Understood, thanks! They do still seem to light up. I will look into replacing the resistor if possible at another time. Thank you!

Ahh I see. That's where I misinterpreted and messed up then! I thought that if I wanted to use a 12v fan I could put the jumper on and it would have the effect of stepping down the voltage... Clearly I didn't think it through...!

I've essentially powered the LEDs and 12v fan with 24v and without the 604ohm resistor then, correct? I assume the damage to the LEDs is therefore irreversible?

I'm now ordering a buck converter so I can reattach the 12v fan...

I've just finished putting together my latest and first truly custom build (I built a precision delta based on dc42's blog posts and BoM - a story for another post!).

I'm in the process of getting to know it and fine tuning my prints. Throughout this process, the 3 white LEDs were always nice and bright like this:

This picture was taken in a near dark room. The reflections in the mirror are the 2 nearest LEDs from on the effector.

Then, yesterday, while in the middle of printing, all of a sudden the LEDs went dim. This is how it now looks in a dark room.

Perhaps it's hard to tell from the image if my phone is compensating for the low light, but believe me it is substantially dimmer. I've tried wiggling my connections and resetting the printer etc. but it seems to make no difference. Note that the LEDs aren't flickering bright and dim - they went dim and stayed dim.

Of course, I am quite happy to accept this new brightness. I just want to be sure it isn't the first sign of some greater electrical problem I should be aware of etc.? As far as I can tell, it hasn't affected the effector in the slightest. The hotend still gets hot, the thermistor is still reporting an accurate temperature and the Z probe works. The heater LED seems to be the same as it always was. As I type now it is happily printing away.

My last detail is that I'm running the printer with a 24v PSU. However, my print cooling fan is 12v. I have used the jumper on the appropriate pins. I didn't think this was the cause of the problem since immediately after changing the fan the brightness of the LEDs was the same as normal. The dimming happened mid-print.

Is this supposed to/known to happen for any reason?
Thanks!

Edit: Reading around a bit more, I have a feeling I may have misunderstood something around using a 12v fan with a 24v PSU and fitting the jumper... perhaps someone could confirm?

WOULD YOU BELIEVE!?! The simple addition of Z2 to M574 fixed it! I'm so happy right now, thanks so much guys!

Backtracking to see why this might have happened to me, it seems that in the configurator, selecting "No Z probe" causes the "Z endstop type" settings above it to be disabled (and so I guess it assumes that one isn't present and omits it when writing M574, which is of course incorrect)? Just a theory really, but either way, grouping the high-end Z endstop and Z probe together seems a little inconsistent from a UI point of view?

Thanks again!

@dc42:

You can ignore the drive 0 and 1 minimum and maximum figures, and the drive 2 maximum figure. They come from M208 default settings and are not relevant for delta printers. The drive 2 minimum is the minimum allowed Z value.

Your M574 command needs parameter Z2 added to it.

Thanks dc42, that saves me some digging! I shall add Z2 to my M574.

@Danal:

Yes, your actual L, R, etc were pretty close. I'd seen an old post with some very different values. I'm pretty confident that your M665 is now quite close. So let's think about other things.

I think what I'd do next is enter the commands in homedelta.g one at a time, by hand, and watch. Which command is it that causes the printer to move so far off axis?

Just from the video, it would SEEM that it is one of the last commands, because we see the first up, then a down, then another up, so it seems logical that the first several commands are working.

Still, I'm very curious why the G90 and G1 X0Y0 would do what we see… so, if you can, enter them one at a time and report back which one moves the effector so far off.

Oh, and be sure you either cut and paste, or "make your eye and brain aware" that the G1 commands have an extra parameter, namely "S1" or "S2" in a few spots. These are the parameters that make Delta homing work.

Some of us (cough,,, me,,, cough) are so accustomed to CNC G-Code that we might have MISSED those pesky little S parameters when checking this out on our own printer. Nah... that'd never happen.

Great! At least I was on the right track!
I have observed the homing routine many times, though I've never tried keying in the homedelta.g sequence myself. My assumption was always that it was the last G1 command that was causing the behaviour, but somehow somewhere along the line the printer became convinced the origin was way out, and all the G1 does is move it to that way out position. I too was not aware of the significance of the Snnn parameters to homing deltas until now! I'll be sure to copy them in their entirety!

I have done my endstop checks, and I'm happy they are all triggered as expected!

Shall report back tomorrow!

Ok, this is my current config.g and homedelta.g

; Configuration file for Duet Ethernet (firmware version 1.20 or newer)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool on Thu Jan 25 2018 11:22:03 GMT+0000 (GMT Standard Time)

; General preferences
M111 S0                          ; Debugging off
G21                              ; Work in millimetres
G90                              ; Send absolute coordinates...
M83                              ; ...but relative extruder moves
M555 P2                          ; Set firmware compatibility to look like Marlin
; Automatic saving after power loss is not enabled

;*** The homed height is deliberately set too high in the following - you will adjust it during calibration.
;M665 R130 L265 B100 H280         ; Set delta radius, diagonal rod length, printable radius and homed height
M665 R134 L271 B100 H280
M666 X0 Y0 Z0                    ; Put your endstop adjustments here, or let auto calibration find them
M208 Z0 S1                       ; Set minimum Z

; Endstops
M574 X2 Y2 S1                    ; Set active high endstops
M558 P0 H5 F120 T6000            ; Disable Z probe but set dive height, probe speed and travel speed
M557 R80 S20                     ; Define mesh grid

; Drives
M569 P0 S1                       ; Drive 0 goes forwards
M569 P1 S1                       ; Drive 1 goes forwards
M569 P2 S1                       ; Drive 2 goes forwards
M569 P3 S1                       ; Drive 3 goes forwards
M350 X16 Y16 Z16 E16 I1          ; Configure microstepping with interpolation
M92 X80 Y80 Z80 E96              ; Set steps per mm
M566 X1200 Y1200 Z1200 E1200     ; Set maximum instantaneous speed changes (mm/min)
M203 X18000 Y18000 Z18000 E1200  ; Set maximum speeds (mm/min)
M201 X1000 Y1000 Z1000 E1000     ; Set accelerations (mm/s^2)
M906 X1000 Y1000 Z1000 E1300 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30                          ; Set idle timeout

; Heaters
M305 P0 T100000 B4267 C0 R4700   ; Set thermistor + ADC parameters for heater 0
M143 H0 S120                     ; Set temperature limit for heater 0 to 120C
M305 P1 T100000 B4267 C0 R4700   ; Set thermistor + ADC parameters for heater 1
M143 H1 S275                     ; Set temperature limit for heater 1 to 275C

; 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

; Network
M550 PUoY CS JB 3D Delta Printer ; Set machine name
M540 PBE:EF:DE:AD:FE:ED          ; Set MAC address
M552 P192.168.0.10 S1            ; Enable network and set IP address
M553 P255.255.255.0              ; Set netmask
M554 P192.168.0.1                ; Set gateway
M586 P0 S1                       ; Enable HTTP
M586 P1 S0                       ; Disable FTP
M586 P2 S0                       ; Disable Telnet

; Fans
M106 P0 S0.3 I0 F500 H-1         ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H T45         ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
M106 P2 S1 I0 F500 H T45         ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on

; Custom settings
;M558 I1                         ; Invert the inductive Z probe

; Miscellaneous
;M501                             ; Load saved parameters from non-volatile memory

; homedelta.g
; called to home all towers on a delta printer
;
; generated by RepRapFirmware Configuration Tool on Thu Jan 25 2018 11:22:03 GMT+0000 (GMT Standard Time)
G91                        ; relative positioning
G1 S1 X405 Y405 Z405 F1800 ; move all towers to the high end stopping at the endstops (first pass)
G1 X-5 Y-5 Z-5 F1800 S2    ; go down a few mm
G1 S1 X10 Y10 Z10 F360     ; move all towers up once more (second pass)
G1 Z-5 F6000               ; move down a few mm so that the nozzle can be centred
G90                        ; absolute positioning
G1 X0 Y0 F6000             ; move X+Y to the centre

Restarted and homed, and sadly the homing behaviour is still the same as in the last video I posted. Additionally, I had previously said that I'd live with it, but I've since realised that the application I have in mind for the printer will require the origin to be consistent, so I really need to get this sorted

The parameters you gave me were not significantly different to the ones I was already using (I changed bed radius, and I've been adjusting H just to try and find some consistency in the homing behaviour with different values. The ones I was using up to now are commented in the file above.) But so far, it is doing exactly what happens in the video.

I'm still a tad confused by the screenshot I posted above of my endstop maximums being different, so I'm currently doing my first dive into the source to look for clues. My reasoning is that on a delta, the endstops at the top of each pillar would be assumed to be at the same level, and then of course adjusted in config.g to compensation for their mm differences in height? Other than that I'm at a loss as to what is causing it.

Excellent! Thanks very much for your tips Danal, I'll be sure to try those things out (hopefully tomorrow) and report back!

Here's a video of it. Not sure how much better I can describe it!

https://youtu.be/BbssbUlbcNU

Not sure if it's related, but I was looking through the settings, and I found that my drive configuration reads so that the max values on the drive are significantly different. Couldn't find a way to change it, but maybe it's relevant?

Ok, home delta has been increased and is no longer a problem.
By this point, I have a working printer, and its results are pretty good… I feel like I'm just going to live with this homing issue for now, since I know how to get around it. If I ever solve it I'll post what I did back here.

Thanks all for your help!

I see! I measured that distance whilst I had the effector positioned as close to the centre of the bed as I could judge by eye, and I got a value of more like 160mm (can't remember the exact value right now). I'm using that value and it seems to be fine/nothing has changed for the worse beyond what is already happening.

As I mentioned before, the homing behaviour is the only thing causing me problems. I have printed a couple of pieces now (using manual Z calibration) and I'm quite happy with the results… (it is ~0.05mm out in Y, 0.2mm out in X, and ~0.02mm out in Z)

I've found my homing procedure to be highly repeatable. Would you be able to tell me what G28 does internally from a cold boot of the printer? It seems like successive homings "narrow in" on the true origin. It's a behaviour I'm having real trouble understanding and therefore solving. As far as I understand, homing doesn't make any change to any parameter that would be written to config-override.g by calling M500?