Quality control

I RepRapped a doorstop for our new bathroom shower: -



It has a 10mm hole most of the way down and a countersink to take a ~5mm wood screw.



A 2mm self adhesive felt pad covers the screw hole and acts as a shock absorber.

It has a rim around the bottom to prevent it rocking if the base warps or the wall is not flat. To support the bottom of the hole there is a one layer membrane: -



I removed it with a 5mm drill: -



I was quite proud of it but my wife had something more like this in mind: -

I can't print chrome yet, so I will have to go out and buy one, and it has three screws which have to be drilled through the tiles into the wall.

The files are on Thingiverse if you prefer function over form.

Pinchless Extruder

While dismantling my extruder for a small mod I accidentally discovered that the worm pulley has so much grip that it will still extrude PLA with the pressure roller removed. It is hard to see on this low quality video but it was extruding 0.4mm filament at 32mm/s.



I will still run it with a roller because it helps to guide it into the tube when self feeding to start a new filament. I also expect softer plastics would need it.

BTW, I have stopped using Vimeo and gone back to YouTube because they added an artificial processing delay unless you pay.

Beefed up bracket

When I started reversing my extruder I noticed the motor bracket flexing. Here is a short video showing it in operation: -

BendyExtruder from Nop Head on Vimeo.

It was immediately apparent that I had not made it strong enough.



As the worm gear is about twice the diameter of the threaded pulley the axial force on the motor is about half the force required to push the filament, i.e. a few kilograms. After making a few objects it cracked along the layer where the bearing housing rises out of the flat motor mount.

I designed a new bracket but I was back in a chicken and egg situation with no working extruder to print it. As Erik pointed out you need a Robin Hood / Friar Tuck strategy of having two machines so that one can make replacement parts for the other. I must get my Darwin up and running!

In the meantime I cobbled it back together with some random bits of metal, some tiny G-clamps and tie wraps: -



I made some of the new bracket thicker where I could: 8mm instead of 5mm, which should be ~2.5 times stronger. I also added some ribs and extruded it at 10°C higher temperature.



This one seems solid as a rock, but it did warp a little more. The stronger you make something the more it warps.

Here is a video of it not flexing: -