Monday, 4 July 2011

First Almost Print

Just thought I do an update on my initial testing of the machine. I was quite pleased that I have managed to get everything wired up correctly and the extruder heated up. I have spent a while trying to level the bed, a job that was more tricky than I imagined. I am not really happy with the way the bed bolts to the y axis plate. On the Prusa design there is a nut above and below the y plate, I find this a bit annoying when adjusting the bed level – I have to keep adjusting both nuts, I can’t see why there can’t be just one nut below the plate, I might test it out at some point.

At the moment I am using RepRap host but I have also been testing with ReplicatorG to see if that will work. I can connect with ReplicatorG fine using the “experimental” Mendel machine profile. The control panel jog’s the axis (although sometimes the distances seem a bit random and sometimes it moves 2 axes instead of just one). The control panel also controls the temperature of the hot end fine however it does not turn the extruder stepper. When I try and print an object with ReplicatorG it starts ok, but then extruder starts to cool down, it doesn’t seem to control the extruder temperature. Not sure how to access the temp settings, I assume it might be part of the Skeinforge profile, but not sure how to get to that at the moment.

With the RepRap host things are working pretty well. Below you can see my first attempt at printing the 40mm test cube object. As you can see I aborted the print part way through, the object is less of a 40mm cube and more of a 40mm filter. The extrusion seems to be patchy, and thin even when it is extruding. I think this could be caused by a couple of things. First my “hobbed” bolt on the Wade’s extruder could be not gripping in certain areas – or the springs set too loose. Second I might not have set the extrusion length correctly (the steps per mm value) so not enough filament is being supplied for the required extrusion. Third the temperature could be too low causing a blockage as filament is being melted. See the picture and video below and let me know if you think you know which of these it is. At least the x and y dimensions seem to be correct!
Another thing is the extruder stepper is getting HOT (on a long print I think it could get damaged), I have tried trimming down the pot but to get the current up enough to turn the stepper. I have decided to use a Pololu for the extruder stepper in the hope that the stepper will run cooler (and quieter).


Host: RepRap Host
Electronics: Techzone Gen 3
Temperature: 200°C
Material: Black PLA
Extrusion Steps/mm: 2.508

From Mendel

1 comment:

  1. It is much easiert to adjust the Y plate if you drill and tap the holes m3, then the nut underneath becomes a lock nut.
    If you leave the upper nut off with the plain 3mm holes the build table wobbles about