Friday, December 04, 2009
No sweat HDPE printing
Some weeks ago I got the idea of putting flanges and guys on long prints to suppress warping. That worked, more or less. The problem with the method is that it requires a lot of preparation in Art of Illusion or other 3D modeling app, preparation that I'd just as soon not have to take.
I'd been working on other things, but a few days ago Bogdan Kecman started designing replacement parts for his Rapman 3 in ABS and I decided that it would be nice to have a set for myself.
Winter having descended on us here, but I'd been using HDPE in that ABS stinks too much to be readily usable in a closed room.
I tried printing Bogdan's parts in HDPE and got the usual warping problems with them.
It was obvious that I was going to have to guy them. I decided to try a variation of the guy and flange gambit. First, I rounded some of the corners on Bogdan's part.
I then used the boolean feature in AoI to remove the volume of the part from the box.
I then expanded the apron a tiny bit so that there would be a gap between it and the part.
Then I ran exported the two parts as a single STL and ran it through Sceinforge and then printed the gcode that came out.
A few moments with a mat knife and I had the part.
The flaws in the layers were caused by my y-axis set screws being a bit loose. A touch of curling did happen with the part's lowest layer. It was pretty evenly distributed around the edge of the print, however, and amounted to <~ 1mm.
The only problem with this approach is that you are left with a patch of the raft on the bottom of the part. I'm going to get a belt sander and mount it belt side up to dress the parts that I get using this method.