G0 Rapid feeds not following KMotion settings

[viulumies]

Hi Tom,
I have a problem that the rapid feed moves in KMotion CNC are not following the settings in the KMotion Step Response screen Velocity, Acceleration and Jerk. They are much faster and cause the steppers to stall. I've checked that the settings the settings are correctly downloaded to the Init.c program. I've as well checked the Trajectory planner settings in KMotionCNC. Tried to lower the rapid moves feedrate from the Trajectory planner as well, without any effect in the speeds.
Only way to change the G0 speed is to copy the KMotion Step Responce settings to the Trajectory planner max speeds (translated to inches/sec) and check the Rapids as Feeds check box.
Is this the way to do it?
...or maybe I haven't understood something.
Eero

[TomKerekes]

Hi Eero,

I can't think of why that would be. What Version are you running? Please post your Initialization file and your Trajectory planner settings. Also the GCode that shows the problem. Are you executing the C Program? You might upload the settings from KFLOP to verify the settings are actually being set.

You should not need to select Rapids as Feeds if you don't have Kinematics.

[viulumies]

I'm running the latest version 5.3.3.
Attached the Init-file (Reset_Sherline.c), the files linked to it (SherlineDef.h and ExtraButtons.c) and a screenshot of Trajectory planner screen.
Now the "Rapids as Feeds" is ticked. It was the only way to slow down the G0 moves: Nothing else was changed. (Today everything worked OK with this "Rapids as Feeds" setting.) So basically for the moment I'm ok. But somewhere something is not quite right...

Looking forward for your advice.
Eero

[TomKerekes]

Hi Eero,

I can't duplicate the problem with those settings.

If I code

Code: Select all

G0 X100
M30

I see a feedrate of 10.3 inches/minute which seems correct. Also if I double the KFLOP Velocity to 28000 steps/sec the feedrate doubles to 20.6 inches/minute.

What are you doing and seeing?

One issue is the Cnts/inch of unused axes are set to 0. Please set to non zero values such as 100 to avoid divides by 0.

[viulumies]

Hi,
I tried to test things as you suggested. With the following results.
My system is a Sherline lathe with KFlop+KStep and KMotion 5.3.3., units in Millimeters, steppers 200steps/rev with 16microsteps.
(You already saw all that from the Init program.)

In KMotionCNC: if I uncheck the "Rapids as feeds"-box, my G0 move gives a speed 305-306mm/min. What corresponds with a little over 16250 steps/mm. This is - and sounds - much higher speed than what testing in the KMotion ”Step response” screen with the setting 14000 Velocity gives (if I understand right this is Steps (or microsteps) per second. 14000 steps/sec should give c. 267mm/min rapid speed (what corresponds what you got, a bit over 10”/min). And with this little Sherline lathe I’m using, the critical speed to avoid stalling in longer moves is somewhere between 15-16000 steps/sec.

If I check the ”Rapids as feeds”-box it sounds like what I hear when testing the step response in KMotion. In the Step response testing the moves are shorter, but the graph shows it reaching 14000 steps/sec, moving a while in that speed and slowing down before moving back the same way in opposite direction. But for some reason The speed in moves with these settings (rapids as feeds) showed on the KMotionCNC screen something like under 100mm/sec. I could not understand. I thought I’ll try to time the the distance of 100mm move…. But than something odd happened: I went back to KMotion to do the GO move, but the steppers didn’t respond at all. The screen shows as if they were moving, but the stepper stay still. The KMoition Axis screen shows both axis are enabled, but there is no current to the steppers. They are as they were not connected, easy to turn by hand, not holding the position. ?
I thought a fuse would have burned, but no. I checked all the connections. Everything is as it should be: KFLop is working, KStep gets the 24Vdc for the steppers and seems to be ok. The box of the electronics is clean…
The one thing I can’t understand is that the I/O screen shows all KStep Bits (168-183) active/checked. I’ve wired bits 170-180, but use only 173 (Limit switch for both axis), 178 for Probe and 179 for Feed hold button. Even disconnecting the cable (a DB25 cable) does not change the situation. I haven’t checked this screen for a long time as everything has been working ok. So I don’t know if them being all active means there is no connection or some short circuit somewhere. And there is detectable no short circuit. Nor any visible damage to either board. This happened this morning. The homing and testing some speed settings went as the days before… maybe 15 minutes all together, so there was certainly no over heating involved.
Yesterday I was working a long day on the lathe repeating some c. 5-6 minute G-code program for well over 100 times, with no problem (”rapids as feeds” was checked).

I tried to find some clarifying information from the forum, if someone experienced something similar… if one can some way reset the boards, but couldn’t find any.
So now I’m pretty much stuck, no idea what to do next…

[TomKerekes]

Hi Eero,

Regarding no holding torque: All the should be required for there to be holding torque is power and enable. Are the 3 KStep LEDs on?

In case something strange has been Flashed to KFLOP it can be reset to its Virgin state by re-Flashing New Version.