Monday, 23 August 2010

Friday the 13th

When I got up last Friday morning my PC had this on the screen: -

This is despite the fact that I had automatic updates set to ask me before installing. This was the result :-

The PC had stopped talking to my Mendel about half way through a seven hour build, so the axes had stopped moving but the extruder was left running for a few hours. The result was that the extruder was encased in a solid ball of ABS about the size of a tangerine. Thanks Microsoft! What I actually said at the time was less polite!

Of course I was planning to put some safeguards in the firmware and also run the machine from an SD card, but have never quite got round to it as I have been printing virtually non-stop for months.

I couldn't remove the extruder from the carriage because the blob was too big to go through the gap, so I had to dismantle the x-axis to release the carriage.

I have seen this happen to other people and it wrote off the extruder, but I thought this one should survive because it is mostly metal underneath the blob.

I tried using a loop of hot nichrome to slice bits of it off. The nichrome cut through OK, but the ABS closed up behind it, so it achieved nothing.

Next I tried a small circular saw attached to a Dremel. That worked OK, but threw off sawdust and bits of ABS hot enough to burn, even through light clothing. I got the bulk of it off that way but when I nicked one of the heater wires I decided to stop.

I got some more off by heating it with a hot air gun and pulling lumps off with a pair of pliers. That was OK but the whole extruder got too hot to hold and it was starting to soften the carriage.

I got the remainder off by running the heater up to 200°C and using a knife, wire cutters and pliers. It took me about 3 evenings in total to remove the blob and the machine was out of action for a week while I reassembled it and calibrated it again.

It now takes a bit longer to warm up, and extrudes more filament during the warm up process than it used to. I suspect therefore that the thermistor is reading low and so it is running hotter. It doesn't seem to cause a problem with the ABS that I am using. I had to increase the time I run the extruder to prime it after warm up though.

I also seem to have managed to bend one of my z lead-screws while sliding the x-axis bars in and out. It doesn't matter as the axis is constrained by the z-bars, but annoying as it rattles a bit.

All in all a bit of a disaster. It's running again now though, but I still haven't put a safeguard in my firmware. I will have to develop it on HydraRaptor and load it into Mendel between builds. I have disabled automatic updates!


  1. Sorry this happened to you.
    Just another thing that ticks me off about MS, what if it had been someone that relied on these things for their business? That's a lot of lost revenue for the time it takes to repair something because of an update glitching it out.

  2. well we all know the solution to this switch to another operating system ie Linux of whatever flavour you prefer.

  3. one word.....linux

  4. You could always disable automatic updates and do them manually.

  5. It does that on the server version as well - what the hell are they thinking of? I've lost work due to it but nothing of the order that you've had to put up with.



  6. Why not try replacing Windows with an OS?

  7. Oh, Linux Ubuntu which I use, is very snappier and stable for tasks as surf on web and RepRap :-)

    Even for when I develop electronics, firmware, CNC ;-)

  8. I am stuck with Windows because CoCreate needs it.

    I don't have any problems with doing other things on my PC at the same time as running two machines. I does have two cores though. When I had a slower single core machine things like Skype or playing music upset my builds.

  9. so much for your 5.5/h that i quickly calculated..

    isen't there any way to salvage half a bed like that? manual repositioning?

    maybe time to have another maching (legacy?) run your prints for you.. maybe you havesomething in your tech trash bin.


  10. Yes, this is the problem of using a desktop approach to an industrial problem.

    Many industrial machines never get updated and are running antiquated versions of an OS but as they are not connected to anything other than the machinery they don't need to be updated and hence don't break. Taking the continual update approach to a industrial machine is not really the best strategy.

    I think if I was going to set up a CNC computer or reprap controller, I'd use an old motherboard in a metal box and transfer files by memory stick. A network card could be installed but left disconnected to allow larger files to be transferred.

  11. I have plenty of old PCs I could run it from but they take up space and use more power than the machine does, so I prefer to just run one PC. The best fix is to load all the data to an SD card at the start so the machine can run standalone. Not hard to do as I have recently done it on a system in my day job.

  12. If we added SD card support properly then we could disconnect the PC/laptop and print stand alone. I mean the standard Gen3 electronics includes the SD card reader - why don't we use it?

  13. Nophead, Say no to propriety software. Drop CoCreate and use Blender / OpenSCAD ;)

  14. Blender is a mesh editor, not a solid modeller so there is no way I will be using that for CAD.

    I should get into openSCAD, being a programmer, but I don't like the idea of making 3D objects by composing primitives. I want to be able to edit 3D objects directly by moving faces, etc, and not bother keeping any construction or intermediate objects.

    The shapes I create in CoCreate are far too complex for me to think how to make them up by boolean operations. Blends and lofts for example.

  15. How about FreeCAD? --

    Would FreeCAD be a good option for RepRap users/designers?

  16. I too can recommend OpenSCAD. It's far from being mature, but it can be very useful already.

    While I create easy shapes with boolean modeling, I do more complex stuff in 2d in QCad and extrude it in OpenSCAD.

  17. Can you please look at this video I did recorded with FreeCAD?

  18. I feed bad for you!! It's terrible to be doing attempts to recover an extruder that you're very happy with.

    Apart from switching to Linux and implementing an SD-card feature, it might be easier (and less radical) to make sure that it stops extruding when the buffer runs dry. My 5D G-Code only extrudes what it's told at every segment, that might also work for you.
    Of course you still have an occasional "fix" from Redmond and a failed 7 hour build. I guess a broken system is worse than the failed build.

  19. Hi Erik,
    Actually I don't use a buffer. It is another thing I intend to implement someday but it works fine without one with a 100Mb Ethernet connection.

    Yes the 5D code would stop at the end of a segment but to make that work I would have to synchronise the clock of my extruder controller to my main controller. That is something I normally do with a time broadcast and an FLL when I use a serial link to drive steppers. (The micro in my extruder does not have a crystal attached, it uses an internal RC oscillator that it is only within a percent or so. Over the length of a 100mm line it could stop a bit early or late by millimetres).

    I stuck with much simpler system of turn it on at the start of a run and off at the end because I don't believe in 5D. The flow rate of the extruder lags the steps, so it makes no sense to synchronise the steps with the axis motors.

    So no buffering, no PID, no 5D, no g-code just very simple firmware and it all works fine.

    In the article I said I was having problems with it taking longer to warm up. It got worse to the point where it was needing 100% power to maintain temperature instead of about 80%. I re-seated the connector for the heater / thermistor and now it works as it did before. I keep having weird problems with connectors like that.

  20. Hi Casainho,
    Thanks for the video. It certainly looks like an improvement on AOI. It still works by composing 3D primitives with boolean operations though so you end up with a tree of primitives to represent one solid. CoCreate does not work like that, it probably does internally, but it is all hidden. You just have one solid object for each part in your design. If you want to change the diameter of a hole you just click on it and change it. There is no cylinder object that is the anti-hole.

    CoCreate is far more productive because you can edit 3D objects directly as single entities.

  21. I use Ubuntu Linux and have Windows installed in a VirtualBox for things that need windows. Why not install Ubuntu and use CoCreate in a VirtualBox. I did find that Alibre would not run under VirtualBox - problem with Direct3D, so I have to dual boot for that. Got to be worth a try to see if Cocreate will run under Virtualbox