What I did on my Anycubic was that I stuck the carriage spacers underneath and didn't worry about it. Worked fine. The carriage is rarely near either pulley unless homed; during prints it's usually much closer to the middle of the rails.

The smart effector is such a win that noone should hesitate to install it if possible.

Just rebuilt my kossel with larger frame and bed. Now the only parts left from the original Anycubic are the linear rails. Had to build my own effector arms due to not finding any long enough for the new size. (Thanks, David, for the pointer on your blog to the video on cutting carbon tubing!) Anyway, apparently I've gone over the limit of the inertia in the system with these new arms. Old arms were 288mm/4mm, these are 495mm/8mm so quite a bit larger. Using smart effector with mag balls, same as before. Now, when the motors are turned off, the effector falls down, where before it would not. Other than not turning the motors off at the end of a print, any good way to keep the effector from falling onto the print? Got a melted dent in a part from the nozzle falling onto it just now.

Anyone have suggestions on how to fix this?

Other than that, the Duet controller made the change pretty painless--just update a few values in config.g and recalibrate, ready to go!

Thanks in advance for any help or comments.

@phaedrux Thanks very much! Fixed.

Upgraded from 2.x this week. (What can I say, it was working for me. ) Now seeing issue and error on restarting, happens both after restarting by changing config.g or by hitting emergency stop.

Printer is a delta with ~325mm of vertical travel. Duet 2, Smart Effector.

Restart applies the location set in the config at boot (X0Y0Z325), but then on homing it sets the coordinates to an odd value and then raises an error.

Example:
Printer is homed, coords x0y0z319.5
G1Z50, coords X0Y0Z50
Edit config.g (no changes), save and restart, coords x0y0z325
G28, coords x-8.9y-1.0z621.1, error: G0/G1: target position not reachable from current position.

I would expect homing to set the X and Y to 0 still, and the Z height to the configured calibrated height after homing.

To recover, I have to:
G92x0y0
G30S-1
G92Z0
G28
G32

Tested with v3.3, same results.

homedelta.g is the one generated by the configuration tool.
; homedelta.g
; called to home all towers on a delta printer
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Wed Feb 16 2022 14:16:30 GMT-0800 (Pacific Standard Time)
G91 ; relative positioning
G1 H1 X355 Y355 Z355 F1800 ; move all towers to the high end stopping at the endstops (first pass)
G1 H2 X-5 Y-5 Z-5 F1800 ; go down a few mm
G1 H1 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

config.g:
; Configuration file for Duet WiFi (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Wed Feb 16 2022 14:16:29 GMT-0800 (Pacific Standard Time)

; General preferences
M575 P1 S1 B57600 ; enable support for PanelDue
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P"Kosselstein" ; set printer name
M665 R235 L500.17 B145 H325 ; Set delta radius, diagonal rod length, printable radius and homed height
M666 X0 Y0 Z0 ; put your endstop adjustments here, or let auto calibration find them

; Network
M552 S1 ; enable network
M586 P0 S1 ; enable HTTP
M586 P1 S0 ; disable FTP
M586 P2 S0 ; disable Telnet

; Drives
M569 P0 S0 ; physical drive 0 goes backwards
M569 P1 S0 ; physical drive 1 goes backwards
M569 P2 S0 ; physical drive 2 goes backwards
M569 P3 S1 ; physical drive 3 goes forwards
M584 X0 Y1 Z2 E3 ; set drive mapping
M350 X16 Y16 Z16 E16 I1 ; configure microstepping with interpolation
M92 X160.00 Y160.00 Z160.00 E2600.00 ; set steps per mm
M566 X600.00 Y600.00 Z600.00 E100.00 ; set maximum instantaneous speed changes (mm/min)
M203 X18000.00 Y18000.00 Z18000.00 E6000.00 ; set maximum speeds (mm/min)
M201 X6000.00 Y6000.00 Z6000.00 E1500.00 ; set accelerations (mm/s^2)
M906 X1200 Y1200 Z1200 E850 I30 ; set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 Z0 S1 ; set minimum Z

; Endstops
M574 X1 S1 P"xstop" ; configure switch-type (e.g. microswitch) endstop for low end on X via pin xstop
M574 Y1 S1 P"ystop" ; configure switch-type (e.g. microswitch) endstop for low end on Y via pin ystop
M574 Z1 S1 P"zstop" ; configure switch-type (e.g. microswitch) endstop for low end on Z via pin zstop

; Z-Probe
M558 P5 R0.4 C"zprobe.in+zprobe.mod" H15 F1200 T6000 ; set Z probe type to effector and the dive height + speeds
M558 H30 ;*** Remove this line after delta calibration has been done and new delta parameters have been saved
G31 P100 X0 Y0 Z-0.21 ; set Z probe trigger value, offset and trigger height
M557 R140 S20 ; define mesh grid

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B4138 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B0 S1.00 ; disable bang-bang mode for the bed heater and set PWM limit
M140 H0 ; map heated bed to heater 0
M143 H0 S100 ; set temperature limit for heater 0 to 100C
M308 S1 P"e0temp" Y"thermistor" T100000 B4138 ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1 ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00 ; disable bang-bang mode for heater and set PWM limit
M143 H1 S280 ; set temperature limit for heater 1 to 280C

; Fans
M950 F0 C"fan0" Q500 ; create fan 0 on pin fan0 and set its frequency
M106 P0 S0 H-1 L0.5 ; set fan 0 value. Thermostatic control is turned off, max 80%
M950 F1 C"fan1" Q500 ; create fan 1 on pin fan1 and set its frequency
M106 P1 S1 H1 T45 ; set fan 1 value. Thermostatic control is turned on
M950 F2 C"fan2" Q500
M106 P2 S1 H1 T45

; Tools
M563 P0 D0 H1 F0 ; 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
M207 S2.0 R0.5 F1500 T900 Z0.5 ; Set FW retraction length and speed
M572 D0 S0.10 ; Set pressure advance

; Custom settings are not defined

; Miscellaneous
M501 ; load saved parameters from non-volatile memory
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss

config-override.g:
; config-override.g file generated in response to M500 at 2022-02-21 11:36
; This is a system-generated file - do not edit
; Delta parameters
M665 L500.170:500.170:500.170 R239.169 H323.941 B145.0 X0.000 Y0.000 Z0.000
M666 X-0.558 Y0.349 Z0.209 A0.00 B0.00
; Heater model parameters
M307 H0 R0.158 K0.714:0.000 D3.22 E1.00 S1.00 B0
M307 H1 R2.481 K0.714:0.000 D8.20 E1.00 S0.80 B0 V24.1
; Workplace coordinates
G10 L2 P1 X0.00 Y0.00 Z0.00
G10 L2 P2 X0.00 Y0.00 Z0.00
G10 L2 P3 X0.00 Y0.00 Z0.00
G10 L2 P4 X0.00 Y0.00 Z0.00
G10 L2 P5 X0.00 Y0.00 Z0.00
G10 L2 P6 X0.00 Y0.00 Z0.00
G10 L2 P7 X0.00 Y0.00 Z0.00
G10 L2 P8 X0.00 Y0.00 Z0.00
G10 L2 P9 X0.00 Y0.00 Z0.00

How big, what plastics are you printing with?

I'm currently using a CHPOWER Creality Magnetic build surface from Amazon. Very flat, prints PLA very well. Downsides: 300x300 mm only (could trim smaller), max 70C temp. Have not tried it with PETG, which I usually like to print with 90C bed temp.

I was looking at the magnetic beds sold by Geckotek, but got an EZ-Stik Hot print surface to try. At first, was really liking it, but started having problems with the filament not sticking after only about 15-20 prints. I think their magnetic beds all come with that surface applied.

Still having the calibration issues I saw on RC4. This is on my delta with smart effector. The calibration seems to oscillate between a few different heights, never converges on one particular height. Also still had the issue with the effector triggering early, had to leave it with sensitivity set to 128 instead of default. After doing that, and saving (with M500) a G32 result that seemed kind of correct and a following G29, was attempting to recalibrate the offset from 0 for the Z probe in config.g using baby stepping to get a feel for how far off it currently was. Baby stepping appears to be very broken. Was using the Due to set the baby step for a 0.2mm patch print, and then measure the actual thickness of the patch with a micrometer. Setting the baby step while the bed is heating does not seem to actually change the thickness--though it does change the baby step setting readout. Pushing the baby step up/down buttons while the extruder is heating (following the bed heat) do not immediately change the reading, but once the extruder is up to temp, the readout does change appropriately. Again, though, the actual print does not seem to change. Once the print has actually started extruding, the baby step does seem to change when the up/down buttons are pushed, but they may or may not match the reading.

Went back to 2.02, G32 converged in about 5-6 iterations. Haven't backed off the effector sensitivity yet to try that.

Had some odd leveling behavior on my delta.

Had a quite hard time getting G32 to converge on a particular height, but finally did. Then noticed several aborted probing points when running G29, followed by reports of 4.x mm max height error. After increasing the force needed by the smart effector from default to 128, got a kinda good height map. Now I have to edit the deflection setting in config.g--I had to add +0.15 mm baby step to get first layer correct. Everything was working quite well prior to upgrade.

What I did on my Anycubic was that I stuck the carriage spacers underneath and didn't worry about it. Worked fine. The carriage is rarely near either pulley unless homed; during prints it's usually much closer to the middle of the rails.

The smart effector is such a win that noone should hesitate to install it if possible.

Thanks, those are all great suggestions!

Back when I was building my delta, I made it large enough to print 400mm round. For monetary reasons, only put in a 300mm round bed. Recently, broke the bed glass and had to replace it, but the only reasonably affordable bed I could find was a square 300mm x 300mm. I think the rest of the printer is capable of printing to the entire bed surface, but it's configured still as 300mm round, so I can't use the corners. Any way to tell the Duet 2 I have a delta with a square bed? Thanks in advance!

I run PLA at 215/210. Need a bit better cooling, but it comes out OK if I don't print thin spires or the like. Using a small stepper for the nimble. Had problems with losing steps with a regular sized stepper.

Here's my settings:
M92 X160 Y160 Z160 E2600 ; Set steps per mm
M566 X1200 Y1200 Z1200 E100 ; Set maximum instantaneous speed changes (mm/min)
M203 X22000 Y22000 Z22000 E6000 ; Set maximum speeds (mm/min)
M201 X6000 Y6000 Z6000 E1500 ; Set accelerations (mm/s^2)
M906 X1000 Y1000 Z1000 E750 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout
M207 S2.0 F1500 T900 Z0.5 ; Set FW retraction length and speed
M572 D0 S0.10 ; Set pressure advance

I too started with an Anycubic Linear plus. The only original parts on the printer now are the linear rails. I was actually considering putting the leftover parts back together to have a third printer, but then I realized I'd just want to re-upgrade that into a duplicate of my second printer.

eventually I'll get off my butt to machine a replacement.

PRINT a replacement.

unhappy with the filament extruder drive assembly

Look at Zesty Nimble. High initial cost, but dead reliable.

For your bed issues, I find clamps printed in PETG work quite well up to ~100C.