why is my H parameter in DC42 branch of Duet not doing anything?

I have a 300mm bed and the autoleveling routine was getting around 0.02mm deviation.
But my machine warped out at some point and I decided to hell with these printed parts...

I built a new effector platform from only machined aluminum parts, and assembled to within .02mm or so in all dimensions. This thing is tight!
I ran around to each bed probe point to measure and record the offset-from-tilt G30 H parameters.
After re-running the autolevel routine my bed height deviation is about .06 (sob).
I thought, "Maybe my H's are backwards" so I inverted the sign on all 9 of my probe points and voila!..no change (literally within .01 from the non-inverted run). The deviation H parameters should have an impact.
I doubled checked and yes I am running the file I also happen to be editing
Me no understando...

System:
Firmware Name: RepRapFirmware (CoreNG)
Firmware Version: 1.11 (2016-04-14)
Win 7, Chrome browser.

Edited 1 time(s). Last edit at 11/03/2016 02:15AM by shadowphile.

Can you post your Bed.g file see if there's anything obvious in there?

Doug

Thanks Dougal; I feel like I should have put this in the Duet forum.

; Auto calibration routine for delta printers
; Before running this, you should have set up your zprobe Z offset to suit your build, in the G31 command in config.g.

M561						; clear any bed transform, otherwise homing may be at the wrong height
G31 X0 Y0					; don't want any probe offset for this
G28							; home the printer

;*** Remove the following line if your Z probe does not need to be deployed
;M98 Pdeployprobe.g			; deploy the mechanical Z probe

; The first time the mechanical probe is used after deployment, it gives slightly different results.
; So do an extra dummy probe here. The value stored gets overwritten later. You can remove this if you use an IR probe.
G30 P0 X0 Y0 Z-99999

;H parameter gives the value that must be added to the G31 Z parameter to get the actual trigger height at that point.
;H = (trigger height measured at the point) - (trigger height at the bed center)
; Probe the bed and do 6- or 7-factor auto calibration

; OUTER RING
G30 P0 X-100 Y40 Z-99999 	H0	; X-Z towers
G30 P1 X-120 Y-70 Z-99999	H-0.05	; X
G30 P2 X-10 Y-150 Z-99999	H0	; X-Y towers
G30 P3 X125 Y-80 Z-99999	H0.1	; Y
G30 P4 X125 Y70 Z-99999		H-0.05	; Y-Z towers
G30 P5 X0 Y140 Z-99999		H-0.15	; Z

; HALF-IN RING
G30 P6 X0 Y70 Z-99999		H-0.15	; half way to Z tower
G30 P7 X-60 Y-35 Z-99999	H0	; half way to X tower
G30 P8 X68 Y-40 Z-99999		H0.1	; half way at Y tower

G30 P9 X0 Y0 Z-99999 S6		; centre, and auto-calibrate 6 factors

;*** Remove the following line if your Z probe does not need to be retracted
;M98 Pretractprobe.g			; retract the mechanical Z probe

G1 X0 Y0 Z250 F10000			; get the head out of the way of the bed

Ah right looks like you are probing in a anti clockwise direction starting halfway between the X and Z Towers and Think this may be your problem Pretty sure you need to probe in a clockwise direction starting from the Z Tower I you go to www.escher3d.com and run DC42's Bed generating wizard that it how it does it and I do know that on a cartesian if you dont do it in a clockwise direction then it doesn't work?

It's certainly worth a try and I am sure that David will see this and comment further before to long?

Also I am not sure when David implemented the H Parameter now so it may be worth while upgrading your Firmware as we are now on 1.16 RC2?

HTH

Doug

Edited 1 time(s). Last edit at 11/06/2016 05:26AM by dougal1957.

When using auto calibration on a delta printer, it doesn't matter what order you probe the points in. That's the intention of the code I wrote anyway. It's when you probe to do bed levelling on a Cartesian printer that the order matters (I didn't write that code).

Correcting for effector tilt (or other causes of varying trigger height) using H parameters won't necessarily reduce the deviation reported at the end of calibration, because geometrical errors that cause effector tilt also give rise to height errors, and the model used by delta auto calibration doesn't include those factors. But it will give you a better first layer.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Voice of the Expert rules here my Apologies for maybe misleading you?

dougal1957, you are protected by the Good Samaritan law

I was not aware that the H parameters would not affect the bed-leveling routine report, that changes a lot for me! With that obstacle removed I can move forward to rebuilding my carriages also as they are a frankenstein of cut-up printed parts, polycarbonate blocks, and wooden shims (blegh!).