Tyger wrote:Hi everyone,
So i got my up a few months ago. i use it for engineering parts but i have som problems.
For one as soon as the nozzle gets hot its starts running (leaking) ABS and when i try to create something big and flat its like it is curving up because of the heat, so it is not flat anymore, but the printer keeps on going so.
Here is a photo of a relatively large (4-1/2 x 2-1/2") part, with a large flat area and solid fill - worst-case for warpage. You can see that it is perfectly flat with no warpage (the slight gaps at the left and right flanges are due to some strangeness in the CAD-STL process, not warpage).
The way I achieve this is by using perfboard and setting the platform initial height calibration so that the first layer pushes a lot
of plastic into the perfboard holes (see the other photo). For extra-demanding parts like this one I also swab down the perfboard with MEK to ensure that there are no oils on it, and also to pre-soften any plastic that's already in the holes.
I close the fan duct damper for the first few layers in order to maximize nozzle temperature and flow, then when the raft is almost done I open it up.
The downside of this technique is that a lot of nozzle backpressure is generated in the first layer(s). If your feed gear is hot you will probably encounter pre-melt and feed slippage/failure. I printed two of these yesterday without any problems, then on the third one I stopped the print because I wanted to tweak something in the CAD. After 5 minutes to make the CAD changes and change the platform I tried to print again but just could not get it to feed, even with forced-air feed gear cooling. I turned everything off and went home; this morning I tried again with a cold machine and it's printing fine without changing anything else. I'm really looking forward to getting my Drew Petitclerc feed pressure mechanism!
I have not yet tried the Kapton + dots-of-MEK-after-the-first-layer technique and don't know if it's capable of withstanding ABS warping to this extent or not. I am only demonstrating what is possible with perfboard and the right settings.
Julia ("La Pesada")