Blue Eagle Labs Kossel Clear (ABS) Build Log

Hey guys,

I think this might be my first 3D Printer Board post so just let me know if I'm in the wrong spot or something.

I originally ordered a Kossel Kit from MakerGeeks but after two months of waiting I cancelled my order. I spent $400 more and received a Blue Eagle Labs (BEL) Kossel Clear in less than a week after ordering. The total with an LCD and SD card reader was ~$925 USD. Shipping was free, 2 day USPS priority mail. They're out of San Diego if anyone cares.

Anyway my first impression of the kit was how minimal it was. I opened the box and it was basically a bag of acrylic parts, 4 stepper motors, some extruded tubes and smaller box with all my wiring/electronics. I triple checked and everything arrived, it's just compact!

The first night I spent about four and half hours assembling the lower assembly with no wiring done. It takes an incredible amount of time to peel off the protection tape on the acrylic haha. The instructions are YouTube based and very thorough. So far I've only encountered minor confusion in the build instructions, but I'm only about 40% done. We'll see how wiring goes, but they have great wiring diagrams as well so I'm not too worried. I should also note that BEL has a great Google Groups forum going on that has active users and active support from BEL. It's very nice.

I'm having trouble linking pictures to the forum right now but I promise I will get some up soon. I'll end this post with a big good job to Blue Eagle Labs. I appreciate the good build quality and thorough instructions.

Awesome bro! Welcome to the world of 3D Printing.

Hey thanks ZorAxe!

Here's a quick update:

Attachment 6713

This was my progress after 4.5 hours. I've since installed the vertical arms and carriages. Unfortunately I dropped one of my carriages and broke one of the acrylic pieces. I used some 3M super glue to make a temporary repair that seems to be holding surprisingly well. I pinged Blue Eagle Labs to see if they could ship me out a replacement. I also asked them if they would be willing to sell me just the 6mm acrylic pieces for the Magnetic ball/arm upgrade (since I already bought the UltiBot mag arm kit) and I'm waiting to hear back.

I noticed that upon instillation of the "dropped" carriage that there was a tiny stiff spot in the bearing/rollers that keeps it from rolling smoothly. I'm gonna investigate tonight where its coming from. I'm putting my money on a dirty/damaged bearing.

Well, time for an update....

The stiff spot in the bearings/rollers was actually not unique to the dropped carriage, they all did it. The good news is their performance doesn't seem to be affected by it. After I got everything wired up and carriages moving via motors they seemed real smooth.

Wiring is still pretty ugly. I just wanted to get RC Marlin loaded and calibrated so I could start sending Gcode. Btw, I learned a lot...really quickly...about what is okay and not okay during calibration and setup. Here's some tips for first time Marlin users:

1. G28! G28! G28! This "Home" command is really important before you do pretty much anything. It gives RC Marlin/Marlin an understanding of where the printer is in relation to the bed. Just power the printer up? G28. Finish a print? G28. Starting a print? G28 just because. I slammed my head into the bed/endstops a few times because I didn't "go home" before sending a command.

2. With RC Marlin, you need to let the "G30 A Dnnn" calibration finish ON ITS OWN. I'm not sure if you can interrupt it, but when I sent an M500 command it "coincidentally" finished on the next iteration but put my Z0.00 way too high. Also, make sure everything is really ready before you start your calibration. Put your printer where its going to live, double check belt tensions, make sure everything is parallel. My belts started slowly slipped until iteration 71 before I acknowledged that belt tension was an issue. After I tightened up my belts, tightened the zip ties, and double nutted the tensioners (so they wouldn't loosen) my calibration was done in like 11 iterations.

3. RC Marlin's "G30 A Dnnn" autocalibration won't set your Z height perfectly using the stock mechanical enstop. You will need to use "M666 Hnnn" to tweak it until it fufills the paper shim test (piece of paper barley slides out from under the printer nozzel) at Z0.00. Use "G1 Z20 F2000" to put your head at 20mm above the plate and work down until you're at Z0.00 to do the paper test. If your hot end tip is too high at Z0.00, make your Z height larger and retest. If it's too low (hits the bed) then make your Z height smaller. Finally, don't forget to M500 after every Z height change and then G28.

4. This guide: http://www.maui-3d.com/kcZeroBacklashInstallation.php has a ton of great RC Marlin information.


Anyway that's where I'm at. I'm fairly well calibrated (my endstops need to be straightened and I'd like to do the calibration at a slower speed when I figure out how) and my paper test is solid. My first calibration square was a little big and didn't really adhere to my bed, but at least I'm extruding filament and the printer isnt crashing into itself!

Finally...I made a cute little video of my first G30 E. It was actually my second but don't tell anyone.
https://goo.gl/photos/JdmEpRmQkTX1XVuN9

Glad you got everything now and it's looking good. Send some pics of your prints when you start printing.

So the first ABS prints I started were too fast. Here is a quick video after I slowed it down a bit:

https://goo.gl/photos/WP513JYVnZQkHX7t6

My biggest fight so far has been the extruder setup. In order to extrude filament at all I had to re-position the binder clip to a horizontal position (vs vertical as shown in setup) to reduce the spring load. Without doing this the extruder just popped/clicked and would not rotate the extruder gear at all. It was not slipping on the shaft or on the filament, it just would not turn.

After reducing the preload on the filament extruder gear it improved the extrusion but it was still clicking/popping/not rotating. I noticed during a print if I reduced the print speed it improved the popping and allowed filament to extrude. I have since lowered my E Step from 100 to 80 and the lowered the print speed to to around 5-10mm/s which allows me to print with minor popping/clicking.

I need to perform an extrusion calibration to make sure that 10mm of extrusion is actually 10mm, but I have pretty much ruled out everything else. I've varied hot end temperature from 230c-240c with no noticeable improvements, the bowden tube is nearly free of resistance, and I've calibrated my motors to be running ~.5v that is recommended. I think a new extruder setup and possibly a new 5:1 extruder motor will be the cure all, but right now I'm just printing slowly.

Here is a picture of one of my latest parts:
Attachment 6801

Update:

Extrusion is still the fight. About half way through one of my latest prints the stock stepper motor basically just gave out and started popping/clicking 100% of the time with very little plastic extruding. I couldn't get the binder clip positioned in any way that improved the situation.

The next day I started researching replacement Kysan stepper motors and found they have a distribution facility 15 minutes from my work. Sam, the rep that ran the warehouse (which is basically a lounge with some shelves), hooked me up with a drop in replacement stepper (1124144) that outputs ~20% more torque than the stock stepper (1124090). I also got a 5:1 that is like 10x more torque, but it has a larger shaft and I don't plan on trying that until I max out the drop in replacement. The 1124144 seems to work great other than some popping on the first layer (which uses 150% extrusion width). I am going to experimenting with smaller extrusion widths to see if it helps the first layer popping. I also need to pursue a better extruder design. I'm still using the stock one. I started printing a "Shanes Extruder", which is a popular design on the Blue Eagle Lab forums. I think with the new motor, extruder design and a MK8 extruder gear, I should be able to really start increasing my speeds.

Lastly...I'm experiencing some fairly bad excess extrusion during retraction moments ("ooze" is the accepted technical term). Basically, the hotend retracts and the extruder stepper stops, but ABS keeps extruding. I'm thinking this could be a temperature or extruder calibration issue. Not sure yet. Either way it's a problem and my hotend ends up hitting the excess ABS globs that get deposited, which in turn causes it to shift a few millimeters to create a "step" in my print layers. Subsequent layers return to normal, but it happens fairly often if I don't remove the globs. I just found this, http://manual.slic3r.org/expert-mode/fighting-ooze, and have a lot to try!

I'm not really looking forward to the calibration and setup stages of my printer, which will hopefully be complete by the beginning of next month. Once you have all the smaller problems sorted out, then I think it will be an easier process from then onwards.

I agree ZorAxe. I'm slowly making improvements in print speed. Oozing is still a problem. I've upped my filament retract from 3mm to 5mm which seems to help, but I think I might end up doing more.

It's odd because even though turning up the filament retract helped reduce oozing, I still see "shifts/ridges" in my print. I'm not sure why my motors can't keep on track. I'm currently toying with motor driver voltages to see if there's a "money spot". I've tried .5v (recommended from manufacturer), .8v, .74v, .7v and I think next I'll work down to .65v. So far the only thing that has shown to improve the print ridges is slowing the print speed way down.

Maybe try run your printer as if it was printing, but without any filament. Set it at a faster speed and try to see if your motors are slipping or skipping steps. Then maybe you can try figure out whats causing it.

Probably the last update...things are working well.

I just wanted to cap off this Build Log with some final notes.

Since my last post I have:
1. Installed a Greg Wades extruder and modified it for a bowden tube.
2. Eliminated the MKV-BV J-Head. Replaced with Ebay 3 Piece hot end ($17).
3. Moved to Shaxon black ABS, 1.75mm.
4. Lowered my Z lift accelerations.
5. Installed a 30mm hot end fan with a shroud.

As it stands the printer is running at 30mm/s with almost perfect print quality. Only very slight spider webs.

In hindsight it's easy for me to recognize that I was trying to extrude my MG Chemicals silver ABS at too high of a temperature. Once I switched to the Shaxon black ABS and started experiencing cold extrusions it was obvious. Layer adhesion was the giveway. The Shaxon was struggling with layer adherence and the MG Chem was sticking fine, but oozing all over. Also, the 3 piece hot end really helped with oozing and heat creep jamming.

What really surprises me is the fairly large difference in temperature requirements for the "same" type of plastic. I'm sure I could have dropped down to 215c with the MG Chem silver ABS and been fine, but the Shaxon black ABS needs more like 245c!

The huge discrepancy in glass transition temperature could be physically felt in the filament. The Shaxon black ABS filament is noticeably stiffer than the MG Chemicals silver ABS filament. Also, the low glass transition temperature of the MG Chemicals ABS was causing it to bend/break at the extruder with high ambient temperatures (95f in my apartment sometimes), and only made the heat creep jamming worse if I wasn't standing there monitoring it when it broke.

Anyway, if I had to pass off any advice from my experiences it would be:
- Get the feel of what it's like to hand feed filament through a "clean" extruder. This well help you diagnose when your extruder is clogged or jammed.
- Start at 230c and then go down by 5c until you start seeing minimal oozing once you stop extruding. It's good to have a little. Then move back up by 5c to find the sweet spot for layer adhesion.
- Don't try to print in high ambient temperatures.
- Extruder E-Step calibration is an art, and is not always 1:1. If someone can argue otherwise...please speak up.