First Plastic

Woo hoo!

The 0.5mm-thin-wall from Thingiverse.

I worked on it most of Saturday, and by about 22:00 I had extruded my first plastic - a small rectangle of PLA. As expected, there's a long way to go.

One of the trickiest parts is the zero of the Z axis - the vertical table movement. It's a left handed coordinate system, so if you're thumb points along positive X and you're index finger points along positive Y, then your middle finger points along positive Z.

Ideally one would like to have the zero point for the Z axis exactly when the platform is touching the extrusion head - and obviously, one would like to have the platform bed perpendicular to the Z axis as well. Both of these are difficult to achieve with any accuracy.

The process for getting the platform perpendicular is to

• move the head to one corner
• jog the Z until one can just slide a thickness gauge (a piece of scrap wood) under the head
• move the head to another corner
• adjust the level screw for that corner until the one can just slide the thickness gauge under it
• repeat the above two steps for the other corners

The process for zeroing the Z axis is to

• jog the Z axis until the platform is touching the head
• adjust the limit switch position so that it is just triggered at that point
• move the platform down
• repeat the above three steps until the triggering of the limit switch coincides with the platform touching the head

First, one needs a fine adjustment control for the upper Z axis limit switch. The way it's adjusted currently is with the two mounting screws in slotted holes.

Second, one needs a calibration procedure that doesn't involve judgment calls on whether a thickness gauge has the same amount of friction as a previous time.