From 15afcf69fe859534ae83f55e16991d3b022b3b81 Mon Sep 17 00:00:00 2001 From: fredizzimo Date: Fri, 25 Jan 2019 19:53:00 +0200 Subject: [PATCH] docs: Improve the BLTouch documentation (#1107) Signed-off-by Fred Sundvik --- docs/BLTouch.md | 127 +++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 103 insertions(+), 24 deletions(-) diff --git a/docs/BLTouch.md b/docs/BLTouch.md index 032455f7..0ae500aa 100644 --- a/docs/BLTouch.md +++ b/docs/BLTouch.md @@ -1,50 +1,129 @@ Connecting BL-Touch =================== + +A **warning** before you start: Avoid touching the BLTouch pin with your bare fingers, since it is +quite sensitive to finger grease. And if you do touch it, be very gentle, in order to not bend or +push anything. + Once you've hooked up the BL-Touch servo connector to a `control_pin` according to the BL-Touch -documentation or of your MCU. Using the original wiring, the yellow wire from the tripple is +documentation or of your MCU. Using the original wiring, the yellow wire from the triple is the `control_pin`, the white wire from the pair is the `sensor_pin`. You need to configure these pins according to your wiring with Klipper: +``` + [bltouch] sensor_pin: P1.24 # Pin connected to the BL-Touch sensor pin. This parameter must be # provided. control_pin: P1.26 +``` + +You also most likely need to configure a homing override to first raise the z-axis, then home the x- +and y-axis, and finally move to the center and home the z-axis. Like this: + +``` + [homing_override] + gcode: + G1 Z10 ; Move up 10mm + G28 X Y + G1 X166 Y120 F6000 ; Change the X and Y coordinates to the center of your print bed + G28 Z + set_position_z: 0.0 +``` + +It's important that the upwards movement is high enough, so that the probe or the nozzle don't hit +any binder clips, even if the probe pin happens to be in it's lowest state. + +Initial tests +============= + +Before moving on, verify that the BLTouch is mounted at the correct height, the pin should be +roughly 2 mm above the nozzle when retracted + +When you turn on the printer, the BLTouch probe should perform a self-test and move the pin up and +down a couple of times. Once the self-test is completed, the pin should be retracted and the red LED +on the probe should be lit. If there are any errors, for example the probe is flashing red or the +pin is down instead of up, please turn off the printer and check the wiring and configuration. + +If the above is looking good, it's time to test that the probe responds to commands from the +firmware. First run `BLTOUCH_DEBUG COMMAND=pin_down` in your printer terminal. Verify that the pin +moves down, and that the red LED on the probe turns off. If not, check your wiring and configuration +again. Next issue a `BLTOUCH_DEBUG COMMAND=pin_up` and verify that the pin moves up, and that the +red light turns on again. If it's flashing then there's some problem. + +Now, it's time to test homing with a twist. Instead of letting the probe pin touch the print bed, +let it touch the nail on your finger. So issue a `G28`, wait until it starts to move down, and stop +the movement by very gently touching the pin with your nail. You probably have to do it twice, since +the default configuration makes it probe twice. But be prepared to turn off the printer, to avoid +damage, if it doesn't stop when you touch the pin. + +If that was successful, do another `G28` but this time let it touch the bed as it should. Calibrating the BL-Touch ======================== -### Z Offset -In order to make klipper work properly you need to tell it in which relation to the nozzle -the probe is exactly located. Lets start with the `z_offset` - the height of the probe when -its expanded: - -Make sure the probe is above the bed by moving the head into an appropriate x/y position: - - g0 x0 y0 - -Now make klipper aproach the bed until the probe triggers using: - - PROBE - -This should deploy the BL-Touch probe, stop the run when it triggers by touching the bed. -Now acquire the current position from the reached `z_offset` using: - - GET_POSITION - -In the output lines the `toolhead` line with the `Z:` contains the required value. - ### X/Y Offset -In order to find the propper vertical offset of the probe you need to know a certain point of + +In order to make klipper work properly you need to tell it in which relation to the nozzle +the probe is exactly located. Lets start with the `x_offset` and the `y_offset` + +In order to find the proper vertical offset of the probe you need to know a certain point of your bed. X/Y = 0 may be a good point for this, any other will do as long as you know it. -Find it by lowering the nozzle next to it using `g0 z0.5`. Create a removeable mark on your +Find it by lowering the nozzle next to it using `g0 z0.5`. Create a removable mark on your bed by i.e. using a non permanent marker. -Now move the tip of the BL-Touch over that point by jogging there with the conrols in the `control` tab of +Now move the tip of the BL-Touch over that point by jogging there with the controls in the `control` tab of OctoPrint. Once the BL-Touch is roughly over the point acquire it using the `GET_POSITION` command. The difference to your marked point is your `x_offset` and `y_offset` to configure in the `printer.cfg`. +### Z Offset + +1. We start by changing the `z_offset` in the `bltouch` section of the configuration to 10. This +setting is very wrong, but it will make it possible to move down to the right height using the +menus. Run `RESTART` after changing it to reload the configuration. + +2. Now run `G28`, to home the printer. Take a note of the point where the pin hits the bed and use +the menu to move the nozzle to that point. Now take a *folded* paper and put it under the nozzle. +Move the nozzle down using the menu, in 0.1mm steps, until it grabs the paper. It doesn't matter how +much it grabs, you are searching for the higest position that grabs the paper. The nozzle should now +be between 0.1mm and 0.2mm above the printbed. If you wonder why we used a folded paper, the answer +is that the granularity of the movement is only 0.1mm, or the same as a normal paper thickness, that +means that you could easily move too far and hit the bed. + +3. Now update the `z_offset` to reflect this, by substracting the current offset (10) by the reading +on the printer display. So if it says 8.2, then `10-8.2` = 1.8 + +4. Restart the printer, issue a `G28`, move to the pin location, then `G1 Z0`, and verify that it's +still grabbing the paper as it was before. If not, then repeat step 2. and 3. until you are +satisfied. + +5. At this point it's a good idea to verify that the offset is close to 1mm, if not, then you +probably want to move the probe up or down to fix this. You want it to trigger well before the +nozzle hits the bed, so that possible stuck filament or a warped bed don't affect any probing +action. But at the same time, you want that the retracted position is as far above the nozzle as +possible, to avoid damage by touching printed parts. + +6. Now it's time to fine tune with a real print. First make sure that your flow rate and steps are +calibrated properly, so that wrongly configured flow rates don't affect the calibration. Then slice +a one layer thick object, located close to where you are homing. I recommend a simple 50x50 mm +square. + +7. While the object is printing, use the tune menu to adjust the "Offset Z", until it looks good. +With some practice, it's possible to find the exact point where it goes from underextrusion to +overextrusion, but some filaments are harder to see than others. Also notice that the tune command +does not have any effect immediately, it takes a couple of movements until the printer uses the new +value. It might also be hard to see exactly what's happening while it's printing, so you can adjust +for example every cm, and then find the best setting when the print is done. + +8. Update the `z_offset` configuration again by using subtraction. So if the display shows that you +tuned the z-offset to -0.100, then it's calculated like this `1.8 -(-0.100) = 1.9`, notice the +double minus sign. + +9. Issue a `RESTART`, and test printing the same thing, this time without adjusting anything. +Perform steps 7-9 until you are happy. + BL-Touch gone bad ================= Once the BL-Touch is in inconsistent state, it starts blinking red. You can force it to leave that