Scara support ?

frafa

Hello,
Again a big thank you for your responsiveness
My tests:

The M669 command used (X150.0 Y-61.0):
M669 K4 P200 D200 A-175:175 B-175:175 1:0:0 S200 X150.0 Y-61.0; set SCARA kinematics parameters

ok
Test moves First arm of 20 ° it's ok?
G1 S2 X10 ;anticlockwise
G1 S2 X-10 ;clockwise

ok
Test moves second arm of 20 ° it's ok?
G1 S2 Y10 ;anticlockwise
G1 S2 Y-10 ;clockwise

All movements in Pronterface in debug mode return:
SENDING:G92 X0 Y0
[ERROR] Traceback (most recent call last):
File "printrun\printcore.pyc", line 241, in _readline
File "printrun\pronterface.pyc", line 1713, in recvcb
File "printrun\pronterface.pyc", line 1669, in update_pos
ValueError: could not convert string to float:

Homing goes in the right direction x/y/z

I manually move the arms to position x0/y0
I power on with Pronterface I send command G92 X0 Y0

I'm testing x/y placements everything works but upside down
When i do x + i get an x-
And when i do a y + i get a y-

I reverse the engines in config.g and the displacements do anything?
I put the file config.g normal, and I reverse the connector of the engines,
Same results the movements do anything

In short I did not succeed in reversing the meaning, how to do?
It's almost perfect we're not far

dc42

In writing the firmware I assumed that the bed is to the right of the proximal joint, and the zero angle position of both arms is with them stretched out to the right so that they point towards the +X direction. Do you by any chance have your arm mounted the other way round?

frafa

hi
My Kinematics
for later End-stops (hall effect +on5v) are on X22.00 Y-35.00

dc42

Ok, so what i have assumed is +X is your +Y, and what I have assumed is +Y is your -X. Thinking about it, there are 4 possible orientations of the bed if we only consider the obvious ones, and I guess the firmware should allow any of them in a configuration option. Or maybe it should allow an arbitrary bed rotation angle.

For now, if you define the top left corner of the bed in your diagram as (0,0) and the axis directions as I have assumed them, then you should be able to print

Regarding homing, I was assuming there will be a limit switch at one end of the travel of each joint.

frafa

Of course I'm stupid, I did not think about it
I test this afternoon

frafa

Hi
define the top left corner of the bed, change on M669 x/y
and print…
ok

Video, sorry the machine is under development all is not clean ...
http://www.openhardware.eu/tmp/DuetWifi/VID.mp4

I still have to solve the same vibrations as with Smoothie …

My M669
M669 K4 P200 D200 A-175:175 B-175:175 1:0:0 S200 X118.0 Y-150;

My reduction motor and pulley
Motor 400 step/revolution 0.9°
Pulley 80/16
Microstepping 256
Calcul Step/° X/Y (Réduct 80/16) ==> 400256(80/16)/360=1422,2222222222222222222222222222

What can be the cause in your opinion not enough mechanical reduction, or other ?

Thank you very much !

dc42

I'm glad you are making progress.

Have you tried adjusting the segments/sec and minimum segment length in the M669 command, to see whether it affects the vibration?

frafa

I am also pleased !
Not tried, i test tomorrow.

frafa

Hello,

I've done a lot of testing, and the best configuration seems to be
M669 S200 T0.5
It's not perfect, but it's better

But on another piece the result is not satisfactory

Saturday I tried on cubes and diamonds to try to understand,
Because the vibrations seem to be present only on the diagonals of the bed …
If you have an idea to improve ...

I will redo the arm to pass in reduct of 160/16
And GT2 belts 10mm high to see if it improves
http://www.openhardware.eu/tmp/DuetWifi/VID_20170713_181706.mp4

frafa

Hello,
I'm Happy
It is almost perfect there are still some vibrations but I think I can further refine the firmware settings

I completely redraw the arms of scara
Now reduction 160/16
pulley DIY gt2 lasercut and Wide belt 10mm high
New experimental firmware 1.19beta10

http://www.openhardware.eu/tmp/DuetWifi/new/VID_20170721_171557.mp4

number40fan

I can't help to think how a set of shock absorbers would help. You have so much mass hung out so far that you are trying to stop and start. Am I wrong in thinking that something that could help dampen the movement would help?

dc42

I'm glad you are making progress! You are the first person to use RRF or a Duet on a Scara printer.

I'll try to implement Scara homing before the 1.19 release. You will need a microswitch at one end of the movement range of each joint.

frafa

Thanks to you for your reactivity !

The endstop will be hall effect 3v logic / v+ on 5v (banggood model)

dc42

Is your SCARA printer home designed and built, or is the mechanics built from a kit? We're looking for some SCARA mechanics to use as a test bed for the SCARA support in RRF.

frafa

Hello
This is a model designed by me being created,
It will be open-source when finished
Download Sketchup 2016 model of the current model being developed: http://www.openhardware.eu/tmp/DuetWifi/scara-v5.skp
humm … google translate ...
Evolutions in progress not final model, but functional...

frafa

Hello,
A big thank you for the support of Scara and end stops on version 1.19RC1
I test tomorrow

My end stops are not exactly on X0/Y0 M206 is supported ?
and move in X0/Y0 after homing ?

frafa

Hello,
Is it possible that you explain how to set up Homing on Scara
https://duet3d.com/wiki/Configuring_RepRapFirmware_for_a_SCARA_printer

dc42

I've just done that.

frafa

Hello
A big thank you for all your work!

My end-stop limit is not exactly in X0 / Y0
Before with smoothie I used M206 to specify offset and move on real X0/Y0 after homing

How to do with ReprapFirmware?

dc42

Your endstops need to be at one end of each of the proximal and distal joint limits as described in the wiki. They detect the limits of movements of the joint angles. Those limits are wherever you say they are in the M669 command.