Scara Setup

DannyDefe · 1 Dec 2017, 04:00

David
I have proximal and distal homing working, but I don't want to use a probe for Z homing.
I'd like the Z to go all the way to the top and hit limit switch for homing.
I have set Z height 200mm

; File homez.g
G91 ; relative movement
G1 S2 Z4 F200 ; raise head 4mm to ensure it is above the Z probe trigger height
G90 ; back to absolute mode
G1 X100 Y100 F2000 ; put head over the centre of the bed, or wherever you want to probe
G30 ; lower head, stop when probe triggered and set Z to trigger height

dc42 · 1 Dec 2017, 08:47

See https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_Cartesian_printer#Homing_Z.

DannyDefe · 2 Dec 2017, 02:47

David I couldn't use that homing sequence, so I put together something from the Delta homing Z sequence. Remember the limit switch is at the top and I will be printing on the top of the desk which is 200 mm down.
thanks for the help

DannyDefe · 4 Dec 2017, 02:47

I've initially got it working!!
So here is the homez.g
G91 ; use relative positioning
G1 S1 Z300 F2500 ; move all carriages up 300mm, stopping at the endstops
G1 S2 Z-5 ; move all towers down 5mm
G1 S1 Z8 F500 ; move towers slowly up 8mm, stopping at the endstops
G1 S2 Z-5 F10000 ; move carriages down 5mm
G90 ; back to absolute positioning

But now that I've got it working I'd like to put the limit switch at the bottom of the travel on the Z, so I'll be homing at the lowest point.

I hope this doesn't sound confusing but Z0 will then be all the way at the top, and usable Z is 200 mm.
This is hard to describe but I will be printing on the top of the distal arm, there will be a plastic dish which I will be extruding clay onto. As the Z descendants the object will continue to print. The clay extruder is stationary above the
machine,
I know this sounds crazy but I've done it before with a Delta and it works fine.

So if you can please help with the Z homing sequence, and also I don't need thermistor so how can we block the lack of these from interfering.
Thanks

; SCARA MINI
M111 S0 ; Debug off
M550 SCARA MINI ; Machine name and Netbios name (can be anything you like)
M551 Preprap ; Machine password (used for FTP)
;*** If you have more than one Duet on your network, they must all have different MAC addresses, so change the last digits
M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED ; MAC Address

;*** Networking
M552 S1 ; Turn network on

;*** Ethernet networking: Adjust the IP address and gateway in the following 2 lines to suit your network
M552 P192.168.1.14 ; (0 = DHCP)
M554 P192.168.1.255 ; Gateway
M553 P255.255.255.0 ; Netmask

M555 P2 ; Set output to look like Marlin
G21 ; Work in millimetres
G90 ; Send absolute coordinates…
M83 ; ...but relative extruder moves

; Disable Fan 1 thermostatic mode
M106 P1 H-1
M584 X5 Y6 Z7 E8 ;Set drive mapping
; Axis and motor configuration
M569 P5 S0 R0 T4 ; Drive 0 goes forwards X
M569 P6 S0 R0 T4 ; Drive 1 goes forwards Y
M569 P7 S0 R0 T4 ; Drive 2 goes forwards Z
M569 P8 S0 R0 T4 ; Drive 3 goes forwards E
; Drive 4 goes forwards
M669 K4 P200 D200 A-179:170 B-120:120 C0:0:0 ; set SCARA mode and parameters

;Endstop configuration
M574 X1 Y2 Z1 S0 ; M574 X2 Y2 Z2 S1set endstop configuration (all endstops at high end, active high)
;*** The homed height is deliberately set too high in the following - you will adjust it during calibration

M666 X0 Y0 Z0
M208 S1 X50 Y-121 Z-1 ; Axis minima
M208 X179 Y121 Z100 ; Axis maxima ; put your endstop adjustments here, or let auto calibration find them
M350 X1 Y1 Z1 E1 E2 I1 ; Set 1x microstepping with interpolation
M92 X25.9820 Y17.777 ; Steps/degree for proximal and distal joints
M92 Z500 E106 ; Steps/mm for Z and E
M906 X1000 Y1000 Z1000 E800 I60 ; Set motor currents (mA) and increase idle current to 60%
M201 X1000 Y1000 Z1000 E1000 ; Accelerations (mm/s^2)
M203 X2000 Y2000 Z2000 E3600 ; Maximum speeds (mm/min)
M566 X1200 Y1200 Z1200 E1200 ; Maximum instant speed changes mm/minute

; Thermistors
;M305 P0 T100000 B3950 R4700 H30 L0 ; Put your own H and/or L values here to set the bed thermistor ADC correction
;M305 P1 T100000 B3974 R4700 H30 L0 ; Put your own H and/or L values here to set first nozzle thermistor ADC correction
;M305 P2 T100000 B3974 R4700 H30 L0 ; Put your own H and/or L values here to set 2nd nozzle thermistor ADC correction

; Tool definitions
M563 P2 D0
G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
G10 P0 R00 S00 ; Set initial tool 0 active and standby temperatures to 0C

M92 E663:663 ; Set extruder steps per mm

;*** If you are using axis compensation, put the figures in the following command
;M556 S78 X0 Y0 Z0 ; Axis compensation here

M208 S1 Z-0.2 ; set minimum Z

;T0 ; select first hot end

; Pressure advance
;M572 D0 S0.5

; Misc
M83
M117 Use https://configurator.reprapfirmware.org/ to set up your printer config
M302 P1
M563 P0 D0 T1 ;enable cold extrusion.
T0

; Heaters
;M143 H1 S260 ; Maximum heater temperature
M140 H-1 ; No bed heater
;M305 P1 T100000 B4138 C0 R4700 ; Thermistor parameters for heater 1
;M307 H1 A577.0 C199.0 D9.8 S1.00 B0

DannyDefe · 8 Dec 2017, 01:41

David did you see my last post? I actually have most everything working !
Now I'm going to work on the Z homing and run some accuracy tests

dc42 · 8 Dec 2017, 09:35

I missed your previous post. I'm glad to hear that it's all working.

DannyDefe · 9 Dec 2017, 01:46

I have the limit switch at the bottom of the travel on the Z, so I'll be homing at the lowest point. The homing sequence works, but then Z should go up 200 mm to Z 0 to begin printing.
G91 ; use relative positioning
G1 S1 Z-100 F500 ; move all carriages up 300mm, stopping at the endstops
G1 S2 Z5 ; move all towers down 5mm
G1 S1 Z-8 F500 ; move towers slowly up 8mm, stopping at the endstops
G1 S2 Z5 F250 ; move carriages down 5mm
G90 ; back to absolute positioning

I hope this doesn't sound confusing but Z0 will then be all the way at the top, and usable Z is 200 mm.
This is hard to describe but I will be printing on the top of the distal arm, there will be a plastic dish which I will be extruding clay onto. As the Z descendants the object will continue to print. The clay extruder is stationary above the
machine,
I know this sounds crazy but I've done it before with a Delta and it works fine.

So if you can please help with the Z homing sequence and to get to Z0 at the top .

dc42 · 9 Dec 2017, 09:44

So Z=200 is at the bottom, and Z=0 is at the top? Then your homing switch is a Z max switch. It sounds to me that you need to:

Reverse your Z axis direction in M569 so that +Z is down;
Change M574 to say that the Z switch is at the max position (Z2)
Set Zmax = 200 (or whatever the exact value is) in the M208 command
Reverse the movement directions in your Z homing file.

DannyDefe · 11 Dec 2017, 12:59

David what command will stop the print when the Z Carriage hits the Z limit switch. Right now it's hitting the limit switch and then breaking the switch

dc42 · 11 Dec 2017, 14:36

A G1 S1 Zxxx command will stop when it hits the Z limit switch, if the switch is correctly connected and configured. Use either M119 or the Machine Properties page of Duet Web Control to check that the limit switch is working and recognised by the Duet.

DannyDefe · 11 Dec 2017, 23:58

I'm not sure if we're talking about the same thing, but this is the command that I'm familiar with in smoothieware
(gamma_limit_enable)

the scara is working fine ,all of the end switches are perfect but during printing if the carriage goes too far it hits the limit switch .
This should stop the machine

DannyDefe · 12 Dec 2017, 00:08

One more question ,how do I eliminate the necessity to have thermistors. I'm extruding clay and I have no need for these so is there a way to bypass without physically hooking them on the board

dc42 · 12 Dec 2017, 08:10

You can set up a trigger to stop the machine if the limit switch is hit, see https://duet3d.com/wiki/G-code#M581:_Configure_external_trigger.

You don't need to connect thermistors if you don't use them. Define your tool to have no heaters in the M563 command, and use M140 H-1 to tell the firmware there is no bed heater.

DannyDefe · 14 Dec 2017, 02:10

Okay this command works (M581 TO Z1 S1 C1 ) and the switch when triggered stops the machine. However it stops the machine when it's first homing, so the print doesn't start. How can we delay this till after the first homing sequence?

dc42 · 14 Dec 2017, 08:23

You can use M581 commands to disable the trigger at the start of the homing files and re-enable it at the end.

DannyDefe · 2 Jul 2018, 00:42

I thought the group would like to know my experience setting up my Duet wifi board with my scara. I've previously had a smoothieware and decided to try the Duet and there is no comparison.
The Duet has fantastic GUI interface, and the help and setup files that David (dc42 ) has created is extremely helpful. Talking about David, he gives excellent support and helped me work through my small issues. If anyone was considering trying this board I would give it a super thumbs up.
I haven't had much time to fine tune the machine and it's going to be used for ceramics only.

scara ceramic printer
[[url]https://www.dropbox.com/s/vsklk2lhr2dk4qy/20180205_111555.jpg?dl=0]

dc42 · 8 Feb 2018, 00:52

Thanks for your kind words!

DannyDefe · 12 Feb 2018, 00:30

David
I would like the ability to do 360 degree continuous prints. This means I'm printing continuously Non-Stop around the perimeter of the Scara.

Because of this request, I also have proximity sensor on the prox arm. This sensor requires 5v, so what's the best way to wire this?
thanks

dc42 · 12 Feb 2018, 07:59

What type of output does the prox sensor have?

DannyDefe · 12 Feb 2018, 15:18

So what's the answer can we run 360 continuous?

LJ8A3-2-Z BX
Voltage: DC 5V
Theory: Inductance Sensor
Detection distance: 4mm
Output current: 200mA
Polarity: NPN
Ouput Status: Normally Open
Detect Object : Iron 15151mm
Response frequency: DC:0.5kHz AC:25Hz
Wire type: 3 wire type (Brown, Blue, Black