Arcol blog Just another RepRap weblog

9Mar/10Off

Series of disasters — Leaving the machine unattended

Everybody is expecting, the machine can be leaved unattended, just doing its job.
What could go wrong anyway?

The prints of the following photo took about a week to produce:

One attempt took around 5 hours to print...

Why were not any of these prints successful? Mainly because of two reasons...

Filament holder fails

The original Rapman filament holder never worked for me. It is so poorly designed, that I dont really understand how could I have been so stupid, that I bought 4 from it (along with my Rapman). Worst investment ever.

So I did a quick mashup from two filament holder:

Im on new white ABS (next article will have more details about it), it comes in 5kg spool, so I winded on my empty spool.

The new ABS is more tough, so it does not really bend (it is hard to wind on a such small spool), so it is prone to get off the spool (just like on the above picture), additionally I winded too much on the spool.

So when the machine printed, the filament come off from the spool, and basically tied a knot.
So the machine hardly could get filament, and resulted lot of skipping steps:

You can see clearly on this photo when the "knot tie" happened exactly:

And here is an another photo, where you can see more clearly the skipped steps (half of the layers has an offset):

The printing quality is excellent. If the filament holder had not failed, this print would be awesome:

I fixed this issue, gluing some paper on the spool (making it bigger), and having less plastic on it:

Nozzle blocked

When I drilled out my spare PTFE tube, I drilled too much into the PTFE tube.
Additionally it is really hard to print with the new plastic.
Often filament stuck into the nozzle, and no plastic comes out of the nozzle.

When there is not enough plastic, the prints looks like this:

Sometime it manages to finish the build, and the part is even usable. But it is
easy to see visually, there is no enough plastic.

The y-motor-bracket, which is near the duck, has not enough plastic.
Here is a top-view to really see the difference:

Solving this problem, needs a carefully designed PTFE-tube, and switching over direct drive mechanism (instead of the current screw driven extruder design).
Im working on them...

Comments (3) Trackbacks (0)
  1. it looks like you really have to tinker with your skeinforge settings! i can see right through your parts! ;)

  2. Yepp, that is true. However it is only an aesthetic issue, the holes are perfect size, and dont affect mechanically the part at all.

    I already dived into skeinforge sourcecode, but it takes time. It is on my todo list, but low priority.

    Laszlo

  3. You could try the in-fill idea on those parts that aren’t quite as solid as they should be, adding some resin or the like.

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