strange problem with g28 command

Controllers Smoothie
1

Hi guys,
I’m building a kossel mini and for it i have used a smoothieboard. I’ve setted up the configuration file found on the github for the deltas, making some changes to the arm solutions. Then i tried to connect with pronterface and see if everything was okay. The endstops are responding as they should (from what i found on the endstop page) and the motors turn in the right direction, moving up and down. At least individually, the problem appears when i issue a g28 command, because they simply start humming, no movement at all. I’ve made a quick test and set two endstops active and the third disabled then i issued a g28 command, it humms again. However, if i trigger the endstop manually the motor moves down and then up and enables the endstop by itself. Even more strange, is that if i issue a g28 command with all carriages triggering the endstops , the mottors move down by 5mm and then up and stop when the endtstops are triggered.
Any help on this would be apreciated.

Thanks and sorry for the bad english.
Bruno Faria

Imported from wikidot

2

Hi !

It sounds like you are trying to home too fast so your motors just stall right away.

Can you try changing the *_fast_homing_rate_mm_s values to lower values and see if that helps ?

Cheers.

3

Thanks, that did it. I changed the fast feedrate to 100 and it didn’t work then i half it again to 50 and it did work. My question now is, can you point me out how this limit can be calculated? Is this the limit my motors can print or this is just for homing? I would like to know more of that… i found out this site prusaprinters dot org/calculator/ but it is not enlightening enouth.

Thanks once again!

4

This is only for homing.
The way to figure out these kinds of speeds ( this is also true for acceleration and junction deviation ), is to try higher values, until you reach a point where it either doesn’t work, or impacts print quality more than you’d like, and when you reach that point, back up a bit.

5

Okay, thanks…