Scara Problem

JoergS5

@Mauxx I have an additional idea: (removed, this was not the reason)

Mauxx

I try to work with 800x800 area with 0,0 at centre of tower (X-400,X400; Y-400,Y400) and this problem is in all 4 central axis
Probably you're right, so how i can set my config?

JoergS5

@Mauxx is the angle limit a physical limit or can you change the limit in the configuration?
If it's a physical limit, you could place the printer nearer to an edge and/or further away from the print bed. This should give you a bigger print area.

For optimal placement I cannot give a recommendation, but it's worth to search, e.g. this document: https://www.researchgate.net/publication/298430720_Optimal_Placement_of_a_SCARA_Robot_-_Lab_Report

Mauxx

@JoergS5 Yes, max angle is physical limit
Sorry for my bad english...

Mauxx

@dc42 have you ever encountered this issue?

Danal

We've all focused on the stuff happening along X while Y=0.

None of that explains what happens at 3:10 or so in the video, the move from X90Y220 to X60Y220 also draws an arc. An arc that falls outside the printable area as specified by M208. None of the joints are anywhere near a limit.

Mauxx

it's really very strange
thank you all for your help!!!

JoergS5

@Danal said in Scara Problem:

We've all focused on the stuff happening along X while Y=0.

None of that explains what happens at 3:10 or so in the video, the move from X90Y220 to X60Y220 also draws an arc. An arc that falls outside the printable area as specified by M208. None of the joints are anywhere near a limit.

That's a valid point. Maybe multiple reasons.

My ideas for things to analyze:

the communication log of Simplify3D
belt connection between steppers and Axes: maybe slipping or other problem. Slipping belt could explain curves at strange positions. => one more idea: maybe acceleration and speed too high, so belt starts slipping. You can test setting speed and acceleration lower

Is it a toothed belt or a non-toothed one? If it doesn't have teeth, you can check whether the belt slips at the stepper pulley when the printer makes a curve. The pulley itself could slip also (pulley on the stepper axis). You use a method which I know as ServoBelt, this produces high tension, needs high torque and may lead to slipping pulley.

@Mauxx which Duet hardware, firmware versions are you using?

Mauxx

Scara give same issue also with Arduino IDE and with RepetierHost draw a Triangle...

I'm sure the belt doesn't slip, i have GT2 toothed Belt

I'm using RRF Lpc on Skr V.1.3 board

When printer draw arc Y motor doesn't move at all

JoergS5

@Mauxx Maybe the scara code is another one than I checked, because I looked into David's code. Where did you download your firmware RRF LPC code? I will check it then.

JoergS5

@Mauxx said in Scara Problem:

Scara give same issue also with Arduino IDE and with RepetierHost draw a Triangle...

I'm sure the belt doesn't slip, i have GT2 toothed Belt

What do you mean with triangle?

Mauxx

When i start print, instead a cube (only in central area) it draw a triangle (half cube)

JoergS5

@Mauxx I don't understand it, do you have an image?

But more important is, which software you are using, so I can check the source. Do you use the sdavi CoreLPC4 port?

Mauxx

@JoergS5 Thank you very much!!!

for the moment I own Skr Board but am willing to buy a Duet
I just wanted to verify that everything worked properly
I practically tried all the firmware (marlin, smoothie) and RRF is the best !!!

Mauxx

@JoergS5 i'm using this https://github.com/sdavi/RepRapFirmware/releases/tag/LPC_RRFv2.04

JoergS5

@Mauxx Thanks for the code basis. The included ScaraKinematics seems to be the same like in the official code base, so this is propably not the problem.

One possible reason ... (removed, this was not the reason...)

Mauxx

So with a Duet Board i will solve this problem? Great!!!
Which board do you suggest?

JoergS5

@Mauxx I would choose Duet2 Wifi or Ethernet. The new Duet 3 is not needed for the application. The Maestro doesn't have FPU, and floating point algorithms are used in Scara. If you want to experiment a lot in the future, a Duet 3 is an option of course. It is a matter of budget also of course.
I have personally a Duet 2 Wifi and Duet 3+Pi 4 and both are great.

Mauxx

nice!!!
if you tell me that with duet there's no issues, i trust you

JoergS5

@Mauxx I have not tested the Scara, but I give you the following promise: if there is an error in the Scara code, I will help fixing it.

I have created a parallel Scara printer:
https://duet3d.dozuki.com/Guide/Five+Bar+Parallel+SCARA/24?lang=en
and source in
https://github.com/JoergS5/RepRapFirmware
for RRF2, so I have expertise.
Maybe you're interested in building a parallel scara in the future also?