Any Kossel Delta Experts?

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08-25-2014, 03:59 AM
Geoff

Any Kossel Delta Experts?

Hey guys, I have built and have managed to get my kossel mini printing... except for one small issue.

My print is starting too low.. I have done the following..

1. G28, home printer
2. G1 Z10
3. go down in 0.1 increments until paper just fits between nozzle and plate
4. send M114 for XZY
5. Get default Z position and minus the Z coordinate.

So in my case, my Z height was 239 to start for the kossel mini.
Pronterface told me when I did my calibration I was 2.4mm off the plate, so 239 - 2.4 becomes my new z default.

6. I make sure my Offset for my probe is correct, I check again and again.. I also have my Zprobe retract calibrated OK to push it back up after it's spot check.

My print starts fine, but always 3 or 4 layers too deep. It blocks the nozzle its so close to the glass. On the 3rd layer or so, it starts extruding as it has enough space now.

I adjust my Z height again... and again.. and again.. and do it over and over, and no matter what value I use, either for the XYZ or the offset, this thing still prints 3 layers too low...

Im sorta tearing my hair out here, I can't think if what I missed as Ive gone over it so many times :mad:
08-25-2014, 09:19 AM
Roxy

So... I'm not a Kossel expert. But I do want a Delta Printer in the worst way!

First, you are trying to adjust your height with the #define Z_PROBE_OFFSET_FROM_EXTRUDER in Configuration.h, right?

Comment #1: If you don't have Auto Bed Leveling turn on, I do not think the G28 command is going to factor in the Z-Probe Offset. Here is the only code in the G28 that references the Z-Probe Offset:

#ifdef ENABLE_AUTO_BED_LEVELING
if((home_all_axis) || (code_seen(axis_codes[Z_AXIS]))) {
current_position[Z_AXIS] += zprobe_zoffset; //Add Z_Probe offset (the distance is negative)
}
#endif

Your list of things you did also does not include a G29 command. Probably you should do a G29 if you do a G28. Without a G29 all coordinates are corrected against a unity matrix and there won't be any offsets factored into that correction.

If you have CUSTOM_M_CODE_SET_Z_PROBE_OFFSET defined, you can issue an M851 command to save new offsets in EEPROM. You can make adjustments up or down super quick. But my advice is not to do that. The distributed code won't tell you what the value of the Z OFFSET is with an M503 command. That was an over sight of whoever did the M851 command. It is a good way to get into trouble.
08-25-2014, 11:12 AM
MK-X

First of all, have you made sure your Delta Radius is correct? If it's too large you will get a concave effect, so the center of the bed will be lower than the sides
08-26-2014, 12:31 AM
Geoff

Quote:

Originally Posted by Roxy

So... I'm not a Kossel expert. But I do want a Delta Printer in the worst way!

First, you are trying to adjust your height with the #define Z_PROBE_OFFSET_FROM_EXTRUDER in Configuration.h, right?

Comment #1: If you don't have Auto Bed Leveling turn on, I do not think the G28 command is going to factor in the Z-Probe Offset. Here is the only code in the G28 that references the Z-Probe Offset:

#ifdef ENABLE_AUTO_BED_LEVELING
if((home_all_axis) || (code_seen(axis_codes[Z_AXIS]))) {
current_position[Z_AXIS] += zprobe_zoffset; //Add Z_Probe offset (the distance is negative)
}
#endif

Your list of things you did also does not include a G29 command. Probably you should do a G29 if you do a G28. Without a G29 all coordinates are corrected against a unity matrix and there won't be any offsets factored into that correction.

If you have CUSTOM_M_CODE_SET_Z_PROBE_OFFSET defined, you can issue an M851 command to save new offsets in EEPROM. You can make adjustments up or down super quick. But my advice is not to do that. The distributed code won't tell you what the value of the Z OFFSET is with an M503 command. That was an over sight of whoever did the M851 command. It is a good way to get into trouble.

Auto level is on, Sorry, I should have included the G29 in my list , yes I run the G29 after the G28, however the G29 on the kossel simply does an autolevel check and retract, so its good for calibrating the Z probe retract but other than that it doesnt give me settings I can use for the actual Z height.

@MK-X I did yes, but I will double check. There is a couple of spots I notice the autoprobe drags on the bed a little, so I think that might be it, I will double check again.
08-26-2014, 08:35 AM
Roxy

Quote:

Originally Posted by Geoff

Auto level is on, Sorry, I should have included the G29 in my list , yes I run the G29 after the G28, however the G29 on the kossel simply does an autolevel check and retract, so its good for calibrating the Z probe retract but other than that it doesnt give me settings I can use for the actual Z height.

@MK-X I did yes, but I will double check. There is a couple of spots I notice the autoprobe drags on the bed a little, so I think that might be it, I will double check again.

As it turns out... BrainScan went through a similar hair pulling debug session starting about here:

http://3dprintboard.com/showthread.p...ll=1#post19007

I don't know if this is what is causing your problems, but the big problem is the M503 command fails to report everything that is happening after reset on the Arduino.

Do you have the EEPROM turn on? Because if you do, you could have a bad value for the Z-PROBE-OFFSET stored in the EEPROM and you won't know it. It won't matter what you change the Configuration.h setting to, it will use the value out of EEPROM. Probably, the simplest suggestion is turn off the EEPROM chit chat until you get everything else running. But if you need it, you can do a M502 and a M500 to restore default (Configuration.h) settings and store them. The problem with doing this, is now the Configuration.h settings will be ignored unless you do the M502 & M500 pair. With that said... That might be what you are fighting right now. If somehow a bad number for the Z-PROBE-OFFSET got stored, it doesn't matter what you set things to in the Configuration.h file. You will need to do a M502 & M500 to load the compiled default values and store them.

At post #58 in the thread we finally get confirmation that was what was keeping him from setting his Z-PROBE-OFFSET in Configuration.h (See the previous post for the analysis)

http://3dprintboard.com/showthread.p...ll=1#post19319

And that is why there is an EEPROM Invalidate command provided in Post # 75:

http://3dprintboard.com/showthread.p...ll=1#post20943
08-27-2014, 12:31 AM
Geoff

1 Attachment(s)

Quote:

Originally Posted by Roxy

As it turns out... BrainScan went through a similar hair pulling debug session starting about here:

http://3dprintboard.com/showthread.p...ll=1#post19007

I don't know if this is what is causing your problems, but the big problem is the M503 command fails to report everything that is happening after reset on the Arduino.

Do you have the EEPROM turn on? Because if you do, you could have a bad value for the Z-PROBE-OFFSET stored in the EEPROM and you won't know it. It won't matter what you change the Configuration.h setting to, it will use the value out of EEPROM. Probably, the simplest suggestion is turn off the EEPROM chit chat until you get everything else running. But if you need it, you can do a M502 and a M500 to restore default (Configuration.h) settings and store them. The problem with doing this, is now the Configuration.h settings will be ignored unless you do the M502 & M500 pair. With that said... That might be what you are fighting right now. If somehow a bad number for the Z-PROBE-OFFSET got stored, it doesn't matter what you set things to in the Configuration.h file. You will need to do a M502 & M500 to load the compiled default values and store them.

At post #58 in the thread we finally get confirmation that was what was keeping him from setting his Z-PROBE-OFFSET in Configuration.h (See the previous post for the analysis)

http://3dprintboard.com/showthread.p...ll=1#post19319

And that is why there is an EEPROM Invalidate command provided in Post # 75:

http://3dprintboard.com/showthread.p...ll=1#post20943

THANK YOU ;)
eeprom :mad:

All systems are GO!

Attachment 2462

Hey, it's not perfect but all thats left is some fine tuning now, everything is good.. almost finished this print and no lift, all corners straight... I wanted the first print to be another kossel part, and right now I am happy as a pig in sh*t ! :)