modification)
My assumptions:
T…
I’ve been helping folks get their X-carve machines up and running. I’ve learned a lot. One of the things that I have noticed is that the grbl parameters seem to be inconsistent, especially when the Arduino has to be re-flashed.
Long story short I wanted to find out exactly what the defaults should be.
I took a new Arduino and used the EEPROM clear example program to clear the contents of the EEPROM (1024 locations), compiled the source code for Grbl 0.9j, downloaded to the Arduino, then ask fo…
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