RepRap: Blog

After looking at the cool stuff nophead is doing, and stealing an idea from Ed, I have improved the nozzle wiping on my RepRap considerably.

The picture shows a doctor blade cut with scissors from brass shim. It has a V notch that the extruder uses to discard excess extrudate.

I have upgraded the Java code in the repository to use this type of wiper, which works better than the previous toothbrush-wiper blogged a few days ago.

Tricks: make the V angle very acute, and curl the profile down slightly so it comes up to meet the nozzle as the nozzle moves over it. Also take care to align the nozzle with the very centre of the notch when it does the wipe.

We still nead a way to clean the cleaner, I think. As you can see, lengths of extrudate build up in the notch and are going to cause trouble eventually.

Labels: cleaning, doctor blade, nozzle wipe

Ed and I have been experimenting with various strategies to improve build quality. One problem is bits of polymer sticking to the head and then dropping onto the build and messing it up. Another is the fact that if you run the acorn-nut nozzle (left above) too close to the surface it smears the molten polymer all over itself, and then re-deposits some of that later where you don't want it.

I made up the nozzle on the right. It is 1.5 mm diameter at the end, with an 0.5 mm diameter through hole. With this in place of the acorn nut, you can run the nozzle over the surface to sweep it flat without pushing the polymer where you don't want it.

It is a bit more complicated to make than the acorn-nut nozzle (which just needs you to drill one small hole in an off-the-shelf part, of course). But it works significantly better.




To clean the new nozzle, we've added a toothbrush along with a nose-wipe cycle to the host software. This keeps the crud off the nozzle by wiping it back and forth at the start of each layer.

Now. How do we clean the toothbrush?...

Labels: build quality, cleaning, nozzle