D-Bot 3D Printer

[Gina]

Good idea

[tekkydave]

I have now printed and fitted an enclosure for the Duet. All the wires have been shortened to the correct lengths and properly crimped or joined. I designed the enclosure to be big enough for the Duet and a Pi3 if required. The sides, rear and top panels and front panel are all separate. This will allow me to customise or enlarge without having to reprint the whole enclosure.

All the wires to the x carriage are via the chain which has its enclosing spring-clips fitted.

I am in the process of redesigning the Power & SSR enclosure, below the Duet enclosure. I want to fit a Powercon connector to allow the bed heater to be unplugged if required. Also I want to have a conduit linking to the Duet enclosure for the SSR control cable.

I also need a cover for the 24V/15A PSU with inlet for the switched mains supply coming from the Power/SSR module. It will also contain a buck converter to generate a 12V supply. Initially I need 12v for the LED strip and the 80mm case fan that will be in the Duet enclosure lid.

 

[Dave_D]

looks the business...

[Gina]

That wire retaining chain looks ingenious

[tekkydave]

Printed the front panel. The slot is wide enough to allow a micro-usb plug to be inserted.

Next to print the lid....

[tekkydave]

I've been experimenting with sensorless homing for the X and Y axes. The drivers in the Duet (TMC2660) are able to detect motor stalls and these can be used to trigger an endstop signal.

Note that this only works on RRF V1.20 or above.

In config.g add:

M574 X1 Y2 S3		   ; X1 = X-axis at xmin, Y2 = Y-axis at ymax, S3 = set endstops to use motor stall
M915 X Y S5 R0		   ; Configure X Y motor stall detection. S5 = set sensitivity to +5, R0 = no action on stall

the M574 replaces the existing one for your X & Y endstops. Depending on your machine and setup you may need a separate M574 for your Z axis, or you may have an M558 instead for a Z-Probe.

I updated each of my homing files as follows:

homex.g

M400			    ; make sure everything has stopped before we make changes
M913 X50	        ; drop motor currents to 50%
G91			        ; use relative positioning
G1 Z5 F180		    ; lift Z relative to current position
G1 X20 F3600		; move X away from endstop
G4 P250             ; Pause for 250mS
G1 S1 X-320 F3600	; move quickly to X endstop and stop there
G1 X20 F3600		; move X away from endstop
M400			    ; make sure everything has stopped before we make changes
G90                 ; absolute positioning
M913 X100           ; reset motor currents to 100%

homey.g

M400			        ; make sure everything has stopped before we make changes
M913 Y50	            ; drop motor currents to 50%
G91			            ; use relative positioning
G1 Z5 F180		        ; lift Z relative to current position
G1 Y-20 F3600	        ; move Y away from endstop
G4 P250                 ; Pause for 250mS
G1 S1 Y320 F3600	    ; move quickly to Y endstop and stop there
G1 Y-20 F3600	        ; move Y away from endstop
M400			        ; make sure everything has stopped before we make changes
G90                     ; absolute positioning
M913 Y100               ; reset motor currents to 100%

homeall.g

;------------------------------------------------------------------------------------------
;   X and Y Homing
;------------------------------------------------------------------------------------------
M400			        ; make sure everything has stopped before we make changes
M913 X50 Y50            ; drop motor currents to 50%
G91			            ; use relative positioning
G1 Z5 F180		        ; lift Z relative to current position
G1 X20 Y-20 F3600       ; move X and Y away from endstops
G4 P250                 ; Pause for 250mS
G1 S1 X-320 F3600	    ; move quickly to X endstop and stop there
G1 X20 F3600	        ; move X away from endstop
G4 P250                 ; Pause for 250mS
G1 S1 Y320 F3600	    ; move quickly to Y endstop and stop there
G1 Y-20 F3600	        ; move Y away from endstop
M400			        ; make sure everything has stopped before we make changes
G90                     ; absolute positioning
M913 X100 Y100          ; reset motor currents to 100%
;------------------------------------------------------------------------------------------

;------------------------------------------------------------------------------------------
;   Z Homing
;------------------------------------------------------------------------------------------
G1 X150 Y140 F6000      ; go to centre of bed
G30                     ; home Z by probing the bed
G1 Z5 F180              ; uncomment this line to lift the nozzle after homing
;------------------------------------------------------------------------------------------

I have disconnected & removed my X & Y endstop micro-switches and I'll see how reliable this proves. Not sure it adds anything apart from reducing the wiring a bit.

[Dr_Ju_ju]

Joseph Prusa uses it on the i3 Mk3, but the Einsy Rambo board uses 2130 drivers, so don't if there would be any differences in action\re-action. 

I was going to try stall-guard, but DC42(Duet) advises against using it, on repeatability grounds, but after I my extruder get sorted (awaiting bearings), I may well give it a go.

[tekkydave]

I'm only using it for homing so repeatability not an issue. It would be if I was re-homing mid print. I'm testing it at the moment so may put the microswitches back if it proves unreliable. I've had issues in the past with microswitches failing over time so swings and roundabouts really.

[tekkydave]

I want to set it up to log stalls on the extruder motor as well.

[Gina]

Interesting

[tekkydave]

Printed a cover for my 24V PSU. The IEC inlet gets a feed of mains power from the main power switch. The 4-pole powercon connector supplies the 24V and 12V feeds back to the Duet enclosure. The buck converter does the 24V to 12V step-down.

The sensorless endstops seem to be proving very reliable so far.

[tekkydave]

Done. The wiring's a bit tight inside so I might reprint it slightly longer for more space. Also, I think it needs some screws in the sides as it curently relies on engaging into the slots either side of the PSU.

The control on top is a 200 ohm 5w wirewound pot in series with the internal fan. It cuts down the noise a lot, especially as I'm only using a few Amps. It  doesnt get warm even with the fan turned right down.

I've also made up a mini distribution strip for the 12v supply. The sockets are (L to R) 12v in, enclosure fan, 2x spare outputs, LED feed. Not sure where I will fix it inside the enclosure yet.

 

[tekkydave]

Designed and printed some brackets for the 24v PSU.

 

[Gina]

Does anyone have the current rating for the Duet hotend heaters?  I mean how much current can the Duet control with its power MOSFETs.  I know the bed heater rating but I can't find the spec for the hotend heaters.  The Duet forum are not accepting new members at present.

[Dr_Ju_ju]

Can't put my hands on the circuit diagram, at the mo, but I believe all 3 on-board mosfets (bed & 2 heater) are the same, so it should be similar to the bed.

 

Circuit Diagram attached

Duet2_Schematic_v1.03.pdf

Edited March 8, 2018 by Dr_Ju_ju
Update

[tekkydave]

According to The Duet Wiki the extruder heaters are 5A each. I'm using a 60W heater at 24V which is 2.5A.

The bed heater is 18A.

[Gina]

Thank you both.  Well found   5A is just enough for a pair of 24v 60W heaters I was hoping to use on my Giant printer with custom made 30mm long heatblock and 25mm long 2mm nozzle

[jeranio]

Hi Guys,

 

Anyone has the dimensions for the wheel spacers used in the d-bot. I want to replace them with aluminium ones. Thanks for any help.

[tekkydave]

I used these spacers from Ooznest (Pick the 6mm ones)

http://ooznest.co.uk/3D-Printer-Mechanical-Parts/Fixings-Spacers/Aluminium-Spacer

with one of these

http://ooznest.co.uk/3D-Printer-Mechanical-Parts/Fixings-Spacers/Mini-V-Precision-Shim

against the bearing. This gives an overall spacing of 7mm. It's important to place the shim in contact with the bearing. If you place the spacer in contact it will stop the bearing rotating when tightened.

If you bought the mini-v-wheels as a kit you will have received a couple of the shims with each wheel. One goes between the two bearings, the other one is spare and can be put with one of the spacers. Don't use washers as a cheap alternative as they are not the correct dimensions and also stop the bearings rotating when tightened.

Hope that helps

 

Edited March 28, 2018 by tekkydave

[jeranio]

Great .. thank you I will order them. I am having endless hassles with both Z and Y bars having play when wheels run free. When I tighten the wheels they start to bind but then the skewness goes away. I sat for hours trying to find a balance between them. I even printed the 3 wheel system by RE-D-BOT (https://www.thingiverse.com/thing:1802733) and even that did not help so now I am changing the hardware to more precise metal stuff to ensure the final product has no errors. Thanks again for the links. I will post pictures soon. Got all on my phone. 

[jeranio]

So, got all the corner brackets ,spacers and shims  (re-ordered with metal types). Waiting for delivery from Ooznest (might take a few days to reach me way down). In the meanwhile gonna strip down frame and wheels in preparation for new hardware.

Edited April 4, 2018 by jeranio
Needed to upload pictures to show progress

[tekkydave]

Some recent upgrades:

1. I printed some better bed supports with adjustment wheels. It's much easier to get the bed levelled. The design was from Thingiverse.

 

2. Upgraded my Precision Piezo probe from the PP20 to the latest Orion model. It is much improved in terms of construction and accuracy.

 

[tekkydave]

Designed and printed a better, more robust enclosure for the mains in/out and SSR. This keeps all the 240V separate from the low voltage electronics.

It houses an IEC switched & fused inlet, IEC outlet to the 24V PSU, the DC/AC SSR and the heated bed outlet (Powercon).

The only low-voltage is the heated bed control from the Duet, via a 12mm flexible conduit from the Duet Control Box.

 

[tekkydave]

Got round to fitting the Raspberry Pi3 into the control enclosure. I'm using MotionEye OS to control multiple cameras. There is an excellent tutorial here. It suggests using an RPi Zero which is ok for one PiCam but slows down a lot with a USB camera plugged in aswell.

I have a standard PiCam plugged into the Pi3 and a cheap webcam in one of the USB ports. The PiCam will be used to monitor the print bed and the other will have a wider viewpoint. I would like to be able to see the spool to check it is moving.

I have fitted a buck converter to the lid to step the incoming 12v down to 5v for the Pi.

 

[Gina]

Good stuff Dave   I'll be looking into cameras before long - got a few other things to do to a couple of my printers before then.  I already have +5v, +12v and +24v available so no buck converters required.  Like you, I shall want more than one camera.  I've got several webcams around in my many boxes