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Poco Troubleshooting, Maintenance and Resources

Packing and Bed Adjustment for Photopolymer Plates & Type High Blocks

The Hacker Poco Proof Press (typically the No. 0 model) features a cylinder with a standard cylinder undercut of .050 inches. This means the bare cylinder sits exactly .050“ below its bearers. [1]

To achieve a correct “kiss impression” on your flatbed cylinder press, the combined thickness of your draw sheet (tympan), packing paper, and the printing stock should equal the undercut plus an extra .002 to .003 inches for squeeze. [1, 2]

Recommended Packing Formula

Your total packed height should sit right around .052 inches above the bare metal cylinder. Because individual paper calipers vary, always check your materials with a micrometer using this standard baseline layout: [1, 2]

Draw Sheet (Tympan): One sheet of oiled .006” tympan paper clamped into the reel rod.
Base Blanket/Cardstock: A non-compressible rubber offset blanket (such as an AB Dick 360 blanket) or a heavy sheet of .020“ to .030” pressboard.
Filler Packing: 3 to 5 sheets of standard 20 lb bond copier paper (roughly .004“ per sheet) or oiled tympan hanger sheets. [3, 4, 5, 6, 7, 8]

Crucial Bed Adjustments

Before locking in your packing, verify whether your press bed is adjusted for type-high (.918”) or galley-height (.968“). [9, 10]

If printing with a galley plate (.050” steel plate in the bed): You are printing at type-high (.918“). Use standard packing.
If the plate is removed: The bed is dropped to galley height. If you print directly from wood/lead type locked on the bed without a galley plate, you will need to add an extra .050” of heavy pressboard or a steel shim under your form to avoid an under-inked, completely faint impression. [3, 10]

Pro-Tips for the Hacker Poco

Keep It Centered: When wrapping the cylinder, cut your inner packing sheets slightly narrower than the cylinder face. Ensure the packing paper does not wander or overlap onto the cylinder bearers (metal rails on the side), which will ruin your registration and slur the print. [11, 12]
Hard vs. Soft: For crisp type and wood engravings, place a hard sheet of pressboard directly underneath your top tympan sheet. If your type is worn or uneven, move the softer bond paper to the top layer just below the tympan to cushion the bite. [8, 13, 14]

Because you are switching between traditional type and photopolymer bases, the trick to a smooth workflow on your Hacker Poco is keeping your cylinder packing fixed while adjusting the height of your printing forms in the press bed.

To prevent having to rip out your cylinder packing every time you switch methods, you should establish a permanent type-high (.918“) standard on your cylinder. Here is how to manage both setups seamlessly:

1. The Fixed Cylinder Packing Setup

Pack your cylinder exactly to .052 inches (your .050” undercut + .002“ squeeze). Use a hard packing recipe to accommodate both mediums beautifully:

Top Sheet: .006” Oiled Tympan.
Under Top Sheet: .020“ or .025” Hard Pressboard (essential for crisp photopolymer highlights).
Fillers: 50lb or 60lb offset/book text sheets (roughly .004“ each) to bring the total micrometer reading to .052”.

Once this is clamped tight, leave it alone. Do not change it when swapping forms.

2. Form Adjustments in the Press Bed

Because your press packing is now locked into a strict .918“ type-high expectation, you will manage your two different forms directly on the bed:

Printing Medium	Bed Configuration	Adjustment Strategy
Traditional Lead & Wood Type	Galley Plate IN (.918” Bed Height)	Lock your type or wood blocks directly into the bed. Wood type can vary slightly due to age and humidity; use underlay tape or thin paper strips under low blocks rather than changing the cylinder packing.
Photopolymer Plates on a Base	Galley Plate IN (.918“ Bed Height)	Ensure your base is specifically a Standard Type-High Base (.858”). When paired with a standard .060“ photopolymer plate, the total height equals exactly .918”.

Quick Workflow Hazards to Avoid

Watch out for “Galley-High” Bases: Some Boxcar or Boxcar-style bases are machined to .903“ (for KF95 plates) or .890” (for KF152 plates) designed specifically for Vanderbook presses with the galley plate removed. If you put one of these onto your Poco bed with the galley plate still in, you will smash your plates, your type, and your packing.
The Wood Type Factor: Hard packing is great for photopolymer, but it can be unforgiving on antique wood type. If your wood type is bruised or uneven, do not change the whole packing structure. Simply slide one or two thin sheets of soft tissue or newsprint directly under the top tympan sheet to give the wood type a tiny bit of cushion, then slide them right back out when you return to photopolymer.

Using a KF95 photopolymer plate on a custom base built to Standard Boxcar Base dimensions is an ideal setup. The math for your Hacker Poco press lines up perfectly with a universal type-high (.918“) bed workflow. [1, 2]

The Math: Base + Plate Setup

Your Plate (KF95): Measures exactly .037” thick.
Your Base (Standard Boxcar Specs): Machined to .875“ thick.
The Adhesive (Sticky-Back Film): Typically averages .005” to .006“ thick. [3, 4, 5, 6]

Because this combination meets the precise standard height of letterpress lead type (.918”), you will be able to lock up both forms seamlessly on your press bed. [2]

Printing Protocol for the Hacker Poco

Keep the galley plate in your Poco bed for both configurations. [2]

When printing photopolymer: Your custom base will sit on the galley plate. Mount your [KF95 plates](https://www.boxcarpress.com/shop/kf-95-letterpress-plates/) directly to the base.
When printing traditional lead/wood type: Remove the base, and lock your type directly onto the galley plate. [1, 7]

Because both setups resolve to .918“, your cylinder packing can remain completely locked into your calculated .052” thickness setup. You will not need to alter your packing formula when shifting between antique type and modern photopolymer.

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