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skeinforge/replicatorg screw up

Posted by zeneslev 
skeinforge/replicatorg screw up
August 11, 2010 10:23PM
Hi all. I am tring to print a z leadscrew base on my repstrap. It's a fairly large piece and the build time on my machine is about 4 hours. I've tried three times to build the piece, and each time about 2 hours into the build, the x axis shifts over about 3 millimeters, screwing up the whole build. This is not a mechanical problem because the error occurs each time in the same place. Does anyone know what would cause this? I've exported the STL file from the solidworks model and then ran it through skeinforge. I've looked at the output generated in skeinforge, and it appears to be normal where the axis shifts. Can anyone help? Thanks so much!
emt
Re: skeinforge/replicatorg screw up
August 12, 2010 03:55AM
Hi

As you are generating Gcode you could look at the code in one of the graphical Gcode checkers. I use EMC as a CNC controller and that shows the model about to be produced. I am sure there are trial viewers available on the net. Look for Gcode editors. Some of those may have the capability. It is sometimes called backplot.

You may be then able to confirm the error is not in the code. I have used skeinforge may times and I have never had an error.

Does the error occur at the same place in the build? Have you tried moving the model in X to see if the error occurs in the same place on the X axis?


Regards

Ian
Re: skeinforge/replicatorg screw up
August 12, 2010 04:32AM
Look at the g-code in the skienforge viewer. If there is no shift in that then it is not an SF problem. The usual cause is that a big part like that warps upwards and the nozzle catches on it causing it to miss steps. Or it might be loose pulley, or too little motor current. The point it slips might just be sharp change in x value, or a bit of the object that tends to be blobby, or when the mass of the object reaches a certain value.


[www.hydraraptor.blogspot.com]
Re: skeinforge/replicatorg screw up
August 12, 2010 10:07AM
Thanks for the replies. I'll make sure to check the gcode later today. I really doubt it is something mechanical. I've taken apart the x axis and put it back together and I still get this problem. The parts are not warping upward because I have a heated build platform. I am actually using a mcwire repstrap to build these parts, so it takes damn forever!
Re: skeinforge/replicatorg screw up
August 12, 2010 09:27PM
So tonight I watched my machine go through the part where it usually screws up and I found out what's causing the axis shift. I have towering enabled in skeinforge. The problem is that my machine crashes right into a part that was just towered! This causes the extruder to shift a little bit because my Z axis is not designed to resist movement in the X direction! However this is a problem with skeinforge because the extruder does infact crash into the workpiece! Is there a fix for this?
Re: skeinforge/replicatorg screw up
August 13, 2010 08:17PM
You could try using the hop option, or disable tower.

For long running rare errors like this, I find it is helpful to set up a video camera to record the print so I can review it later and fast forward past the boring stuff.



Darwin clone, Gen 2 electronics, Arduino Duemilanove w/ AtMega328, 5D Firmware, Pinchwheel extruder
[www.codeerrors.com]
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