Epson P800 Pizza Wheel Hack

I work with alternative printing methods (Cyanotype, Kallitype, Argyrotype) using digital negatives. The Epson P800 printer I purchased is a fine printer, save for one problem: pizza wheel marks.

Media eject traction wheels: The bane of my existence.

Alternative printing forums are littered with posts complaining about this issue. The paper eject wheels mar glossy media (including the transparency film used for digital negatives), and in doing so, leave a dark dot in a print exposed with the printed negative.

Repetitive black dots: Not the plague, but annoying nevertheless.

To solve this problem, I tried different approaches:

  • Set platen gap to wide

None of these changes fixed the pizza wheel marks. I reached out to Epson for assistance since my printer is under warranty. They suggested I change the platen gap to wide, and closed the ticket, refusing to answer my follow-up requests for help.

Frustrated, I reached out to InjketMall for a recommendation on a different printer that didn’t exhibit this problem. I heard back from Walker Blackwell, whose reply was brief, and monumentally helpful.

Printer mods: I will not fear hardware hacks.

The article Walker pointed out written by J. Keith Screiber was helpful, offering this insight into the operation of the Epson printer:

We take advantage of the retracted position of the star-wheel mechanism when the Front Feed is in use by tricking the printer into thinking that the Front Feed is closed even though it is in the open position. (J. Keith Screiber)

Keith offers a solution to the pizza wheel problem: use the rear paper feed while keeping the paper eject wheels disengaged. The Epson 3880 Keith uses (and my P800) won’t print from the rear paper feed while the single-sheet tray is disengaged (e.g. the pizza wheels cannot be retracted for printing). However, what if we trick the printer into thinking the single-sheet tray is engaged, even when it is not?

Keith’s hack works for his Epson 3880, but the 3880 is an end-of-life product that I didn’t want to get involved with in buying used. I needed to apply what I learned to the P800.

Hack Your P800

Using the Epson P800 service manual and the insight from Keith’s article, I was able to trick my P800 into printing from the rear feed even when the single-sheet tray (and the paper eject wheels) are disengaged. It required a single, custom tool.

It’s a stick. You’ll also need a screwdriver.

This printer modification is not permanent, and requires only a little fiddling to get a stick (or piece of baseboard trim wood, as I used here) into the necessary shape. You don’t lose any printer functionality with this hack: you can still use the single-sheet feed tray when desired, as well as any other printer functionality.

It’s probably also true that if you stick random pieces of wood inside sensitive parts of your printer, you could break things, and Epson may not be willing to help you with it. Proceed with caution, and at your own peril or success.

Remove Some Plastic

You’ll need to access the front-left housing compartment.

Source: news.epson.com. Highlight mine.

Accessing this compartment requires that you remove the rear housing compartment, followed by the left housing compartment.

Remove the Rear Housing Compartment

Remove the five screws highlighted below from the rear of the printer using a standard Phillips-head screwdriver.

Source: news.epson.com. Highlights mine.

After the screws are removed, gently remove the rear cover in an up-and-back motion. My cover removed from the left first, then I shimmied the top line of tabs to remove completely.

Removed rear cover. Ignore the lighting mess in my kitchen.

Remove the Left Housing Compartment

The left side housing compartment was difficult to remove, but after a few minutes of upward motion (from the top and side), the three tabs shown below released. The bottom inserts with two right-angle clips; try not to force it at a heavy-handed angle.

Three tabs to rule them all.
Don’t touch the stuff inside.

Remove the Front Left Housing Compartment

Once the left side housing compartment is removed, the front left housing compartment is easily removed with gentle upward pressure, leaving you with this view:

Inside the front left cover. Intimidating, at first.

Next you can re-attach the left side cover, then re-attach the rear cover. For continued use of this hack, you’ll need to leave the left front cover off. I suggest a dust cover when the printer is not in use to prevent a lot of dust from getting inside these sensitive parts.

Open the Single Sheet Feed Tray, Observe Cam

Open the single sheet feed tray while watching the white plastic cam move away from the printer internals. As the cam moves with the opening and closing of the single sheet feed tray, a small leaf switch is repositioned, indicating that the tray is open or closed for the printer logic board. This is best illustrated using Keith’s image below.

Source: How To Disable Star-Wheels On An Epson 3880, J. Keith Schreiber

The illustration Keith put together for the Epson 3880 is close enough to make sense applied to the P800, shown below.

Leaf switch on the P800. I’m not much into macro photography.

Fashion a Stick

In order to trick the P800 into believing the single sheet feed tray is closed (when it is really open, and therefore the paper eject wheels are not engaged), we need to push on the leaf switch when the single sheet feed tray is open. The switch automatically releases when it is not under pressure, so we need a tool that will gently push the switch into the closed position, using slight tension between the cam head and the printer housing to keep it in place until we remove it.

After some experimentation, I trimmed down a piece of oak trim board to 8" (20cm) long, 1/16" (1.5mm) thick and 3/16" (4.5mm) wide. In Keith’s article he uses a printer cleaning swab from InkjetMall. You will likely need to experiment with a tool long enough and thin enough to reach the leaf switch, with enough friction to keep it held in place without too much pressure.

Insert the Stick

To trick the P800 into thinking the single sheet feed tray is engaged, open the single sheet feed tray, then insert your stick right above the cam and gently press on the leaf switch, using the tension between the cam and the printer housing to keep it in place. Best shown in pictures below.

Once you’ve shaped your stick as needed, you’re ready for printing without pizza wheels.

My Process

First, test prints are created without special fiddling and I accept that there will be pizza wheel marks. When I have created my (small) test prints and I’m ready to make the final digital negative, this is the process I follow:

  1. Turn the printer on with the single sheet print tray engaged (pushed in)

Conclusion

Except for the pizza wheel marks, I have no complaints about the P800. It makes beautiful prints on quality paper, and I’m happy with the density I can achieve in a digital negative. I wish the pizza wheels weren’t a problem, but with this hack I’ll be able to continue with my alternative processing hobby while I look into vacuum-fed printers.

Questions? Let me know in the comments section below. Thanks to J. Keith Screiber and Walker Blackwell for their insight and help.