Hi I’ve built a K8200/dual extruder (2xK8203), but filament it’s not extruded smoothly from extruder.
I’ve set the X/Y/Z MOTOR DRIVER voltage to approx 0,425v, I’m wondering if I have to raise to 0,92v the EXTRUDER DRIVER voltage like in Vertex.
Does anyone knows how to set?
Thanks
I have been looking as well and have not found a clear reference on how to adjust the stepper driver that is included with the K8203. Most Google search hits on that topic lead to people asking, but not getting an answer.
Are you able to extrude filament by hand? (Heat the extruder and then rotate the bearing on the back of the extruder.) Check alignment of the teflon tube and the small nozzle guide. You should be able to look down the top of the 8203 and see the bed through the nozzle.
If the mechanism seems smooth, then boost your reference voltage. The direct gear drive clearly needs more “oomph” than the geared extruder, else why would they include the upgraded driver? Barring any clear documentation to the contrary, it is probably best to stay within the safe ranges spec’ed for the original driver - between 0.45 to 0.6V.
Here is the most detailed post I’ve been able to find about K8203 installation:
It would be nice if someone from Velleman could verify the motor driver adjustment procedure and safe ranges.
Thanks Dr.!
I’ve seen the post … fortunately I’ve found an already set firmware (futurashop.it/3d-e-cnc/stam … _3DRAG_DUE) so I’ve not encountered the issue on the TRUE/FLASE flags.
I think I properly mounted the kit (both of them actually) but unfortunately I loaded the extruder so now I’m not able to see through the nozzle 
EXTRUDER #1 - Motor on the LEFT
If I push with the hand the filament, the extruder #1 has difficuties in flowing PLA (@200°C) the extruded filament makes often curl that goes up stiking to the heatblock. Then I’ve elevated the driver to 0,6v and printing with Repetier it goes better but still making curls OR filament extruded with different tickness cycling from a very tiny to a Greater one closing with a kind of drop shape then restarting wity the very tiny … and so on. So it’s very unsatisfactory, I was expecting a continuos same sized flow.
EXTRUDER #2 - Motor on the RIGHT
For extruder #2 pushing by hand I see a better flow. I really would like to test the extruder in a test print but I do not know how to set Repetier(or GCode) giving the istruction to print on #2 and not on #1. I’ll study this night.
** UPDATE **
I found an answer on this paper futurashop.it/Allegato_PDF_ … ALDRAG.pdf (in italian) the extruder driver must be set to 0,8V!
I’ll work on it later …
after having installed the config.ini sent by FuturaShop I solved! Not able to paste file, it should be this velleman.eu/downloads/files/ … config.zip updated for the lates slicer.
All,
A few weeks ago I decided to upgrade my belt driven extruder (upgraded with an E3D hot-end) by the direct drive extruder as offered in the Velleman K8203 kit. I did not install the included hot-end but modified the angular mount to fit the E3D hot-end.
Before:
After:
In the past I printed magnificent pieces and since the upgrade the quality of the printed parts went heavily backwards. It looks like the extruder steppermotor was missing steps and has not enough torque to turn smoothly. As a result the extrusion looks like a cobblestone path.
The force required to push 1.75mm PLA through a 0.35mm hotend at 190° Celsius is between 15 N = 1.5 kg (slow) or 25 N = 2.5 kg (fast). The Nema17 steppermotor is able to produce 30 N, so there should be something else wrong.
I’ve spent at least 3 nights browsing the web to find a solution and another 3 nights with trial and error:
[ul]- steppermotor driver set to 0,75 - 0,80 - 0,85 - 0,90 volt
Nothing helped !
After some more sleepless nights, I noted the following facts:
First of all it feels the driver spring is way too strong and pushed the filament too hard between the bearing and the filament pulley. I could barely push the filament by hand. As a result the Nema 17 steppermotor floats betweens microsteps and nervy skips.
This issue was easily handled: I grinded off one resolution of the spring.
After reading an in depth description how steppermotors works, I concluded the 1/32 step modus as default set on the high power DRV8824 driver wil not do the job. As test I replaced the DRV8824 driver by the original A4988 board with default 1/16 step modus and guess what: the extrusion was as soft as a baby’s skin !
Of course the A4988 driver is not able to deliver enough current as needed in direct drive modus for a long time without getting extremely hot, so this solution was only a temporary one for test purposes. Next I cutted the M1 and M2 traces on the backside of the controller board and inserted the high power DRV8824 driver over again. Cutting M1 and M2 forces the DRV8824 in 1/16 step modus with the same extrusion result as with the A4988 board, but now able to work for a longer time.
Sorry for the double post, but perhaps this is also useful for you…
After changing the driver with a 1/32 you need to set the EEPROM to 150.
Here the procedure sent from futura
Hope the problem is this one!
Ciao
how did you change the voltage i couldn’t find a reference point to connect my multimeter to
Look in this link.
http://manuals.velleman.eu/article.php?id=39
This is for the K8400 but it is the same driver.
Hi, I had working K8203. Had to rewire/replace all ribbon cable now that extruder won’t run - little vibration and tiny whine. I tried on the x y or z and they drive motor just fine. I also tried another DRV8825 with still no luck.
Any direction on where to head with this issue???
Thanks in advance all!
Check the control voltage on the DRV8255 - it should be set to around 0.92v.
If the motor works from another (x, y, or z) channel, and two different 8825’s have the same behavior, it could point to a problem with your controller board. If you have an oscilloscope, you could remove the stepper driver and probe the control signals going to the board to see if you are getting clean stepper pulses. Maybe the Arduino GPIOs have suffered damage somehow?
Did you make sure the orientation of the driver board is correct?
Hi thanks for your help. I don’t have an oscilloscope, but yes board orientation is correct. I believe I got it working somewhat and think it’s going, but skipping steps here and there, based on print consistency when it’s extruding only a small amount. It seems to “get by” on more steady extrusion when I upped my extrusion multiplier to see how it would affect the flow. So maybe an issue with the board and stepping like suggested…?
Thanks again for your help!
Crazy question.
Did you update the firmware?
You don’t need a scope to set the reference voltage just a volt meter.
Yes 
Firmware was updated prior. I emailed them @ velleman support and they promptly sent out a new driver board. I installed and am printing with no “whine”. Now I just need to remember how to calibrate the e-steps. I don’t remember what arduino to use / not to use, etc. I never saw a formal guide on that from them except for flashing the firmware from what I remember.
Hopefully on the right track here! No more ribbon cables, prints looking very good considering no calibration… of course I credit ALOT to S3D in my experience too!
Thanks again and let me know if you have a quick to do for e-step calib (on the firmware side). I understand the calcs to adjust once tested 100mm for example. Have a great evening!
