Scara support ?

dc42

I've just corrected the wiki page about configuring a SCARA printer. The proximal joint and distal joint homing files are called homeproximal.g and homedistal.g, not homep.g and homed.g as I documented originally.

frafa

Hi

Added files
same problem G28 wont reset coordonate X/Y (Z ok)
position is ok motor stop but X/Y Does not go to zero

see video
http://dl.free.fr/jhn5CLUfH

frafa

if i test just

[[language]]
G1 S1 X-200 F3000

```move ok
stop position ok
but not Zero coordonate ….

number40fan

Nvm, got the video to finally download.

frafa

Hi

[[language]]
G1 S1 X-200 F3000

```Wont reset zero coordonate, Bug ?

dc42

@frafa:

I need to be able to shift the position after homing to x0 / y0
Either with M206
Either with G92 after move on x0/y0
how to do ?

To shift the X=0 Y=0 point:

1. Make sure that you have set the arm angle limits in the M669 command P and D parameters accurately, so that when you home the arms the homing switches trigger at those angles.

2. To verify this, after homing, send G0 X0 Y0 S2 F2000. This will send both arms to zero angle. Check that both arms are pointing along the direction that you have chosen for the X axis. Note: The "arms" are the lines from the proximal joint to the distal joint, and from the distal joint to the nozzle. These are the lines that must both point along the X axis at zero angle. If you have joints and/or the nozzle offset to one side from the physical arm, then the physical arm will not point along the X axis.

3. The X and Y parameters in the M669 command specify the X and Y offsets of (0,0) from the location of the distal joint. If you send G0 X0 Y0 F2000 (without the S2 modifier) then it will go to that position. You can put this command at the end of your homeall.g file if you wish. If this doesn't send the head to where you want X0 Y0, and step #2 above worked correctly, then you need to adjust the X and/or Y parameters.

frafa

Hello
Sorry but I do not understand …

@dc42:

1. Make sure that you have set the arm angle limits in the M669 command P and D parameters accurately, so that when you home the arms the homing switches trigger at those angles.

M669 P and D commands are the lengths of the arms?
You are talking about Annn: mmm and Bnnn: mmm?

Is it possible that you give me the approximate values (aaa … bbb) by looking at my schema as I understand the sense of the measurement of angles? compared to what ?

M669 K4 P200 D200 A??? B??? 1:0:0 S150 T0.1 X65.0 Y-150.0; set SCARA kinematics parameters ok S200

dc42

I find it easier to understand if I rotate that diagram by 180 degrees so that +X is to the right and +Y is up.

If the diagram shows the arms in the homed position (i.e. both arm joint microswitches triggered), then the homing position of the proximal joint is about -120 degrees. So your P parameter should be -120:xxx where xxx is the maximum angle it can rotate anticlockwise relative to the X axis.

The distal joint appears to me to be at an angle of approximately +150 degrees relative to the proximal arm. So the D parameter should be -yyy:150 where yyy is the maximum angle it can reach clockwise relative to the proximal arm.

The proximal arm homes fully clockwise (bottom end of its range) whereas the distal arm homes fully anticlockwise (top end of its range). So your M574 X and Y parameters need to be X1 Y2.

See the expanded calibration section at https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_SCARA_printer#Calibration.

frafa

Hello
I do not understand why you talk about P and D
P and D are the length of the arms?

Tonight we were 4 people at the fablab to try to understand
Not successful …
I rework on scara Monday

number40fan

upload photos

Delete if this is of no help.

dc42

@frafa:

Hello
I do not understand why you talk about P and D
P and D are the length of the arms?

Tonight we were 4 people at the fablab to try to understand
Not successful …
I rework on scara Monday

I am sorry, you are right, I should have said A and B, not P and D.

I have a SCARA printer now and I expect to convert it to Duet electronics next week.

frafa

Hello

Thanks to you two for the help provided

Monday I retest the homing

Impatient to see your scara !

frafa

Hello

inverted Endstop on y2
Finally i have homigs that work

Calibration is complicated it would be nice to think a more simple mode,
It is easy to have precisely the values of X and Y in M669
On the other hand, finding the values A and B is difficult.

For example, g28 moves to endstop position,
after we move with G1 x / y precisely to real x0/y0
And with a command define A and B (ex: g92 x0 y0), possible?

Possible to forbid z + if limit switch is activated, how to do?

I want to test your IR sensor, offsets are managed on scara ?
https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_Cartesian_printer#Z_probe_section

dc42

I'm glad you got it working.

The IR sensor is managed on SCARA exactly as for other kinematics. See the Testing and Commissioning section of https://miscsolutions.wordpress.com/mini-height-sensor-board/.

Once the printer has been Z homed, the soft endstop at the Z height configured in your M208 command will be enforced.

frafa

Ordered on duet3d.com
IR Probe
e3d PT100 Sensor
PT100 Daughter Board
Thanks for all

frafa

Hello,
My limit of the Z is currently in max (388)

[[language]]
M208 X300 Y300 Z388; Set to maximize (adjust to suit your machine)
M208 X0 Y0 Z0 S1; Set axis minima (adjust to make X = 0 and Y = 0 the edges of the bed)

After homing the Z if I make a g1 z390, this is possible, how to prohibit it?

dc42

I'm sorry, when I refactored the kinematics code I forgot to change the SCARA code to apply the usual limits to all axes other than X and Y. I'll fix this in the next release. There will probably be a 1.19.1 release to tidy up issues such as this one.

dc42

I've been testing the SCARA support on my new SCARA printer. There is a bug in the forward kinematics calculations. No wonder you were having problems! I will have a fix soon (and it will include the Z axis limits too).

frafa

Hehe cool
I look forward to sensor IR sense
The French post office is slow at the moment …
Thanks in advance

Possible to see your scara : p
I'm curious to see a business model

dc42

There are pics of my SCARA printer at https://miscsolutions.wordpress.com/2017/08/09/testing-the-robotdigg-scara-arm-3d-printer/. It's a very cheap printer - Duet electronics are too good for it! But it's good enough for me to use it to test the SCARA support.