3D Printing (Part 8)

Part 1234567891011

This post is all about the new printer that I bought for my own pleasure and private use ! It globally fullfils my own requirements which could be enumerated in this way:

  • Budget: less than 800€
  • Printed material: PLA and ABS, others if possible; 1.8 mm filaments
  • Open source: mandatory
  • Extruder: 1
  • Printed volumes: 160x160x160 mm minimum
  • Turn key/Kit: no preference

Although I keep a constant attention to the 3D printers, I spent some time on the net seeking for printers which would match my expectations. The offer is widening from day to day, however, many attractive printers are advertised yet but still under development. So that I quickly resumed my early searches and made my decision for… the Vertex K8400 from VELLEMAN. This printer looks like it is the fusion of the early k8200 and the Ultimaker 2. The Ultimaker 2 was pretty high in my list but the price is steady high and far exceeding  my budget, on the other hand the k8200 looks good but I disliked the frame arrangement. So that the mix of both was of interest for me. The Vertex is available in a surprising wide range of price, starting at 600 € and getting up to 800€ depending upon the vendors. I carefully reviewed the building instructions which looked very detailed and very nicely illustrated. From the pictures I got the feeling that the material used by VELLEMAN were high standard. No time to loose I went to the order section of CONRAD and placed an order for one.

vertex

I arrived in a nice clean package, some sort of cardboard suitcase where all parts are well packed and labelled. I found no damaged parts although fragile parts (e. g. glass plate) coexist with heavier ones (e. g. PSU). I assembled the whole printer in two consecutive half-days. So far my advises are:

  • Place all parts in a large surface in order to find them easily and avoid to mix them up.
  • Read carefully the instructions and take your time.
  • Use good quality tools.
  • If you have no experience at all in 3D printers, it might be a good idea to join a FabLab or such community in order to get help.
  • Use the forum. As usual there is “à boire et à manger”, in other words there is poor and good quality information.

And here are a few tricks from my own experience:

  • Twisting the signal wires is boring but it helps a lot routing them properly and nicely. Do the routing as the last step, including down to the main board.
  • The Spiral Wrapping Band is hard to install and useless. I prefer the plastic ties.
  • A multi-meter is useful. Although it is not mandatory, I strongly suggest that you have own in order to check voltages and possibly temperatures if your multi-meter features such option.
  • Be very, very meticulous at adjusting the printing head rods. The better the adjustment, the lesser the frictions and constraints, the lower the power sunk from the drivers, the cooler the stepper motors. And ultimately and probably the better the prints.
  • Use alcool to clean the Buildtack surface, no acetone. This Buildtack surface is awesome be must be treated with care.

And now, it’s time for testing !

zon zon zwiss zwiss rol rol rol rol zon zon zwiss zwiss rol rol rol rol zon zon zwiss zwiss rol rol rol rol … crack ! Failure ! I could not install the filament properly, although I could push it manually through the extruder (in other words, this was not a temperature nor a clogging problem). Once the filament in place, the prints were incomplete and all observations were converging towards the extruder driver. Although these drivers use high quality chips from TI, one over millions may fail, and it just happened to me.

DRV-8825

As the chip was overheating constantly, I though that it was a heat dissipation problem. But neither a small heat dissipator nor a cooling fan helped. After replacing the defective module, none from my “improvements” proved to be necessary. The module was replaced under warranty simple and easy. However, it took me a week before I got the spare part.

Please note the small adjustable resistor on the top of the DRV8825 module. You must adjust it in order to set the proper trigger level for over-current sensing, please read instructions >here<.

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