The process of taking apart my old Canon Pixma MX340 multi-function inkjet has been remarkably easy, something that took deliberate effort by Canon. I recognize their effort and I am grateful. It's been a fun learning experience and I realized I'm a little sad to be close to the end of mechanical disassembly. But that's not going to stop me from finishing the job!

The paper feed motor and adjacent gears (including the rotation quadrature encoder) is the final metal assembly still attached to the base. It also hosts the plastic-and-foam assembly that sits under the paper as it is printed. A typewriter platen is responsible for both feeding paper and holding it against inking impact. Here, the two tasks are handled by two separate parts. The metal shaft with a gray friction coating is responsible for feeding paper, and the rectangular black plastic-and-foam assembly holds the paper directly under the print head. I'm not sure which part technically counts as a platen here, but I'm going to call the rectangular plastic-and-foam assembly the platen.

I see several Philips-head fasteners blocked by the friction-coated feed shaft.

Turning a plastic handle allowed me to lift that shaft up and away, exposing those fasteners.

The fastener left of center is spring-loaded though it's not clear to me what forces that spring is intended to absorb. The center of this platen is a soft porous foam discolored by a few high-traffic areas of ink absorption. I used this printer for many border-less photo prints. The printer apparently accomplishes this feat by shooting ink beyond the borders to make sure everything is covered, and that ink ends up in this foam. There is a distinct over spray pattern corresponding to 4" x 6" photo paper in addition to a less distinct pattern for less frequent full width 8.5" x 11" photo paper prints.

Removing the platen and flipping it over, I see several holes where oversaturated ink can drip down to the ink absorbent pads below. It looks like I never needed that provision as the lower pad is still pristine white.

Removing the platen also allowed me access to the remaining fasteners. I had hoped there was only a single piece of stamped sheet metal as they would make it easier to keep the paper feed motor and shaft assembly in one piece. Unfortunately they are two separate pieces. So after lifting them out of the base, things are a little loose and floppy.

Once I made sure none of the rotating pieces are in contact with my table surface, I pressed the power button. The power-up self-test sequence still runs! Things sounded weird because the print carriage was not designed to run facing upwards, and the paper feed motor is no longer driving a bunch of gears. Plus the printer complained that no ink cartridges were installed. But still, it ran! I'm glad it's still in running condition as I still want to probe the print carriage encoder. I will start that process by disassembling its rail assembly.

This teardown ran far longer than I originally thought it would. Click here to rewind back to where this adventure started.