Migbot Prusa i3 Unofficial Support Thread

By the way just to say one things, buy anythings check first don't run it first, as to me check try don't rush and play safe is the most important. just to update, just check on the plug and it have spark when put in my tower plug. Do check on that too.

Probably should not be much a surprise at this point, but the linear bearings that came with the Migbot are junk. I noticed some shaking in the extruder and heard grinding. When I took things apart I seen the metal ball bearings cut into the plastic outer race. Your Z-axis may last for some time but your X & Y should probably be replaced ASAP. I modified the original files for the Migbot posted earlier, and created new bearings that were a little more robust.

Step 1) Go to local big box store and buy copperhead BBs. (may also want to get some high temp bearing grease)
Step 2) Make sure your printer is tuned [www.thingiverse.com]
Step 3) Print attached files,I would recommend using ABS....at least for anything near heat. (If you are using Slic3r, turn on expert mode, go to print settings, and uncheck "Detect thin walls")

Since I am using much larger ball bearings, the OD for the linear bearing is 18mm, the Migbot frame pieces then needed to be modified....some of mine were warped and needed to be replaced anyway. Let me know if you have any issues.

Tom

One more thing that might help...you may want to lock tight (or superglue) the nuts that hold the Y-belt bracket in place. Mine have a tendency to come loose and are a pain to get to.

Given the lack of quality control, it is very likely that the thermistors included with the kit, are not matched up to the temperature tables in firmware. This would result in incorrect temperature readings. Not very godd for reliable printing, and could also be dangerous.

The other possibility is what Eve is mentioning, in that it could be crap filament. In either case, the correct course of action is to eliminate the problems, and not conform to them.

Figuring out if the thermistor is mismatched may not be trivial. If you can trust the vendor, ask them to provide the actual part number. The configure.h at the begining of this post lists which thermistor has been con#igured. If it turns out that the actual part is not an EPCOS 100K, then the change should be made in the file, and recompile and reload the firmware.

Slightly off topic, but temperature sensors tend to be nonlinear in their response. Just because it works at one temperature, it does not mean that you can just assume an offset. This could lead to fire, so always play it safe.

Edited 1 time(s). Last edit at 06/02/2015 09:53AM by jcabrer.

Here is some light reading on the topic of thermistors.

Keep in mind that my comments above are speculative at this point. I do not know one way or the other if the thermistor is incorrectly identified. I'm only proposing logical causes for the discrepancies that are being encountered.

I've been using and building Repraps for 5+ years and though I cannot say that I have seen it all, I have seen a lot. There are well established practices on how to design, build, configure, and operate these machines. Unfortunately, the information gets buried deeper and deeper every few months, as new posts are added to the forums, so it always seems like everyone is inventing the wheel for the first time. With that being said, there is always room for improvement, so it never hurts to experiment, but like a good scientist should, always start from a solid foundation, and test a single variable at a time.

Some general advice:
1. Level the bed.
2. Address the little issues, no matter how small.
3. Stick to known good temperature profiles. PLA 70/180 - ABS 110/230
4. Keep your filament dry, and clean. Do not let dust settle on the spool.
5. Slow is better than fast.
6. Never leave your printer unattended.

I think it is safe to assume the thermistors are working right.....ish ( you are going to have some variance due to hardware, firmware, environment, and where you take readings). You may want to make sure you are using the correct firmware settings.....

#define TEMP_SENSOR_0 3
#define TEMP_SENSOR_1 0
#define TEMP_SENSOR_2 0
#define TEMP_SENSOR_BED 3


Here are Matterhackers PLA suggestions

Color Recommended Temperature Recommended Range
Black 195c 190c - 210c
Glow-In-The-Dark 190c 185c - 205c
All Other Colors 210c 205c - 220c

[www.matterhackers.com]

Edited 1 time(s). Last edit at 06/02/2015 11:58AM by tkin.

Here's where I am at currently:

Got fed up with my Z-endstop and bedlevling issues, I would get it leveled with the z-axis hommed, but when I'd start a print the zozzle would be too high - I'm sure this can be adjusted in the firmware, but it was doing my head in. I removed the Z-endstop and put the Autoleveler back on. With the X and Y endstop properly working and after modifying the start.gcode in Cura to account for the Autoleveler I did a quick test print and son of a gun the dang Autoleveler worked perfectly!

I tested with my temp at 190 and it was stringy and chunky.

Upped it to 225 and it was oozing a bit every so often.

Lowered back to 210 and while there was some skipping in the infill it printed pretty good.

When I get home I'm going to double verify the firmware temp settings tkin suggested and do another test at 215 and 220 to see if they are any better/worse than 210 (depending on if the temp settings are correct in my firmware, other wise I'll correct and start from the low range again)

Edit: Just to note, the PLA filament I'm working with currently is a blue translucent color

Edit 2: I also moved my filament to the top of the printer and this seems to have had a positive impact on printing as well

Edited 2 time(s). Last edit at 06/02/2015 12:04PM by CAlleman.

ok I have a really dumb question about the proximity switch setup. I bought the model without the proximity and just had the momentary switches for x, y and Z axis. do i just take of the z axis switch and wire up the plug? oh and what pins do what for that switch, (I bought an SN04-N2 Proximity switch to put on) just not sure of the wire colour code to convert etc.
sorry for the vague use of English, had a very early start to my day.
thanks again

oh before I forget it's the MKS base ver 1.2 main board if that makes any difference
Josh

Edited 2 time(s). Last edit at 06/02/2015 04:55PM by rumjar86.

Hey Josh,

I've got the MKS version 1.3, but I'm assuming they are pretty close - my Proximity switch came pre-wired with the same plug end that the endstops have. I will check what color wires go where when I get home tonight.

Once you have it wired you just plug it into the Z- Min port on the board which is the same one the z endstop should be currently in. Just remove the Z-axis endstop completely once you have the proximity sensor installed and change your start.gcode to the values in the screenshot that came with the printer

Edited 1 time(s). Last edit at 06/02/2015 05:14PM by CAlleman.

@Josh,

Here is the pin out for the Proximity sensor:

This would be looking down at the connector with the metal clips showing - Brown, Blue, Black

Hope that helps!

I've been trying to get this printer working for the past two days, with varying degrees of success and frustration. Seemingly having most issues that people have stated above, now it seems that everything is working fine except for the extrusion motor (quite the deal breaker). My wiring colors does not seem to match the ones posted

the PCB connection is Red-Blue-Green-Black with the motor connections being Red-Green-Blue-Black which seems to work for for all of them.

Quote
evetanlm
Follow this picture wire fix on mine migbot prusa and it work.

Where does the small connector go, as I do now have this on my kit.

Hi,

I bought my first printer 2 weeks ago and have it built. I was about to calibrate the extruder when I found that the heat bed will only heat up to 44 degrees. I increased the voltage on the power supply to 14v and low and behold got the heat bed up to 49 degrees. I'm a bit lost as to what the problem might be and would love some help.
Thanks
Mark

check on the thermistor, maybe install wrongly. as alot of stuff all wrong, not surprise. check on extruder too for the wiring as I post above, the wiring color, as the supplier wire wrongly and everythings in mess of mine. Today will start the run again see how.

If you have a multimeter, check the resistance. For a 12volt supply it should measure about 7 ohms. If the value is higher, blame it on quality control. Make sure connections are solid.

Quote
jmkslave
Hi,

I bought my first printer 2 weeks ago and have it built. I was about to calibrate the extruder when I found that the heat bed will only heat up to 44 degrees.

JMK, I had a similar problem, my heat bed would only heat up to about 95 degrees no matter what I tried. What I found is the board has three circuits and mine was only heating on the back two. You can check with a digital thermometer, or just feel it with you hand where the heat is at. When I took the plate off my bed and inspected the MK2 heat bed I seen a very small burn mark, where one of the three circuits failed. If you Ohm the heat bed it will still test good as long as one of the three circuits are complete/working. My guess is you have two bad, and need to replace it as well.

Tom

One more thing....if you ask the people producing the Migbot to send replacement parts, they will just ignore you. Their "engineers" (with sarcastic inflection) are supposed to contact you weeks in the future with a solution. So then contact Paypal, state you had these things wrong and you want a partial refund.

Edited 1 time(s). Last edit at 06/03/2015 06:18AM by tkin.

Right, so I have a problem - after assembly, I connected the power cable. It worked fine at first, with some small calibrations needed. So I unpowered the printer, because I had to cut some cables a little as well, and did this, but was very careful to put everything back into the same place, following the diagram from the google drive linked here. When I reconnected the power the next day, I noticed a burning smell, and unplugged the power cable, which was very hot. I swapped the cable, and now my printer is unresponsive, and my x axis is not working, although I've tried different motors. The Y and Z axis also move very slowly at times. Did I mess up my motherboard, and if so, how can I fix this? I've tried asking Leo, no response yet.

Quote
andreaseh
Right, so I have a problem - after assembly, I connected the power cable. It worked fine at first, with some small calibrations needed. So I unpowered the printer, because I had to cut some cables a little as well, and did this, but was very careful to put everything back into the same place, following the diagram from the google drive linked here. When I reconnected the power the next day, I noticed a burning smell, and unplugged the power cable, which was very hot. I swapped the cable, and now my printer is unresponsive, and my x axis is not working, although I've tried different motors. The Y and Z axis also move very slowly at times. Did I mess up my motherboard, and if so, how can I fix this? I've tried asking Leo, no response yet.

check the fuse at F4 see if you burned it out. also which email address did you send to? I sent one to one address only later on to be directed to their support address 396826364@qq.com

Thanks, I'd mailed it to the wrong address. How do I check if a fuse is burned out?

@andreaseh
If you are unable to move the X-Axis, and you smelled burning, there are two likely possibilities. The fuse is not one of them, since you say Y and Z axes are still operational.

1. You may have damaged the stepper driver on X. That's the little IC with the adjust screw next to it. If this is the case, there really aren't too many options, other than replacing the board. It would be possible to repair the board, but it requires a bit of skill, and a replacement chip. There is also no garantee that the chip was the only component damaged.

2. It could be that you reversed polarity on the connections, and damaged some section of the ATMEGA microprocessor that controls X. I once had something like this happen when I accidentally plugged 12VDC into a thermistor input.

Unfortunately, there is no good news here. If you smelled smoke, chances are very good that the damage is permanent.

Try this, don't say i say, you skype him at "leo.t077" this is the faster way, as he have mention to me before his email always have issue

anyone can help one issue, when connect to computer it extract reverse way. wiring is all check all fine, only this issue left.

Attach is the wiring photo of mine, as my X,Y,Z is moving very nicely but the only things is the extruder reverse way.

Quote
evetanlm
the extruder reverse way.

Check this section in Marlin (E0 should be your extruder)...

#define INVERT_X_DIR true // for Mendel set to false, for Orca set to true
#define INVERT_Y_DIR false // for Mendel set to true, for Orca set to false
#define INVERT_Z_DIR true // for Mendel set to false, for Orca set to true
#define INVERT_E0_DIR false // for direct drive extruder v9 set to true, for geared extruder set to false

Hehe, can i know where to check, sorry as not familar with this. Please await your help

i'm using repetier-host

Quote
evetanlm
i'm using repetier-host

I can't really help you with Repetier....it may be easier for you just download Marlin, since everyone else in the thread seems to be using it. You can then just paste my settings in configuration.h section....which should get you close; but you may want to adjust these for your machine.

#define DEFAULT_AXIS_STEPS_PER_UNIT
// Travel limits after homing

ok noted, will try it now

Thanks u Tkin

Evetanlm is using Repetier HOST, not Repetier firmware.

Let's get a little more information before reflashing. Especially when there is a language hurdle

Hello,

Thank you all so much for all the amazing information you have posted here. We just put together or Migbot Ultra Prusa i3 Diy Kit WITH the AutoLeveling Option (Proximity Sensor) from 3D Printers Online. This is the first time we have ever put together a 3D Printer. It took us roughly 4 hours to put together. It has the "MKS Base v1.3" Motherboard.

In general, everything seems to be working well when we drive it Manually. The movements along X, Y & Z seem to be fine. The Extruder and Heated Bed also heat up perfectly. And we are able to Extrude PLA perfectly. We moved the Print Bed all the way Forward, the Extruder all the way to the Right and relatively leveled to the Bed. And pressed "Set home offsets"

If we use the "Move axis" options, when we turn the dial, the Bed and Extruder move in, what we believe are the right directions. If we rotate the Dial to the Right, the Bed moves backwards till around 200 and when we turn to the Left it returns to the original position at zero. Same goes for the Y and Z. When we turn the Dial to the Right, the Y moves Left to 200 then, when we turn to the left, it goes Right back to zero. Z moves up when we turn Right, then down back to Zero when we turn it Left.

We calibrated the Auto-Level Proximity Sensor to be 2mm above the print head. However, we have two issues... and they are most probably related;

1. When we select "Auto Home",
a. The print bed goes ALL the way forward and starts grinding the belt teeth.
b. The Extruder moves to the Far Right
c. The Z-Axis moves DOWN... Hits the Limit Switch... but instead of stopping... it pushes the Limit Switch assembly DOWN trying to move past the Print Bed.

2. I tried setting the "Set home offsets"again. But when I try to start a print, it moves the head UP by around 4mm and begins Printing. in the Air.

3. We received a White Wire with an LED at the end. But have NOT IDEA where to plug it in??? Not sure if this is the LED jcabrer mentioned in one of his posts.

We would appreciate any assistance.

Best regards,
3DST