I already worked with a BfB3000 in the past and I also own a Rapman from that same company.
So I know that printer and I must say that it never convinced me compared to my Rapman made from a kit.
But I got it for free so I won't complain !

Checking and testing procedure

Before trying to print anything I started to check a few things like I always do when I'm facing a new machine :

  • visual check : do I see anything that seems wrong ? (missing bolts and nuts, untighten belts, etc.)
  • moving test : can the printer move freely by hand on X and Y ?
  • power supply test : do I have the proper power supply ? Does the machine turns on ?
  • motors test : can the printer move freely on all 3 axes with the "Manual move" menu ?
  • extruders test : are the extruders warming up ? Do the extruders motors work ? Do they extrude ?
  • end stop switches test : do they work well ?

And only if everything seems good I then move on to more testing :

  • firmware : what is the installed firmware version ? Is it the last one ?
  • home position : does the machine homes fine ?
  • bed leveling : is my print bed leveled ?
  • bed Z offset : how far is my bed from the extruders nozzles ?

Finally when the printer seems ready I print a test object :

  • quality check : did my test object print well ? How does it look ?
  • accuracy and calibration : is my test object accurate regarding its dimensions ? Do I need to calibrate the printer ?

After all these tests were done this is what I found :

  • the power supply I was given with the machine is not powerful enough. The BfB3000 expects a 15V / 90W power supply when I only have a 12V / 60W.
    The machine can deal with it but it takes a LOT of time to warm an extruder up to 245°C.
  • the print bed isn't flat which makes leveling and Z offset nearly impossible to achieve.
  • the end stop switches are working well but seem to be non-reapeatable which is a bad point especially for the Z axe. On the BfB3000 the end stops are magnetic sensors which is a bad choice from my point of view.
  • the printer needs to be calibrated

These points have to be adressed...

Improvements

I changed the power supply for a 15V / 90W. The extruders warming up time decreased to an acceptable value.

I added a Rapman acrylic bed on top of the original BfB3000 bed. But it makes it thicker and I will need to adjust my Z offset to match that extra thickness.

I did several tests with the Z end stop magnetic sensor and finally decided to move it on one side of the machine and to not use the bed embedded original magnet.
I then tried different magnet sizes and strenght but without success. My Z offset keeps on varying from one print job to another which is very annoying !

So I finally decided to use a regular end switch instead and designed some parts that will hold a long adjusting bolt (I used a M5 x 70mm long one like on the Rapman).
I designed 2 sets of parts so they can be mounted either on the right side or the left side of the printer. I mounted mine on the left side. The right side parts are untested but should work just as fine.
This solution works fine and the printer can now do reapeatable Z homing. Finally !


BfB3000 Z limiter (left)
BfB3000 Z limiter (left)


BfB3000 Z limiter (right)
BfB3000 Z limiter (right)

BfB3000 Z limiter (assembled)
BfB3000 Z limiter (assembled)

Adjusting screw M5 x 70mm
Rapman M5 x 70mm adjusting bolt (red)


Z limiter mounted
BfB3000 Z limiter mounted (left side)

BfB3000 Z limiter (closeup)
BfB3000 Z limiter closeup

You can download this design from Thingiverse

Other small improvements

I think the way the filaments are feeding the extruders isn't optimal.
The filaments have to travel thru small tubes on a long distance which induces a lot of friction that might ask to much strenght to the extruders motors and might induce sleepering.
I decided to only keep a few centimeters of tubes where needed and changed the long piece of tube that goes thru the cables chain for a bigger one in diameter.
I used a piece of tube from Gardena's micro-drip system (4.6mm diameter).

Gardena micro-drip 4.6mm
Gardena micro-drip tube

Next improvements

I think my design could be better if it was the other way round (if the end switch was at the top and the adjustable bolt at the bottom).
It would make it easier to deal with the end switch's cables because it won't move up and down along with the bed (fixed end switch with bed dependent bolt).
It will also allow the use of an even longer adjustable bolt (in case one needs to print or draw on top of a thick thing).
So I will probably redesign it when I have some time but ATM it does the job so I stay with that.

The other reason why I decided to move the Z switch on one side of the machine is because I plan to make a hot bed.
But this will be another story...
So stay tuned !