Best surface for IR probe accuracy



  • Hi, just purchased an IR probe today, and I'm printing a mount as I type.

    I noticed that for several surfaces you mention painting the bottom with black paint, I work at a coatings manufacturer for the aerospace and oil and gas industries so have several options 😏 What type is best, IR absorb or reflect or refract? Also is there any problem painting the top surface of my alloy bed rather than the bottom surface of the pei or glass.

    I actually plan on doing some experiments to find the coating that gives the most accurate results, I'll probably formulate something I can bake on that gives a hard surface I can print directly on.


  • administrators

    The ideal surface for the IR sensor is one that is opaque to IR light and has a matt surface. When it is used with a transparent surface such as glass or thick PEI, the reflection from the back surface combines with the reflection from the top surface, which degrades the accuracy. Painting the back surface matt black reduces the reflection from the back; but it is better to avoid using transparent surfaces if you can.



  • Thanks I now know where to start.

    Going to coat some test panels and test them for repeatability and try to print on them.

    I'll report back on the results in a couple of weeks work permitting.



  • Forgot to ask what wavelength are we looking at?

    There are a lot of new IR pigments becoming available


  • administrators

    @stewwy, the wavelength is 850nm.



  • Good evening to everyone
    I have the problem of the printing plate that I can not level it with the mini ir sensor, at room temperature all the flatness of the plate is there, at 110 degrees I find it very high in the middle.
    Well my situation is that after a two-month standstill to wait for an opaque black prinbite "more or less opaque ..", I bought it because having taken a while ago an IR I wanted to make a leap of quality but so 'has not been, and I continue to have problems of flatness', here I leave you the configuration of my Cartesian printer, which is a geeetech i3 pro b transformed to 24v e3dV6.1 and titan that mounts a nema 17 thin on extruder, the engines x, y, z are nema 17 of the quimat model 17hd48002h-22b, duet wifi "the only thing that so far has not given me the slightest problem"

    Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
    Firmware Electronics: Duet WiFi 1.02 or later
    Firmware Version: 2.02RC3(RTOS) (2018-10-17b2)
    WiFi Server Version: 1.21
    Web Interface Version: 1.22.4-b1

    Config:

    ; Configuration file for Duet WiFi (firmware version 1.21)
    ; executed by the firmware on start-up
    ;
    ; generated by RepRapFirmware Configuration Tool on Sat Oct 06 2018 20:36:03 GMT+0200 (Ora legale dell’Europa centrale)

    ; General preferences
    G90 ; Send absolute coordinates...
    M83 ; ...but relative extruder moves

    ; Network
    M550 PLanzet 3D ; Set machine name
    M552 S1 ; Enable network
    M587 S"FRITZ!BOX 3390" P"67443721948076126438" ; Configure access point. You can delete this line once connected
    M586 P0 S1 ; Enable HTTP
    M586 P1 S0 ; Disable FTP
    M586 P2 S0 ; Disable Telnet

    ; Drives
    M569 P0 S1 ; Drive 0 goes forwards
    M569 P1 S1 ; Drive 1 goes forwards
    M569 P2 S0 ; Drive 2 goes backwards
    M569 P3 S1 ; Drive 3 goes forwards
    M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
    M92 X80.24 Y80.46 Z400 E413 ; Set steps per mm
    M566 X1000 Y1000 Z200 E400 ; Set maximum instantaneous speed changes (mm/min)
    M203 X6000 Y6000 Z420 E6000 ; Set maximum speeds (mm/min)
    M201 X1000 Y1000 Z1000 E1000 ; Set accelerations (mm/s^2)
    M906 X1000 Y1000 Z1000 E800 I30 ; Set motor currents (mA) and motor idle factor in per cent
    M84 S30 ; Set idle timeout

    ; Axis Limits
    M208 X0 Y0 Z0 S1 ; Set axis minima
    M208 X210 Y200 Z160 S0 ; Set axis maxima

    ; Endstops
    M574 X1 Y1 S1 ; Set active high endstops

    ; Z-Probe
    M574 Z1 S2 ; Set endstops controlled by probe
    M558 P1 H5 F400 T8000 ; Set Z probe type to switch and the dive height + speeds
    G31 P500 X-10 Y0 Z0 ; Set Z probe trigger value, offset and trigger height
    M556 S0 X0 Y0 Z0 ; Set orthogonal axis compensation parameters
    M557 X20:200 Y10:190 S56 ; Define mesh grid

    ; Heaters
    M307 H0 B0 S1.00 ; Disable bang-bang mode for the bed heater and set PWM limit
    M305 P0 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 0
    M143 H0 S150 ; Set temperature limit for heater 0 to 120C
    M305 P1 T100000 B4725 C7.060000e-8 R4700 ; Set thermistor + ADC parameters for heater 1
    M143 H1 S280 ; Set temperature limit for heater 1 to 280C

    ; Fans
    M106 P0 S1 I0 F500 H1 T50 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P1 S1 I0 F500 H1 T45 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
    M106 P2 S1 I0 F500 H1 T45 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on

    ; Tools
    M563 P0 D0 H1 ; Define tool 0
    G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
    G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C

    ; Automatic power saving
    M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; Set voltage thresholds and actions to run on power loss

    ; Custom settings are not configured

    ; Miscellaneous
    M501

    Bed:
    ; bed.g
    ; called to perform automatic bed compensation via G32
    ;
    ; generated by RepRapFirmware Configuration Tool on Sat Oct 06 2018 20:36:03 GMT+0200 (Ora legale dell’Europa centrale)
    M561 ; clear any bed transform
    ;G29 S2
    ; Probe the bed at 5 points
    G30 P0 X10 Y10 H0 Z-99999
    G30 P1 X10 Y190 H0 Z-99999
    G30 P2 X200 Y190 H0 Z-99999
    G30 P3 X200 Y10 H0 Z-99999
    G30 P4 X110 Y100 H0 Z-99999 S5
    ;G29 S1



  • some idea?



  • @leblond if it’s flat when cold and high in the middle when hot, the problem is probably a physical warping of your build plate from differential thermal expansion. Can you check that with a straight edge with a flashlight behind it?

    What’s the physical construction of your bed stack?

    Does running auto level with the bed hot change anything?


  • administrators

    @leblond, can you run mesh bed compensation and publish the height map here?



  • willingly, only if I knew how to do it



  • un attimo



  • RepRapFirmware height map file v2 generated at 2018-10-21 22:56, mean error 0.222, deviation 0.150
    xmin,xmax,ymin,ymax,radius,xspacing,yspacing,xnum,ynum
    20.00,200.00,10.00,190.00,-1.00,56.00,56.00,4,4
    0.040, 0.240, 0.070, -0.070
    0.207, 0.390, 0.295, 0.072
    0.370, 0.468, 0.368, 0.135
    0.153, 0.343, 0.357, 0.112
    I wanted to calibrate it as hot as the problem can not be removed



  • @RCarlyle
    the building is 220x220x160
    2mm heated aluminum platethe building is 220x220x160
    2mm heated aluminum plate


  • administrators

    @leblond said in Best surface for IR probe accuracy:

    RepRapFirmware height map file v2 generated at 2018-10-21 22:56, mean error 0.222, deviation 0.150
    xmin,xmax,ymin,ymax,radius,xspacing,yspacing,xnum,ynum
    20.00,200.00,10.00,190.00,-1.00,56.00,56.00,4,4
    0.040, 0.240, 0.070, -0.070
    0.207, 0.390, 0.295, 0.072
    0.370, 0.468, 0.368, 0.135
    0.153, 0.343, 0.357, 0.112

    I think the IR sensor is giving reasonably good readings, although it would be easier to tell if you reduced the mesh spacing to 28mm or lower.



  • @ dc42 do you talk about mesh spacing?
                 I had to make a 3x3 grid

    1 to find the center of the bed

    2 if I did a spacing of 20mm I had changes from -2 to +2 +/-

    since I have the sensor, the only printing base that has improved and 'that arrived yesterday of the printbite, but I continue to have these changes, tonight when I come back from work I try to recalibrate it hot and post' results, if you need 'of data then PLEASE speak to you normally, unfortunately I am not an engineer with a hat like you, but a humble worker, but I'm getting better ... thanks for the understanding and good work.



  • Good evening to everyone
    Well as promised I tried to calibrate the print plate to 110 and these three images show the result.
    image 1: car bed not calibrated
    image 2: calibrated car bed
    image 3: mesh
    0_1542928743451_auto bed 110 gradi non calibrato.jpg 0_1542928767722_auto bed 110 gradi calibrato.jpg 0_1542928780158_auto bed 110 gradi calibrato mesh.jpg



  • I have been using the heated beds from E3D, the older big box bed and recently their 120 volt high temperature bed. I painted the underside of the glass with white high temperature spray paint from McMaster Carr. initially to increase the visibility of the print over the black heated bed surface. This has been ideal with the IR Probe, I left the outer 10mm unpainted and the LED turns off when the sensor passes over the unpainted portion above the black. So the white paint does improve the sensor accuracy. Works great.



  • I forgot to mention the nozzle crashed into the glass when I installed the new unpainted bed.


  • administrators

    @leblond said in Best surface for IR probe accuracy:

    @ dc42 do you talk about mesh spacing?

    Yes, I meant use a mesh with smaller spacing/more points, e.g. 7x7 or 9x9.


  • administrators

    @edkirk said in Best surface for IR probe accuracy:

    I painted the underside of the glass with white high temperature spray paint from McMaster Carr.

    If you are using our mini differential IR probe, that's completely the wrong thing to. The correct thing (as described in the fitting instructions) is to paint the back surface matt black. This is to make the reflection from the front surface of the glass stronger than the reflection from the back.

    If you are using some other type of IR sensor then this probably doesn't apply and I can't help.


 

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