# Mini Kossel, Effector use and calibration

Posted by Dark Skunk
 Mini Kossel, Effector use and calibration March 07, 2015 02:39PM Registered: 9 years ago Posts: 67
I am still working on my Mini Kossel (MakerGeek 1/19/2015 with all the upgrades kit). Instructions were rough but with help from here I have it 'running'.

Problem 1: I have an electronic effector of some sort. If the extruder end hits the bottom a little red light goes out.
Question: Am I wrong a believing this is a Z Min End Stop? It doesn't seem to work for me. If I run M119 it's always shows open regardless of that light. I believe it's wired properly. It will run the machine right through the glass if I let it. Thoughts?

Problem 2: I'm struggling to get this sucker calibrated. The instructions from MakerGeek is really just a pointing to everyone else's work with a few frankly confusing additions. I'm green though so I'm working to build my understanding. My extruder will hit the glass with a listed height of 42.50 (on the LCD). Do I need to enter that somewhere to make sure I don't blow through it? Maybe it's just the effector issue that is causing everything.

Any help would be appreciated.
 Re: Mini Kossel, Effector use and calibration March 07, 2015 02:53PM Registered: 9 years ago Posts: 67
This may provide insight as well. I believe I have at least some calibration off. I am seeing this:

X axis: If I type in to move 10mm it actually moves 10.74
Y 10 = 10.76
Z 10 = 10.48

On the calibration end, I must need to change that somehow. I'm determining by putting the extruder just off the plate and move it in the x and y direction pressed up against a micrometer. It's plus or minus a 10 depending on location and likely my measurement system. Z is the same basic setup.
 Re: Mini Kossel, Effector use and calibration March 07, 2015 03:08PM Registered: 10 years ago Posts: 14,680
The thing on the effector with a light is probably intended to be used as a Z probe, not a minimum end stop. Can you post a photo?

To calibrate the machine:

1. Set the motor steps/mm in the firmware or config file correctly. This should be the number of stepper motor steps per revolution (normally 200), times the microstepping factor (normally 16), divided by the number of teeth on the motor pulley, divided by the tooth pitch of the belt. On my Mini Kossel, it is 80 steps/mm. Get this right and the Z movement should be correct (i.e. if you command 10mm you get 10mm).

2. Set the homed height in the firmware or config file to the height of the nozzle above the bed when the printer is homed. Then the nozzle will be just touching the bed at Z=0.

3. Set the endstop adjustments and the delta radius. I describe this here [miscsolutions.wordpress.com] but those instructions are for 32-bit Duet electronics and RepRapFirmware. For other firmware, the principles are the same, however instead of sending gcodes to adjust the parameters you may have to edit a config file then rebuild and upload the firmware.

4. To get X and Y movement just right, adjust both the diagonal rod length and the delta radius parameters, keeping them in the same ratio.

Edited 1 time(s). Last edit at 03/07/2015 03:10PM by dc42.

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
 Re: Mini Kossel, Effector use and calibration March 07, 2015 03:41PM Registered: 9 years ago Posts: 67
Here is the picture.

I'm checking the steps you mentioned. Is this the location? This is what I have been messing with in the Arduino Configuration.h

#define DEFAULT_AXIS_STEPS_PER_UNIT {93, 93, 20, 92.3} // (NOTE: Was {100, 100, 100, 450} Makergeek said 94.1176 for x,y,z and 92.3 for e)

I just put Z to 20 in attempt to see an impact in the Z movement. I didn't see much if any.

Also when trying to load, it says load complete (from Arduino) BUT I see this:

Binary sketch size: 109,948 bytes (of a 258,048 byte maximum)
avrdude: stk500v2_getsync(): timeout communicating with programmer

Maybe it's not uploading anymore for some reason. Any thought on that?
 Re: Mini Kossel, Effector use and calibration March 07, 2015 05:00PM Registered: 9 years ago Posts: 67
Apparently Arduino was not uploading. It said Done Uploading but the key item at the bottom saying timed out was pretty significant. I'm going to to the start on calibration again because none of the incremental changes were doing anything.
 Re: Mini Kossel, Effector use and calibration March 07, 2015 06:16PM Registered: 9 years ago Posts: 67
I must have knocked the serial point a while back. I'm now calibrating. Seems to be pretty close to on the money.

NEW QUESTION: I see that the extruder head is about 2mm lower in the center of the glass bed in the center than on the sides. Is that concerning? Maybe I will find that answer in the calibration instructions. Thank God for the Blomker instructions. Whoever made those wasn't kidding around...

1 more question: Is there a good way to search on this forum? I hate asking questions that have been asked before but I wasn't getting anywhere with the search.
 Re: Mini Kossel, Effector use and calibration March 07, 2015 06:21PM Registered: 10 years ago Posts: 14,680
Quote
Dark Skunk
NEW QUESTION: I see that the extruder head is about 2mm lower in the center of the glass bed in the center than on the sides. Is that concerning?

You need to increase the delta radius setting in the firmware by about 2.2 times the height error, so by about 4.4mm. I expect you will find this in the calibration instructions you are using. When you have your Z probe working, you can probably run an auto calibration command in the firmware to do this automatically.

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
 Re: Mini Kossel, Effector use and calibration March 07, 2015 07:09PM Registered: 9 years ago Posts: 67
Z Probe is causing me issues. Keep crashing into the bed. I'll start a new thread.
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