Thursday, December 25, 2014

Prusa i3 Rework: Build Log #6- Motor Assembly

This is the sixth part of my build log of the Prusa i3 Rework, describing the attachment of the motors to the axes. I'm moving towards printer operation, and I've passed the halfway point of the build. By now, I've been working on the build for about two weeks.

Above are the parts needed for the setup of the Z-axis mount.  If you look closely, you can see that the threaded rod on the right is slightly bent. The rods control the Z-axis movement (up and down), and a bent rod causes the upper layers to become slightly offset. It's not major on my printer, so I haven't replaced the rod, but with a more bent rod, the prints would become quite bad.

A closeup of the couplers used to attach the threaded rods to the motors.

The couplers are important because they allow play in the axes. This means that a bent Z-axis rod can still function well.

Here are the threaded rods and couplers threaded through the X-axis assembly.

And here are the Z-axis motors, attached to the couplers and the frame. The Z-axis is the only axis with two motors- all of the other axes have only one. It is also the only axis to use threaded rods. The other axes use GT2 timing belts.

Here is the broken Z Axis Bottom Left part with the motor attached. It holds together pretty well even without the zip tie.

This is the Z-axis endstop, mounted on the Endstop Z Holder part. This part is very hard to adjust once it is attached to the rest of the frame.

These screws on the back are impossible to get to when the Endstop Z Holder is attached to the rest of the printer. Not my favorite part of the Rework, but it's not a huge issue because most Z-leveling can be accomplished with the jackscrews on the bed.

Here is a pulley for GT2 belts on the motor for the X-axis. It's important that one of the grub screws for the pulley is on the flat of the motor shaft.

And here is the motor attached to the X End Motor part.

Here is the fourth motor, mounted on the Y Motor part. The nuts shown tighten the part in the correct position.

A closeup of the endstop part. The endstops that I have were designed by MakerBot (presumably before they became closed-source), and they are in desperate need of a redesign. The connector that goes over the screws needs to be bent backwards (carefully) for each endstop, which is inconvenient and can ruin the endstop.

At this point, use the nuts and washers in the middle of the threaded rods on the X-Axis part to attach it to the frame assembly. Make sure that the assembly is pushed up against the threaded rods before the nuts are tightened so that the printer does not rest on the motors. Make sure that the end of the X-Axis with the motor on it is facing towards the front.

After completing that step, here is the frame, with the motors attached and the body assembled. Beginning to look a bit like a 3D printer, hmm?

This post is the sixth of ten that goes over my Prusa i3 Rework build. These posts are in the order given on RepRap's wiki page for the Prusa i3 ReworkAll of the images from the build are in this Flickr photo album.

My build log: