Double-sided proxy printing that actually lines up

The recommended way: one Duplex PDF

The Duplex PDF (fronts + backs) button sits in the Export block of the sidebar, below the main export button. It writes a single file, proxies_duplex.pdf, with the pages interleaved: sheet 1 fronts, sheet 1 backs, sheet 2 fronts, sheet 2 backs, and so on. Every card contributes its actual back: double-faced cards their real second face, everything else your uploaded custom back or the built-in default card back. Cut guides print on the front pages only - you cut from the front, so the back pages carry no marks of their own.

The back pages are placed mirrored for the flip edge you pick in the selector next to the button. That mirroring is the point of the whole feature: when a sheet turns over its long edge, left and right swap physically; over its short edge, top and bottom swap. The export accounts for that, so each back lands exactly behind its own front - double-faced cards in any column included. On landscape paper the axes swap with the page, and the export handles that too.

• Automatic duplex unit: print proxies_duplex.pdf double-sided at 100% scale ("actual size") and set the driver to the same flip edge as the selector - Long edge flip is the default on both sides for portrait paper.
• Manual two-pass printing: print only the odd pages, re-feed the stack, then print only the even pages onto the same sheets, turning the stack over the edge you picked in the selector.

Your Row Align offsets (calibration below) keep working: in the duplex file they are applied to the back pages only, with the sign you calibrated - the fronts are the reference side and stay put. One honest caveat: a duplex unit feeds paper along a different path than manual re-feeding, so when you switch between the two, run the one-sheet test once more and adjust the offsets if needed.

The manual path: fronts and backs as separate PDFs

The original two-pass workflow is still there and still the right tool for one specific job: printing a stock of uniform back sheets in advance (the backs run prints exactly what the preview shows, nothing is mirrored). Three controls handle it:

Know the limit of this path before you rely on it: the backs PDF places every back at the same position as its front, unmirrored. Flipping the sheet on the long edge physically swaps the left and right columns, so on a 3-column sheet only the middle column can ever line up with its own back - no offset value fixes a column swap. With one uniform back for every card this does not matter at all (any back behind any front is correct, which is exactly why this path suits pre-printed back stocks). But if you have double-faced cards in the left or right column, use the Duplex PDF export above; the manual path cannot align them.

Long-edge vs short-edge flipping

When the sheet turns over for the second pass, it turns around one of its two edges, and that decides which way up the backs come out:

• Long-edge flip: the sheet turns around its long side, like a page in a book. On a portrait A4 card sheet the backs stay upright. This is what you want.
• Short-edge flip: the sheet turns around its short side, like a notepad. On portrait paper the backs come out upside down relative to the fronts.

Card faces are close to symmetric top-to-bottom in position but not in content, so an upside-down back is obvious the moment you sleeve a card. For the portrait A4 sheets Fabricard exports by default, flip on the long edge: if you re-feed the paper by hand, turn the stack over sideways; if your printer duplexes automatically, pick "flip on long edge" in the driver. The Duplex PDF export has a matching selector next to its button - keep the selector, the driver and your hand movement telling the same story, and run the test sheet below before committing a full deck.

Page order and paper feed

1. Print proxies_fronts.pdf first, at 100% scale ("actual size" - never "fit to page", that changes the card size and ruins alignment on both sides).
2. Take the printed stack out and put it back into the paper tray for the second pass.
3. Print proxies_backs.pdf onto the same sheets.

The re-feed step is where most duplex jobs go wrong, because every printer pulls paper differently: some print on the face-up side of the tray, some on the face-down side, and some reverse the page order in the output tray. Find out once instead of guessing: take a scrap sheet, draw an arrow on it pointing away from you, feed it, and note which side got printed and where the arrow ended up. Also keep multi-page jobs in order - if your printer stacks output face up, the pages come out in reverse and you need to restore the order before re-feeding, or the backs of page 1 will land on the fronts of page 2.

The one-sheet test: measure before you print the deck

Never calibrate on a full deck. One sheet tells you everything:

1. Load your deck, leave Cut Guides switched on (they are on by default) - the corner marks are your measuring reference.
2. With the duplex file: print pages 1-2 of proxies_duplex.pdf double-sided (or page 1, re-feed, page 2 by hand). With the manual path: print page 1 only of the fronts, re-feed that single sheet, then print page 1 only of the backs.
3. Hold the sheet against a bright light or window, back side toward you, and look at how the back images sit relative to the fronts shining through.
4. Measure the shift with a ruler, in millimeters, separately for horizontal and vertical - and check the top row and the bottom row separately, because many printers drift more toward the end of the page than at the start.

A shift of up to 3 mm is normal for home printers. It is also exactly what the next section corrects.

Fixing a 1-3 mm shift: Row Align

The Row Align block in the sidebar has six number fields: rows R1, R2 and R3 (top, middle, bottom row of the sheet), each with an X and a Y field. Values are millimeters, from -4 to +4 in 0.1 mm steps, and they nudge that row of cards in the export:

• Positive X moves the row to the right, negative X to the left - as seen on the printed back side of the sheet.
• Positive Y moves the row down, negative Y up.

So if your test sheet shows the backs sitting 1.5 mm too far left and 0.5 mm too high (looking at the back side), enter X = 1.5 and Y = 0.5. If only the bottom row is off, correct only R3 - per-row fields exist precisely because drift often grows down the page. Reset offsets under the block sets all six fields back to zero.

One thing to know: in the classic exports the offsets apply to whatever you export while they are set. They are meant for the backs run, so keep them at zero when you export the fronts; the preset buttons in the next section make that a two-click routine. The Duplex PDF export handles this by itself: inside the duplex file the offsets shift only the back pages, the front pages stay at their reference positions.

Re-run the single test sheet after entering values. Two test sheets is the normal total; a stubborn printer might need a third.

Save it once: presets, and when to re-calibrate

Next to Row Align sits the Presets block with a Front and a Back column, each with a Save and a Load button. A preset stores the full layout state: paper format, card gap, bleed, all cut guide settings and all six row offsets. The routine:

1. With offsets at zero and your layout dialed in, click Save under Front.
2. After calibrating the back offsets, click Save under Back.
3. From then on: Load Front, export fronts, Load Back, flip backs, export backs. Done.

Preset-driven duplex offsets: for the one-file route you can skip even the Load clicks. Save your calibration once per side as above, then switch on "Apply presets on duplex export" under the preset buttons. Every duplex PDF now applies the right offsets to the right pages automatically: front pages take the Front preset, back pages take the Back preset, mirrored and per printed row. While the toggle is on, the live offset fields are ignored for the duplex file, and a preset you never saved counts as zero offsets. The tool shows in green which preset matches the current fields.

The calibration belongs to a specific combination of printer and paper. Re-run the one-sheet test when anything in that combination changes: a new printer, a different paper weight or brand, sometimes even a driver update. Presets live in your browser's local storage, like everything else in Fabricard - nothing is uploaded anywhere.

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